Three Bolts: Mk 4 Roadster Build

[carbon-12]

In addition to the custom parts I plan to include in my build, I also plan to upgrade to a hydraulic clutch. Since I ordered a Mk4 Roadster complete kit, I have the Wilwood pedal box, which is configured for three master cylinders. This makes adding a hydraulic clutch a reasonably simple upgrade, at least as far as the pedals go.

Since I've been help up a little on the work on the front end and rear end of my kit, I moved ahead in the assembly manual, which brought me to pedal box installation. Yesterday, as I started in on this work, I began to think about the master cylinder side of the hydraulic clutch.

This presents a little puzzle. Here are the givens:

- My slave cylinder has a bore of 0.7".
- The recommendation is for the slave to move the throw-out bearing 1.2".
- I want to get a Wilwood master cylinder, since it will bolt in to the pedal box which came with my kit.

The Wilwood Compact Remote Reservoir Master Cylinder looks just like the ones which come with the kit (to work the brakes). This model comes in four sizes: 5/8", 0.70", 0.75", and 13/16". Which is the correct size to get?

The seemingly obvious answer is 0.7", to match the slave, but is that right? Since the master needs to push to slave 1.2", it needs sufficient fluid capacity to move the piston in the slave that distance. Which of the four Willwood masters can do this? I did some some geometry to find out.

First, I calculated the area of a circle whose diameter is the cylinder bore. Since the formula for the area of a circle uses doesn't use the diameter (which equals the bore), but its radius, the bore needs to be cut in half before multiplying it by pi. Then, I multiplied this by the stroke to get the volume of a cylinder with that bore.

volume = (bore * 0.5) x π * stroke

The detail pages for the Wilwood master cylinders bear out this math. Here are the numbers they give for the 5/8" master cylinder:

Bore	Area	Stroke	Volume
5/8" (0.625")	0.31 sq. in.	1.4"	0.43 cu. in.

Since 5/8" equals 0.625, and half that is 0.3125. The area is 0.3068, which Wilwood rounds up to 0.31. It's confusing that this turns out to be nearly the same as the radius, but well… math.

0.3068 = (0.625 * 0.5) x π * 1.4

Here are the calculations for all the cylinders, slave plus the four masters.

Cylinder	Bore	Area (sq. in.)	Stroke	Volume (cu. in.)
Slave	0.70"	0.3848	1.2"	0.4618
Willwood 260-6087	0.625" (5/8")	0.3068	1.4"	0.4295
Willwood 260-6088	0.70"	0.3848	1.4"	0.5388
Willwood 260-6089	0.75" (3/4")	0.4418	1.4"	0.6185
Wilwood 260-11972	0.8125" (13/16")	0.5185	1.4"	0.7259

Since the master must push enough hydraulic fluid to move the slave 1.2", it must have at least 0.4618 cubic inches of fluid capacity. As you can see, all but the 5/8" Wilwood master cylinder has sufficient capacity.

In the end, since the question of pedal feel and pedal box geometry figures in as well, I bought both the 0.70" and 3/4" Willwood master cylinders. I'll probably install and test each of them. That will require an extra bleed of the hydraulic line, but I'm curious which will work better, and which I'll like more.

[carbon-12]

When I attended the Factory Five Racing Build School this past December, I took down many pages of notes detailing the tips and tricks the teachers shared with us. One of these notes was: “Upgrade brake pads”. I remember jotting this down as the teachers were speaking to us, and their main message was that there were few things you could do in your build that would be as inexpensive, as easy to do, and would have as big an overall effect on the performance of the car on the road.

So, while getting better brake pads provides a great bang for the buck, and is a simple upgrade to make, there is one complication—getting the right size pads.

On my kit, I plan to run 15" tires since I love the look, and I chose the FIA Pin Drive Wheel Set to go with them. To match up with these wheels and tires, I have the 11.65" IRS Brake package and the Pin Drive IRS from Factory Five. In the fronts, I have the brakes which came as stock with the complete kit.

The pads which shipped to me in my kit are Wagner Thermo Quiet, model MX804 for the fronts, and model PD627A for the rears. I suppose the internet could have converted these numbers into information I could use to buy compatible alternatives.

I did something even simpler. I called . The fellow on the phone said that a 2000 Ford Mustang GT uses the same front brakes as I have, and a 1999–2004 Ford Mustang Corba uses the same size as my rears.

Now that I knew the correct size, now I needed to choose the replacement pads themselves. Fortunately, there's a wealth of information available online, both in forums, and on vendor websites. I didn't see one option stand clear of all the rest, so I went with EBC Red Stuff, since they've received decent overall feedback. I got model DP31242C for the fronts, and DP31156-2C for the rears.

I still was a bit worried that they would be the same size, but as you can see, my concerns were unfounded. Both the fronts and rears look like perfect matches.

front-brake-pads.pngrear-brake-pads.png

[edwardb]

In addition to the custom parts I plan to include in my build, I also plan to upgrade to a hydraulic clutch. Since I ordered a Mk4 Roadster complete kit, I have the Wilwood pedal box, which is configured for three master cylinders. This makes adding a hydraulic clutch a reasonably simple upgrade, at least as far as the pedals go.

In the end, since the question of pedal feel and pedal box geometry figures in as well, I bought both the 0.70" and 3/4" Willwood master cylinders. I'll probably install and test each of them. That will require an extra bleed of the hydraulic line, but I'm curious which will work better, and which I'll like more.

The Wilwood MC's you purchased are likely undersized. Math is interesting (and I'm a technical person myself) but there are a lot of variables. Here's a proven combination that is demonstrated to work with the Wilwood pedal box: Wilwood 1-1/8 inch MC and CNC 7/8 inch slave push cylinder. Mike Forte, who has sold probably as many setups for this as anyone, recommended this to me as the most current successful setup, and I can verify it works. Attached at the clutch fork cable location, gives exactly 1.2 inches of travel. I just set it up in my Mk4 a few weeks ago. Don't recall what transmission you're using, but Forte's sells all the parts for T5 or TKO's. This link in my build thread has pictures of the clutch fork end, and a video of how it works with this combination. http://thefactoryfiveforum.com/showt...l=1#post134526

I too mocked up the setup with the engine/clutch/trans outside the chassis before installing. Fortunately there were no surprises as evidenced by the video. It was worth it to make sure I wasn't going to take the engine back out to change or adjust things. Having said that, once you introduce brake fluid into the system, and then take it apart and back together repeatedly, it's nearly impossible to keep brake fluid from getting all over things. And that stuff is destructive. Do your best to keep the mock-up and trials to a minimum IMHO.

Update: Took the time this AM to review your build log site (Sorry find it a little confusing with information in two locations) and see that you have chosen a T5 and purchased a slave cylinder setup already. The information I provided above may not be of too much value based on where you're at now. But having a description and view of a successful setup hopefully will be helpful for you. Good luck with your build.

[carbon-12]

The Wilwood MC's you purchased are likely undersized. Math is interesting (and I'm a technical person myself) but there are a lot of variables. Here's a proven combination that is demonstrated to work with the Wilwood pedal box: Wilwood 1-1/8 inch MC and CNC 7/8 inch slave push cylinder. Mike Forte, who has sold probably as many setups for this as anyone, recommended this to me as the most current successful setup, and I can verify it works. Attached at the clutch fork cable location, gives exactly 1.2 inches of travel. I just set it up in my Mk4 a few weeks ago. Don't recall what transmission you're using, but Forte's sells all the parts for T5 or TKO's. This link in my build thread has pictures of the clutch fork end, and a video of how it works with this combination. http://thefactoryfiveforum.com/showt...l=1#post134526

I too mocked up the setup with the engine/clutch/trans outside the chassis before installing. Fortunately there were no surprises as evidenced by the video. It was worth it to make sure I wasn't going to take the engine back out to change or adjust things. Having said that, once you introduce brake fluid into the system, and then take it apart and back together repeatedly, it's nearly impossible to keep brake fluid from getting all over things. And that stuff is destructive. Do your best to keep the mock-up and trials to a minimum IMHO.

Update: Took the time this AM to review your build log site (Sorry find it a little confusing with information in two locations) and see that you have chosen a T5 and purchased a slave cylinder setup already. The information I provided above may not be of too much value based on where you're at now. But having a description and view of a successful setup hopefully will be helpful for you. Good luck with your build.

For my clutch setup, I used a vendor who is not a forum supporter, and so I didn't mention him here. That's against the forum policy, and I don't want to break the rules. That explains the difference between my post here, and the one on my external site. I apologize for the confusion.

As for the setup itself, I believe in math. There's no arguing with it when you feed in all the correct inputs, but I completely understand that my simple equations may be too simple to accurately model the system. I am prepared to make adjustments and buy new parts if that's what it takes to make everything work. Recently, I contacted Mike Forte to source some parts for my IRS, so if I need to call a do-over, I know I can turn to him to get this hydraulic clutch worked out.

Thanks for the advice about the brake fluid, too. Generally, I like running as many tests as I can. It's good to know that I should probably skip the tinkering once I add the fluid.

I appreciate your help. Good luck with your build!

[David Hodgkins]

Ken, there is no rule against mentioning non-vendors as part of your build thread. There is a rule against using members to repeatedly push products while not being a vendor(read about it here), but I wouldn't worry about that.

Please, feel free to discuss everything you are doing as part of the build.

[edwardb]

Ken, there is no rule against mentioning non-vendors as part of your build thread. There is a rule against using members to repeatedly push products while not being a vendor, but I wouldn't worry about that. Please, feel free to discuss everything you doing as part of the build.

Thank you. I was just looking for the forum rules to get the specific language. I was 99.9% sure this was the case, because I mention non-forum vendors in my build log and it's never been a problem. But certainly none of them are asking me to. I just do it as info for other builders.

As for the setup itself, I believe in math. There's no arguing with it when you feed in all the correct inputs, but I completely understand that my simple equations may be too simple to accurately model the system. I am prepared to make adjustments and buy new parts if that's what it takes to make everything work. Recently, I contacted Mike Forte to source some parts for my IRS, so if I need to call a do-over, I know I can turn to him to get this hydraulic clutch worked out.

I believe in math too. (I was a math major...) My point was only that all the math in the world is nice but in this case there is already a well proven setup and you could easily burn through a lot of time and money to get back to the same place. You have to decide what fits your build, but the experiences of others are one of the huge advantages of this forum. FWIW.

[carbon-12]

Ken, there is no rule against mentioning non-vendors as part of your build thread. There is a rule against using members to repeatedly push products while not being a vendor(read about it here), but I wouldn't worry about that.

Please, feel free to discuss everything you are doing as part of the build.

Thanks for the guidance. Given the way I started off in this thread, I figured I'd tread very lightly for a bit.

[carbon-12]

Thank you. I was just looking for the forum rules to get the specific language. I was 99.9% sure this was the case, because I mention non-forum vendors in my build log and it's never been a problem. But certainly none of them are asking me to. I just do it as info for other builders.



I believe in math too. (I was a math major...) My point was only that all the math in the world is nice but in this case there is already a well proven setup and you could easily burn through a lot of time and money to get back to the same place. You have to decide what fits your build, but the experiences of others are one of the huge advantages of this forum. FWIW.

Yep. I see your point. I already got started down the path I'm on before I started using this forum, and so I didn't have the advantage of the experience you all have gathered up over time. I haven't yet sunk a lot of time and money in my effort to get my clutch working, and I won't. I wouldn't mind too much if I'm able to discover another path to a working system, since I think that would benefit everyone, but at the same time, I don't want this upgrade attempt to get out of control. As I look at it, I'm building a whole car, not a hydraulic clutch.

As for math, I use numbers all day long in my job as a computer programmer, but I last studied math as a separate discipline in the 1980s, when I was in the 11th grade. So, I'm just glad you didn't correct my calculations. You still can if you see any mistakes. I have a thick skin. :-)

Thanks again for your advice.

[bansheekev]

Another vote for the 1 1/8" Wilwood combination master (which is a different style from Wilwood - not the compact master supplied with the complete kit) and 7/8" CNC setup from Forte. I installed mine a month ago and it worked perfect from the get to. I didn't even mock it up outside the car as the drivetrain was already in the car. Didn't matter, worked exactly as expected. I go-karted the car over the weekend and the clutch pedal throw and feel is exactlly what I wanted. The pedal travel is about 4.5" (with a stop at the bottom of the pedal throw to prevent overextending the slave) and the clutch fork travel is 1.2".

I had done a ton of reading and talking with people about it and this setup is definately the sweet spot. Some have used slightly smaller masters (1" for instance) but the pedal travel needs to be longer (6" +) and it is on the edge of not getting enough slave travel. Reason for mentioning this is that the 1 1/8" master with its shorter throw allows me to set the pedal height further away from me (same height as the brake pedal) which gives me a lot more legroom (i.e. comfort).

Just my $.02

Kevin

[2bking]

Ken,

The math is good and will tell the travel of the slave vs mc which is about all you need to know. The important rule is to not have such a large mc so as to force the slave piston out of the bore. Hopefully the slave has a little more than 1.2 inches of travel so the mc needs to be just large enough to get the 1.2 inches in the slave. This will give the least pedal effort. If you go bigger in the mc, the pedal effort will be higher and clutch movement will be faster (think full release at mid travel of the clutch pedal). Depending on available travel in the slave, you may force the slave piston out of it bore or get hydraulic lock when the piston hits a retainer. If the hydraulic lock occurs, the pedal will not go full travel to the floor.

[carbon-12]

Ken,

The math is good and will tell the travel of the slave vs mc which is about all you need to know. The important rule is to not have such a large mc so as to force the slave piston out of the bore. Hopefully the slave has a little more than 1.2 inches of travel so the mc needs to be just large enough to get the 1.2 inches in the slave. This will give the least pedal effort. If you go bigger in the mc, the pedal effort will be higher and clutch movement will be faster (think full release at mid travel of the clutch pedal). Depending on available travel in the slave, you may force the slave piston out of it bore or get hydraulic lock when the piston hits a retainer. If the hydraulic lock occurs, the pedal will not go full travel to the floor.

Thanks for the help. I'll post an update when I have the clutch hooked up and (hopefully) working.

[carbon-12]

In my work as a computer programmer, I often need to think about problems at several different levels of abstraction. At the highest level, I'm writing a complete program to accomplish a certain set of goals. At progressively deeper levels, there are typically:

• Frameworks, where each is a large collection of many classes.
• Classes, where each is a collection of methods which, taken together, implement a specific feature or job.
• Methods, where each contributes to the overall feature or job of the class.
• Lines of code, where each implements a step of a method algorithm.

This certainly isn't the only way programs can be broken down, and this heirarchy describes the kind of code I write (end-user applications) in the language I typically write in (Objective-C). These details don't matter, nor does the terminology or technology.

However, the levels of abstraction do matter. When I'm writing code, I usually am focused on a particular one of these levels, but that doesn't mean I can forget about all the rest. The process of writing a program means repeatedly moving up and down this heirarchy to make sure that all levels are done right, and each relates well to its neighbors.

This works well for me in my job, and I'm trying to apply the same kind of heirarchical thinking to my Roadster build. After I took delivery of my kit and started taking inventory, I was overwhelmed by the sheer number of parts and the random order in which they appeared. As I started in on the few steps in the assembly manual, I struggled just to find all the parts I needed to begin work.

It's taken about a month, but I'm getting more comfortable with thinking about my kit in terms of subsystems. Tonight, I began to sketch out a diagram which organizes the project into the major parts which make up the whole car. It's not complete (or even correct) yet, but it's a start.

kit-subsystems-v02.png

[DaleG]

"The pedal travel is about 4.5" (with a stop at the bottom of the pedal throw to prevent overextending the slave) and the clutch fork travel is 1.2"."

Unclear what you mean by a "stop"; how is it installed?

[MPTech]

VERY logical!

Get accustomed to spaghetti code, you'll be less stressed! LOL

The Build Manual can help guide some of this too. You will also need to be cognizant of sequence, especially when you start riveting panels and installing for the final build.

I started keeping a Punch List of things I wanted to do and update it FREQUENTLY.
My first page was things I wanted to do that weekend or within the next week or so (immediate term items). I checked them off, or added to them after every build session and kept a printed copy on my desk at work so I could jot down notes as they popped into my head or on the drive into the office.
and the following pages (yes 3 or 4 pages of items) were things I thought of that I wanted to document so I didn't forget or remember after a point of no-return. These items were broken down by areas like you identified: engine, interior, wheels, wiring, trunk, exterior, and NEED to PURCHASE, etc.

[carbon-12]

VERY logical!

Get accustomed to spaghetti code, you'll be less stressed! LOL

Heh. Your advice reminds me of this gem: “I love hitting myself in the head with a brick, because it feels so good when it stops.”

The Build Manual can help guide some of this too. You will also need to be cognizant of sequence, especially when you start riveting panels and installing for the final build.

I started keeping a Punch List of things I wanted to do and update it FREQUENTLY.
My first page was things I wanted to do that weekend or within the next week or so (immediate term items). I checked them off, or added to them after every build session and kept a printed copy on my desk at work so I could jot down notes as they popped into my head or on the drive into the office.
and the following pages (yes 3 or 4 pages of items) were things I thought of that I wanted to document so I didn't forget or remember after a point of no-return. These items were broken down by areas like you identified: engine, interior, wheels, wiring, trunk, exterior, and NEED to PURCHASE, etc.

I like the idea of making a list associated with each subsystem. “NEED to PURCHASE” is a great addition, too. I'll give this a try over the weekend.

[mike w]

In my work as a computer programmer, I often need to think about problems at several different levels of abstraction. At the highest level, I'm writing a complete program to accomplish a certain set of goals. At progressively deeper levels, there are typically:

• Frameworks, where each is a large collection of many classes.
• Classes, where each is a collection of methods which, taken together, implement a specific feature or job.
• Methods, where each contributes to the overall feature or job of the class.
• Lines of code, where each implements a step of a method algorithm.

This certainly isn't the only way programs can be broken down, and this heirarchy describes the kind of code I write (end-user applications) in the language I typically write in (Objective-C). These details don't matter, nor does the terminology or technology.

However, the levels of abstraction do matter. When I'm writing code, I usually am focused on a particular one of these levels, but that doesn't mean I can forget about all the rest. The process of writing a program means repeatedly moving up and down this heirarchy to make sure that all levels are done right, and each relates well to its neighbors.

This works well for me in my job, and I'm trying to apply the same kind of heirarchical thinking to my Roadster build. After I took delivery of my kit and started taking inventory, I was overwhelmed by the sheer number of parts and the random order in which they appeared. As I started in on the few steps in the assembly manual, I struggled just to find all the parts I needed to begin work.

It's taken about a month, but I'm getting more comfortable with thinking about my kit in terms of subsystems. Tonight, I began to sketch out a diagram which organizes the project into the major parts which make up the whole car. It's not complete (or even correct) yet, but it's a start.

kit-subsystems-v02.png

As a project engineer managing multi-million dollar projects with hundreds, if not thousands of tasks, I too use the WBS (work breakdown structure) method to catagorize and link the tacks. It helps the mind breakdown a large project into sub-projects that can be well understood, managed and scheduled. I like the way you think!

[carbon-12]

As a project engineer managing multi-million dollar projects with hundreds, if not thousands of tasks, I too use the WBS (work breakdown structure) method to catagorize and link the tacks. It helps the mind breakdown a large project into sub-projects that can be well understood, managed and scheduled. I like the way you think!

Fortunately, I don't have multiple millions of dollars at risk on my kit build.

[carbon-12]

I make mistakes. Even though I try to work deliberately, and plan ahead carefully, and consult the accumulated wisdom available online, I still make plenty of mistakes. While it's great when a task goes smoothly, and I can move on to the next without trouble, many times I need to patch up some small bit of bungling before a job is done. Maybe more experienced builders don't have so much trouble, but for me, fixing mistakes is a big part of the kit-building process.

Earlier this week when I was assembling the pedal box, I got most everything together, and it came time to tighten down the bolts as it says in the assembly manual. Since I'm upgrading to a hydraulic clutch, I have a third master cylinder on top of my pedal box. As I put on the wrench to tighten down the two bolts holding on the clutch master cylinder, I stripped a bolt.

This was a bit careless of me, but as I thought it over, I decided that I shouldn't feel too bad. The studs coming out from the pedal box don't protrude too far past the mount for the master cylinder, and there isn't much room to get the bolt started before it starts to get tight. Still, I should have been more careful.

Obviously, I needed to fix this up. My first idea was to try a different bolt on the stripped stud. If the threads were not too badly damaged, it's possible that a good bolt could set things right. Unfortunately, this didn't work.

My next idea was to use a tap and die to clean up the threads. In the past, I've had some success with using light pressure with these cutting tools to repair stripped threads. Since I didn't have my own set, I went to Amazon.com and bought this GearWrench 82812 114 Piece Large Combination Tap and Die Set.

tap-and-die-set.jpg

Last night, I gave the new set a try. Since I wasn't intended to cut new threads, but just repair existing ones, I experimented to find the right size tap and die for the bolt and stud to match the threads already there. With the die, I didn't even need to fit the handle—turning the die by hand was enough. The bolt needed a bit more persuasion.

die.jpg tap.jpg

Both repairs worked great. In a half-hour, everything was fixed up.

It felt bad to make the mistake of stripping the bolt in the first place, but it felt better to work through the problem and find a relatively simple fix up.

[carbon-12]

A few days ago, I received the wayward castle nut I needed from Factory Five to continue work on the front suspension of my Roadster kit. I pressed on, but eventually, I decided that the upper control arms just didn't look right. After I had them mounted up, put together the rest of the front suspension, and added on the brakes, I decided that I had gone wrong somewhere. This was a vague notion, since I've never done this kind of work on a car suspension before but, I felt confident that I had made a mistake. I decided to go back over the manual, look at some pictures on the forums, and see if I could figure out what the variables were that I failed to get right.

ball-joint-angled-wrong.jpg

I'm reasonably sure I had the control arms upside-down. Even though I tried to be careful, I didn't know what I was looking for when I was reading the assembly manual, so I missed a key detail. This led me to mount the ball joints in the wrong side of the control arms, which caused the ball joing to be angled severely once I bolted the control arm to the spindle.

It's difficult to describe in words, but here goes: the low portion of the angled control arm should be on top and facing in toward the chassis. The ball joint should be screwed in from that side. Maybe this picture will help to illustrate the point.

correct-uca-side-up.png

The fix was easy, if a bit time-comsuming. I unmounted the control arms, unscrewed the ball joints, flipped the control arms, and screwed the ball joints back in. I'm still in the process of putting everything back together, but I'm pretty sure that I got it right this time. If anybody smarter knows better (that probably means you!), please say the word.

[Jeff Kleiner]

As shown in your photo the entire UCA assembly is upside down with the ball joint screwed in from the wrong direction:



You've already identified the error with the ball joint angle but also be aware that the crossbar links (red arrow) should have the offset to the top of the bar rather than below. When everything is oriented properly the ball joints will angle outward as shown in your "driver's side" photo, the fixed/welded leg of the ball joint plate will be on the forward end on the driver's side and on the rearward end on the passenger side and the grease fittings on the crossbar links will point up.

Carry on and good luck!

Jeff

[carbon-12]

Thanks for the additional help. I plan to get everything put back together this evening. I'll make sure the fixed/welded legs are oriented as you say. Thanks again!

[carbon-12]

I needed to work through some mistakes on my front suspension, but I think I finally put together correctly this afternoon. I intended to do this work two days ago, on Thursday night, but as I was going over the parts getting them ready for reassembly, I noticed that I had somehow opened a gash one of the ball joint boots.

gash-in-ball-joint-boot.jpg

This wasn't a major setback, but it delayed me for a couple of days as I ordered replacements. I went out on the forums to see what the collected wisdom had to say about ball joint boots. I found recommendations for Energy Suspension ball joint boots, and since they're inexpensive, I ordered some for both the upper and lower boots.

The part numbers are as follows:

- Lower ball joint boots: Energy Suspension 5.13102
- Upper ball joint boots: Energy Suspension 9.13130

Both products come in G (black) and R (red) variants, so the specific parts I ordered were 5.13102G and 9.13130G. They come with two in a box, so one box is enough. They seem to fit better than the parts which came with the kit. I'm happy with them.

passenger-side-front-suspension.jpg

With the new boots in hand, I reassembled the front suspension. The ball joint hanging down from the upper control arm looks much better now. As you can see, I also had a helpful tip from Jeff Kleiner. The key point is to note that “the fixed/welded leg of the ball joint plate will be on the forward end on the driver's side and on the rearward end on the passenger side and the grease fittings on the crossbar links will point up”. I made sure to get that right as well.

[carbon-12]

One of the most surprising aspects of building my Roadster kit has been the discovery that each and every step presents problems to solve. While I haven't damaged any parts, or made any expensive errors, or injured myself seriously, nor have I sailed through a set of pages in the assembly manual without hitting some roadblock which caused me stop, think long and hard about how to proceed, look on the forums for help, or jump into the car to go to Home Depot. This kit is not a jigsaw puzzle or Lego set. Finding the right part is not the key to moving on. Everything takes more work than that.

This weekend has provided adequate proof for that assertion, in the form of several little snags which slowed progress on my pin drive independent rear suspension (IRS) installation.

First, I needed to get the differential (the “pumpkin”) installed in the chassis. I tried several different angles to no avail. Then I found some advice, which said to start by placing the pumpkin pointing upwards on a jack, and alternate a few times between raising the pumpkin, angling it forward, and twisting it to fit through the opening. I got it seated in five minutes.

pumpkin.jpg

[Secondly, I was unsure about the orientation of the lower control arms. Coming fresh off my experience with an upside-down installation of the ball joint on the upper control arms for the front suspension, I wanted to make sure I didn't make a similar mistake on the rear. The lower control arms for the IRS have one straight and one angled side. They also have bosses for the spindles and the shock. The manual is very clear that the boss for the shock should go down, but it says nothing about the orientation of the sides. I stared at this for a few minutes—and was briefly confused since I mistook the mount for the upper control arm as the mount for the shock—but it all became clear when I figured out that the CV axle would only have the space to come out of the differential if the straight side of the lower control arm went toward the front of the car.

IRS-lower-control-arm.jpg

Thirdly, I had trouble with the spacers for the shocks themselves. The long spacer was simply too long. Even though I decided to go with the body side down for the shocks, there wasn't enough nearly clearance for the top of the shock cylinder—it collided with the mounting boss. I calculated that I would need to shave off about a quarter of an inch to make a decent fit, and since I don't have any tools in my garage to make such a cut, I headed off to the TechShop this morning.

long-spacer-too-long.jpg

I figured I would use a grinding wheel, but after a couple minutes of trying that and making very little progress, one of the other fellows working in the shop noticed what I was doing, and offered to help. He was working on the lathe, and came into the grinding room to debur a part he was working on. He said that he would be happy to take them down to the size I needed. This was a wonderfully generous gesture, and within fifteen minutes—and after saying many thanks—I was back in the grinding room deburring my two spacers.

spacers-shortened.jpg

Next, came the task of inserting the CV axles into the differential. As I slid them in, I noticed they would not go in all the way. The splines seemed to mesh, at least partially, but the C-clip on the end of the shaft stopped it from going further. I did some measuring, and looking with a flashlight, and momentarily wondered if the number of splines on the shaft matched those inside the differential. I counted twenty-eight splines on the shaft, and found the order form from Mike Forte. It showed that the differential also had twenty-eight splines. Since that wasn't the problem, I went to my computer and searched the forums some more. I found some advice, which said that, indeed the shafts install with the C-clips in place, and all that's required is “a little shove”. I went back out into the garage, backed out the shaft a little bit, forced it forward in a battering ram motion, and it easily clicked into place. It seems silly that this problem had such an easy solution, but since I have never put together an IRS before, there was no way for me to know.

The final problem of the day has no easy solution—at least there isn't one today. I didn't know that inserting the hub into the IRS spindle/knuckle was going to require any special work, but it does. These parts fit together with a very tight tolerance of just a couple thousandths of an inch, and there's no way I can do the work in my garage with the tools I have. I need to find a shop to do the work, and I think I already have a lead. When I had my Lotus in for some service last week at Dietsch Werks, I chatted with Rob Dietsch when I picked up the car. I mentioned my Factory Five project, and he offered to help me if I needed anything. I already knew that I would have to find some professional help to get the alignment done right, and he said he could do that for me. I'm going to contact him tomorrow to see if he can help get these hubs pressed into the spindle. I'm confident that even if he can't help me himself, he'll know who can.

spindles-and-hubs.jpg

In all, I think I made good progress over the weekend. If I can get this hub and spindle situation resolved over the next few days, I think I can get the IRS installation finished up by next weekend.

[2bking]

The final problem of the day has no easy solution—at least there isn't one today. I didn't know that inserting the hub into the IRS spindle/knuckle was going to require any special work, but it does.

I didn't need anything special except a 36mm socket. Start the axle shaft through the knuckle and put the hub on from the outside. The axle is long enough to start the axle nut and it will pull the hub and axle together in the bearing. The 36 mm socket fits the rear axle nut and front spindle nut.

[carbon-12]

I didn't need anything special except a 36mm socket. Start the axle shaft through the knuckle and put the hub on from the outside. The axle is long enough to start the axle nut and it will pull the hub and axle together in the bearing. The 36 mm socket fits the rear axle nut and front spindle nut.

I am not an expert in this area, and maybe you are, and maybe I'm fretting needlessly over this task. However, it seems to me that your approach is a variation on the “threaded rod” technique, and this Google search (search terms: “threaded rod irs hub”) shows that some experts question whether this results in a hub which is seated properly. This Google search (search terms: “20 ton press irs hub”) shows others think that most of the force of a 20-ton hydraulic press is needed to seat the hub correctly.

Maybe your hubs and spindles are different from mine, and maybe theirs are different from both of ours. Perhaps it's not possible to make blanket statements about proper technique. I don't know. Does anyone else have an opinion or experiences to share?

[carbon-12]

I called my Lotus garage today, and they said they could press in the hubs. It's a neat place to visit. They always have a lot of cool cars around. I'm going to have them do it. I'll post pics when the work is done.

[carbon-12]

While I intend to do most of the work on my Roadster kit by myself, there are some jobs I'll leave to outside professionals. These jobs fall into two categories:

1. Things I consider too difficult to do. This includes building an engine—I bought a package from The Engine Factory. I don't think I'll be able to get the front or rear alignment just right—I'll probably use Dietsch Werks, my Lotus shop. Someday, this will also include painting the car—I don't have a contractor lined up yet.
2. Things I consider too dangerous to do. This includes anything related to safety, where a failure could quickly lead injury or worse. For example, while I've already assembled the front brakes, and I hope to get to the rear this coming weekend, I won't drive the car on the road until I've had them checked by an expert.

This past weekend, I discovered a new work item in the second category: pressing the hubs into the spindles for my independent rear suspension (IRS). I didn't know that getting the hubs and spindles together would be any more difficult than the fronts, but it's a bigger job. The two parts are a press fit, where the tolerances are very close—within a few thousandths of an inch. Some of the builders I've seen on the forums figured out ways to do the work themselves (with either a threaded rod or a home hydraulic press), but I read comments which gave me pause.

Since a failure of this fit could cause a rear wheel to fall off, I decided I would feel better to let experienced mechanics do the work. Enter Dietsch Werks again. I took the four parts over to them on Tuesday afternoon, and they were ready that evening. They charged me for fifteen minutes of labor. I consider this a great deal, and it gives me confident that the job was done right.

This post shows a picture of what the hubs and spindles looked like before I sent them out. Here are a couple pictures once I got them back from the shop.

[carbon-12]

I mounted the rear wheels and tires for the first time this evening.

wheels-on.jpg

I had been hoping to get the car off the jack stands and standing on all four wheels over the weekend which just finished up, but I ran into a little problem. The nut for the rear axle takes a 36mm socket. The fronts also have a 36mm nut, and I didn't have a socket that large when I was putting that end together a couple of weeks ago, so I stopped working, got into the car, drove the Sears, and bought a socket. I figured I was set.

Unfortunately, the rears screw on much further than the fronts, and the socket I bought wasn't very deep, so the threaded rod at the end of the rear axle bottomed out before I could get the nut all the way on.

I discovered this two days ago on Saturday, but I was busy in the evening, so I just ordered a deeper socket from Amazon. It arrived tonight. With it in hand, it was easy to turn it on far enough to hold the axle and spindle in place (I'll torque it down to spec later on, once I'm sure I have everything right).

36mm-sockets.jpg

I went for the pin drive adapter and pin nuts next, and here I discovered the next problem. The directions for my wheels say that the studs should only have
5/8" exposure for the pin nuts, otherwise the tightening tool for the pin nuts won't have enough grip to torque the nuts to 60 ft-lbs. Sure enough, my studs are about 1/4" too long.

studs-too-long.jpg

I continue to be amazed how, at every step, something doesn't fit as it came in the kit. Everything must be made to fit. I guess I'm starting to expect it, so even discovering that I'll very likely have some stud-cutting in my near future, it couldn't dampen my spirits—I really liked seeing the wheels and tires on the car.

[MPTech]

Ken, you're really moving along on your progress, getting the wheels / tires on and dropping it on the ground is a rewarding milestone.
Congrats on the Roller! Just wondering, do you have a theme in mind with the wheels you're running? I like them.

Don't get discouraged, there will always be challenges with the build. Hey, if it was easy, everybody would have one.
I can tell you that you will forget all the setbacks the first time you drive it and someone is totally impressed that YOU BUILT IT YOURSELF!

[David Hodgkins]

I think everyone that has built one of these cars ends up with that deep well socket in their tool set...

Also, everyone who builds these cars at some point realizes it's a bit more than simply "tab A into slot B" and that light fabrication is part of the process. I've never had to do any welding but "gently massaging" panels to deal with welds and making them fit together precisely is a bit of an art.

I've always looked at the build as the fun part of the process. Tinkering on the build is cathartic. Have fun with it and look at it as a hobby and the build will go a lot smoother.

You're making good progress!

[jrichards]

The term cathartic is the perfect term. Not everyone understands why working through challenges and turning a wrench can be relaxing. For me it is very relaxing after a stressful week at the office.

Ken - please keep making mistakes and posting them on your website! But for your post on the UCR's being upside down, I may have made the same mistake. Your website is great Keep up the work and thanks for posting your progress.

[carbon-12]

Thanks for the moral support, everyone.

I thought I would run into some complications at the start of the project, due to both my lack of experience with the kit, and with mechanical projects of this magnitude. I figured that once I got into the work, things would smooth out a bit, and there wouldn't be issues to overcome at every step.

Since that doesn't seem to be the case, and since you're all telling me that it's correct to be that way, I'll just adjust my expectations. That's OK. I haven't run into anything which completely stymied me yet, and if I do, I know where to ask my questions.

Besides, I just got back from Home Depot with my new Makita 18-Volt LXT Lithium-Ion Cordless Reciprocating Saw. Talk about catharsis!

I'm going to see if I can use the new saw to cut down those wheel studs. I'll post pictures after I do the work.

Thanks again for the encouragement!

[David Hodgkins]

Make sure you put the Lugnuts on before you cut the threads. Tthat way the Lugnuts will act as a die when you take them off after the cut. You also may want to file the ends before removing the nuts.

[carbon-12]

Make sure you put the Lugnuts on before you cut the threads. Tthat way the Lugnuts will act as a die when you take them off after the cut. You also may want to file the ends before removing the nuts.

Will do. I think I may have an actual die which is the right size. I'll check in the tap and die set I described in post #98 in this thread.

Thanks for the advice!

[Jeff Kleiner]

...I just got back from Home Depot with my new Makita 18-Volt LXT Lithium-Ion Cordless Reciprocating Saw. Talk about catharsis!

I'm going to see if I can use the new saw to cut down those wheel studs....

Give it a try and let us know how it goes but the lugs are very hard and I suspect you'd have better luck and get cleaner cuts using a thin kerf cutoff wheel with an angle or die grinder.

Keep plugging away at it and enjoy the journey!

Jeff

[carbon-12]

Just wondering, do you have a theme in mind with the wheels you're running? I like them.

Thanks! I like the look of CSX2001, the first production Cobra. I'm thinking of painting my car in black as well, although I don't think I'll add the meatballs and #1.

AC-Cobra-CSX2001-012.jpg

[carbon-12]

Give it a try and let us know how it goes but the lugs are very hard and I suspect you'd have better luck and get cleaner cuts using a thin kerf cutoff wheel with an angle or die grinder.

Keep plugging away at it and enjoy the journey!

Jeff

Thanks. I won't be too disappointed if the new saw doesn't work for this application, but I've wanted a reciprocating saw for a long time, and this was my excuse.

[MPTech]

Thanks! I like the look of CSX2001, the first production Cobra. I'm thinking of painting my car in black as well, although I don't think I'll add the meatballs and #1.

You picked a very cool example, that's been one of my favorites. Very aggressive looking black on black on black!

I agree with Jeff, using a reciprocating saw may tear up the threads pretty bad.
I've found a thin cutoff wheel or dremel to be great for cutting bolts, then I run them on my wire-wheel to smooth the thread cuts on the end. (don't know if you'll be able to do that if you have the studs installed, but you need to clean them up so you don't have issues with the lug nuts)

[carbon-12]

Since I like the look of 15" wheels with spinners, I ordered the FIA Pin Drive Wheel Set from Factory Five at the same time I ordered my kit. Once the wheels arrived, I had them powder coated black, and fitted with a set of Avon CR6ZZ tires.

Since I have the front and rear suspension together, the next step is to put the wheels and tires on the car, lower it off the jack stands, and set in on the ground to adjust the ride height and do some basic alignment. I hope to get to those jobs this weekend.

But this was my goal last weekend, too, and if you've been following along on this thread, you'll know that I ran into a snag—the studs protruding from my wheel hubs were too long for the pin nuts. The pin nut tightening tool wouldn't have enough grip to torque the nuts to 60 ft-lbs. I needed to shave off about 1/4" from the ends of the studs.

pin-nut-and-tightening-tool.jpg
The pin nut tightening tool and a pin nut. The end of the tightening tool which is facing up fits into the end of the pin nut which is facing up. Fit the other end of the tightening tool into a socket to torque the pin nut to 60 ft-lbs.

My original idea to cut the studs was to use a reciprocating saw, and I even went out to buy such a saw, since I didn't have one in my tool crib. However, I got some expert advice from Jeff Kleiner and MPTech, and they persuaded my to use a Dremel tool for the job instead. Since I have one of those, I fitted it with a metal cutoff wheel, and gave it a go.

cutting-stud.jpg
The sparks flew as I cut the wheel studs with a Dremel tool.

It worked great. Since the threads on the rear studs don't start until a 1/4" from the end, I didn't need to worry about fouling the end of the threads. I just needed to cut off the unthreaded portion. Even so, as a precaution, I threaded on a die before making each cut, but I've now cut the five studs for each of the rear wheels, and I didn't need the die's help to fix up the threads. After making each cut, I dressed the end of each stud with a wire wheel fitted to the Dremel tool, then I blew the whole wheel area with compressed air. All the pin nuts screwed on with the lightest hand pressure.

putting-on-wheel.png
Putting a pin drive wheel on. From left to right: hub, add brake rotor, add pin drive wheel adapter, add pin nuts, put wheel on, thread on spinner. Once the ride height is set, I'll put the car back on jack stands, take the wheels back off, and fit the rear brakes.

Today, as I said earlier, I plan to trim down the studs on the front hubs, put on all four wheels, and set the car on the ground. Once I do that, my kit will be a roller!

[MPTech]

Good to hear that worked for you.
In retrospect, I guess you could have had those studs removed and shorter ones pressed in, but this works too.

Your wheels look great!