Shoeless GTM #501 Here we go!!!

[Shoeless]

After a little back and fourth with AEM, they have finally agreed to cover the issue with my ECU under warranty!!!

Can't wait to get it back and reset my last tune and pick up where I left off in December getting this thing to the tuner.

Next surgery is May 2nd, so hopefully I can get this in before then, but no worries if I can't, I'll get it tuned after. BTW the recovery from the first surgery is going really well. No work on the GTM yet, but I am up and running around the best I can.

[VRaptor SpeedWorks, LLC]

That's really good to hear...both on AEM and your recovery time!

[Shoeless]

Got an interestingly large package from CA today. Opened it up and realized it was from AEM. Instead of repairing my unit with a new board, they simply sent a brand new replacement

I'll finally be spending some time this weekend meticulously uploading my prior tune manually and getting the GTM back up and running.

Recovery is going well, a little hiccup the other day with some nerve issues and shooting pain going down my right leg, but thankfully that's subsiding.

[crash]

Wow, that's great news.

Please report back if there are any differences with the new unit and if you think they are improvements.

[Shoeless]

Wow, that's great news.

Please report back if there are any differences with the new unit and if you think they are improvements.

I was pleasantly surprised to be given a brand new unit. The original work order from them wanted to replace the main board for about $700 and I respectfully requested warranty consideration. I shared the unit was activated less than one year from the time the issue started and had been sent to AEM twice on my dime for inspection and only when I had a local tuner in CA contact their engineering department to push the issue, did they find it. After sharing this they granted warranty coverage, but again I did not anticipate a brand new unit. I’m very thankful for how they have treated this in the long run.

I blew off work Friday early afternoon and got to work. Installing the ECU in the GTM, registering the unit and downloading the firmware, followed by manually putting my tune in. I had taken over 50 screenshots of how it was set when everything was functioning properly, so instead of upload an old tune in case there was some glitch that caused all this to be fine with, I did it all manually. I did the DBW setup wizard and it set everything flawlessly, I didn’t have to change one single parameter. Couple hours after I started and she fired right up!!!!

I just got back from a few more trips around the block to test everything and the only issue noted was my fuel level sensor is stuck at full. I plugged my voltmeter in and jacked the car up on the passenger side and the resistance didn’t change one bit. So looks like my passenger tank is going to come out next to see what’s up.

With this being the only issue, I’m very pleased so far.

I can report I spoke with Joel at Racespec in NY at length for about a possible swap to a Motec setup. On top of the STEEP learning curve I’d have simply going to a new ECU, I’d have to modify my harness (possibly significantly), large expense, and the most concerning is lead time. An M130 would do everything I need, but even Motec can’t give commits on delivery. It could be 1 week or more than 3 months. I may have to shelf this idea until I possibly build an Ultima RS next and design that harness specifically for a Motec.

[Shoeless]

Got the fuel level sender fixed. Seems I had the pump clocked perfectly to allow the float get jammed in the inside of the tank at the full level. Loosened up the top, gave a little rotation and fixed the issue. Glad I didn't drive around much more as I as on 1/4 tank

[Shoeless]

GTM 501 made it to the dyno yesterday and I picked her up today. She made a respectable 539 HP and 524 FTLBs of torque. The engine dynoed out at 625 HP and 595 FTLBs of torque. That's only an amazing 13.8% drop from crank to wheel. The Mendy SDR-5 Stage 2 did its job today.

[crash]

Congrats! Huge milestone and great numbers.

Can't remember if you told us already, but what mods did you do to this engine?

[Shoeless]

Congrats! Huge milestone and great numbers.

Can't remember if you told us already, but what mods did you do to this engine?

Thanks Crash!!!!

I bought this engine directly from Blue Print Engines and asked them to delete the engine computer, engine harness, and DBW pedal as I was going to go with a Standalone ECU to add some functionality. Here's the link to the site with all the specs. I kept it exactly as delivered from BPEs other than changing to a genuine LS3 90 mm throttle body (I probably would have stayed with the LT5 87 mm, but I thought this was my issue first off back in December) and having it tuned on 93 octane.

https://blueprintengines.com/product...am-psls4272ctf

[crash]

Ahhh, 427, that makes sense.

Good to see that you beat their advertised numbers. Nice when a builder under rates their engines...or maybe the ECU and TB had something to do with it.

[Shoeless]

Ahhh, 427, that makes sense.

Good to see that you beat their advertised numbers. Nice when a builder under rates their engines...or maybe the ECU and TB had something to do with it.

The tuner told me he can make it a little “spicer” if I really wanted, but since I will mostly street it versus track it, we settled where we are. I’ll be trying to get a little more driving in this weekend before my surgery on Monday to look at some data logs. I’m glad a found the right tuner with a load bearing dyno to tune this thing the way it should be.

[Shoeless]

Hey guys,

I've been putting some more break in miles on the GTM making it past 400 miles today and have a bit of an issue out of the drivers side CV. I noticed black spots slung on the exhaust and transaxle case a little while back so I cleaned everything up and did some driving the other day and today. It looks like CV grease is coming out of one bolt hole and slinging on the transaxle case. The torque stripe is still intact so it doesn't look like it loosened up at all.

If you guys remember I did have to pull the transaxle a while back for a front seal, so maybe I had some residual grease in the hole that has worked itself out? I put probably a couple hundred miles on it after replacing the seal before I noticed this.

What do you guys think?

[crash]

There is a reason I tell people that it takes 6 hours for me to properly assemble a set of axles. It is not just putting the parts together, I take a LOT of time cleaning sealing surfaces and putting silicone on them to get a proper seal. If you haven't done this it will almost always leak. Of course a lot has to do with the grease you use also. The grease we use does not liquify very easily, but we are having trouble stocking it. I did find an alternative, but it is 3 times more expensive and I am just testing it on the race car now. I really need to do a video on how to seal a set of axles, but have not got around to it. I am usually very crunched for time when doing axles as it is one of the last things before the car can drive. Anyway...clean with brake/carb cleaner, thin layer of silicone, reassemble. If your grease is very liquid at room temperature this may be difficult to do at this point.

[Shoeless]

Thanks for the feedback crash.

I used a mixture of Bel Rey and Swepco 101, so I think I'm good there. I'm thinking when I pulled the transaxle for the repair I probably didn't have the surface between the CV and Transaxle output clean enough before I bolted it back together. I remember I likely rushed this and didn't clean way enough and I definitely didn't use silicone. So both of these could be contributing to this issue.

Are you doing a thin layer of silicone on both the mating surface between the CV and Transaxle Output surface as well as the CV and the metal cap for the boot? If I pull this apart in attempt to follow your recommendation, I want to do this right.

[crash]

You can think of it as just putting a very thin layer on the CV on both sides on the mating surfaces, and then bolting them all back together. In other words, just silicone one surface per sealing area. One where the CV and the boot flange meet, and one where the CV and the transaxle output flange meet. If you do this on the CV side, it makes cleanup a little easier the next time as most of the silicone stays on the CV.

[Shoeless]

You can think of it as just putting a very thin layer on the CV on both sides on the mating surfaces, and then bolting them all back together. In other words, just silicone one surface per sealing area. One where the CV and the boot flange meet, and one where the CV and the transaxle output flange meet. If you do this on the CV side, it makes cleanup a little easier the next time as most of the silicone stays on the CV.

Awesome, thanks for the clarification.

I know what I'll be doing next couple of weekends, taking my time and doing this right. I've got some parts off at the powder coater so no running the GTM anyways

[Shoeless]

I got some free time yesterday and decided to pull apart the drivers side CV that was leaking. After the reiteration of cleanliness, cleanliness, cleanliness, I took some time to clean up the garage and especially the workspace I'd use for all the work before I even started tearing everything apart. Lord knows this is about to be messy enough



After some disassembly, I was able to pull the six bolts and remove the axle. Surprisingly the last bolt (the lowest one in the below pics), where the leak was most prominent, was loose. When I say loose, the torque stripe was still in place, but the loctite was not present at all and the bolt easily came out. Either I missed pulling this bolt out, cleaning with brake cleaner, blowing the hole out, applying the loctite, and reinstalling, or I didn't clean the hole properly. I'm leaning toward the later as I always take a marker and mark my work as I go when doing stuff like this. No worries. I'm just glad this happened before I have the body mounted and car complete.





The next two pics are after pulling the CV off the axle. The entire lip of the boot cap and corresponding surface on the CV was completely covered in lube. Looking at the boot cap surface where it mates to the face of the CV seemed covered as well.





I spent the next hour or two completely cleaning everything. The bolts all got freshened up on the wire wheel removing old Loctite and torque stripe, same with the "dog bones" cleaned up and sprayed with brake cleaner. The outside and sealing faces on the CV was next after repacking with the excess lube. Then onto the bolt holes. This was kind of a pain in the butt until I thought of using wads and a rod from a gun cleaning kit. This worked perfectly. Repeat going all the way around until the wads came out clean. One last clean of the O.D. and mating surfaces and everything is prepped for reinstall.



I also religiously cleaned out the transaxle bolt holes and face with break cleaner. I thought it would be a good idea to pick up a M10x1.5 bottoming tap to run through the transaxle threaded holes to clean out all the old residual loctite. I'm waiting for this tap to come in as well as some cut tip applicators for the silicone I'll add to the mating surfaces of the CV. I will use Permatex 82180 Ultra Black Oil Resistant High Temp silicone when I put this all back together.

[crash]

Here's a tip...tear one of your blue paper towels into one inch square small pads. There is a really small bridge on the CV on 3 of the ball areas that needs to be clean and is a bit tricky. You will not need the applicators for the silicone. What you need to do is apply the silicone with one of your fingers. Squeeze a small amount onto your finger tip and then wipe it in a THIN layer onto the CV sealing surface after cleaning with one of the small wipes with brake clean. You need to do this with the CV on the axle shaft and RIGHT before you reassemble everything. The silicone needs to still be tacky when assembled into car. Alternatively, and what I usually do, is to put the silicone on the boot side, then torque that down onto the CV with CV bolts and 10x1.5 nuts so that the silicone seal is made properly, then I remove the nuts right before installation on the transaxle output. This makes it so you don't have to rush. On the other side of the axle, I assemble complete with the stub shaft on the work bench so I can get the sealing correct and I find it much easier to just stick the axle in the car with only the transaxle side to worry about. You will need to at least remove the toe link from the upright in order to facilitate installation with the stub shaft on. Usually I also knock the lower ball joint off too so that things don't get really tight trying to get the axle in there. Trust me when I say that this is much easier than trying to deal with the sealing surface of the stub shaft when it is in the car and trying to mount the CV to it already installed in the upright. You can not do this, however, if you are using the Corvette outer CVs.

[Shoeless]

Thanks for the tip on using 10x1.5 nuts with the CV bolts to seal and hold the boot to CV connection together to let that silicone dry and not needing to worry about that part when I go to reinstall in the car. I would not have thought about that and definitely simplifies one part of the equation.

[Shoeless]

I was able to take some time over the last couple weeks and get the axles reinstalled and I got some parts back from the powder coater. I didn't like the simple silver finish on the valve covers so they got the same silver hammertone treatment to match all the other powder coated parts.

[Shoeless]

Got some time away from my typical summer fishing routine to put the last 70 miles on the GTM to finish the prescribed break in period and test the CV repair. It was a great day of venturing further away from the house, hitting a few main roads to rack up the miles a little faster and avoiding the cops So far the CVs are sealed up nice and the car was performing nicely. Late in the afternoon I hit the 500 mile mark, completely sunburn as I wasn't wearing a hat or sunscreen, and was finally ready to punch is and see how she does. OMG this thing is a bat out of hell!!! During the first run I got a yellow warning light on my dash, but no warning message came up. Note, everything in the dash was configured by me, so I took some time that night to review all my warning lights and messages as well as adjusting the RPM gauge scaling. Also, I tried to do a little data logging to look at everything, but the logging wasn't working either. Simple fix that night in the 1D table on the switch inputs (I have a log switch on the center dash).









The following day I was able to get out and do a couple higher RPM runs with the data logging working as it should. No warning lights came up on the dash, so I went back and pulled the data to make sure everything was within range.



There is so much info to gather and analyze from being able to data log. On the top chart I simply plotted 11 channels of the 100 that I currently have set up. The top chart has Lambda1 (driver's side engine bank), Lambda 2 (passenger side engine bank), and Fuel Pressure. Looking at Lambda 1 and 2, the graphs follow each other so you can deduce that both sides of the engine are operating in sync. You want to look at this to determine if one side is running richer/leaner compared to the other. As for Fuel pressure, there is a fluctuation from ~59psi to ~65psi while I was really getting on it on the left side of the chart (note vehicle speed on the bottom chart as well as throttle %) with more of a steady ~63psi to the right of the chart where I was cruising with a couple plips in the throttle. I'd say this looks good to me and the Lingenfelter High Flow Fuel Pump is doing its job.

On the middle chart I plotted Battery Voltage, Oil Pressure and Temp, as well as Coolant Temp. Battery Voltage should be stable around 14.4V as that's what I have the PWM signal and duty cycle output from the ECU to the Cadillac CTSV alternator to do. I'm happy with what I'm seeing here with no more than 0.1V fluctuation. Oil Pressure and Temp is acting in a manner that I would also deem acceptable. Pressure and Temps kick up with higher throttle runs. Oil temp becomes stable around 83 deg C - 181 deg F (not sure why it logged in Deg C, as I have it set to Deg F, I'll figure that out later). This was a quick higher throttle run, so not sure how high I should expect oil temps to go up. I'm sure Crash can share some real world on track oil temps to help me calibrate myself. Coolant temps also came down with higher speed getting more air to the radiator.

The bottom chart I plotted Vehicle Speed, Throttle %, NLWheel Speed (Non-Driven Left - Front left wheel speed), DriveWheelSpeed (Rear wheel speed - I need to see which one its pulling). The main thing that stood out to me is what I thought was a high throttle run through the gears was actually not. First gear I only used about 40% throttle, second gear I only used about 50% throttle, and third gear peaked at 80%. The dips in the throttle curve on the left are the shifts (I need to work on those LOL). Looking at and comparing the Driven and Non-Driven wheel speeds, the are nearly identical telling me I had zero wheel slip on this run. Not sure what the little dip on the left is, maybe when the log conditions met in the ECU and it picked up (even though I have a log button on the dash there is additional criteria you can set for it to start and stop logging - vehicle speed, MAP, ...).

Overall some very cool stuff to look at and confirm the car is functioning the way it should and the critical areas are doing well.

[Windsor]

Pull up STFT (Short Term Fuel Trim) and LTFT (Long Term Fuel Trim) if you can. You'll likely have four graphs since they're usually per-bank.

They'll tell you a better story than looking at the Lambdas.

[Shoeless]

Pull up STFT (Short Term Fuel Trim) and LTFT (Long Term Fuel Trim) if you can. You'll likely have four graphs since they're usually per-bank.

They'll tell you a better story than looking at the Lambdas.

Thanks for the pointer. I can say I definitely didn't have this logging in the 100 channels I had set up for this run. Looking through the AEM manual and searching online, if they have something like this it doesn't look like they call it STFT and LTFT. I'll have to research this a bit.

[crash]

I am running the oil temp in the 250-270 range. Full synthetic Neo race oil. 15w-50.

That fuel pressure is pretty high. We used to run about 60 PSI but the tuner said it is far better to run higher flow injectors and a lower duty cycle and fuel pressure. He said this gives the ecu room to make enrichment adjustments via duty cycle if needed, and if you have a fuel leak it is far different at 50 psi as opposed to at 60+ psi. He says it is much safer with the larger injectors. We are now running 50 psi.

[Shoeless]

I am running the oil temp in the 250-270 range. Full synthetic Neo race oil. 15w-50.

That fuel pressure is pretty high. We used to run about 60 PSI but the tuner said it is far better to run higher flow injectors and a lower duty cycle and fuel pressure. He said this gives the ecu room to make enrichment adjustments via duty cycle if needed, and if you have a fuel leak it is far different at 50 psi as opposed to at 60+ psi. He says it is much safer with the larger injectors. We are now running 50 psi.

Awesome, thanks for the feedback.

I can’t remember if I’ve asked before, but what injectors are you running?

I’ve got LS7 injectors setup through the baseline wizard in the AEM. There are lots of different fuel enrichment tables and options I can use for different strategies.

[crash]

Awesome, thanks for the feedback.

I can’t remember if I’ve asked before, but what injectors are you running?

I’ve got LS7 injectors setup through the baseline wizard in the AEM. There are lots of different fuel enrichment tables and options I can use for different strategies.

Sorry for the late response but I wanted to check with the tuner. He says that we are running "Deutsch Tech" injectors, but I can not find the company on the internet to give you a link.

[Shoeless]

Sorry for the late response but I wanted to check with the tuner. He says that we are running "Deutsch Tech" injectors, but I can not find the company on the internet to give you a link.

No worries on the delay, more of just curious what you guys run in your program.

Maybe Deatschwerks?

https://deatschwerks.com/collections/injectors

[Shoeless]

Doing some research on the AEM Infinity and looking for STFT and LTFT and it appears they are not available as the system seems to works a bit differently. Going through all the channels available to log and there are several trim/feedback channels that may give me what I'm looking for. It was a bit rainy yesterday in S FL, so I didn't have the opportunity to go run and do some data logging, instead I decided to break out the corner scales and work on that a bit.



Initial numbers from simply trying to set the ride height and have the front sway bar unloaded were pretty far off:

No driver:
LF - 473 RF - 305
LR - 627 RR - 785
Cross with % - 42.56%
Left - 50.23%
Rear - 64.47%

With driver:
LF - 543 RF - 326
LR - 721 RR - 805
Cross with % - 44.59%
Left - 52.35%
Rear - 63.37%

I started off making single changes at the corners that needed to gain and lower weight to see how much change I could impart in the system. After some learning, I found out I could change the weights around 10-20 lb per corner by simply raising or lowering one corner by one full turn on the spring perch. I would then hook the sway bar up and then load the system three turns and gain another 5-10 lbs per corner. The left weight is what you go after first, but since I won't be adding any ballast or moving anything else around, that's pretty set. With that set, the goal is to go after cross weight. Small change after small change and checking numbers with and without the driver and I finally dialed it in.

Final numbers without the driver:


Final numbers with the driver:


Next is to go back and check all the alignment numbers and make any minor adjustment needed.

[VRaptor SpeedWorks, LLC]

Very nice! Curious how far off from "even" your spring perch measurements ended up side to side?....if you just take a measurement from the bottom of the spring perch to the bottom of the threaded sleeve?

[Shoeless]

Very nice! Curious how far off from "even" your spring perch measurements ended up side to side?....if you just take a measurement from the bottom of the spring perch to the bottom of the threaded sleeve?

Thanks Shane!!

I can definitely grab some measurements and share that with the group. I didn't get a chance to roll it out of the garage and look closely at ride height, but looking at the adjustments I made to get weight on the front right and land at 50% cross weight, I'm betting the right front is higher than the 4.5" target.

[VRaptor SpeedWorks, LLC]

I think I shared the (related) story here a few years ago about the GTM I got in here that a customer had just bought from someone else. He wanted me to do some work on it and check things over, and said that it did not handle well. We got the car unloaded and I was driving it back to the shop and blipped the throttle a bit and immediately one of the back tires started spinning. I thought that was odd as normally these cars just hook up and go and I was getting wheelspin by just blipping the throttle a little with no real corresponding acceleration. Once I got it in the shop, I figured out what was going on.....they had one rear coil over cranked way up along with the opposite corner and the other 2 corners were cranked way down. According the seat-of-the-pants and wheel spin, I doubt the one rear tire had more than a hundred pounds of weight on it. The whole car was virtually balancing on 2 wheels and the other 2 were not much more than training wheels.

[Shoeless]

I think I shared the (related) story here a few years ago about the GTM I got in here that a customer had just bought from someone else. He wanted me to do some work on it and check things over, and said that it did not handle well. We got the car unloaded and I was driving it back to the shop and blipped the throttle a bit and immediately one of the back tires started spinning. I thought that was odd as normally these cars just hook up and go and I was getting wheelspin by just blipping the throttle a little with no real corresponding acceleration. Once I got it in the shop, I figured out what was going on.....they had one rear coil over cranked way up along with the opposite corner and the other 2 corners were cranked way down. According the seat-of-the-pants and wheel spin, I doubt the one rear tire had more than a hundred pounds of weight on it. The whole car was virtually balancing on 2 wheels and the other 2 were not much more than training wheels.

Holy smokes that's pretty scary!! I know I shared this one as it was scary as all can be. I have a friend that lives in Jupiter, about 30 min south of me, that bought a completed GTM (I think SN 004) that started out with pretty poor handling. He took it to a local shop and discovered that somewhere in its life, the attachment points of the control arms were slotted completely open to allow for outward adjustment of the control arm. The shop promptly fixed that for him and welded in pieces to not make it a death trap if any of the suspension bolts come loose. They did an alignment for him and definitely improved his handling, but they didn't have scales to properly corner weight it. Now that I've done it, obviously still learning, but I have gear and know how, I offered to have him come by and I'll do his GTM.

Here is where I ended up measuring from the top of the spring perch to the end of the threaded body on the coil over. A little eyeballing, but close enough.

LF: 2.170" RF: 2.325"
LR: 2.830" RR: 3.250"
Sway Bar: Loaded 3 1/8 Turns on the passenger side

I was a little surprised by these numbers. Again, I still need to look at ride height and go test drive, but took two craft sticks and cut them at 4.75" and 4.5" to check the frame at the front and back (Shane's method) and ballparked it on my garage floor with the car on the flat patch tiles. The front right is high compared to the front left and the rear is probably within 1/8" left to right.

I should have taken the before measurements at the corners just for reference, but I went back to all my notes I took during the corner weight process to see all the changes step by step. I should have made them a bit easier to reference back to, I think I made a mistake or two, I need to go back to my notes tonight to make sure I'm reading them correctly. Overall I made 16 distinct changes through the whole process. Some of these were simply attaching the role bar, loading it 3 x turns, and then unloading and disconnecting. Also, after change 10, I went back to the settings at change 7.

I'll look at my notes tonight or tomorrow and see if I can interpret the overall changes by corner from start to finish. I can say I originally had the sway bar unloaded left to right.

[VRaptor SpeedWorks, LLC]

So those measurements are to the top of the threaded body or the bottom?....from the measurements, I'm assuming the top?.....so the springs on the LH side of the car are more compressed than the RH side? That makes sense if that's the case. Thanks for getting those measurements for me.....was very curious as to how close together they would be L to R.

"took two craft sticks and cut them at 4.75" and 4.5" to check the frame at the front and back (Shane's method) and ballparked it on my garage floor with the car on the flat patch tiles."

Holy cows.....where do you keep all of this information so that you can find it or remember it?!?!

Since I have the tires sitting on shims so that they're all level, I don't measure to the floor and instead measure down to my laser level line.....so I mark the craft stick with a line that is the distance from the frame down to the level line (minus the distance from the top of the tire shims to the laser line).....front measurement on one side of the stick and rear measurement on the other side of the stick so I only need one stick.

[VRaptor SpeedWorks, LLC]

20220928_085533.jpg

20220928_085527.jpg



Pretty high-tech equipment!!....it used to have another craft stick hot-glued to it to use as a handle....but I think I ran it over with the creeper and broke the handle off....

[crash]

Just for clarification, all suspension adjustments should be done with sway bars detached. The bars should be zeroed and attached as the very last step of the process. Also, ride heights should be done with all fluids in the car, bodywork on, and two people in the car's seats. After you get this number you can then remove the people and fluids and make another reference measurement. That way you don't have to waste peoples time every time you want to adjust things in the future. You will notice significant differences between a full car and an empty car.

[Shoeless]

So those measurements are to the top of the threaded body or the bottom?....from the measurements, I'm assuming the top?.....so the springs on the LH side of the car are more compressed than the RH side? That makes sense if that's the case. Thanks for getting those measurements for me.....was very curious as to how close together they would be L to R.

"took two craft sticks and cut them at 4.75" and 4.5" to check the frame at the front and back (Shane's method) and ballparked it on my garage floor with the car on the flat patch tiles."

Holy cows.....where do you keep all of this information so that you can find it or remember it?!?!

Since I have the tires sitting on shims so that they're all level, I don't measure to the floor and instead measure down to my laser level line.....so I mark the craft stick with a line that is the distance from the frame down to the level line (minus the distance from the top of the tire shims to the laser line).....front measurement on one side of the stick and rear measurement on the other side of the stick so I only need one stick.

The measurement are from the top of my spring perches to the end of the threaded body. Keep in mind I have helper springs on mine so there is some space taken up from that. Actually, the springs are more compressed on the right side of the car. I think it's the front coil overs that are inverted and have the Stance Air Cups as well taking up some space.

Not sure how my brain stores all this very helpful info that I pick up along the way LOL Guess that's the engineer in me and if its something I know I won't be able to remember, I take copious notes

20220928_085533.jpg

20220928_085527.jpg



Pretty high-tech equipment!!....it used to have another craft stick hot-glued to it to use as a handle....but I think I ran it over with the creeper and broke the handle off....

Love the high tech equipment LOL.

I like the mention of the laser level line as you have the cars up on shims. I have the exact same thing as that is step one before doing the alignment or corner scaling, creating a flat patch. I do it with laminated floor tiles that measure 1mm thick each. You simply mark where the cars tires end up, roll it out of the way, and put the number of floor tiles you need on each corner to get a level flat patch. I use a piece of extruded aluminum and my digital camber gage to set this.

[Shoeless]

Just for clarification, all suspension adjustments should be done with sway bars detached. The bars should be zeroed and attached as the very last step of the process. Also, ride heights should be done with all fluids in the car, bodywork on, and two people in the car's seats. After you get this number you can then remove the people and fluids and make another reference measurement. That way you don't have to waste peoples time every time you want to adjust things in the future. You will notice significant differences between a full car and an empty car.

Great point on the ride heights with everything noted getting one measurement and then taking another as a reference.

I do have a question on your setup. I'd imagine that with the PDG GTM you can take the liberties of proper ballast to assist your alignment and corner weighting with only the one driver in the car. I think I remember you stating you did a larger fuel cell on the passenger side of one or a few of your races. This gave you a bit of an advantage over some of the other cars.

I ask as Ted did a video years ago when he corner weighted his GTM and once he attached the sway bar, after all other adjustments, he loaded it 3 x turns to get the proper weight on the front right and cross weights. If I could add ballast, I'd imagine I would not need to do this.

[crash]

It sounds like Ted was preloading for a particular track configuration. My personal opinion is that this is not how to get desired cross in a car, but he has done a lot more circle track racing than I have. I always set bars at zero preload for tracks that turn both directions. If the track has five left turns and two right turns, then certainly we would put more fuel in the left side of the car if we were not running full tanks. We run no ballast unless a particular series has a minimum weight that we do not meet. These series usually run short sprint races and so we just adjust with added fuel. It is a very VERY rare case where we actually add weight in the form of lead.

[Shoeless]

It sounds like Ted was preloading for a particular track configuration. My personal opinion is that this is not how to get desired cross in a car, but he has done a lot more circle track racing than I have. I always set bars at zero preload for tracks that turn both directions. If the track has five left turns and two right turns, then certainly we would put more fuel in the left side of the car if we were not running full tanks. We run no ballast unless a particular series has a minimum weight that we do not meet. These series usually run short sprint races and so we just adjust with added fuel. It is a very VERY rare case where we actually add weight in the form of lead.

I can't tell you how much I appreciate the openness and candor in the feedback. It has really helped me in so many areas of my build, and I'm sure others as they read along.

It's nice to make these large adjustments/changes now and once I get the car back from bodywork and interior, i'll should only have minor tweaks to dial it in.

I finally went back over my notes for each individual step I made in my corner weight process and what the measurements were. I'll put this all in excel and print it our nicely and share with the community so everyone can see each step of the process.

What I can say is between the last couple of changes I made, it looks like I landed around 49.03% cross weight with an unloaded sway bar. I'll be able to double check this maybe this weekend. At this point I guess I should really ask myself, will I as a complete amateur not pushing this car to its limits, will I ever really be able to tell that much of a difference?

[Shoeless]

I took some time this morning and cleaned up my notes for the step by step corner weighting process. I started off with an estimated ride height (I didn't use the laser level method Shane noted above, but I did use it for the final ride height checks) and 3/8th tank of fuel. I then checked all the corner weight measurements with and without the driver for a reference start. I then started with making a change on one corner to see how much it really changes the weights. The changes ranged from 12lbs to 21lbs depending on the corner. Obviously the corner that the change was made on shows the highest change and the cross weight went up 1.35%.

Step one is to set the left weight and then go after cross weight. With no changes in ballast, the left weight is essentially fixed (as can be seen from the start all the way down to the end, its nearly identical) and needed to go after the cross weight. If the cross weight is less than 50%, you can raise the RF or LR (or both) or lower LF or RR. So I started making these changes moving towards a better cross weight. Along the way I would hook up the sway bar and load it 3 x turns towards the passenger side to see the difference that would make (seeing Crashes comments above I may completely do away with this and go back to the scales to make further changes). After the 10th change I could see things were going out of wack, so I went back to change 7 and then moved forward. Finally landing on the last numbers w/ and w/o the driver and then I just checked ride height this morning w/ and w/o the driver as well. Having 180 lbs of dumbbells is my substitute for me as the driver. I put a 20 lb weight as the pedals and the rest on the seat.

From here, I'm going to go for a drive this morning and see how she handles. Being a little more careful ride height wise as the front left is pretty low now. Once I see how she handles, I'll likely remove the load on the roll bar and test drive again just for a reference. Who knows if I'll be able to tell much of a difference as I really can't push it to its limits on the side streets by me, but we'll see