Hindsight's build thread

[Hindsight]

About 25 at that event. Probably 100+ at the racing event at Road Atlanta the other weekend.

Most common are:
- Miata with a body kit
- S2000 with a body kit
- Lotus
- Alfa Romeo

75% of the people ask, "How much do you have in it?" I'm too embarrassed to admit that and need to come up with a better response. So far I just say, "too much" and tell them that most people have between $20k and $30k into theirs

[Blwalker105]

Congrats Hindsight, nice job!

[Hindsight]

After driving it a lot yesterday and today, unfortunately the exhaust smell is still pretty bad in the cabin. Worse at speed. I believe it is getting swirled up directly from the exhaust tip as opposed to the engine bay because the odor changes nearly immediately when I punch the gas. I think the slip spoiler I have in the back probably worsens the swirling due to the low pressure area I'm sure it creates just behind it, which is above the exhaust.

I think Sealing the cabin isn't going to do anything to help. I think the only two options left are to try a rear diffuser to see if the low pressure area it creates results in the exhaust getting pulled down instead of up, or to do a side exit out the side of the rear bumper like on the blue R. Otherwise I am out of ideas. I need to fix this real quick though because it takes the fun out of driving it.

This is what I'm considering doing for a new exit. If I do this, it will be like the fourth exhaust system I have made

[Frank818]

This is what I'm considering doing for a new exit. If I do this, it will be like the fourth exhaust system I have made

If only you knew how many exhausts I've gone through on my Corrado.

First, finally you got that damn plate!! Your quest is over, now you're legal, you can go to the grocery with it.

Did you notice on the pic the vertical blade in the diffuser (what are they called anyway?) are CF. Mines are alu. That may be the 2nd gen diffuser, though.

Yeah try out the diffuser, it looks super cool on the car and maybe it'll help.

[Hindsight]

Thanks Frank.

The diffusers are just so expensive. I also feel like the diffuser should be wider than the one FFR makes.... why not go all the way across right? Channel all the air from under the car instead of just some. But I'm not an expert on that stuff. I am guessing the one in the pic is a gen2 because it is very new (it was built within the last few months I believe).

[Hindsight]

I took the dash out to loom the portions of the wiring harness that live under the dash. While it was out, I pulled the pedal cluster, disassembled it, and then drilled three new holes in the brake pedal. Two of the holes I drilled were so high that I couldn't do it with the pedal in the car, or even on the pedal cluster bracket. I drilled a hole 1" above the OEM hole, and another one 1.25" above the OEM hole. I drilled another about inch or so below the OEM hole. The next step will be to test out the top hole with the current 1" master cylinder for brake pedal feel. If it still isn't enough, I will swap out the 1" master cylinder for the 7/8" master. If that still isn't enough, I'll probably just throw the booster on and go power brakes, maybe using the new hole I drilled that sits below the OEM hole to try to offset some of the "touchiness".

[Frank818]

Your problem is that the brake pedal feel is very touchy?

[Hindsight]

No, the opposite. Too much pedal effort.

[Frank818]

Which is why you may reduce the piston's size, I get it. You will have to press further on the pedal but it's all a matter of finding the right equilibrium between how far you push (travel) and how hard you push. Exact same situation with the clutch, actually, a prob you don't have though.

[Hindsight]

Frank, that is all correct.

I spent this evening and yesterday working on this and believe I have come up with the perfect brake pedal hole location: 7/8" up from the OEM hole, center to center. I tried a whopping 1 1/4" and while the car was easy to stop, the brake pedal travel was too much and the brakes felt mushy. At 7/8", it feels like a great balance. I would like the pedal to be a bit more firm, but doing so would mean increasing effort. So I think 7/8" is the magic number. I am quite happy to have this behind me. Removing and replacing the pedal assembly with the windshield in place is a serious pain in the ***! I have done it twice now in two days. To get the 1 1/4" hole, I had to remove the brake pedal from the pedal cluster. I don't think you'd be able to drill the 7/8" hole without removing the pedal either, but you can just barely remove the pin at that hole height.

Before I claim total victory, I would like to run the car on the track again but as of right now, I'm quite happy with how the brakes feel.

[Frank818]

I wouldn't want ever to remove the pedal box. That and the fuel tank, I'll do anything to not remove. I hope I drilled my hole at the right place. I couldn't feel a prob when I tested the car, but I never went in 2nd gear and the brakes are fully new, still need to bed them in. It's cool though your solution was so simple, "just drill another hole and it'll work".

[Hindsight]

Put some more miles on the brakes. They are much, much better, but..... still not where I'd like them to be. Based on my testing, drilling a hole higher than where I am at now makes the brakes too spongy and there isn't enough travel, which means that moving to a smaller master cylinder would have the same exact effect. I am starting to hypothesise that the 06-07 WRX brakes have a lot of volume and you just can't get enough leverage and travel on calipers this size without a big master and a booster to help with the corresponding pedal effort. I'm beginning to think I will ultimately need to install the donor brake booster on my 818. I have read some say the brakes are "touchy" when doing that but I'd like to experience it myself, and if they are, I can try to offset that a little by going a little lower on the brake pedal hole (1/2" below OEM position, or so).

Took the day off yesterday to run some 818 errands. First up, going to the Subaru dealer to get a backup key coded to my ECU/Immobilizer. Worked great. Next up, I drove to a local auto upholstery shop and had a shift boot and e-brake boot made out of leather. I just have it laying in place in the car now.... I need to fabricate a bezel / trim ring for it. Then I swung by Top Speed Motorsports to show the guys there how the car turned out, and to get a weight on it. Weight is with a 100% full tank of fuel, no driver.

[Sgt.Gator]

Check out the Chase Bays brake booster eliminator. There may be some info there that is helpful: http://www.chasebays.com/02-07-subaru-wrx-sti/

[Zach34]

I had stock fox-body mustang brakes in my roadster for a long time. I used an aftermarket manual-brake master cylinder from Jegs or some place that was advertised to replace the power brake booster/master (I suspect for drag racers looking to reduce weight). It was obviously a different diameter than stock, but I don't remember what it was. Anyway, the feel of those brakes was great - better than a lot of power-brake setups I've driven. Very little pedal travel, but you didn't have to stand on them at all. Overall effort was maybe 10-15% more than your average power brake setup. I changed to 6-piston Wilwoods in the front for the track, and while it was better, it wasn't a night-and-day improvement.

Those fox brakes were gigantic, cheapo single-piston deals.

Try a different master cylinder.

[Hindsight]

Hey guys, thanks for the replies. I do have a 7/8" master cylinder that will bolt right up (I have been running the stock 1" master from the donor car up to now).

Someone please correct me if my logic is wrong here: After testing several brake pedal hole positions, I found that going too high causes too much travel and not enough pedal feel. Essentially, you are just playing with work/force/distance. Wouldn't going to a smaller master accomplish the exact same thing as moving the pushrod hole higher? You are simply reducing the amount of fluid displaced for a given pedal distance, which gives greater leverage, no?

I'll definitely swap the master out if it would help. Sgt Gator, I checked out the link you sent me and they use a 7/8 master in that kit as well. So the question is: Is changing the master pushrod location effectively doing anything different from changing the master cylinder diameter?

[tmoretta]

By relocating the push rod higher aren't you changing the angle of the pushrod too? Might it bind in the cylinder, cause a leak etc?

[UnhipPopano]

question is: Is changing the master pushrod location effectively doing anything different from changing the master cylinder diameter?

You can answer this question both yes and no. While changing the mechanical leverage of the master cylinder is equivalent to changing the changing the relative sizes of the hydraulic pistons. When you move the attachment point on the pedal without moving the pedal up or down, you are adding an angle to where the pin is pushing on the cylinder, and that can reduce the effective force, as well as cause the hydraulic master to fail.

So long story short, it would probably work better to change the Master Cylinder out.

[Zach34]

question is: Is changing the master pushrod location effectively doing anything different from changing the master cylinder diameter?

Theoretically no, but as you point out there are other factors at play.

The amount the pedal travels is due to things like the distance the caliper pistons have to move to put the pad in contact with the rotor, any compressible air in the system, the compressibility of the brake fluid (very little), and the amount of flex in hoses, tubes, and caliper brackets.

[Frank818]

Your interior looks very cool. It looks very cool with the black screws on the inner door panels, never thought of that.
Did you come back home with the white Porsche? For some reason I believe not. You should have.

[Hindsight]

The Porsche on the lift in that pic is a GT4 Club Sport. Top Speed Motorsports has a lot of clients with some seriously deep pockets. Most of their business seems to be building 1000+ HP GTRs, and they are doing a lot of Porsches now as well. Still do some subies and some exotics also. Thanks for the kind words on the interior!

Back to the brakes, yes the pushrod is at a bit more of an angle but it isn't too bad and it certainly doesn't hit the opening. Replacing the master is such a pain due to dealing with brake fluid getting everywhere and working under the windshield cowl but I guess it can't hurt to try. I had to weld up the old hole in the brake pedal (drilled where FFR suggests) because it was a little close to the new hole I drilled so I will have to re-drill that hole again probably. But I think I am going to focus on some other things first since the brakes aren't as good as I want them to be but they aren't terrible now. I have plenty of other things that are terrible right now and need to be addressed before my next track day on October 21st.

[Hindsight]

I put in my order for Ohlins double adjustable coilovers. Very excited to have these on the car. I order to take all the measurements they need to calculate spring rates and valving, I had to set the vehicle to ride height and take a bunch of measurements. I went ahead and set the car to the full 4.5" ride height per the manual and ugh, it looks like crap! Looks like it is about to go off roading haha. My previous ride height was about 3 7/8" front and about 4" rear. The 3.5" R ride height is just too low for the street and I wouldn't make it over the bumps in my neighborhood. If I go 4" through coilover adjustment, then I'm sacrificing some suspension travel (of which the 818 does not have much of). The total stroke of the 818 shocks is only 3.75" (though effectively there is probably closer to 4 or 4.5" of total travel due to the motion ratio, but that's still not a lot of travel).

If anyone is interested in a set of these coilovers, fully spec'd out for the 818 (road racing specs), let me know. I have a buddy of mine who will be offering them through his business.

[metros]

I'm interested to see what specs the ohlins have to offer. Keep updating your thread with info on those.

[Bob_n_Cincy]

I put in my order for Ohlins double adjustable coilovers. Very excited to have these on the car. I order to take all the measurements they need to calculate spring rates and valving, I had to set the vehicle to ride height and take a bunch of measurements. I went ahead and set the car to the full 4.5" ride height per the manual and ugh, it looks like crap! Looks like it is about to go off roading haha. My previous ride height was about 3 7/8" front and about 4" rear. The 3.5" R ride height is just too low for the street and I wouldn't make it over the bumps in my neighborhood. If I go 4" through coilover adjustment, then I'm sacrificing some suspension travel (of which the 818 does not have much of). The total stroke of the 818 shocks is only 3.75" (though effectively there is probably closer to 4 or 4.5" of total travel due to the motion ratio, but that's still not a lot of travel).

If anyone is interested in a set of these coilovers, fully spec'd out for the 818 (road racing specs), let me know. I have a buddy of mine who will be offering them through his business.

First let me say, that I would not even know where to begin selecting a shock absorber.
But I know this guy, CEO of Race Tech.
Watch this cool video of Paul.

http://www.racetech.com/page/id/78

[xxguitarist]

What spring rates did you wind up with from that exercise?

[Hindsight]

What spring rates did you wind up with from that exercise?

Haven't received that info from Ohlins yet. I just sent them all the measurements like motion ratio, corner weights, unsprung weights, current shock properties like stroke, etc. They plug all that into a computer and come out with the ideal spring rates and valving for your intended use (autocross, road racing, or street).

[Frank818]

3.75" of travel on Koni's shocks? I measured more like 3".

Picture on the web of those awesome Ohlins?
How did you measure motion ratio, unsprung weight and other stuff?
Since they will be FULLY adjustable, even they don't come up with the perfect valving and rates it should not matter cuz you can adjust them anyway, right?

Because of my quite different weight in the back I believe at some point I'll need a new set me too.

Mind sharing how much it cost ya?

[xxguitarist]

Haven't received that info from Ohlins yet. I just sent them all the measurements like motion ratio, corner weights, unsprung weights, current shock properties like stroke, etc. They plug all that into a computer and come out with the ideal spring rates and valving for your intended use (autocross, road racing, or street).

OK, understandable. Look forward to seeing what they come back with.

3.75" of travel on Koni's shocks? I measured more like 3".

Picture on the web of those awesome Ohlins?
How did you measure motion ratio, unsprung weight and other stuff?
Since they will be FULLY adjustable, even they don't come up with the perfect valving and rates it should not matter cuz you can adjust them anyway, right?

Mind sharing how much it cost ya?

Double adjustables still have limitations on how far you can adjust the damping. The Penske 7500DA on our RX8 are good for a +/- 100-200 lb spring rate range without a revalve, so you wouldn't want to necessarily have the stock valving.

[Frank818]

Yeah sorry I didn't mean that exactly, I meant that if measurements are wrong or Ohlins does it wrong, as long as it's inside the available adjustment it should be ok to find the perfect setup?

[Hindsight]

3.75" of travel on Koni's shocks? I measured more like 3".

Picture on the web of those awesome Ohlins?
How did you measure motion ratio, unsprung weight and other stuff?
Since they will be FULLY adjustable, even they don't come up with the perfect valving and rates it should not matter cuz you can adjust them anyway, right?

Because of my quite different weight in the back I believe at some point I'll need a new set me too.

Mind sharing how much it cost ya?

mc_rt_ttx36_01_hr-1280x703.jpg

Motion ratio: You measure from the inner control arm pivot point (the bolt), out to the lower shock bolt (measurement a), then out to the lower ball joint center (measurement b). Divide a/b and that is your motion ratio. Basically it defines what % your shock moves compared to the wheel. On a macpherson strut car, it's going to be 1:1 but on double wishbone, it will be less. And this is why you can't compare spring and shock rates between two cars with different suspensions because if their moment ratio is different, the effective spring and shock rates will be different too.

I measured unsprung weight by removing the upper shock bolt, putting the wheel and tire back on, and setting the tire on a scale. This captures the weight of the tire and all the suspension components. The shock stoke was measured by completely disassembling the coilovers, including removing the bump stop. I am guessing your measurement did not include removal of the bump stop which is why mine is higher.

I don't know the cost yet but I am guessing it will be over $3,000 and under $4,000.

[Frank818]

Man oh man that looks good!

They will fit directly without any changes, a perfect bolt-on swap?

You ordered from www.ohlinsusa.com?

You're right, my 3" was with the bump stop on.

If I feel the Koni's aren't good for my build, I'm in for those custom Ohlins, man!


Can you install them and take a ride by this w-e? lolll Just kidding, you won't even have them yet.
We're all eager to see the results, though!

[xxguitarist]

mc_rt_ttx36_01_hr-1280x703.jpg

Motion ratio: You measure from the inner control arm pivot point (the bolt), out to the lower shock bolt (measurement a), then out to the lower ball joint center (measurement b). Divide a/b and that is your motion ratio. Basically it defines what % your shock moves compared to the wheel. On a macpherson strut car, it's going to be 1:1 but on double wishbone, it will be less. And this is why you can't compare spring and shock rates between two cars with different suspensions because if their moment ratio is different, the effective spring and shock rates will be different too.

Not to be too picky, but the motion ratio also depends on the angle of the shock body- ours are relatively upright, so it's not a big deal, but it's a relevant factor.
The other approach is to put the car on jack stands, remove springs, jack wheel up to near static height, measure shock length, jack up wheel 2" more (probably moving from somewhat drooped to somewhat compressed) and measure the shock length again. This way there's no trigonometry involved :-)

[Frank818]

Static height is the normal ride height?

[Hindsight]

Andrew - good point!

Frank, I am ordering them through a friend who gets them through a racing company. There is some engineering involved in sizing the springs and valving for the whole setup, and this is what the racing company does. They do come ready to bolt directly on to the car, fully assembled, yes. However, having said all that, the cost estimate I originally received and then what I was told yesterday for actual cost was way off. The actual cost is close to double what I mentioned above which is too rich for my blood. I still need to discuss it in more detail with them to determine what other options there are but at this point, I'm not sure I'll be going down this road. I will keep you posted.

[Mitch Wright]

I have been in discussions with RideTech (Fox Shocks) as a winter project for my car. Before I get serious I will be playing with the current spring shock set up this fall to have a good baseline. The car will be on track this weekend for the first time as a complete ride Saturday (if it doesn't rain) and Sunday.

[Frank818]

Oh man oh man, I'm not in either for 6-8k (+25% after stupid exchange rate for me).

Maybe in my case different springs from Koni would be enough, or just different springs and shocks, the closest to what would work best. Maybe that's also an option for you?

[Canadian818]

Springs are cheap, try different setups before spending crazy money. Also consider playing with your aerodynamics. If I'm not mistaken, you had no splitter or front aluminum installed on your track day? Also your bumpsteer hadn't been addressed yet? Almost everyone whose tracked they're cars have increased they're spring rates, especially in the rear.

[xxguitarist]

Hindsight, I'm sure there are other very good options, double adjustable, and appropriate for the car, at a much better price.
We can put you in touch with Angelo at Anze if you're interested in Penskes.

[Hindsight]

Frank, yeah there are other options that I will explore.

Adam, yeah I was planning on doing the bump steer and aero and updating the alignment at the same time I install the shocks and springs. Part of why I wanted to go with Ohlins is the distributor I was getting them from will do all the fancy math to determine the suspension frequency, ideal spring rates etc. But a second, less ideal yet cheaper option is to get stiffer springs, as you mentioned. That is what I was planning on doing originally but got excited about having a professionally calculated setup that was dual adjustable so I didn't have to do as much trial and error on my side.

Andrew, thanks for the input. My buddy is also a dealer for Penske and is working to price out a set of those for me as well. I'll see what he can dig up and go from there. Thanks again.

[Mitch Wright]

As has been said I recommend dialing in what you have to lock in a good baseline before spending money on parts that will put you in a situation of out tricking yourself and or chasing the car. Start with the basics:
Scale the car with the driver as it will hit the track.
Bumpsteering the car is a must.
Have a plus and minus adjustment for your starting alignment settings.
Get all your Aero on the car that you plan to start with if any. Ride height and rake will have some effect on aero performance.
Learn the car and the adjustments you have before making BIG changes and just make one change at a time.
Something like an AIM Solo has some basic data gathering capabilities/track mapping along with lap times that you can down load and overlay.
Basic rules for sorting out a car is one step at a time and make sure you can always go back to your best baseline, keep good records.

[Hindsight]

Thanks Mitch.

So I decided to take baby steps. I'm going to leave the front 350# springs in place, add in the front sway bar, swap the rear 275# springs out for 500# and swap the yellow Koni shocks for the Red Koni shocks that come on the R. I have all the parts and now just need to find time to do the install. I will also use the OEM eccentric bolt to set the camber (instead of using the a-arm), add shims to the LCA, adjust front and rear bump steer, and do another full alignment. I have a track day next Friday the 21st but am not sure I will be able to make it with all that to do.