nc7s4

Sure thing. I just wanted to make a note here in case the rebuilder put in the same flawed order that I had recommended earlier!

Quick update regarding my new springs and shocks. They do not work!! 10-In heavy springs are too tall. Even at the top of the shock perch the ride height is too high. Need to figure out how to fit shorter springs. I think that only the rear of the car has clearance issues, front will fit industry standard 2.25 ID springs. The rear of the car will probably still get 1.875 ID springs, but the problem with that is that they are limited in what you can get. It looks like the heaviest 8-in option is 250 lb. That may be what I end up with in the back. If the front can fit 2.25 in springs then there is any rate imaginable in that size 8 in long.

That is an r160 differential from a WRX, I think. Good news is that it will be easy to replace the r160 with another r160 if you choose to do that. Those parts are easy to find since they came with several different Subarus. Bad news is you thought you got an STI rear end. I was also suspicious looking at your rotors in the back. Those look like WRX rotors which is a standard setup. Compare pictures of the rear cover for a r160 and an r180 to what you have. The STI came with an r180. Regarding the engine mounts, here is a picture of how I fixed mine. I got these rubber bushings from Amazon which have been holding up fine

That adjuster was pretty sketchy on my car. Really flexed when on the brake, to the point where it was concerning me that the pedal box might break off entirely. Here's how I hard mounted it

Those are the wilwood 12 inch rotors that come stock with the WCM. All cars I have seen have those in front.

Jumping ahead on you by about 10 steps but I just got these shocks and springs delivered in the mail. After a lot of pondering I decided on this set. Hopefully it saves you sometime shopping around Advanced racing suspension in Indianapolis. Person's name is Corey. Springs I went with are 500 front 300 rears. Shocks are not adjustable but tuned by the manufacturer to the setup. They know the car

Bruce that's me!!

If you do have the STI upgrade that is most excellent. I broke the WRX differential (R160) this year and others have experienced the same. The STI upgrade gives a much stronger rear end (axles, hubs, rights and the R180 LSD) - at the cost of being heavier. But it seems to be necessary for running on a track with slicks. There are many different R180 diff's out there - different LSD's and ratios. It would be of interest to confirm the model year STI and particular details about your diff. Normal setup for rotors are cross drilled 12 inch wilwoods all 4 corners. If you have 15's that would be of interest to see for sure. But considering you are running 15" wheels - i doubt your rotors are 15" because that would not fit. My car had WRX OEM (solid steel) rotors in the rear before I did the "STI rear end upgrade". Then it got the 12 inch wilwoods same as the front - how it should be IMO. But then there are other tweaks that need to be done to the brake bias. Such as swapping the rear MC with a 7/8 bore to achieve less braking force in the rear. The balance bar is apparently not going to generate enough bias with both 3/4 MC's For wheels the race setup was 15x10 inch steel wheels with 9.5 inch hoosiers. I run 245x15 Toyo R on the 15x10's.

Welcome to the family! The car looks to be pretty great. Could you post some more pictures? One thing I can recommend after getting it all cleaned up is identifying what you have before getting into tuning it up. These cars vary widely in components and setup. Things to check Spring rates, damper tuning Wheel size and tires sizes State of the ECU/tuning What differential does it have? Probably an r160 but check it out Brakes - wilwood rotors at back? Take some pics Does it have the standard s2000 engine and transmission? Post this stuff so we can discuss what is / is not needed.

@charles5448 here are some more recent numbers for my car note: this setup is about to change because I am changing from 500/500 springs to 500/300 springs. 500/500 was likely contributing to an oversteer condition - which I tried to get rid of with some extra negative camber and rear toe-in . When the new springs go on - I think it will end up quite a bit different. Here is a quote from Loren on the baseline setup which I will try to shoot for with my new shocks & springs. BTW - "Advanced Racing Suspension" in Indianapolis is a great place to go for the springs and shocks should you chose to replace them. Guy I spoke to is named Corey and he is familiar with the WCM setup > Ultralite typical set up is -1.2-1.5 camber all the way around. Front caster 4.5-5.5. The 5.5 will be a little heavy on steering but it track very straight. I run rear toe at zero. The front toe .1 degrees toe in.

Out of curiosity why do you think the caterham and wcm are not comparable? I did a quick search and the motion ratios are apparently almost exactly what I figured the wcm to be. 0.57 front 0.89 rear Just trying to reconcile why there is such a huge difference in the recommended setups and the caterhams are running ~200 vs ~500 spring rate

Running 4.5° of caster. Good to know that the pictures don't look unusual to you. Only reason I have right now to change anything is to get a positive identification on what I am running. I took some measurements of the wire diameter number of coils, inside diameter and ran it through a sketchy calculator that told me the spring rate. That is why I am guessing they are 500 lb Could disassemble everything and get them checked, but by then I might as well replace them considering the relatively low-cost of doing so. My situation is definitely limited by driver skill. Won't really need any upgrades until the car handling becomes the bottleneck. Nice to have all of this lined up though as I do intend to keep making improvements. Appreciate your experience with the arb situation. Maybe not needed after all.

@Croc one explanation for the high rate is that this thing doesn't have any arb front or back so they ran the stiffer springs. I've heard of people fitting an ARB to it but haven't gotten any good images of how to do it. Would probably be better to run some softer springs with arbs....

Had a little issue with the math. Wheel rate is Kspring*MR^2 To solve for the rear spring, assuming 50/50 weight distribution.... I think it is Rear spring = ( <Front spring rate> * (.57^2)) / (.89^2) So for a front spring of 550 I'd get a rear spring of 225 This math scans with what Loren recommended

Yes these spring rates for the wcm are way stiffer than caterham. 2x stiffer I am using the advice from westtexass2k who ran 550/250, apparently, based on his prior posts here. I can only assume the force/motion ratios are way different for the wcm vs caterham. Goal is to set the car up for road racing. Arb, springs and dampers will all work together to address this excessive body roll but right now I'm just considering the spring rates Here are some pics of what looks like too much body roll and how I took the angles. Not totally convinced this body roll is bad but it looks a lot different from super 7 race cars that are not as rolly

Getting back to this. My car can only fit small body shocks and springs. I think that other wcm ultralights can fit bigger outer diameter springs, but if I tried that they would interfere with the rear axles. So I believe I am stuck with 1.875 id springs and small body shocks. Small body shocks get expensive quick. Here's what I am thinking based on those motion ratios above. To get the wheel rate equalized front and back. We're going to need a slightly softer spring in the back. From looking at the forums it looks like some folks have got a lot softer in the back than I would if I were going for a balanced setup. Maybe there are other reasons to go softer in the back. So .57 / .89 = .64 After lots of searching, the stiffest spring I can find is a 600 hyperco in a 1.875id x 10 inch. These seem rare! Other makes stop at about 400 lb/inch 600 * .64 = 384 The car is slightly heavier at the back so I'd go up to 400. Softer setup could be 500 / 350 Shocks - that I don't know. Qa1 suggested these but they aren't adjustable 8Q45. I think that my setup is relatively close to this at 500/500 and the qa1 small body shocks that came with the car. I don't think I will invest in any changes yet and focus on driver training. @charles5448 Hyperco part numbers for their 1.875 id 10 inch long springs. This is the best set I've found and mostly seems available from summit etc

MR for front is approximately 0.57 MR for rear is approximately 0.89 Info used: Front: 0.81 * cosine (45) = 0.57 Rear: cos(27) = 0.89 D1 - 10 7/8 D2 - 13 1/2 D1/D2 = 0.81

Motion ratios incoming! I will measure the actual distance traveled Not sure if this will be the same for all wcms but maybe a useful reference

Hello, does anyone have the motion ratios for the wcm on hand? I'm trying to be scientific about my shocks and springs setup for next year

Also you need to put some ballast in when you set the ride height. Measurements above are with no driver weight.

134mm and 99 mm taken at the blue tape marks. Note that this might not be so useful because it's measured with the street wheels which has a much larger rear vs front. 225/40/17 vs 245/40/17. Race setup is all 245/50/15 Race setup was used to set the ride height and that was a difference of 15mm front to back. Front was set first to give the oil pan enough clearance. Thank you @MV8I am now pretty sure there are cut down 500lb springs. I searched through summit racing and other places. The only 1.875 id springs that are 500 lbs are 10 inches long. My car was ran a lot lower prior to me getting it, so they probably had to cut the springs down All starting to make sense

I ran some similar calcs based on the wire size and got that too. However, looking at what qa1 sells in this size shows the lighter springs. Mine sure look like these ones https://qa1.net/springs/1-7-8-inch-id/

Tire pressure in the back? I run around 20psi. Toe in the back, camber?

I've been looking at my springs a little bit more today and they are 1 7/8 inside diameter. So I think they might be 150# !! Already have some calls into different places to get some heavier ones. I think mine are waaay too light. Thanks for asking I might not have investigated. I think your setup sounds pretty good- it's what others have had success with. What diff are you running? I have a line on a good deal for a WRX STI r180 which could be a huge upgrade. I did it recently What's your rake? My car started out with tons of rake and I leveled it out. Now it's 15mm difference front to back. Started like 40mm That setup was causing mid turn, power off oversteer