Jump to content
HybridZ

Road race suspension setup questions


Guest 75Turbo

Recommended Posts

Guest 75Turbo

I'm wondering what basic suspension setups for road racing/ open-track events people run. My current setup is...

F Springs 350#

R springs 400#

suspension techniques non adj swaybars 1-1/8F 7/8R

Very old (currently replacing) tokico shocks set to #5 both ends.

Hoosier 225/50/15 tires

F Camber -2.5 R Camber-1.5 0 Toe

Approx 330HP @ 2300lbs

 

My complaint is very poor brake performance (bias ok, just locks easily) and what seems like excessive corner exit understeer (under power) and very twitchy rear end under trail braking.

 

I've noticed that John Coffee runs several seconds a lap faster at Willow Springs than I do (Avg for me is 1:36) . Assuming our driving abilities are simular, I'm wondering how to approach his times. (I really want to beat the Z06's at 1:34!)

 

All ideas/theories are welcome.

Link to comment
Share on other sites

My first guess is that your spring rates are too high especially for Tokico Illuminas. Those shocks are at their rebound control limit with spring rates at 300#. You're also running a big front anti-roll bar and need more camber all the way around.

 

Does your car have a roll cage or a roll bar?

 

FYI... 1:34 is the ITS 240Z lap record at WSIR. That's with 200hp and 225/50-14 tires in a 2,435lb car.

 

FYI2... although I would love to take the credit, the 1:29s turned at WSIR were done with Bryan Lampe driving. I've yet to get a timed lap at WSIR in my car as currently setup. I'm traditionally 3 to 5 seconds a lap slower then Bryan at that track, but maybe I've learned something.

Link to comment
Share on other sites

Guest 75Turbo

John, thanks for the reply. My car does have a roll cage although is doesnt tie into the front strut towers (bad design on my homemade intake).

 

When I first got the car on the track it had 300# F springs and 250# rear springs which resulted in massive understeer everywhere and what felt like excessive dive/squat when braking/accelerating. If I stick with the higher spring rates is there a shock you would recommend using.... I'd really like to run ground control shocks, but the $1600 is a little hard to swallow. (actually convincing the wife is the hard part)

 

What spring rates/ roll bars/ tires sizes and camber are you running (if you'll share that info)?

 

Lastly, maybe I should get Bryan to drive my car! (jk)

Link to comment
Share on other sites

If you want to stay with those rates your cheapest solution is Koni single or double adjustables with some custom valving. Call Erik Messley at 714-713-9096 for info.

 

I'm running 275# front and 300# rear springs with Penske triple adjustable 8760s. My car has a roll bar with some good bracing triangulating the front strut towers. I would recommend those same spring rates as the max for the Tokicos. What size anti-roll bars I run is misleading because of the Penske shocks.

 

Try to get 3 to 3.2 degrees negative camber in front and 2.5 to 3 degrees negative in the rear along with about 1/8" toe-out in front and 1/16" toe-in in rear. You'll also want to run a slightly asymetrical alignment (camber and corner weights) for WSIR. Remember, WSIR is mostly fast right turns.

 

I swap tires depending on how much money I've got and what's the best set on the shelves. Normally Kumho V700 Victoracer 265/45-16 or Hoosier R/A3S03 in 275/45-16, both on 10" wide wheels.

Link to comment
Share on other sites

Guest 75Turbo

Thanks for the info. You have one of the fastest Z's (barring huge box flared cars) that I've heard of. Honestly, I was guessing your spring rates were going to be in the 400-500# range. I'll look into the Koni's and experiment with some spring rates... obviously lower rates work great.

 

Thanks again for the info, Nathan.

Link to comment
Share on other sites

Guest MistressMotorsports

Great, another potential Messley tuned car in the works. Those Porsche guys are going to be really pissed off.

 

75T, I also have a road race car, somewhat similar to John C's in that we both make a touch over 300 hp and that Erik Messley tunes our cars. My setup is similar to John's except I have the 275 pound springs in back and the 300's up front, which is pretty wierd but works in my car. I'm running more conventional (cheaper) Koni Sport inserts, and a 1 inch adjustable front bar, 3/4 inch rear bar. Although John has big mama 10 inch wheels and I only have 225/60/14 tires on 14x7 inch wheels, we both run the approx 3 degrees camber that John recommended and similar toe.

 

The corner exit understeer and twitchiness under braking may be more shock related than anything else. Is the car predictable and neutral in steady state corners? When I initally took my car to Willow Springs, I was also getting on throttle understeer, especially exiting turn 2. A bit less rebound in the front shocks cured it like magic.

 

Definitely give Erik a call and talk to him, he is pretty much the god of west coast Z setups. I think running the 1:29's that Brian did in John's car is going to be difficult with only 225 mm of rubber (I have the same problem/excuse), but :31 and :32 should be do-able. Basically figure and ITS time minus a couple seconds for power.

 

BTW, what groups do you run with? Are you racing or open tracking? I've been racing with HSR, TCRA, and some others. It would be nice to have other Z's around to play with.

 

Mike

Link to comment
Share on other sites

Guest 75Turbo

John C... thanks for the referal to Messley! He was incredably helpful and very nice to talk to.

 

MistressMotorsports... thanks for your reply. I'm going to run the Koni singal adjustable (8216?) inserts that Messley recommends for people on a budget. (is there such a thing as a budget race car?) I'll use 300# front and 330# rear springs just because I have them lying around. Slightly stiffer than what Erik reccomends, but at least in the ballpark. I'm also going to have my roll cage tied into the front strut towers after he told me how much flex goes on up there. (I can almost taste the 1:32's!!) As far as who I run with... NASA HPDE4 (open track - time trial). Normally I try to make all of the NASA (so-cal) events, but my wife and I bought a house earlier in the year and its been tough between working on the house, working on the race car, spending time with the family and finding money for everything. I'm going to miss the next event (car wont be ready) but will hopefully make it to the rest of them this year. It would be awesome to meet and run with you guys!

 

Thanks for your replies, Nathan

 

Almost forgot... yes the car was basically neutral in most corners and predictable although it would get serious oversteer from just breathing the throttle and a strong push when accelerating. More so than other cars (not Z's) that I've been in.

Link to comment
Share on other sites

Guest Willow Warrior

Ditto on the Spring rate recommendations. I am 300rear, 275 front. With the Illumina shocks. Adjustable anti-roll bars. Bone stock motor that wont blow up. 150hp, I think. I ran 1:38 at Willow Springs in March. Could go faster if somebody has 14X7 Panasports for sale. Grabbing more sack also helps.

 

Nathan, Coffey, Eckhaus, let's all get together. Perhaps at Streets of Willow in October? We'll run the long bowl turns too!

 

Stephen

Link to comment
Share on other sites

Is that the Cobra U thing? I can probably do that. Sam Williamson, John Williams, and Brian Spadano are also talking about running it. That would give us 6 Zs out there. Stephen, your Cobra customers are gonna be pissed.

Link to comment
Share on other sites

Guest Willow Warrior

I have Streets of Willow on Friday Oct 3rd.

 

HSR-West is racing on the big track Sat, Sun.

 

This means it's a 3-day weekend of crazy stupid fast at Willow! Spectators are welcome..

 

Stephen

Link to comment
Share on other sites

You mean "Mr. Tear A Splitter Off Each Session " Messley? You mean "Pound the Curbs and Rip Out Wheel Well Liners" Erik Messley? You mean "Go Off in 9 and Keep My Foot In It 'Cuz I Got a Good Lap Going" Erik Messley?

Link to comment
Share on other sites

You mean "Mr. Tear A Splitter Off Each Session " Messley? You mean "Pound the Curbs and Rip Out Wheel Well Liners" Erik Messley? You mean "Go Off in 9 and Keep My Foot In It 'Cuz I Got a Good Lap Going" Erik Messley?

 

ROTFLMAO!!

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...