Step 1: Buy the 'big' stuff.

Let's see what we've got here...

Hmm - Front Koni coil over suspension with 400lb springs.

What else have we got?

Koni rears to match the fronts.

Anything else? Glad you asked:

31mm HOLLOW torsion bars (30mm effective).

Thanks to Nader F. (Rennlist member) for contacting me and selling me his year old suspension, after hearing of my upgrade needs. Good price for a suspension that will definately improve my car's handling characteristics on the track.

Say goodbye to this (ie body lean!):



-Z-man.

 

Glad you finally got a solution. I am sure the new suspesion will do well by you .... for a little while ;-) Have fun with those t-bars, but you'll git her done.

 

Nice!

Saw a pic on pelican of your car braking on the track. Bumper seemed to scrape the ground..cool pic..! Hopefully that won't happen anymore

 

31mm t bars are a good match for 400lb front springs??
What's the plan for front geometry correction after lowering??
Cool setup, i'm going to get 29mm t-bars for mine pretty soon.... that's going to be a fun job.....
Vlad.

 

Z - When are you doing the installation? Are you doing yourself or having it installed?

 

Purrfect... remember that 31mm hollow is 30mm effective. The 400/30 and 350/30 are the most popular setups around.

 

Good deal, Z. Now get to making them a little prettier... chop the lower perch and pick a color

 

Yellow is known to reduce lap times by 25%.

And take Skip's advice--remove the lower perch, it will make adjusting the collar much easier.

 

please post on how you feel about it and the rates. I will be going with Koni's and GC's soon I hope.

 

Vaino -
Al P has volunteered to help with the installation. Hopefully, I'll be getting all the other stuff necessary (bushings, spherical bearings...etc) within a month, and installing everything in March, so I'll be ready for Pocono & Lime Rock in April.

You mean this?


Well, my plan is to get the ball joints with the extended pivot rod (?) so that with the car lowered, it won't rub against the A-arms. I have two year old A-arms in the car now, so I figure I can run a season with the new ball joint and then spend the $$ on the Charlie Arms.

That is my understanding. If I find there's too much understeer in the setup, I can always adjust my Welt rear sway bar a little, or if I can't dial it out that way, I can dump down to a less-stiff spring - like a 350lb unit. Balance front the rear is more important than overall stiffness, IMHO.

Eyal - I'll let you know how the car behaves in April, after playing on the track!

-Z-man.

 

I recently did the GC coilover setup on my Konis. Thanks to Jason @ Paragon, everything worked out great! I went with 400# fronts. I have a crappy setup in the rear, which is 968 M030 koni's and 200# springs. The rear needs to be reindexed as it sits too high, so the car doesn't feel 100% right. After trying to skate around it, I'm going to just go with a 30mm rear torsion bar setup and ditch the rear springs.

I highly recommend running 350-400# fronts if you don't mind a slightly stiff ride. To me, it rides better than stock as I really dislike the unsettled feeling of soft stock suspension. Now the car is much more planted and has less body roll. Though, with the fronts set to ~1 turn from full soft, it rides very nice. It's still a little bumpy on rough surfaces. Though on long, rolling, uneven surfaces it rides very smoothly. IMO, there isn't any point doing a GC conversion unless you run at least 300# rates. 250# and less are for kids.

For an example of "stiffness", prior to this I had regular Koni yellows with Weltmeister 250# springs. With these set to full stiff, the car felt overly bouncy and stiff, yet still had the bodyroll and handling characteristics of slightly upgraded springs (a nominal improvement at best IMO). This stiffness seemed unnecessary to me, considering the car still did not handle all that spectacular. Now, with 400# springs and set to full soft, the car feels firm but compliant, and is at least as soft as the 250# set to full soft.

 

With this description, it looks like I may be considering 450F/500R give or take about 50-100 pd feet. (I have yet to research) With the OTS valving on the konis hold up fine? If your running soft with 400 pd springs, it seems like its fine.
Eyal

 

Eh, it's not exactly "soft" per se. It's decently stiff and feels like any 240sx with coilovers I've ever been in. Although, many of the coilover 240sx's I've been in ride much smoother when set at full soft due to more optimal valving for the specfic spring rates. Though, if I set it to full stiff it's plenty stiff for the street. After seeing the pics you posted, it looks like you have TONS of bodyroll and nosedive. Let me assure you, 400# fronts will completely solve this. I'm still on stock sways and there is very little body roll now, and no noticeable nosedive. If you do much street driving, it's really not necessary to go stiffer than 400# fronts. However, if you are doing lots of track work, alot of this won't apply as it really depends on what type of track use.

I wouldn't go much over 400# on our cars, for regular street use. From everything I understand, the stock Koni yellow valving is optimal for up to ~400# rates. After that, I'm not sure if it wears them out more quickly, but it's not supposed to be optimal valving performance wise at least. I daily drive my car, and the roads here can get pretty bad so having the stiffest suspension isn't the best idea.

Eyal 951, just to give you some basics so you don't have to research too much, rear coilover springs when used with torsion bars are only ~56% effective. The front springs are supposedly ~90% effective. What you want to do is calculate the effective wheel rate. All you do is multiply the rate by either .9 or .56 (whether it's front or rear). With a 400# front, that should equal ~360# front wheel rate. After lots of research, I'm basing my setup off the rates used by many of the Turbo Cup cars. I believe they used progressive 410# front springs and ~30mm torsion bars (335#). If you calculate that you get a 369# front and 335# rear wheel rate. If you have rear coilovers with stock torsion bars (126# for a non S 951), you could run a 375# rear spring to come up with a 336# rear wheel rate. A 600# spring also equals a 336# rear wheel rate if you're not using torsion bars. With upgraded sways, those rates should make for a nice, fairly neutral setup. I figure, since the turbo cup cars used these rates, add ~300-400lbs of weight for a street car and those same rates should be fairly road compliant. Rates are subjective though, and it all depends on how you like your car to drive (over/understeer,etc).

To give you an example, I'm only using 200# rear springs w/ the stock torsion bars right now. This comes out to a 360# frt wheel rate and 238# rear wheel rate. Let me just say that it understeers ALOT! If you run 400# fronts, I'd try to go with somewhere between a 280-340# rear wheel rate. The lower end of that range should give you a decent amount of understeer, while the upper end should give you a little oversteer at the limit.

Everything I mentioned is just what I understand from my research. If my math or info is incorrect, please correct me.

 

Zoltan,
I'm really glad you finally on your way to getting your set up. Keep the pics and reports coming. When you guys do the t-bars, use Chuck Moreland's write up. ps DON"T tighten everything down until it all fits right. I just got done with all of this. Not too bad with enough ground clearance, and a couple of jacks...but I didn't have to re-index. Nice stuff! Good luck. E

 

Z-man - nice setup. you'll love the reduced body roll and improved steering response, especially with your long history of track experience.

porschefile's done his research, and everything he posted agrees with what i've seen. the OTS konis are good up to 400lb, from what i've seen. with 350lb springs on my 944S, it felt stiff and bouncy over larger bumps, but if you keep the struts set at about halfway, it's tolerable

BTW, did you guys know GC is now offering a complete strut assembly for 944s?

http://www.ground-control-store.com/...hp/II=672/CA=6

I'm buying their setup for my M3, but I think they may be on to something here