LS1 NA suspension problems
 

So as some may remember I am race preparing a 94 with a LS1/T56/8.8. The car has been on jackstands for a few months now due to a lot of work on the suspension and drivetrain. The good news is as of this afternoon the car is back on the ground and running under its own power. The bad news is I have ground clearance problems.

Current suspension setup related stuff...
- I have the racing concepts LS1 conversion kit which has a very low k-member and a low differential mount. Good for CG, bad for ground clearance.
- Full Energy Suspension poly bushings installed
- Tein SS shocks with 8F 6R springs
- 15"x8" 6ULs with Nitto NT01 225/45
- Corrado front rotors, sport brake rear rotors
- Carbotech XP10 front, XP8 rear
- Wilwood rear proportioning valve
- Will be adding large front splitter and rear wing (large APR dual element)
- This is a track oriented car so street ride quality is of little concern.
EDIT: Forgot to mention... RB Hollow front sway bar with 949 adjustable end links, stock NA rear bar.

Even though the ride height is set a tad low, like maybe only 1/4"-1/2" low, I only have 2" of chassis ground clearance in the back (diff housing) and less than 2" in the front (k-member). This is with Tein SS. That is way too little IMO. I am at risk of scraping the chassis and unloading the suspension in the middle of a corner. No thanks. And this is with no aero in place yet so downforce will only make it worse. And we do not exactly run on pool table smooth tracks around here.

The problem is not so much the Tein SS, but the fact that the k-member and diff clearance are quite a bit lower than stock as it is. It already was having some clearance issues with the stock length shocks I just removed (KYB GR2). The Tein setup lowers the car quite a bit so it just worsened the problem.

I'll be looking into suspension options this week. Off the top of my head...
1. A simple option is to put some very stiff springs in it, raise the preload, and hope I do not get spring lock. Even just slightly too much preload will cause spring lock. I saw this on my NB with the Tein Basics, very similar to the SS. Just 1/4"-1/2" too much ride height and the springs were binding. I know it was spring binding BTW.
2. An expensive option is to get some ride height adjustable shocks like Tein Flex. Cha-ching... The Tein SS I have now are in good shape so I can recoup some of the cost by selling them. Either that or put them on my NB Turbo car and sell my NB Tein Basics, also in good shape.
3. I wonder if longer, stiffer rate springs would work? Hmmm...
4. I suppose I could use spacer blocks on top of the top hats but that seems klugey to me.

Thoughts?

Raise it up, buy flares, and run 17x9s w/ 275/40/17s?

I got the idea for spring spacers off FCM's site. Dunno if it'll work with your Teins, but worth a shot. He emailed me the drawings even. Fronts are UHMW .6", rears are aluminum .66". Could be a cheap temporary fix if you have access to a lathe.

Someone else suggested this to me too. But, unless I am thinking about this wrong, would this not do the same thing as adjusting the spring perch? I still have a lot of adjustment range left but am concerned about the inevitable spring bind.

Tempting, but no. I think the Tein Flex option would be lighter and cheaper :)

meh, sell me your tein ss and buy flexes...

See I don't know anything about fancy suspension. So yes, it would do the same thing as raising the perches if I'm not mistaken. Your next option that does more or less the same thing is to put a spacer between the body and top hat. FCM had those on their site too. Essentially like those squeak reducing gaskets, but ~1/4" thick.

Agreed I think that would work. In fact that is what I meant by option #4. All I would need to do other than fab the spacers is lengthen the bolts that attach the top hats to the chassis. That or drill new holes and do an offset or rotation.

buy some 7'' Qa1 springs in the rate of your choice. maybe 550/400 or something. that'll prolly keep you off the chassis, and you shouldn't have to worry about spring bind. plus it would be cheap to boot. i think i paid $36 per spring from summit racing.

I think that is worthy of serious consideration. All else being equal, longer springs should allow for more travel before they bind. Even before raising the ride height the preload adjusters (perches) have room for springs that are at least 1-2" longer. I forgot springs are that cheap at Summit, and I don't HAVE to use Tein springs as long as they fit. I'll check it out.

EDIT: Well, scratch that. QA1 does not make a 70mm (~2.75") i.d. spring which is what I need for the Teins. I might as well get the Tein springs. 949 sells them for $60 each and I can get them in 7" or 8" length. The ones I have now are 6" length. I foresee a call to 949 tomorrow.

I wouldn't be horribly concerned about on track at that height, but if you took an off track excursion, or went over a curbing....OUCH!

Yeah it sounds pretty ugly when I hit a bump too hard and the k-member bottoms out. BAM! Plus the right side exhaust down pipe is already beat up. I need to redo it actually.

I think at the very least I should probably get some stiff springs and run it in what we called go-kart mode in my FSAE days. I considered doing this before but Emilio (949) talked me out of it saying the SS did not have enough damping to control the stiffer springs.

I test fit my 7" 2.5" ID QA1s on my SS the other day, and they work. Simply don't use the upper spring locator (not needed). The perches have a rubber ring on them that will conform to the smaller diameter, and they fit just fine on the metal part of the perch.

Let me know if you want me to take pics.

Am I missing something? My SS are adjustable and with stock springs can actually raise the car over stock height.

OH REALLY? So the upper end of the spring locates OK without the gold anodized piece? Hmmm... Thanks for the info. Looks like the QA1 option is back on the table. I need to go look at the FCM table again and calculate my spring rate stagger. IIRC I think something like 700F/450R or 550F/325R might be in order. Hell at $36 a spring maybe I will get a few sets.

Picts would be cool if you do not mind. I think I know what you mean but it would not hurt to get a look at it.

So I think this is the deal. The stock springs are a lot longer than the springs that come with the Tein kits and thus have more travel .So they do not bind as early and you can run more ride height and still hit the bumpstops first.

I've yet to road test it due to current non-start problems, but I've run many other setups with 2.5" springs sans locator. It might make a little more noise, but I'd never know.

I'll take pics, and I'll also check to see if the Tein spring locator could be machined down for the 2.5" springs if you really wanted to use one. Otherwise find someone with an eBay kit with the plastic locators they didn't use.

So with my setup described above I went to the FCM worksheet and came up with a 600F/350R setup on the springs with a FRC of about 59.5% which is close to the 'ideal' of 60%. 650F/350R moves the FRC to about 61%. 550/325 is about 60%. Neutral to a bit of understeer is OK as I should be able to induce some throttle oversteer with the LS1 :giggle:

So assuming the QA1 springs can be made to work, I can get those rates in a 7" length QA1 spring at $36 a piece from Summit.

Any comments from the track suspension users? Sav? Emilio?

I don't know about track use, but can the Tein SS dampers handle a 200lb/in increase in spring rates?

Yeah that is definitely pushing it. I might have to go with the 550/300 setup instead, maybe even a 500/300 which is still OK on FRC with a 12mm rear sway. If not, that would put me back into selling these and getting the Flex setup. I have not been able to find any used Flex sets though and the new ones are pricey even from Emilio.