Last time at the track, it seemed like maybe the car was a little too tail-happy, maybe. Right now I'm just thinking about options. Car has the factory front bar for a TC (IIRC, 1.31") and the factory rear bar for a Cobra ('03-'04). I'd like to compensate by increasing grip in the front, instead of decreasing in the rear. Also, I'm planning on going with softer springs (right now 350 lb/in & 550 lb/in f/r), hopefully something closer to a rate that equates to the FMS springs (~250 lb/in in front?) If I go with 250s up front, that equals about 400 lb/in in the rear, if staying proportional to the current combination.
Questions:
Did the factory go to a smaller rear bar for the later year Cobras?
Is there a bigger front bar that will fit, factory or aftermarket?
Any suggestions on a different spring rate combination?
any ideas on the a/s bar?
If the car is tail happy wouldnt you want More traction in the rear??? not the front???? Then again, i dont go to tracks (mainly cause of the lack of them)........
AFAIK, all IRS cobras had the same 1" rear sta-bar.
i think steeda makes a 1 3/8" front bar. would be just a bit larger than your current 1 5/16"
250lbs coils sounds really soft for a car you open track. why are you thinkin about runnin softer springs?
I know this isn't super helpful in answering your suspension questions, but I would corner weigh the car and see what could be done to optimize corner weights. Next, (assuming near optimal suspension setup) I would see how much +/- steer can be found by playing within the recommended pressure range of your tires. once the benefit of these two concepts has been realized (assuming they aren't already) I would then go forth with more mods.
ahhh gumby made some sense of it for me.......
Gumby,
I talked with somebody at MM this week, somebody more knowledgable than when I was putting things together. It appears that I don't have enough suspension travel, especially droop, and that's the reason for the rough ride, not the spring rates.
I'm going to try getting things adjusted this week, but the solution may require some work. There's not much room to move the coilovers downward. I was thinking about slotting the strut mounting points to move the top of the spindle away from the strut, then using the CC plates to set the camber properly. That might provide enough clearance for the tires. I won't know until I get under there and measure.
Question: will that screw up the suspension geometry?
Question: is there another way to get more travel? Maybe some adapter plates to locate the strut higher relative to the spindle?
massCougarxr7,
You buttstuffyzed the problem correctly, if the car is tail happy, then the rear is (probably) stiffer than the front. The important thing here is the relative nature. The ways to compensate for the problem are
a) increase traction in the rear (I'm considering widening the rears)
b) soften the rear
b) stiffen the front
ASSuming the rear isn't too stiff, then cornering gains could be gotten by stiffening the front, or increasing traction in the rear.
Somebody can step in here if I've gotten something wrong.
too little droop in front? fox mustang struts i assume?
from my understanding, keeping the most positive relationship between the spindle and the strut will improve your geometry. therefore, its better to adjust at the top and not slot the strut ears for negative camber. i dont know if going the other way, more positive at the bottom, would fall under "more is better" or not. ive never seen a car that had enough adjustment at the top to try it.
what is your ride height?
Yup, because of the spindles. And because they're later versions, they actually reduce the travel more than the older ones do (spindle mounts relatively higher).
The problem isn't the ride height (I guess about 5"), but the wheel/tire position to the strut. There isn't much room to drop the lower spring perch. There is no way to fit the coilover between the strut and tire.
And yes, you're right, those ears don't leave much room to operate.
Perhaps you're getting some odd rear steer?
We did some mods @ KB's to allow for better rear "bump steer" adjustments.
Gumby, your IRS rear has the modified inner tie rod mounts, correct?
that is a good point as well. yes, mine does have the modded inner mounts.
skidoo, have you measured your rear bumpsteer?
I have not measured it. The alignment shop might have, I'll check with them, see if they remember.
I do have the adj tie rod ends and the a/s bar end links.
What did ya'll do to modify the inner mounts?
Added some more adjustment down. The brackets were widened by something like 3/4" (It's been at least 8 years, so I don't remember the exact measurement) to allow for more room to adjust.
We replaced inner stock tie rod end with a std spherical piece. (The rod was also replaced with a new rod as well, I think I touch longer as the aftermarket rod ends were shorter than the stockers)
I don't suppose you have a visual aid?
these might help. they are the best i have on hand.
here you can see the mounting point for the inner tie rod end. notice the seam, and the new material that has been added to the lower portion
(http://i25.photobucket.com/albums/c73/gmby23/87%20turbocoupe/DSC00732.jpg)
and here you can see the heim, spacer stack above the heim, and the new tie rod.
(http://i25.photobucket.com/albums/c73/gmby23/87%20turbocoupe/DSC00736.jpg)
MM offers a height adjustable outer that can help, but AFAIK KB was the only one to offer the modifications to the inner pick up point.
ummb... does t3skidoo have an IRS too???
http://foxtbirdcougarforums.com/showthread.php?t=19556
You miss stuff when your not around.
While I don't know much about the IRS, you talked about your front droop.
Do you have camber/caster plates yet? The Maximum Motorsports plates gives you spacers to where you can move the strut up and down in relation to the plates. While it may not be much, it could be something that would help with your front droop.
Either way, they wont hurt.
Yep... I've been living under a rock.
I really used to look forward to your threads. I really liked dark thunder. When I first joined in the ezboard days, you and Dare used to make my day.
Responses to posts -
Mods (that I can remember)
Front - CC plates, 'long' control arms - relocated inboard ~.3/4", SN95 spindles, brakes, (Koni single adj) struts, coil-overs, MN12 inner/outer tie rods.
Rear - IRS, MM bushings and a/s end links, coil-overs, bilsteins w/ extensions
Yoko AVS on 18x9s all around, 265-35s on +12 offset /275-35s on +40 offset
1) The alignment shop didn't check rear bump steer when they aligned the car.
2) There's more room between the strut and tire than I previously thought, so front suspension travel is fixed now, and the ride seems to be better - will know after I get it aligned next time.
3) another thought occurred, first time at the track, there was just a touch of oversteer. later, there seemed to be more. The only real change was tire wear, the fronts are worn much more than the rears. I'm wondering if increased front grip isn't causing the rear to seem loose?
I REALLY hope your having your alignment done by a shop who knows how to set up for road racing and not just joe shmoe's tire shack...lol. Can you post up pics of the front tire wear you were talking about? Anything irregular about the wear pattern? Also, what were your alignment angles set to during your last alignment?
Good luck,
Don
The alignment shop regularly does a/x and road race cars. That said, it does look like they could have put a bit more neg camber in the front.
Tires - check here (http://"http://www.foxtbirdcougarforums.com/showthread.php?t=23531")
Inner links question - Is it as "simple" as getting a longer link or does there need to be a different mounting point?