Oversteer mania...

[mazur]

Just for some background, I used to own an E36 M3 w/ coilovers and got used to the neutral (with a touch of understeer) handling...considering I'm not mashing the gas.

I now own an E30 (and loving it) with 450/750 coilovers with about 3* F and 2.5* rear camber. The problem I have been having at the track is that I seem to oversteer excessively. The car just starts stepping out mid corner when most of the car's weight is shifted.

I was thinking that perhaps to shift the weight distribution rear-ward and add about 1* camber, I could try lowering the rear to the max. Though I'm not sure if this is the best fix. Would removing the rear sway bar benefit me?

I know wider tires would be the best solution, but due to backorders on good tires in 245/45/16, and me needing tires at the time, I had to settle with a set of 225's.

[1991 318is]

Sedans work better with more rear weight up to 55%. That's hard to get on an E30 but the more the better. Is that the car in the sig photo? With an S50? The usual solution is to soften up the rear.

[JeffRR]

Like 318i said you've gotta shift the roll stiffness forward, if its pulling the rear bar or going stiffer in front. I'd rather add front bar, its nice to keep the roll stiffness high to reduce the transition times. If your having trouble putting power down then you need to look at shocks, going to assume that your running a stock diff.

If you can shift some weight, that's a great idea, but not usually easily accomplished in a short amount of time.

I'm thinking that the camber shouldn't be an issue at -2.5deg rear, but its hard to tell unless your taking temps ideally. If you run too much camber your going to have issues putting power down, especially with a S50. Tire temps would be great but once again might not be practical in your situation.

Watch the ride height, you don't want to lower too much where your get into a bottoming condition. I think its pretty common for modded production cars to run out of travel, even during steady state cornering (mid-corner) with only body roll not even taking into account road surface imperfection.

[iflytii]

What sway bars are you running? Like others have said, stiffen the front or soften the rear. Without knowing exactly what you are running for says, my gut tells me your 750# springs are the culprit. With those springs, you could likely remove the rear sway and fix a lot of your oversteering problems.

How low does your car sit now? Lowering the car a tad in back can help but better advice would be to find someone with a set of scales and corner weigh your car. That takes all the mystery out of your setup and gives you a baseline to adjust against if you want further adjustments.

[mazur]

Thanks for the suggestions guys.

I have the C3M coilovers, so most will know that comes with the Konis. I also have stock sways and a 3.73 LSD.

I guess I'll try removing the rear sway and try running the rear shocks softer with the front a little stiffer. Putting the power down is a joke. With the short gearing of the 3.73 and ZF tranny and my skinny tires, I don't see that happening anytime soon, lol

I have no idea on tire temps...need to get myself a perometer.

Watch the ride height, you don't want to lower too much where your get into a bottoming condition. I think its pretty common for modded production cars to run out of travel, even during steady state cornering (mid-corner) with only body roll not even taking into account road surface imperfection.

I'm actually testing it out at full low right now and am not bottoming out at all. Though the camber seems a little extreme (looks like it'd be 4*, lol) and looks a little funny. I havn't really been able to tell if it has helped since I have no places around my house to simulate a racing condition.

Pic below shows where I had my ride height at. Front is lowered to where LCA are parallel with the ground. I'm planning on doing corner weighing in near future. Just looking for a shop to do it or someone that'll rent me out some scales.

[matt]

Pull your rear bar NOW.

You are running a kickass setup for an e30 with NO rear bar.

[matt]

PS: Wider tires are only the best solution if you're overheating the tires you have.

[BimmerToad]

Try increasing the size of your front bar, either through mounting the stock bar to the strut (ala M3) or through a larger bar.

IMO I would keep the rear sway on. You would probably have to increase your spring rates more to be stiff enough to remove the rear bar.

I used to think a small / no rear bar would help put power down out of corners, but that's a task for a properly built LSD

[golde30]

i vote for pulling the rear bar. Erik325i ran his e30 on the track with same exact suspension, minus the rear bar, and he loved it.

[matt]

Try increasing the size of your front bar, either through mounting the stock bar to the strut (ala M3) or through a larger bar.

IMO I would keep the rear sway on. You would probably have to increase your spring rates more to be stiff enough to remove the rear bar.

I used to think a small / no rear bar would help put power down out of corners, but that's a task for a properly built LSD

More rear grip still helps. And who has the money for a properly built LSD?

750 is plenty enough spring rate to run with no rear bar.

[surebimmer]

Is this throttle oversteer? Are you running street tires? I think the 3.73 rear end with the ZF isn't helping your oversteer.

I have the same setup 450/750 Ground control with an s52 with a -3 camber front and rear. With a RD rear sway bar set on soft with 3.25 rear end and it seems to be balanced very well.

[mazur]

Haha...I guess I'll be pulling that bar tommorrow after school.

The front swaybar already ties into the strut via mount that comes with the C3M kit, so got that covered.



As for tire size, I truly believe it'll help. I remember what a difference it was to go from 235's to 245's on my E36. Part of the problem is also that, like Azenis, the Hankooks heat up too quickly on a road course.

[mazur]

Is this throttle oversteer? Are you running street tires? I think the 3.73 rear end with the ZF isn't helping your oversteer.

I have the same setup 450/750 Ground control with an s52 with a -3 camber front and rear. With a RD rear sway bar set on soft with 3.25 rear end and it seems to be balanced very well.

I'm getting oversteer just by cornering.

I would never mention throttle oversteer as being an oversteer problem, but as a problem putting the power down.

The prior isn't helping the latter.:p


What tire setup are you running?

And yah, I really do need a 3.25...I use 2nd gear when I leave intersections, lol

[jlevie]

I have a sneaking suspicion that your rear springs are too stiff in relation to the front springs. But the first thing I'd want to see would be what the corner weights are.

[JeffRR]

Oh ya, with that ZF and the 3.73 your going to have trouble putting down power no matter what you do with the roll stiffness balance (bar/spring tuning). Pulling the rear bar is going in the right direction, and its easy to do at the track in-between sessions. That will help your mid-corner OS and exit OS. Like I said before ideally you'd like to keep the rear bar and balance with more front but that's $$, pulling the bar is a cheap and easy fix.


As far as the shocks, assuming that they are SA koni's, its a rebound adjustment only and most likely will not have an effect on corner exit. If you had a compression adjustment you'd soft'n the compression bleed (low speed).

I'm in the same boat with the ZF box and the 3.73, I'm still finishing my car but at 1st I'll be driving her with the 3.73. Eventually I'll drop in a 2.93~3.25, but I want to get her running 1st.