Left Turns Suck - Need Inputs 335

[porschelou]

Need some input. Our 86 e30 race car ( M30 conversion) gets very loose during left hand turns. The car oversteers without much help with the throttle. Right hand turn are awesome - the car sticks and goes - no issues. We race at CMP / VIR and all 5 drivers experience the same issue so it isn't just my driving style.

It has IE Stage 3 springs, Sport shocks/struts, full Mad Max aero kit , 3.73lsd , with many alignment jobs. Factory rear sway and Convert front sway. We run the fronts at -3 degrees and I think the rears are around -2 degrees (we don't have camber kit on the a-arms).

Any ideas why the left turns would get loose vs right hand??

Getting ready to put a 4.10 LSD in for the next race - so the torque in the corners will be crazy. Would having 40% lockup help vs. factory??

Thanks

[Jb325is]

that looks crazy... Corner weights? Has the car ever been scaled?

[porschelou]

Before we put in the 3.5L the front left was 200lbs heavier
The car acts the same with either motor
We put the 3.5 in position 3 which keeps the CG almost the same as the
2.7L
No weights

[nrubenstein]

My general observation with every BMW that I've ever driven is that power biases to the right rear.

[seatown88]

that looks crazy... Corner weights? Has the car ever been scaled?

This.

I would be very interested to see what your corner weights are, I imagine that your cross weights are off causing the instability in left hand turns

[e30pq]

It sounds like a suspension issue.

Check your rear subframe mounts.
What's the condition of your rear shocks?
What about your rear swaybar? Check your swaybar mounts.

[L8 apexr]

Corner weight(with driver) should be your 1st step followed by a baseline alignment then retest.Seems to me the corner weight must be WAY off if it turns right better than left as the car will inherently be left side heavy.Another thing is sway bar preload,make sure the bars are unhooked for corner weighting,need adjustable end links for sure to hook them back up neutral.
Ony chance of mismatching springs somehow with one rear spring softer/stiffer than the other?.

[e30pq]

It sounds like a suspension issue.

Check your rear subframe mounts.
What's the condition of your rear shocks?
What about your rear swaybar? Check your swaybar mounts.

I don't have corner scales so I personally wouldn't reach for this as a first step.

I do however have a floor jack and some jack stands which is why I would take that path first.

Whatever is easiest for you.

[L8 apexr]

Its a scale problem,pretty much all other issues will cause problems left or right turns equally.

[e30pq]

Yes and no.

I had a right rear subframe bushing issue that only showed itself on left hand turns.

[unevolved]

Cornerweights are huge. At the very least, measure ride height from ground to top of fenders, or SOMETHING and make sure you're not way off. Cornerweights being way off could do exactly what you're describing. It's happened to me.

[porschelou]

Thanks for the reply's -
- Sounds like the consensus is our corner weights are way off.
- We don't have adjustable sway bar end links. Since the car has IE springs we do have preload on the sway bars.
- Sway bars should be neutral (no preload) correct? I'm not allowed to run adj endlinks but can cut / weld the factory set to length them.
-The sport shocks are older but I have used a new set of street shocks and it didnt' feel any better.

I'll get the car scaled before the next race. Question - if I have a corner that is way off it sounds like I should put weight in the opposite corner to balance? Right?

Thanks for the help.

[nrubenstein]

Thanks for the reply's -
- Sounds like the consensus is our corner weights are way off.
- We don't have adjustable sway bar end links. Since the car has IE springs we do have preload on the sway bars.
- Sway bars should be neutral (no preload) correct? I'm not allowed to run adj endlinks but can cut / weld the factory set to length them.
-The sport shocks are older but I have used a new set of street shocks and it didnt' feel any better.

I'll get the car scaled before the next race. Question - if I have a corner that is way off it sounds like I should put weight in the opposite corner to balance? Right?

Thanks for the help.

You can adjust with spring pads.

[porschelou]

I saw that (I think it was) IE sells different thickness coil spring pads. I'm assuming I can stack those up the help shift the weight around. Those will work fine in the rear.

The fronts are captured by the strut housing. How do you adjust those?

[nrubenstein]

I saw that (I think it was) IE sells different thickness coil spring pads. I'm assuming I can stack those up the help shift the weight around. Those will work fine in the rear.

The fronts are captured by the strut housing. How do you adjust those?

There are spring pads available for the front, or just remove them. You *may* be able to do all the adjustment with the rears, spending on how far off the car it. Increase ride height to add weight. Decrease to take it away. Remember that the right rear and left front are linked and vice versa.