Chassis setup help? Corner weights

My car tends to spin the inner rear tire when coming out of right hand corners; I'm wondering if changing the loading on the rear tires might help the situation.

Most resources on this topic here in america talk about this in dirt circle track cars that only turn left and have staggered rear tires (the right rear is actually bigger than the left rear)... i dont think much of that information applies to a road car so getting advice on this topic has been difficult.

The car is an old f-body and will be impossible to achieve a perfect 50-50 side to side weight distribution because if the drivers position. But, i can achieve a 50-50 crossweight - though, this means that either one of the front tires or rear tires is going to have to carry more weight.


If i have more weight on the rear left tire, the car should tend to have more oversteer in right hand turns due to overloading that tire first. But, will this also exacerbate spinning the inner tire when exiting the corner?
 

Malcolm

Supporter
50-50 cross weight is what I have always aimed for with corner weights when not a single seater but perhaps checking to see if you have an LSD might help more?
 
No idea about oval stuff.
But I assume you have an LSD, is it working properly.
The other is the inside rear shock is it to short, on droop it bottoms out then lifts the inside tyre.

Jim
 

Ron Earp

Admin
Most resources on this topic here in america talk about this in dirt circle track cars that only turn left and have staggered rear tires (the right rear is actually bigger than the left rear)... i dont think much of that information applies to a road car so getting advice on this topic has been difficult.
Plenty of knowledge and information about running a Camaro or Mustang is out there on various forums, NASA, and SCCA racing. Find some American Sedan (SCCA) or America Iron (NASA) racers near you and they can help.
 
Gen 3 isn't it? IIRC those things have the long torque arm off the diff. It is offset toward the LR wheel so transfers more weight to the LR, as per this pic notice the aftermart bracket on the housing can be shifted toward the centre, this should help in your case. Also have you shifted other items like driver set toward centre & battery to try and achieve more equal weight distribution.
 

Attachments

You need to fabricate a new bracket for the torque arm so that its attachment points are closer to the center of the rear axle housing( Green & Silver), also the forward attachment point to the chassis should perhaps be closer to the longtitudinal centreline of the car, but you will have to factor in any offset weight & engine torque for that as well ( It might help to make the chassis & housing brackets wider with spacing washers to allow fine tuning, redesign of the torque arm to ensure driveshaft clearance a must do!).
That stout axle bracket on LR for panhard will also be adding a few pounds of unsprung weight to the left rear.
Still concerned about your LS unit, would prefer to see a type that locks rather than just applies resistance under power application
 

Attachments

Ron Earp

Admin
As long as we're fabricating then I'd get rid of the torque arm. I'd replace that with a third link (trilink) that you can probably buy. And while I was at it I'd rebuild the brackets for the panhard rod for adjustability. Below is a shot of a chassis bracket (long skinny one) and axle bracket to bolt the panhard to that I made for our newest Mustang. The brackets have slots so the track bar and be adjusted up and down for roll center. Not beautiful but they work very well. Probably can buy something similar as well.









I know Jac loves fab pictures of people actually doing something so I figured I'd indulge!
 
Tri- Links are sorta OK, BUT very hard to find the optimum installation position of the top/3rd link that gives the best traction/braking/ cornering. Some folk have resorted to having two forward chassis mounts on a toggle arrangement to try and get best of both parameters, fairly sensitive to ride height as well with the shorter arm length. Don't know what rules might apply to the Camaro, but I would concentrate on revising the torque arm so that it has the freedom at the forward end to only apply body lift under acceleration without causing a bind thru other suspension antics.
As an aside I followed a mid 90's mustang thru town a while back and couldn't believe how much it moved around on the rear suspension in stop/go traffic situations.
 
I have a lsd. Brand new too. I think the issue might be what jim suggested or I have too much rear swaybar.
What kind of limited slip do you have? Clutch plate? It's likely you can get a different clutch pack with a higher slip ratio. Or, if it torque bias then it shouldn't be spinning at all......

I had a 60% clutch-type LSD....and a worn 80% LSD....both had about the same slip values on the bench.....so I got a new 80% clutch pack and there was no more inside wheel slipping. Of course, I softened the rear sway bar as well a bit (to keep the rear inside wheel in contact with the ground) but it seemed to me the first step was getting the diff set up and working properly. Just my $.02.
 

Ron Earp

Admin
As an aside I followed a mid 90's mustang thru town a while back and couldn't believe how much it moved around on the rear suspension in stop/go traffic situations.[/COLOR][/B]
That's running the stock QuadraBind rear suspension. Only works because it binds up. No good stuff on the Mustang SN95s stock. Actually, I'm racing one this weekend in LeMons that is using the QuadraBind. It rolls, binds, takes a set, and it does okay, but nothing like our cars. We've run the two parallel "trilink" like arms too....
 
From some of the research I have been doing, i found that the panhard bar height (and thus roll center height) are very high in the stock position. It looks like there can be a jacking effect in right hand turns due to the panhard chassis mount being on the right hand side, and the left side of the bar being so low. This puts an upward force on the right rear tire during a right hand turn if I'm not mistaking. This combined with the stiff rear anti-sway bar conspires to really unload that right rear tire. That might be the cause of the wheel spin.

The diff I'm using is a Auburn Racers Unit. I really dont have much of a comment on it. The other diff i could have gotten was a torsen T2R which is a bit more expensive. I have heard that Torsen has been having quality control issues and that their diffs dont last as long as they use to, so i went with the auburn.

Took the car out the other day, lots of oversteer. I have heard lowering the panhard bar can really help plant the rear. I'll give that a try.

Heres some in-car video.
http://youtu.be/zRVdVlkJ2Xw
 
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