Thoomas

Hi all rennlisters!

This is my first thread here at rennlist and I need your help.

I´m buliding a racecar of my -90 GT. Yesterday I did a wheel alignment and I was aiming for a front negative camber of 3,0.

It didn´t go to well because with the max adjustment it just went to 1,2!

Are there any mods that I can do to get more camber adjustment in the front suspension?

Best Regards,

Thomas
-90 GT

Thoomas

Up!

Thoomas

Thougths or ideas, anyone?

stuartph

Thomas


I thought the camber could go more than 1.2 more like 1.5

Maybe a set of steel upper A arms by 928MS might help you get alot more

Cosmo Kramer

You can also put on upper control arms from a pre 86.5 car, they are shorter and will definitely give you the negative camber you are looking for.

Thoomas

Yes, on one side it went to 1.5 but on the other only 1.2 so we put it on 1.2 on both sides.

Thanks for the tip on 928MS a-arm. Just sent a question to Carl about it.

Thoomas

I heard that it was the other way around.

Put the new type of upper a-arm on the pre 86.5 car and you will get more negative camber..... or......

GlenL

I got a touch more camber by changing the shape of the eccentrics and the ball joint. I filed down the small side of the eccentric and added some material (JB Weld) to the large side. The ball joint needed to be filed a bit to allow the extra motion. Note that this was on my '80 and the parts are similar, but not exact.

Not going to get you to 3 degrees. but a touch more.

The A-arm swap is the other way around. S4 are shorter and thus let the early cars get more camber. So much more so that you need to shim the A-arm out to be in the 2-3 degree range. I'm going to do this...someday.

James Bailey

Correct the early longer lower arm will give you too much negative but then you shim the upper arm out a bit (Y shaped GM spacers) and you can have the 2-3 degrees negative camber that some race tires seem to need.

Lizard928

you cannot use the early upper a-arms on the later hubs due to different geometery.

Carl's first revision of his upper a-arms resulted in the camber that you desired.

As Glen L has stated, you can use early lower a-arms, and shim the uppers out slightly to get the camber you desire.

Cheburator

You can also lower the ride height. I got 2.25deg -ve on my racer by lowering the ride height to 110mm at the front and then playing with the adjustments...

mark kibort

WAIT! There a few racers here with some experience on what will work. 3 degrees??? what do you think you have, a 911 or BMW???

Look, just drop the car to 120mm front and 140mm rear, and max out the camber on the front, on a hunter machine and be done with it. it will be near 2 degrees. 1.5 to 1.8 is just fine for a competitive 928 for best handing AND tire wear. Anderson did the max camber for a long time and all the guy did was cord tires. went to a more moderate camber, runs his tires longer and his car handles better too.

So, 1.5 to 1.8 degrees camber, slight toe in. (I mean very slight, almost 0) and about 1.8 to 2 degrees in the rear with 0 toe. (not .5 degrees as the spec range allows)

mark kibort

2.25 degrees is a little too much. you will have a lot of push, unless your car is really softly sprung (where you would need that camber due to body roll)

those who dont know 928s, dont understand the geometry of the suspension and why you dont need the camber as you would on other types of cars.

FredR

Thomas,

You can try Carl's lower frame brace- the theory is it helps to stop the lower A arm from folding inwards under high loading which needs more static camber to compensate. Carl reckons [and I support the notion] that the brace reduces the need for the equivalent of 1 degree of camber. The only issue I had with this was clearing the alternator which we solved by fitting a shorter alternator belt but YMMV and have no problem at all. Carl also provides spacers that help but in my case did not completely solve the problem

It seems that the camber range varies quite a bit from car to car and what you experienced is similar to what I found on stock set up. I found that the passenger side [LH drive] gave more camber on both my 928's. I suspect that is down to some curbing by the PO's possibly mishaping the wheel carrier a tad.

When it comes to alignment the WS manual just gives you the acceptable ranges but no advice on tuning as though they did not care.

If you follow the route indicated in the earlier post above note that the earlier lower arms have a discrete suspension mount design for that arm and it must also be used, [and not the one from the S4 arm].

Before you do anything, measure the range that can be achieved on both sides. Because of the difference in adjustment ranges on either side of my 928 I ended up fitting the longer lower arm on only one side [with the lower camber value limit] and leaving stock on the other so that I could achieve my aim of setting camber at 2 degrees. With 265's up front I cannot get a sqeak out of the front tires on hard cornering and ideally need rear sections around 325 to keep up with the front end instead of the 285's which means that even with the Devek bar fully dialled in my car is still a bit on the loose side.


Regards

Fred R

mark kibort

If its a race car and you get the ride height where you want it, the bottom helper bar will hit stuff and could cause all sorts of problems. Anyway, it is really not needed as I have 315 front hoosiers pulling some pretty high G loading and video showing no movement (side camera view), as well as tire wear proving that as well.
The key thing is that you need the ride height correct for racing. you need the correct springs and bars.
put it at 1.5 or 1.8 degrees after you lower your car and you will be good to start racing for a couple of seasons with no reason to adjust. trust me.

So, start out and adjust your suspension. what are you at now , ride height?
what springs and shocks are you running?
bars? wheels and tires?
power?
cage?
overall race weight?
will you be doing any street driving? mind a harsh ride?

these are just a few of the things that will determine what you will need as far as settings.