How to increase castor and camber?

[stephen low]

G'day All

Just reviewing what is possible to achieve with my front suspension and wanted to sound out people's experience.

My front suspension set up, consisting of S2 lower arms & S1 uppers in my GForce, only achieved camber settings of around - 0.5 degrees with about +2.5 degrees castor at alignment.

I believe the upper arms are handed rearward with all three spacers at the front, so maximising castor in this configuration.

What I want to try and find out from anyone with this exposure, particularly in a GForce or RMC kit, is how you could help increase castor without loss of camber. In fact I'd like achieve around - 3 degrees camber with + 3 - 4 degrees castor.

Can anyone suggest changes I could try to help the settings I have, short of chassis changes.

Series 2 uppers are fractionally shorter from the pivot arm so would help increase negative camber, but even with shims at front, I am assuming their lack of handedness compared to series 1 arms would mean they'd offer less castor than I can presently achieve.

Car is currently jacked up at front for engineering and I understand lowering will somewhat help but I think this will only be a marginal effect on both settings

I look forward to your comments and advice.

Cheers

[Tony Cram]

Stephen,

I am sure everyone will have an opinion here.

My RMC has the exact same setup as yours. Couple of things to check.

1. Make sure the bottoms arms are in fact Series 2 and are on the right side of the car (ie right and left). The ball joint casting at the end of the wishbone should be angled forward. I have heard cars with these bottom arms on backwards.

2. Check the top wishbones are also the right way round also particularly series one. Make sure all the shims on the top ball joint are all at the front of the ball joint. This helps with caster. I think there has been a discussion post on this previously.

3. Best Caster I could achieve was 3°, if I tried to go further the wheel went too far back in the wheel arch (Didn't look right). I am running with 1° Camber. I can get more camber if needed but I think it is unecessary for the road. 3° Caster works fine for my RMC. Holds tight on the road and does not shift in the bumps. If I went any more I would consider chassis changes different wishbones and then probably power steering.

Other than changing chassis config or grinding out the wishbone support bolt/arm (Not a great idea!!), you can fabrcate new wishbones and make them adjustable both top and bottom giving you ultimate adjustment.

Lowering may help a little but marginal I would think unless your ride height is not correct. Perhaps you should measure ride height of my car when you see it next. I will probably bring it to next meeting.

Cheers


TC

[stephen low]

Thanks Tony

Given my previous exploration of suspension issues thread I had checked out my arrangement. Am confident I have the lower arms set forward as you describe and uppers rearward with shims at front too.

Agree in that I don't want to be grinding bits and pieces and I am not sure what gains I'll make on lowering the car.

I do know my aligner managed to gain about 1 degree of castor on one side of the car through manipulation of the suspension, to bring it up to about the 2.5 degree mark. I think this then compromised his ability to improve the camber on one side and thus he had to keep the settings equivalent at about the - 0.5 I have.

Just keen to tweak a bit more of bot into the car, particularly camber.

What ground clearance do you have in your car Tony?

I know the 50 series front tyres on my car add to the roomy look in the front wheel arch and lower the overall ride height slightly, two reasons why I'd like to get 60 series tyres onto the front.

I might just have to compromise until I get the rims I want with tyres to suit.

Cheers

[Harrymac]

Hi Stephen,

You can also fit a spacer on the front bolt between the chassis and the upper fulcrum arms to get more castor. Good luck.

Harry.

[stephen low]

Harry

Thanks for that.

I'm not sure if that's what was done in my case, but it had passed through my mind.

Cheers

[Tony Cram]

Stephen,

Not sure if my first thread made sense. My first thread is really indicating the minimum you need to do first. The extra shims that Harry above is suggesting is what you need for final adjustment. This is where you find the limitations ie things like set back Camber vs Castor etc. It is all about comprimise at this point unless you are willing to do major work on chassis as you suggest. 2.5° Castor should still be alright.

These shims can be made, but just go down to repco / bursons they are a standard shim for wheel alignment (I think HQ holden are the same size in various thicknesses). Good luck.

Cheers


TC

[stephen low]

Harry / Tony

Are these a taper item that is located by both bolts of the pivot arm?

Or are they some form of washer or open ended item that fits over the bolt attaching the pivot arm to the chassis and simply sandwiched between these on tightening?

Cheers

[Tony Cram]

Stephen,

Open washer type.

PIC


INSTALLED


Cheers

TC