Caster vs Camber?

[teamshaw]

Hi. My POG is a dedicated track/hillclimb car. Based on Sam’s thread I rotated my front strut tops to prioritise caster over camber. The alignment guy thought that I would be better off going back to the original settings, but I’m not so sure? What do you track guys reckon?

Latest settings attached.


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[simon k]

The caster there is good but zero camber will be horrible. You should put in some TT ball joints and a set of eccentric subframe bolts and you'll get a couple of degrees.

Your back end is a bit of a mess too. I could help you with that

[teamshaw]

Great thanks. I will try and source those bits and get them in.

I’ve got some shims to go into the rear, they are next on the list. What toe/camber do you suggest?


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[simon k]

I did the TT ball joints without drilling the bottom arms, I just filed the holes in the ball joints till the I could get the bolts in, pushing them as far forward as i could

I can help with eccentric bolts if you want some.

Left-rear is good, make the right match it

[Sydneykid]

The caster there is good but zero camber will be horrible. You should put in some TT ball joints and a set of eccentric subframe bolts and you'll get a couple of degrees.

I did the TT ball joints without drilling the bottom arms, I just filed the holes in the ball joints till the I could get the bolts in, pushing them as far forward as i could

Agree

Front caster is great, needs neg camber, around 3.5 degrees for circuit work and longer high speed hillclimbs (eg; Bathurst), possibly get away with 2.5 for short lower speed hillclimbs. I'd never run toe in on the front, zero at least, up to 2 mm or so toe out each side.

Rear camber is OK, needs the same amount of toe out on the RHS as it has on the LHS.

Cheers
Gary

[sambb]

got a pic of your strut tops fitted in the car?

[Ozsko]

The caster there is good but zero camber will be horrible. You should put in some TT ball joints and a set of eccentric subframe bolts and you'll get a couple of degrees.

Your back end is a bit of a mess too. I could help you with that

I hate eccentrics for suspension adjustment as they move in two planes at the same time and this can't be avoided. I would go to extreme lengths to avoid using eccentrics but that is just my dislike of them for suspension adjustment. Truly horrible things to be avoided at any cost.

[simon k]

I hate eccentrics for suspension adjustment as they move in two planes at the same time and this can't be avoided. I would go to extreme lengths to avoid using eccentrics but that is just my dislike of them for suspension adjustment. Truly horrible things to be avoided at any cost.

interesting.. I wonder if we're talking about the same thing though - these are to take up the manufacturing clearance in the front subframe mounting points and accurately position them... discussed here -> Tramlining & Excessive Torque Steer.

[Sydneykid]

I hate eccentrics for suspension adjustment as they move in two planes at the same time and this can't be avoided. I would go to extreme lengths to avoid using eccentrics but that is just my dislike of them for suspension adjustment. Truly horrible things to be avoided at any cost.

Can be looked at both ways, sometimes I want to adjust either, for example in an inner lower front control arm installation I can adjust roll centre, up or down to the max, without affecting the camber OR I can adjust the camber, in or out to the max, without affecting the roll centre. Pretty useful for the one item cost and installation. The in betweens requiring both together is where it gets tricky, if I want an exact amount of each, that can be hard to achieve. But being realistic, they are mounted in rubber or polyurethane bushes so ~1/8 degree (of camber) or ~2 mm (of roll centre) is hardly material. There's multiples more than that in the dynamics, the deflection of the bushes, the bending of the strut, the flex in the hub, not to mention the twist in the chassis itself and even the flex in the wheels.

In the formula cars with carbon fibre tubs etc we adjust using 0.5mm shims, but in a production based road car spending time and brain power on trying to achieve exact static suspension geometry is not an efficient use of resources.

Cheers
Gary

[seangti]

Teamshaw, I'm running Kmac tops on mine that are camber castor adjustable. I'm running at max castor which I think it around 4deg, with -3.5deg camber of left and -2.5 deg on right. All the QLD tracks are right handers. I can't recall toe settings.

I've also got the rear whiteline shims. It's been too long with this set-up to know anything different, but I had progressively added camber from conservative to track centric and notice improved 'stance' during cornering. So you'll certainly get improvement going from -1.5 to -3+.

I've not done the eccentric bolts or ball joints. It rarely gets driven these days