[serotoninsteve]

Hello,

I would like to know how should be the relation between camber and toe settings?

I mean as ex. I'm actually running 1.9deg camber in the rear with very little toe in, about 0'08" tot.
When I look at my tire wear, it wears more at the inside, but the griplevel is not high enought to wear the outer schoulder at all.

The rear fells not very stable, squats out under hard acceleration.

So I want to lower my camber to about 1-1.2deg (front is about 1.8deg),
should I get more toe in or stay with my settings.

My understanding is as follows, when I have more camber the tires are naturally forced into a toe in setting,
but should that be compensated with more toe in or less?

Any professional insights would be appreciated

Thanks in advance

Steve

[serotoninsteve]

Bump

Anybody?

[CJ421]

The relationship isn't quite how you describe; a change in camber would not necessitate a change in toe and vice versa. Ride height can affect both however; lowering these cars will increase toe and camber in general. But you would adjust toe and camber for different reasons.

Negative camber is what helps grip in turns and prevents the tire from rolling over onto its sidewall under hard cornering. You should always have some negative camber for that reason. Toe affects stability and turn-in. Toe-in as BMW specs our cars front and rear provides high-speed stability (visualize the tires on opposite sides trying to move toward each other) and also reduces the car's tendency to tramline. There should always be some toe-in in the rear for stability. Toe-out (up front) is typically used in high performance applications to ease turn-in but can make the car 'dart' at high speed. Neutral toe (up front) is a hybrid of both with the benefit of having the least amount of wear.
Toe affects tire wear more than camber in general. Your tires are wearing on the inside due to physics; more weight is resting on the inside of the wheel because of the negative camber. Toe exacerbates that.

Camber in the front and rear of our cars has a very limited adjustment range unless you invest in aftermarket parts. Same with the toe.

Edit: and the squat you're experiencing under acceleration is inherent to these cars w/ stock suspension; it's a combination of soft spring rates, bushings and underpowered dampers.

Hope that helps.

[serotoninsteve]

Thanks for your explanations.

Only for info, my car already has the M3 subframe bushings, upper arms and black Powerflex bushings pressed in the toe arms.

My toughs are like this (all when tracking in a straight line, no cornering):

If I set a lot of camber, the tires deflect under the cars weight, so the inner rolling diameter is smaller than the outer.

Now when tires are turning, the tires want to have toe-in due to the difference in diameter, but if the adjusted toe setting is less than what the tires request,
so there is one force working against the other and the tire is burning energy and wearing rather fast at the inside?

If I set more toe-in (still the same camber) to the point where the requested (again by unnatural position of the tires) toe-in meets exactly the geometrically adjusted one,
shouldn't that be the optimal setting regarding wear?

If I now dial in even more toe-in, the forces should switch at some point from wearing the inside to wearing the outside due to adjusted toe-in working "stronger" on the tire.

That's the relation I'm not sure if it exists and how much toe would be a "natural" setting.

It's often rcommended 3/16 tot at the rear, but at which camber setting?

[VTECaddict]

You are completely overanalyzing it. Don't worry about the physics of what the tire is trying to do. Consider the alignment settings fixed and independent of the tire.

How much more inside wear are we talking about and what tire brand and size? My car on OEM RFT and OEM alignment settings wore the inner edge of the rears way more drastically than my stretched 265 rear with -2.9 camber and 0 toe.

[serotoninsteve]

Originally Posted by VTECaddict

You are completely overanalyzing it. Don't worry about the physics of what the tire is trying to do. Consider the alignment settings fixed and independent of the tire.

How much more inside wear are we talking about and what tire brand and size? My car on OEM RFT and OEM alignment settings wore the inner edge of the rears way more drastically than my stretched 265 rear with -2.9 camber and 0 toe.

I'm running GOODYEAR Eagle F1 Non RFT from 09 in stock 255/35-19.
Camber is -1.9°
Total toe 0°06'

They hold pretty good, only more wear at the inside but normal.

When I look at my ouside edge it isn't used at all.
The lateral grip-level is not reached,
that's why I want to lower the camber to something around -1.1° with more toe to regain in traction and stabilize the rear end.

But at 1.1°, what is a good toe-setting for fast road driving and a few trackdays?

[CJ421]

I like zero toe up front because it results in the least amount of wear. For the rear of the car, I generally stick to the stock BMW specs with the exception of the camber, which on my car is a bit more negative because I'm lowered. I suggest having some toe-in in the rear for stability purposes.

1.1 degrees is too little camber for a track day IMO, your tire is going to roll over onto the sidewall and wear/heat up excessively. You will not maximize their grip. At the very least, try for 1.5 degrees, if not closer to 2. Provided you run minimal toe (or zero up front), the difference in tire wear between 1.1 degrees and 2 degrees should be almost unnoticeable.