I know it's said that -1.5 degrees of camber would be best on a Cosworth. But when I was reading in 'How to prepare the Sierra for motorsport' it said:
"The best balance between ride height, traction and rear wheen camber occurs when the static laden camber of the rear wheels is 0 deg - i.e. the wheels are precisely vertical. This applies whether 16in. or even smaller road wheels/tyres are used. It means that under acceleration the car squats down slightly and gives the best possible rear tyre grip, and in normal conditions of cornering the tyre starts from an ideal geometrical position. There is no advantage in setting up the Sierra to have permanent negative camber in the static laden position."


When looking at the 4 vehicle build specifications at the back of the book it gives a few different settings that were used on the works rally cars:
0 to 0.5 degrees negative
0.25 degrees positive
0.25 degrees positive
0 degrees


On the Group A manual for the Escort Cosworth it says to run -2.75 degrees on tarmac and 1.75 degrees for gravel. But I wonder if the settings could be different because of 4x4 vs. rwd. As apparently negative camber gives better cornering grip, but zero camber gives better traction which might be more important on a rwd car.

 

Does anyone have any experience with running 0 to -0.5 degrees of rear camber?

 

The issue is the poor geo over the rear suspension travel, the camber changes from positive at full droop to negative at full compression.
Getting the balance against your use is the important bit.

On my 3dr rally car I ran zero~.25deg rear for traction/cornering grip.

On my escort rear 0.5deg, front up to 2.5deg.

 

Was that both on standard beams? Mine has a 6 degree beam fitted.

 

Gets better on a 6degree, still not awesome though.

 

So you would say -1.5 is too much for the rear? But were your settings on a standard beam, 6 degree or something else? Or wouldn't it matter much which beam?

 

What is your primary use?

 

Primary use is road use. I just wonder if straight line traction would be better when running less camber (currently about -1.5 degrees), or whether then handling/grip in corners would get less.

 

There is so much more to it than deciding if straight line traction or cornering will be affected, obviously if the wheel is perpendicular to the tar then the tire should have 100% of its road contact patch, but having any camber away from zero reduces this, plus the geo change under squat if any will add or subtract to your static figure.
If you have these figures you can tune your settings, if you don't anything you do is purely guess work.

The same applies to cornering, as the body rolls around its axis the load at any given wheel changes, thus if your suspension geo changes through compression this dynamic adds or subtracts to your static.

Sorry there's no easy answer but an educated guess gives a good starting point.

 

What dampers and rates, what length springs and poundage do you have?
What type and thickness roll bars?

 

Ahmed bayjoo fast road springs, Konis at the front and Bilsteins at the rear (which I'm thinking of changing to Konis as the Bilsteins are a bit hard). At the front a 28 mm ARB and 21 mm at the rear. And 3dr hubs and a 6 degree beam.

 

So road spec, at that i would be wanting around 0.5~1.0 deg on that to balance and average between traction and cornering, but it will always be a compromise.
Try it and see how it feels.

 

Thanks, I will give it a go and see how it feels.