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Effect of positive rear camber
smart51 - 9/10/09 at 07:58 PM

What is the effect of positive rear camber on a RWD car?

For those who haven't read my previous posts, I'm trying to tidy up the handling of my Suzuki cappuccino. Replacing the tyres with good ones helped a lot. Inflating them to 28 PSI (the book says 23 PSI but I have 10mm wider tyres!) has improved things as well. I've been looking at the geometry and the book says 0° camber +/-1 for the front and 1° for the rear. Positive camber for the rear sounds a bit odd to me. What would be the effect of this? The car does lean a bit in the corners BTW.

hobbsy - 9/10/09 at 08:05 PM

Are those rear engined?

I suppose if they are expecting it to squat a lot having static positive camber means it will come back to no or negative camber under squat. But you've still got to consider under cornering. Seems a bit strange to have it in a car designed in the 90's...

Unless its 1 degree *negative* camber they are quoting anyway for the rear???

[Edited on 9/10/09 by hobbsy]

smart51 - 9/10/09 at 08:08 PM

Front mid engined rear drive. Suzuki claimed 50/50 weight distribution with a passenger on board, which suggests a slight front weight distribution when empty. The car weighs 700kg unladen so the weight of a driver and passenger may lower the rear camber slightly when laden.

nick205 - 9/10/09 at 08:14 PM

Haven't looked, but is there a Capuccino owners forum/club - might be able to advise by experience.

How about looking at the camber change through the suspension travel. Might be a faff removing the shock etc, but it might give you an indication of what goes on dynamically.

Might also be worth simply holding a spirit level to the rim and then having someone climb into the drivers seat?

smart51 - 10/10/09 at 06:38 AM

Yeah, there is a forum and they're quite helpful on there but I'm after more general car dynamics info.

My thoughts are that positive rear camber means any change in grip at the rear and the back of the car will pull one way or the other. on initial turn in, the extra weight on the outside wheel will cause the rear of the car to move out slightly. In steady state fast corners, the car will have a tenancy to oversteer. What do you think?

40inches - 10/10/09 at 10:20 AM

quote:
Originally posted by smart51
Inflating them to 28 PSI (the book says 23 PSI but I have 10mm wider tyres!) has improved things as well.

Increasing the width of the tyre will only increase the contact patch if you decrease the pressure(wider and thicker), if you use the same pressure the contact patch is the same size (same width as standard tyre but thinner), increasing the tyre pressure will make the contact patch smaller = less grip

smart51 - 10/10/09 at 10:36 AM

More pressure in this instance = less tyre wall roll. The handling really is improved by this. 23 to 25 PSI improved it a bit. 25 to 28 even more. Perhaps it has less ultimate grip but it has much better control and stability.