Why the RA has so big influence on steering precision/feel
Why the RA has so big influence on steering precision/feel
(OP)
Hi
Had to drive another cost reduction measure the other day. In a vehicle with a torsion beam RA with additional ARB it was suggested to remove the ARB with expected results.
So how could I theoretically explain why the steering feel is more compliant and the vehicle has poor precision. The same feeling as when you e.g. reduce low speed damping. I've been trying with weight transfer and tyre loads but didn't get anywhere. In "English" I could explain but what is the theory behind it?!?
//René
Had to drive another cost reduction measure the other day. In a vehicle with a torsion beam RA with additional ARB it was suggested to remove the ARB with expected results.
So how could I theoretically explain why the steering feel is more compliant and the vehicle has poor precision. The same feeling as when you e.g. reduce low speed damping. I've been trying with weight transfer and tyre loads but didn't get anywhere. In "English" I could explain but what is the theory behind it?!?
//René
Best regards
René le Grand
www.bourgest.com





RE: Why the RA has so big influence on steering precision/feel
Reducing rear roll stiffness relative to the front will:
- reduce total roll stiffness, thus increasing body roll at a given cornering load, results in a loss of precision;
- increase the proportion of cornering loads due to weight transfer that the (probably already overloaded due to front wheel drive??) front wheels have to absorb, this leads to an even greater bias towards understeer.
RE: Why the RA has so big influence on steering precision/feel
You could stiffen the rear spring rates to bring back some roll stiffness, but stiffening them enough to completely compensate for the loss of the rear antiroll bar will probably make the ride quality poorer.
RE: Why the RA has so big influence on steering precision/feel
Maybe you need to look at how these things vary with time. I suspect that the new roll frequency is somewhat lower than the original one. What happens if you add some low speed damping?
Norm
RE: Why the RA has so big influence on steering precision/feel
More load transfer at the front, so the pneumatic trail changes across the car, so the steering generates a different torque for a given Fy.
Cheers
Greg Locock
SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.
RE: Why the RA has so big influence on steering precision/feel
RE: Why the RA has so big influence on steering precision/feel
Cheers
Greg Locock
SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.
RE: Why the RA has so big influence on steering precision/feel
To pass the car has to have a really spicy handling trait.
Regards
Pat
See FAQ731-376: Eng-Tips.com Forum Policies for tips on use of eng-tips by professional engineers &
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RE: Why the RA has so big influence on steering precision/feel
RE: Why the RA has so big influence on steering precision/feel
RE: Why the RA has so big influence on steering precision/feel
K&C= Kinematics and Compliance
The difference between -0.0 and +0.0 I'm not so sure of either. + is toe-in and - is toe-out.
Thanks for your answers though. I think also it has a lot to do with the time delay in lateral acceleration build up between FA and RA.
Best regards
René le Grand
www.bourgest.com
RE: Why the RA has so big influence on steering precision/feel
Cheers
Greg Locock
SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.
RE: Why the RA has so big influence on steering precision/feel
WRT roll center, the Benteler beam may have a problem with it being too HIGH. You will need to investigate it.
Ken
RE: Why the RA has so big influence on steering precision/feel
Cheers
Greg Locock
SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.