FWD Vehicule caster 1

[Rat5]

Hello,
Why does generally FWD and AWD vehicles have less caster angle than RWD vehicles ? Is this to lower the self centering effect of the driven wheels ?


Thanks

 

[BrianPetersen]

??

What examples are you using to make the statement?

Millions of rear-axle-drive cars and light trucks have been built with geometry having very low caster angle.

 

[GregLocock]

Ford Ranger (RWD or 4x4) has 3 degrees, as does the last generation of Corvette (from memory). We ummed and arred over Ranger, trying to see why we'd need more than that, here's some old corvette stuff

1963-1982 Corvette Performance Alignment Specifications

Caster: positive 3-1/4 degrees (plus or minus ¼ degree) (there should be no more than a ½ degree variation side to side). To offset for crowned roads set the left caster to 2-3/4 degrees positive and the right 3-1/4 degrees positive. Not all 63-82 Corvettes will allow the 3-1/4 while some may allow another ¼ degree, the idea is to max out the positive caster. This will affect steering feel requiring more effort during turning while allowing the steering wheel to return to center quicker.

Camber: ½ to ¾ degree negative front and rear. Track only cars: 1-1/4 degree negative front and rear

Toe-in: ¼ inch positive total both wheels

Factory Settings

Caster setting: positive 2-1/4 degrees (plus or minus ¼ degree) decrease left side caster ½ degree for crowned roads.

Camber setting: 0 to 1-1/2 degrees positive

Toe-in: 1/8 inch positive to ¼ inch positive

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

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[Rat5]

Brian, i was tanking the example of the E30 and E30IX. The IX strut towers are much more towards the front than its rwd counterpart

 

[GregLocock]

The IX was an AWD conversion of the RWD E30. I'd guess they just ran into a packaging problem with the original strut.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[cibachrome]

1) Drive axle plunge.
2) Caster adds understeer via higher tie-rod loads. FWD cars already have a high understeer tendency because of weight distribution.
3) Some use caster offset instead of caster angle.
4) Caster adds steering effort via the added tie-rod loads which might have to be attenuated at the expense of fuel economy and horsepower loss.
5) Caster is added to align the peak tire Mz with the peak Fy output to prevent negative SW returnability. ("Oh, what a Bad Feeling"). Sorta pointless for a FWD vehicle which won't be trying to set max-lat records anyways.