Castor angle??
Discussion
I have just rebuilt the front suspension on my Griff and have found the top ball joint has shims which would appear to adjust the castor angle.
Is that what they are for? I have read Steve's book and he makes no reference to castor angle.
My local garage says the castor is 1/2 a degree out on one of the front wheels???
Can anyone tell me what the castor should be?
Ta very much
Is that what they are for? I have read Steve's book and he makes no reference to castor angle.
My local garage says the castor is 1/2 a degree out on one of the front wheels???
Can anyone tell me what the castor should be?
Ta very much
The top ball joint mount is adjustable anyway, there are two bolts clamping it to the top wishbone which have elongated holes in the wishbone to allow for adjustment. You are recommended to mark the position of the bolts on dissassembly so you can put it back together with the same camber setting.
Not sure about the "shims" on the ball joint. There should be one large thrust washer, not shims. I can't see any point in having further adjustment here, but I may be wrong.
Is it castor or camber we are talking about? Castor angle (or toe in as it is sometimes called) Did I really say that?
... rewind ... Toe-in ( or toe in as it is always called!!) is adjusted at the steering rod end, which has a ball joint threaded into the end of it with a locknut (which will be rusted to hell probably). Camber is adjusted at the top ball joint mount as above.
Both of these are further adjusted by the car in motion when the soggy rubber bushes wiggle about and the 5mm play in the wishbone mounts undoes all your good work.
PowerFlex bushes are a useful mod!
Edited by philshort on Wednesday 28th November 21:10
Not sure about the "shims" on the ball joint. There should be one large thrust washer, not shims. I can't see any point in having further adjustment here, but I may be wrong.
Is it castor or camber we are talking about? Castor angle (or toe in as it is sometimes called) Did I really say that?
... rewind ... Toe-in ( or toe in as it is always called!!) is adjusted at the steering rod end, which has a ball joint threaded into the end of it with a locknut (which will be rusted to hell probably). Camber is adjusted at the top ball joint mount as above. Both of these are further adjusted by the car in motion when the soggy rubber bushes wiggle about and the 5mm play in the wishbone mounts undoes all your good work.
PowerFlex bushes are a useful mod! Edited by philshort on Wednesday 28th November 21:10
Good point about the bushes but I just want to set the car up right for ordinary road use so I am not worried about a little compliance in the bushes.
Castor is the setting I am after (kingpin inclination) this is what causes the steering to self centre.
You mentioned the slots at the top they adjust the Camber
The track rod ends adjust the tracking as you rightly point out.
Castor is the setting I am after (kingpin inclination) this is what causes the steering to self centre.
You mentioned the slots at the top they adjust the Camber
The track rod ends adjust the tracking as you rightly point out.
Ooops! 
Castor angle isn't the same as toe in! Its the angle between vertical and the line between the upper and lower ball joints (rearward inclination of the steering axis to be precise!).
On mine there is a spacer affair the same shape as the top ball joint mounting, its about 10mm thick. I suppose it might be a shim, and if you had 2 smaller ones instead you could put them either side of the ball joint mounting and alter the castor by moving the top ball joint fore and aft.
There's quite a good explanation of steering geometry at http://users.owt.com/mitchman/Media/TOURING/BENWILSN.HTML . Nice refresher course for plonkers who post rubbish about the subject!
Edited by philshort on Wednesday 28th November 21:06
Castor angle isn't the same as toe in! Its the angle between vertical and the line between the upper and lower ball joints (rearward inclination of the steering axis to be precise!). On mine there is a spacer affair the same shape as the top ball joint mounting, its about 10mm thick. I suppose it might be a shim, and if you had 2 smaller ones instead you could put them either side of the ball joint mounting and alter the castor by moving the top ball joint fore and aft.
There's quite a good explanation of steering geometry at http://users.owt.com/mitchman/Media/TOURING/BENWILSN.HTML . Nice refresher course for plonkers who post rubbish about the subject!
Edited by philshort on Wednesday 28th November 21:06
Ahh no - and there was me listening to advice from philshort on puttin a big engine in a griff!
I changed the castor angle on the cerby mid way through my last trackday and it very nearly was my last trackday.
The adjustment allowed by the standard shims is a bit severe and I felt it resulted in the back end getting very light when braking hard (from about 125mph), add a bit of a dip in the circuit on one side and I went in to a very scary spin.
I intend having several thinner shims prepared to allow for finer adjustment.
cheers
I changed the castor angle on the cerby mid way through my last trackday and it very nearly was my last trackday.
The adjustment allowed by the standard shims is a bit severe and I felt it resulted in the back end getting very light when braking hard (from about 125mph), add a bit of a dip in the circuit on one side and I went in to a very scary spin.
I intend having several thinner shims prepared to allow for finer adjustment.
cheers
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