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RigMan
06-10-01, 09:35 PM
Having sorted out my camber and tracking, I have turned my attention to Castor. On my Jaguar front suspension I have the 'straight' upper wishbone arms (as opose to the 'cranked' type). Does any one know whether removing the castor shims which are meant to be located to the REAR of the upper ball joint (front on the cranked type) aid/improve the front wheel self centering ability or not?

All answers greatfully received!

RigMan.

dave
07-10-01, 11:24 AM
do you have lower wishbones that have the ball joint socket cranked at an angle?
if yes it should be cranked forward.
the top wishbone is a little weired their are two types that i know of, first the most common type has a kink in both arms near to the the bushes these are found on the same cars as the above described lower wishbones and each arm is the same length and shape the only diference is the hole where the jag bumpstop rubber is screwed in ie.both on the bottom side. if you have this set up all three castor shims should be to the front of the car.
however if you have the same lower wishbone but have the other type upper wishbone (whishbone arms do not have a kink near to the bushes and are of unequal length with shorter leg at the rear) the three shims all fit to the rear of the car . for any other combination ,like a straight lower wishbone
and an ofset upper wishbone as described above in ( ) i would assume that the shims go to the front but if youre not sure give peter or gary at dax a call.
Good luck.
DAVE PRO.DAX BUILDER;)

RigMan
07-10-01, 12:31 PM
I have the second of the two scenarios that you described above where the shims locate to the rear of the upper ball joint. The question remains; do I remove the shims to improve wheel centering/positive camber or add them? Also, when adjusting castor, does this upset the front tracking?

Thanks

RigMan:-)

dave
07-10-01, 08:48 PM
to give stronger self centering remove shims from the rear and put them in the front, best tried one at a time.
because the wishbones are angled to the rear on a dax as you move the shims to the front this will alter the camber of the car slightly to the negative (top in). and there is a very good chance that this will also affect toe in/out but these effects could be so slight that they fall within original tollerences.
are you experiencing a serious handling problem or is this just fine tuning?
Good Luck

DAVE PRO.DAX BUILDER;-)

nbracken
07-10-01, 10:26 PM
Dave, I have the upper arms with the crank in them. The self centering on my car is fine but the steering does get really pretty heavy as I put on more lock. If I move shims from the front to the rear progressively will this reduce self centering but also lighten up the steering weight? The steering weight only becomes a problem beyond about the 50 pct mark.

Thanks

dave
07-10-01, 11:30 PM
IT SHOULD DO. BUT DO TREAD CAREFULLY , DO THEM ONE AT A TIME AFTER ALL YOU DON'T WANT TO TAKE A SHARP LEFT TURN AND BEFORE YOU KNOW IT END UP ON THE FOOTPATH.
DAVE PRO.DAX BUILDER;-)

RigMan
10-10-01, 10:48 AM
Thanks for your responses Dave. I am basically fine tuning, but being a little critical have found that the steering under speed is not exactly 'reasuring'. I have removed one shim each from the rear of the ball joint but did not replace it to the front rather I just left it out.Is this a problem? I no longer seem to have to drag the steering back to centre any more as I exit a corner, but the steering seems to be a bit nervous on a 'straight'. This would suggest camber, but I have alreaddy set that up to within 0.5 degrees of spec.

Thanks,

RigMan

robert
11-10-01, 01:59 PM
Don't forget that if you put much castor change on, you will affect the bump steer, so you might want to chack this after the castor change.

Just a thought.

Robert
Forum Admin

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dave
11-10-01, 03:11 PM
RIGMAN , YOU MUST PUT THE SHIM BACK IN, THE ARMS ARE DESIGNED TO HAVE THREE SHIMS IN THERE EITHER AT ONE SIDE OR THE OTHER, WITH A SHIM REMOVED THE ARMS WILL NOT BOLT UP TRUE PUTTING EXCESSIVE LOADS ON THE TOP WISHBONE BUSHES ALSO THE BOLTS THAT RETAIN THE TOP BALL JOINT WILL PROTRUDE TOO FAR AND YOU RUN THE RISK OF THE THREAD HITTING THE DISC WHEN YOU OPERATE THE STEERING.;-)

dave
14-10-01, 01:13 AM
RIGMAN HAVE YOU SORTED IT YET?;-)

Grease Monkey
03-11-03, 03:09 PM
I've just been looking through these old posts as i'm reassembling my XJ front wishbones.

I've got the type with lower balljoint mounting angled slightly forward, and asymetrical (longer at the front) upper wishbones.

I appear to have 4 castor shims behind both existing upper ball joints though. Should i leave one out on each side when i reassemble?

Adrian



There ain't no replacement for displacement.. GD427 on order:) ... arriving May :( :( :( :(
Why the hell and i doing this?!!

Miket
03-11-03, 04:59 PM
Adrian

If there was four in original donor axles, then put four back when you rebuild.

Antony
14-03-05, 12:12 PM
As discussed earlier in this post, the top arms have four shims, they are there to move the top ball joint back or forward, the number of shims never changes (do not discard any) just change the number from side to side to setup your geometry!

If you discard any it will load up the inner pivot points! if they were spacing a metal pivot point fulcrum which is bolted to the chassis then normally adding or discarding is the order of the day!