steering self centering

[graham]

Hi,

From reading my sva book it seems to suggest that the steering must self centre after turning. Any one any issues with this on their test.

My car doesn't.(and would be better if it did) I have Jag XJ6 upper(straight) with three caster shims to the front of ball joint, and lower wishbone is the cranked forward type. Only 1 washer/shim for the camber (between) upper wishbone and chassis. Running negative camber (visual) and maybe a little two much toe in (visual)

Wheels are 8inch with 215/60/15 but I guess wide wheels dont help.

Can Anyone point me in the right direction to acheive self centering with trial and error as it has to work methinks for sva and I cant legally drive it to someone with the aligning equipment beforehand.

Also there seems to be two ways of adjusting camber - by adjusting ride height OR extra camber shims.

Would appreciate any help.

Graham

[Miket]

Graham

It would help to know the make of the Cobra.

[kdavies3]

If you are going for SVA you'll be jacking up the front suspension any way to acheive the minimum height for the front indicators (unless you intending to fit secondary ones.)
I would recommend you set up the toe in as it will make a big difference. Obviously you won't be able to set it up properly until you're at the correct ride height post SVA.
Have you checked for any tightness in the rack or front ball joints.

Kev Davies
Dax, 383ci Chevy Stroker, Tremec TKO
South Wales

[TINKA]

Hi Graham, yes your car will need to self center when you take it for it's SVA, The chap doing the test will drive around the test center to make sure all is as should be.
I think I am right in saying that if you adjust the camber, the effect of that will be bump steer so you should set that up roughly as the manufacturer says and then leave well alone. For self centering you need to add caster shims. If you add them in front of the top ball joint ( front of the car ) then this should help, I think the only down side to this is if you add in too much your steering will just get too heavy but that is not a failing point and can be sorted after the test.

If this has no effect then check to see if your steering rack or the steering column is tight, as this will also have the effect of stopping self centering. In fact I would do this first, just disconnect the steering column from the rack (so you can check them independently ) and see if either is tight.

Hope this helps Martin :tu :tu :tu :tu :tu

[graham]

Yep will check all that first, and raise ride height to achieve pos. camber. I have perhaps too much toe in but I will try each thing one at a time.

Thanks and I will keep my fingers crossed for SVA Friday AM.

Graham

[graham]

Yep, SRV8.

Graham

[kdavies3]

Good luck Graham, keep us posted.

Kev Davies
Dax, 383ci Chevy Stroker, Tremec TKO
South Wales

[graham]

Cant beleive it. O/s front wishbone (upper) is straight type, I think from XJ6 but n/s is cranked back, ball joint off centre (XJS) so an inconsistant castor angle each side.

My build manual says XJ6 upper wishbones Is that right. So I will end up with each side the same with a bit of castor (shims to front) instead of loads of angle with the XJS. Right?

Graham

Off to Jag spares in da mornin.

[graham]

Been advised by Jag spares to get XJS top wisbones, these are off set and give me more castor angle to help with self centreining. I hope this works.

Graham

[VinceGledhill]

You may have put the top wish bones on the wrong way round.

When I removed mine I thought that all the 4 parts (both sides) were the same. But on close inspection I found that they weren't.

I would therefore check them and change them round if incorrect.

To give better self centering you need more caster angle.

HTH

Regards
Vince
Time served Auto Electrician
Lucas Leeds 1979-1983