V8S - Steering Geometry

[keithyboy]

Front toe in: +3.2mm +-1.5 mm Camber: 0+-0.5 degrees Castor: +3.5 +-0.5 degrees
Rear toe in: +3.0mm +-1.5 mm Camber: -1+-0.25 degrees

Having completed the front end rebuild of my V8S - I clearly now need to get this properly set up, the handling on its initial run out was interesting to say the least! I've taken the above from any earlier post (S2 Giles) and need to know if the data is the same for the V8S. The castor cannot be set (as I understand it) but I do have a mate with access to quality equipment to get the camber and tracking properly set up. Advice welcomed please as this is not an area where I claim to have any expertise whatsoever! (Standard replacement suspension items used btw on the front with the exception of rebound adjustable spax's.)

[GreenV8S]

quote:Front toe in: +3.2mm +-1.5 mm Camber: 0+-0.5 degrees Castor: +3.5 +-0.5 degrees
Rear toe in: +3.0mm +-1.5 mm Camber: -1+-0.25 degrees

Having completed the front end rebuild of my V8S - I clearly now need to get this properly set up, the handling on its initial run out was interesting to say the least! I've taken the above from any earlier post (S2 Giles) and need to know if the data is the same for the V8S. The castor cannot be set (as I understand it) but I do have a mate with access to quality equipment to get the camber and tracking properly set up. Advice welcomed please as this is not an area where I claim to have any expertise whatsoever! (Standard replacement suspension items used btw on the front with the exception of rebound adjustable spax's.)

I don't think there is any one right answer and it will depend to some extent on things like spring and damper rates, ride height, what type/size/pressure tyres you have and so on. Also you can get horrible handling if any of the bushes or pivots are worn, corner weights are out or any of the springs or dampers are out of spec. (New doesn't *necessarily* imply working properly.) Having said that, assuming everything is in good order, if you're noticing handling issues (and it's good that you are) you could address these with specific targetted changes rather than nudge everything back to exactly the factory spec and hope this makes it handle how you want.

But for what it's worth, as a starting point I'd be inclined to increase that front camber to around -1 deg as a starting point, and reduce the front toe-in slightly. Also depending on ride height consider raising the back slightly, that camber is a little on the high side and raising the back also helps reduce aerodynamic lift at speed.

But before you do any of this, pay close attention to tyre pressure and condition, and after you double check the damper settings go back and tripple check them. Small changes here can transform the handling.

Hope this helps,
Peter Humphries (and a green V8S)

[HarryW]

Spooky this thread I was considering asking a similar question only last week .

Peter (or steve), I understand that the very early V8S's had a similar chasis and ride height to the S2/3's, but when they changed to the S4/V8S the ride height certainly came up and the track width was changed, was/is there a factory setting for the revised car?
As when I had mine checked out after new boots being fited the readings appeared to be different on both sides of the car (haven't got the figures to hand) but I don't have any major issue with the car crabbing or pulling. I want to make it linear on both sides but do not want to get it adjusted until I'm more than 100% happy with where it's going.

Harry

[shpub]

The first thing is that the only standard thing about the chassis and ride heights are the fact that they have them. In practice I have seen cars that have leaned to the left, leaned to the right, been higher and been lower. All this becomes irrelevant when you get in the car as this again changes the ride height. So the standard is whatever works for you. Alternatively if you want to set it to the factory level, I might suggest booking ahead for that nervous breakdown.

The body may not even be level on the chassis as the number of rubber mounting pads can get mixed up.

99%of the V8S have the wider track. I hve never seen a S3 version although as I mentioned int'bible there are some about. The geometries are the same for all the cars but I agree with PH idea of more negative camber but be aware this can increase front tyre wear on the edges if you drive in a spirited fashion. Also be aware that everytime you adjust/change the right height, the geometries need to be checked, particularly toe.

Also as Pete says, many other things can effect the suspension.

Steve
www.tvrbooks.co.uk

[keithyboy]

Thanks guys - I guess its just a case of "suck it and see" then. I'll let you know how I get on!

[keithyboy]

Eventually decided to let Raven set up the steering geometry. Around 1 degree of camber was what we finally came up with. Reversing the installation of the upper wishbones (L & R) on the rebuild didn't help either - something thats easy to do and not so easy to spot - well done Mike! Handling is fine now - it's just a matter of tweaking the spax's settings to suit.

[HarryW]

Just to drag this one up again, PeterH if your on line tonight your thoughts on this:-
I've just had the steering rack refurbished and obviously the track rod ends and hence the toe settings have changed . The problem is now it is a lot more nervous at speed than it used to be, am I right in asuming that too much toe may have been dialed in to cause this and reducing it should help .
Oh how I wished I taken a note of what the settings were before it was done, as it was rock solid at 130mph plus before .
It is noticeable at speeds in excess of 70mph btw.

Harry

[shnozz]

Harry - can you let me know the outcome of this. Whilst the new bulkhead bearing does steady mine a little, I still think this may be something to do with mine being "twitchy" at high speed.

[GreenV8S]

HarryW said: Just to drag this one up again, PeterH if your on line tonight your thoughts on this:-
I've just had the steering rack refurbished and obviously the track rod ends and hence the toe settings have changed . The problem is now it is a lot more nervous at speed than it used to be, am I right in asuming that too much toe may have been dialed in to cause this and reducing it should help .
Oh how I wished I taken a note of what the settings were before it was done, as it was rock solid at 130mph plus before .
It is noticeable at speeds in excess of 70mph btw.

Harry

I expect the replacement was an identical rack. If not, do a sanity check on the length and height to ensure you haven't picked up any bump steer. Also I assume nothing else has changed, ride height and damper settings unchanged, tyre pressure checked and OK all round.

Have you had the tracking set since the rack was fitted? It will definitely need it. It's worth checking the camber too while you're at it, just in case they disturbed the upright for some reason while they were at it. The amount of toe-in you want depends to some extent on the camber (I add about 0.1 deg toe-in per extra deg -ve camber) but from memory you would be looking at about 0.5 deg toe-in with the standard camber.

Hope this helps,
Peter Humphries (and a green V8S)

[HarryW]

Cheers for the reply Peter, as far as I'm aware the original rack was refitted, albeit refurbished . It is certainly more direct, I think it's just a case of the toe in (track rod ends) needs adjusting, the camber shouldn't have been touched. I'm just p*ssed off with myself for not having the previous settings recorded as i was more than happy with the feel at speed with those, I can see this being a trial and error thing now .
Cars back in soon for the cam change , I'll get the toe reset then to 0.5deg to begin with, btw what is that in mm as most of the readings I've seen are measure in mm .

Harry