Positive camber?

[Mike Stevens]

Has anyone ever seen positive camber on a big saloon before? The spec says 0.5 degrees positive +/- 1 degree, but looking at the front wheels of the PI it looks much more than the maximum of 1.5 degrees. I have tried to measure it and came up with a 1.5 degrees positive with the car on ramps, but zero again when back down on the ground. The wheels still look to be 'in' at the top though.

I have also tried measuring the spring fitted height under load (while on the ramps). It all looked OK and roughly the same as the 2000, but the front of the Pi is definately about 2" higher than the 2000 - and that's with a heavier engine too. I measured at the front bumper as well as ground to the top of the wheel arch.

I am wondering if this is the issue - the height being too great and making the wheels tuck in a bit. The next thing to try is different front springs but Triumph only made 3 different front springs for the big saloon and if the springs I have are too high, then where did they come from? A Stag maybe - does anyone know the standard rate of the Stag springs?

The upshot of this is that the car is 'interesting' to drive. The positive camber is giving some bad understeer which certainly makes you sit up and notice! OK, it was a dark and wet night, but I have been driving big saloons since 1974 and I don't think I've ever had understeer before. (I did on a GT6 once though...!)

Cheers,
Mike.

[Steve G]

Hi

You say that the wheels are in at the top. To me that would indicate that the car has negative camber.
If your wheels are like this /----\ looking from the front or rear of the car than that is negative.
If your wheels are like this \----/ then that is positive camber.

Normally the heigher the front suspension is the more positive camber you will get so the car is sitting on the outside edges of the tyres. If the height is excessive then the tyres might start going back to having negative camber.

I can't remember all the ins and outs with the springs other than there being pre-facelift and facelift springs on Mk2's. The facelift ones make the car sit higher. If you have something else on the car then it might have stag ones as you say.

The camber can be adjusted slightly by altering the amount of shim washers where the strut bolts onto the hub. I seem to remember that the shim washers fit behind the lower 2 mountings of the 4. No shims will give more positive camber.

Hope this helps, perhaps a picture of your car will show just how hight it is and how the wheels are sitting.

[Mike Stevens]

You say that the wheels are in at the top. To me that would indicate that the car has negative camber.

Sorry, I got that wrong. They are definately 'out' at the top, giving positive camber. I had thought about the shims on the strut (the ones that fall off when removing a strut!), but I wouldn't have thought that they would make that much difference. I plan to swap the struts anyway to see if that makes helps so I can check for the shims then. This car seems to have had a very checkered past so who know what's happened.

Certainly the ride height is 2" higher than the 2000 so I think the springs are wrong, but what from? The limited research I've done so far suggests that Stag fronts are 110 rated, which is less that the standard big saloon springs at 129.

Thanks for the thoughts....

Cheers,
Mike.

[TedTaylor]

If the spring is excessively long/stiffer than normal this could cause the distance from the top strut mount to the bottom swivel to be excessively long. Just done a few geometrical scribbles and if longer than standard spec this would cause the end of the track control (steering) arm/bottom swivel to be pushed down in relation to the track control arm front cross member pivot point bringing about your positive camber (if my scribbles are correct). This would also move this lower point back far enough against tie bar (which would also drop slightly) and could affect the castor angle. This could b****r up the steering geometry and cause some most interesting effects as you have noticed.

When the factory built the MK1 rally cars they raised ground clearance using bigger wheels and not longer springs because of the effect on the streering geometry.

With Land Rover/Range Rovers/Discos this sort of high lift can affect the castor angle to change to such an extent that steering wander occurs when driven forwards and is almost undrivable in reverse (hence castor corrected tie bars for 3inch plus lift).

I would suggest you check the length of the strut from top mount to the lower swivel - ideally by removing the strut, but you could get a reasonable idea in situ with the spring not under compression (jack car up under body/cross member and remove wheel to take its weight from the equation). Check that length with your spare strut/spring which being off a car would not be under compression and see if there is significant difference. Or with the car on the ground check the angle of the lower suspension arms (track control (steering) arm and drag strut) in comparison to the ground by comparing with a car also on the ground which is riding correctly.

If there are no significant differences between the lengths of the struts/angle of the arms I would suggest you look at other components in the steering system especially the lengths of track control (steering) arm and drag strut. Also whether the stub axle is bent though any bend would most likely be such as to cause negative camber.

Ted

[Steve G]

The shim washers do make quite a difference. Where they are fitted their thickness has quite an effect.
If the springs are making the front that much higher then as Ted said it will affect the front end geometry a lot.
I swapped pretty much all of my suspension for slightly uprated parts from Chris Witor and it isn't overly stiff. If the springs are wrong I would get some new ones as that and decent shock absorbers makes a big difference.

[Jonathan Lewis]

Hi Mike,

Like Ted, my suspicions would be directed at the rate and/or fitted length of the front springs. If the front ride height is too great, then I suspect that the positive camber condition is probably a result rather than the cause - unlike some cars with double-wishbone suspension, I don't think that it is possible to mis-assemble the 2000 front end with componentry the wrong way around to give an unintended geometry. As far as I'm aware, the only 'factory' spring options for this set-up were 129lb pre-facelift, 129lb post-facelift, 90lb 'S' saloon and 110lb Stag, none of which would I expect to boost the ride height by 2". If, however, the car has had a chequered history, then perhaps someone has at some past time fitted some additional packing pieces, custom-wound coils or even off-the-shelf units intended for an entirely different application?

I also agree with Captain Slow about the presence (or lack thereof) of shims between the strut base and hub carrier having quite a pronounced effect on camber angle (i.e. ten thou difference in shimming to maintain roughly the same camber angle between pre- and post-facelift cars) but would have to question whether incorrect shimming could alter ride height by the degree you seem to be experiencing.

One last thought which is probably (hopefully!) wildly off-base. At the rear, partial failure of the subframe outer bushes can cause a variable camber condition by allowing the effective pivot point of the trailing arms to move up and down as the car moves forwards and backwards. Could any excess play or wear in the track control arm bushes or drag strut bushes exert a corresponding effect at the front?

Best Regards,

[Alec]

Hello Mike,

I have always noticed a lot of understeer on all my 2000s, usually on tight slow corners and with lots of throttle, the front tends to wash out. On medium to fast i would say it is more neutral. I think that the camber varies to positive as the steering lock increases.

I have no shims on my current car, and with slightly lowered suspension the camber is positive. The shims go on the upper bolt holes so adding shims gives positive camber.

I have investigated ways of altering this but theoretically so far. I discounted adjustable track control arms as that affects the caster, unless you shim the drag strut as well. I looked at these adjustable strut bearing mounts, but to achieve a camber variation rotates the mount so again affects caster. Incidentally, doing some calculations the top of the strut has to move a lot inward to get a small variation on camber. So far I haven't decided what to do, just get ready for plenty of steering input when pushing hard

Alec

[Jonathan Lewis]

The shims go on the upper bolt holes so adding shims gives positive camber.

Hello Alec,

I thought that the shims went on the bottom bolts, hence adding shims gives increased negative camber? At least, that is the way that mine is set up, and would seem to correspond with my recollection that the facelift cars had additional shims to correct the camber condition for their increased ride height.

Jonathan

[Alec]

Hello Johnathan.

the illustration on my parts manual shows them going to the top bolts, if original shims are used they will fit either top or bottom if my parts book is correct. If not and the shims are intended for the bottom, then original shims would only fit there as the two bolts are different diameters.

I just looked at my MK 1 manual (ST, not Haynes) and there is no mention of shims. I'll have to go to my workshop and check my MK 2 manual and see what it shows?

Incidentally all figures are given as static laden.

Alec

[Steve G]

Thanks for confirming what I said about the shims , I was starting to wonder if I had remembered correctly.
I managed to find some nice thin washers to get fine adjustment on my car.
I don't recall ever having bad understeer on my car although it does wander about a bit at speed , probably due to the wide wheels and tyres I have on it. I made some spacers for the drag struts to increase the castor and this has helped a bit.