GT6 Front Suspension - uneven height

[Kevin Atkins]

Hello all, I've had a bit of a search but couldn't find anything specific to my particular issue. Long story short, the front suspension height is uneven - the offside seems about right, and the wheel fills the well in the way that I have seen on photos of other GT6's. The nearside is down though, and the wheel seems more 'tucked in' to the well, if that makes sense. I'll attach some photos - I've found it difficult to capture, but walking around the car, it's immediately obvious.

I have replaced all bushes, uprights, top ball joints, stub axles and wheel bearings, both springs and new dampers. Wishbones seemed fine - I measured them and there was no difference NS vs OS. At the moment, the car is fitted with a trunnionless setup, which I don't like, so it'll be going back to standard trunnions with new uprights, but in all cases, the issue has remained - the nearside is down. I've also measured with a tape measure which confirms.

I believe the lower wishbones can be shimmed but I think that will only tend to affect camber and castor as opposed to height?

The only other variable I can think of would be the suspension towers - the car was subject to a restoration about 25 years ago, and in the photographs, I can see the NS tower was removed for some reason. I believe the towers can be shimmed for height, but by my way of thinking, if someone had forgotten to add shims that were previously there, that would tend to raise the suspension height?

Any ideas would be welcome! Thanks in advance.

[dougbgt6]

From that angle I would say the higher side is too high. Might be wrong 

Doug

[johny]

I take it the heights of the back arches are equal?

[Kevin Atkins]

25 minutes ago, johny said:

I take it the heights of the back arches are equal?

No unfortunately not - the whole of the NS is down.. I've had to fit a completely new setup to the rear - new swing spring, as a previous owner had fitted an early fixed rear spring.. so before, it was very low at the back and the rear wheels were splayed out. But NS front was still the same with that setup.

[johny]

I know it can be difficult to find if the problem is at front or back so I wonder if its worth getting the car on flat ground and getting each end at a time up on axle stands. Then see if the other end still has a height difference...

[Peter Truman]

Have you looked at the Anti Roll Bar on my Vitesse the RH side was low I removed the ARB and when layed flat on the ground one side sat 3/4 in up in the air ie twisted,  I had it reset ie normalised with a 1/4in preset the other way the car now sits even ie wheel arch to ground equal on both sides.

[Pete Lewis]

yes just pop a arb drop link off to see it the arb is affecting ride  heights

there are shims between the turret and the chassis rail top face to take up any odd tolerances in fits  many get left out 

but dont think that would make any wild difference   

i would certainly jack in the centre at the front to check any rear and then jack in the centre at the rear to check the front to really see  which end is causing the lean 

have you measured the fitted lenght of the spring ( data in the WSM)

Pete

[Nigel Clark]

I've also had a twisted ARB cause uneven ride height on my GT6.

Nigel

[Pete Lewis]

there was always some discussion on the thin  ARB had a designed twist  ,  doesnt make much sense to me 

the thicker ones available now are quite flat .

always set up the front and rear toe to maintain handling and bunny hops on bumps 

you dont need anything very special just good diy

 

[JohnD]

Of course, it was a dealer option in the US to fit an lifting spacer to the spring on the driver's side suspension turret.   I presume this was in case a potential owner came along who was, shall we say, a bit lardy?

John

[PeteH]

Would not be the first time a PO has fitted a replacement (even wrong?) for a broken spring singly?. In my view springs should always be fitted in matched pairs.

Pete

[Kevin Atkins]

Thanks for all the replies and suggestions everyone - sorry it's taken me a few days to respond, back at work now and the working week is usually busy 😜

I'll try jacking in the centre front / rear and see if that gives a clue as to the lean.

Just had the tracking set up correctly, so at least the front geometry in that regard is now correct - it's made a really huge improvement to steering / handling, transforming the feel of the car completely. Much better! But the lean is still very much in evidence.

Re. the front suspension - I've got new springs fitted, new anti-roll bar (which was definitely flat, the one that came off was slightly twisted), new drop links, pretty much new everything. The trunnionless kit has caused the ride height to drop at the front, and there's a bit of negative camber on the front too - I'm going to get the original setup back on I think (and guess I'll end up having to have the tracking done again, ho hum)..

Will let you know how things turn out - might be a week or two before I get a chance to take it all apart again, meantime will just enjoy driving it!

[68vitesse]

When I got my Vitesse it had a lean, turned out to be the rear diff mounting holes in the chassis were worn on one side letting the diff twist. Had to cut the bolts, rusted into the rear bushes, and weld washers to the chassis to repair the holes after which all good.

Regards

Paul

[Kevin Atkins]

4 hours ago, 68vitesse said:

When I got my Vitesse it had a lean, turned out to be the rear diff mounting holes in the chassis were worn on one side letting the diff twist. Had to cut the bolts, rusted into the rear bushes, and weld washers to the chassis to repair the holes after which all good.

Regards

Paul

Ah, that's an interesting point - is that the holes through which the long bolt goes at the back of the diff? I hadn't even thought of that - I did check the mounts that the front of the diff carrier attaches to, thought I might have maybe got the rubber bushes trapped incorrectly but that was all good. I guess it wouldn't take much wear on those rear holes to cause quite a pronounced effect at the wheels?

[68vitesse]

4 hours ago, Kevin Atkins said:

Ah, that's an interesting point - is that the holes through which the long bolt goes at the back of the diff?.

That's the one, but mine had two short bolts instead of one long one.

Regards

Paul 

[Kevin Atkins]

Just thought I'd post a progress update. The lean was definitely coming from the front suspension - I jacked up the front and rear in the centre of the car as suggested and the rear seemed OK.

So I dismantled the front suspension again - the new springs (definitely sold as GT6 items) from one of the bigger suppliers, mentioning no names, were a good inch or so shorter than the originals, so the originals have gone back on, to heck with them looking a bit crusty, they work. But at the same time, I added a shim in between the top of the spring and suspension tower on the NS. Ride height is now more even, and also more correct - it was too low before.

I think there's still an issue with the NS - the wheel still seems tucked further into the wheel well than the OS, and the top of the spring tower on the NS looks 'arched', so wondering whether it's suffered some damage in the past. For now, it's OK and the car drives just fine, and I just want to enjoy driving it for now. I'll attend to it in due course..

[Peter Truman]

On 24/07/2023 at 03:42, 68vitesse said:

That's the one, but mine had two short bolts instead of one long one.

Regards

Paul 

So has my 68 Mk2 Vitesse, I was told by someone that the two separate bolts are due to the Rotalex rear axle?

[JohnD]

Kevn,

Glad you have found the cause,  simple but obscure, but don't trust the dealers!

I'd reread the thread as it's a Sunday am, and your OP, where you said "I believe the towers can be shimmed for height"    This is a common misunderstanding, that arises because the parts diagrams show a shim, Part No. 128356 , between the inner edge of the suspension tower and the chassis rail.    However, there is no provision in the design for  moving the tower up or down.    It's bolted to the rail in four places with no slots!

I think that the shim is a production bodge to compensate for uneven quality control at Triumph!   The tower is a fairly complex pressing, completed by multiple welds, so that the fit of tower to rail may have been less than perfect!   If the parts closed up, the line worker would tighten and move on, if there was a gap, they'd add a shim.  If your car has one, refit it, if not don't worry!

 

John

Edited September 24, 2023 by JohnD

[Kevin Atkins]

Thanks @JohnD - that's very useful to know when I come to sort properly.

[Peter Truman]

my daughters Mk2 Spit was rebuilt in the 90's and had accident damage to the front driver's side necessitating a replacement chassis, the owner in error fitted a Herald turret which raised the engine height, which was a clearance problem so to fix it I fitted a Spit turret which cured the height, but the new turret required a square shim washer between the chassis top flange and the turret underside, so yes shims may be required. The new S/H chassis was fully checked by a Triumph guru here for straightness and alignment on a rig he has and was spot on!

[Kevin Atkins]

@Peter Truman - thanks, this is all good information to know for when I sort..

..which might be sooner than later - having refitted the old springs, whilst better than before, I think the front is still sitting a bit too low. I fitted trunnionless uprights and I believe these also have the effect of lowering the effective spring rate? I have bought some spring spacers to go under the spring from Rimmers - these seem too large to fit inside the bottom of the spring - the part of the spacer that goes inside the spring as around 4mm greater in diameter than the inside diameter of the spring.. Is it a case that when assembled into the spring / shock assembly, under compression the spring should expand slightly around the spacer and grip the spacer? It seems a bit wrong to me..

[JohnD]

Kevin,

Car springs come in two Inner Diameter sizes, 2.5" and 2.25".  O.25" = just over 6mm (6.35mm).  Could that be the difference?    

Triumphs use the smaller size.

John

Edited October 14, 2023 by JohnD

[Kevin Atkins]

Thanks @JohnD - ah, I didn't realise that! That sounds like it could be the issue then - neither the original springs, nor the replacements which were also about an inch shorter than the originals (and now off the car), fitted over the spacers.