Triumph GT6 front wheel rub on bulkhead

[Alex Lowe]

Hi all. 
 

im struggling with this issue. I’m coming to the end of my restoration and the front wheels are very close to the bulkhead when the steering is on lock and even rubbing. Distance I’m getting in the photo bellow. 
 

what could be causing this as it didn’t happen before the body came off the chassis. Tyre size is the same 175/70/13. It’s had new shocks and springs standard height springs. And canleys trunionless upgrade. 
 

my only thoughts currently are. 
 

1. the body is too far forward on the chassis but looking through the bolts at the very front don’t seem to have any adjustment room. 
 

2. were the canley uprights sided and iv got mixed up causing the wheel to sit backwards (don’t see this as likely) 

any thoughts or suggestions would be really appreciated

Alex. 

[chrishawley]

Short  answer if that I've no idea.. but maybe a couple of guesses might stimulate the thinking process.

I suppose a clue to the fore-aft location of the body on the chassis is to look at the relationship between the the bracket on the scuttle to the chassis outrigger. As far as I can see from your photo' that relationship can't be terribly wrong. That said, when I did my GT6 (v.extensive welded repairs) I did find I had to rework the front outer mounting points (through the tubes) to get the shell far enough back.

I've no direct experience with trunionless but the v.links don't leap out as a prime candidate for problems. But what about the chassis brackets for the wishbone? It is possible for these to be transposed if removed duration restoration. Rear is illustrated as below. Having never done them transposed myself I'm guessing about how it would affect things. I suppose while checking those an inspection of the chassis rails would be in order.

Tyres? Not really. 170/70r13 is a common option. Sure, they're about a inch wider than 155/80s so may reduce clearance around the wheel arch but can't be a major factor here.

 

There's a couple of thoughts. Perhaps others can improve on those thoughts.

 

 

[Pete Lewis]

my thoughts were the pivot brackets could be swapped  so the wrong offset play havoc with your castor angles on turns 

pete

 

[Alex Lowe]

8 minutes ago, Pete Lewis said:

my thoughts were the pivot brackets could be swapped  so the wrong offset play havoc with your castor angles on turns 

pete

 

Which way round would be correct for a mk3 gt6 mine is curranty set up with the lower wishbone sloping down towards the car. So rear bracket mounts wishbone in the middle and front bracket at the top. 

[Pete Lewis]

Lower Wishbone, Road Spring and Damper : Canley Classics

sounds about right  front is offset uppermost  the rear one is set downwards 

Pete

[Alex Lowe]

29 minutes ago, Pete Lewis said:

Lower Wishbone, Road Spring and Damper : Canley Classics

sounds about right  front is offset uppermost  the rear one is set downwards 

Pete

It seems I have defiantly got the suspension set up correctly then. Which puts me even more at a loss. Having measured against a friends spit it all seems to be the same and yet my wheels rub and his have a good 2cm of clearance. Same tyre size apart from I have 5.5j over his 5.0j

[Mark B]

This is usually caused by the ride height/tyre width. The distance between the bulk head and tyre increases as the car is raised, as the bulk head tapers in towards the front outrigger. A little bit of height adjustment either way can make a big difference to clearence. As long as the the front tub to out rigger bolts are are in place then the tub must be in the the correct position,  there will be minimal tub movement/adjustment when loosened.

[Alex Lowe]

4 minutes ago, Mark B said:

This is usually caused by the ride height/tyre width. The distance between the bulk head and tyre increases as the car is raised, as the bulk head tapers in towards the front outrigger. A little bit of height adjustment either way can make a big difference to clearence. As long as the the front tub to out rigger bolts are are in place then the tub must be in the the correct position,  there will be minimal tub movement/adjustment when loosened.

My thoughts exactly the front most bolt holes are fixed therefor as you say not much adjustment. 

 

The suspension has had new gas shocks and new "standard springs" I believe from James paddock if my memory servers me correctly. 

Tyre width 175/70/13 seems to be the tyre size most people go with and was not causing issues before the full strip down. 

Could the body hight on the chassis not be correct ie not enough shims from body to tub? 

[johny]

Thats a possibility but more likely, as has been suggested, is the car (body and chassis) is sitting lower so that due to the angle of the bulkhead the tyre ends up closer to it. The new springs could be softer or a different length or the shocks have their lower seat welded in a different position with respect to their bottom fixing than the originals. I think theres another thread on here where someone has fitted spacers between the shock top plate and chassis mounting to raise the car ride height although of course if the problem lies with the shock bottom seat the spacer is better off being located there...

Edited May 1, 2023 by johny

[Mark B]

3 hours ago, Alex Lowe said:

Could the body hight on the chassis not be correct ie not enough shims from body to tub? 

There's originally only one alloy spacer fitted between the bulk head and inner front outrigger mounting point about 3/16 thick so would make very little difference. Think the problem is spring length/spring seat combination.  This is the advantage of having adjustable spring seats where you can play around with ride heights. Triumph Tune used to sell ally spacers that went between the shock seat and spring to raise the height.

[johny]

I suppose it could be that the Canley upright pushes the wheels out a bit further than standard and that will make a difference as the further out the tyre sits the further it moves back and forth for the same angle of upright rotation...

[Alex Lowe]

1 minute ago, johny said:

I suppose it could be that the Canley upright pushes the wheels out a bit further than standard and that will make a difference as the further out the tyre sits the further it moves back and forth for the same angle of upright rotation...

That's possible and does make sense how ever iv never heard of anyone have such issues when swapping to the Canley uprights. Again the wheels don't look further out than before but with out an original set up its impossible to tell. 

[johny]

Looking at their picture of it and comparing with standard Id say yes the bottom ball joint has to be further out and, to keep the same angle of the upright, the top is further away from its ball joint resulting in more swing.

You could measure wheel track width across the car but it would be best to compare it now to the original set up...

[Alex Lowe]

20 minutes ago, johny said:

Looking at their picture of it and comparing with standard Id say yes the bottom ball joint has to be further out and, to keep the same angle of the upright, the top is further away from its ball joint resulting in more swing.

You could measure wheel track width across the car but it would be best to compare it now to the original set up...

Hmm can do but difficult to compare and a bit unsure on what I could do about this to rectify with out reverting back to trunnions which I do not want to do. 

[johny]

Main thing is find an explanation. If so then maybe you need wheels with more off-set (25mm?) or narrower tyres (155/80?) - both of these options should bring the travel arc of the outer edge of the tyre in a bit.

[Pete Lewis]

is the rack centralised   does this tyre rub happen on both sides ???

this pops up over the years with little solution  some hammer the baulkhead to get clearance  ( not recommended ) dont think any have come up with a sensible solution 

Pete

[PeteH]

The only 2 things that come to mind are, ride height is (Now) lower?. OR the wheel offset is incorrect?. Has the castor angle changed?.

Pete

[Alex Lowe]

Well as suggested iv added one set of shims to the bottom wishbone as the passanger side had non drivers did. Was advised by my local TSSC chat to make them even. Seems to have made some difference need to take it out for a drive with some masking tape so i can see if rubbing is still happening. After that I think its time to look into the 3/8 spacers for the shocks 

[Peter Truman]

Changing tyres was mentioned this Could get expensive if you have 5.5 in wide wheels as if I remember 155 tyres are too narrow for  5.5 rims so new wheels might be reqd too.

stick with other solutions