Alex Lowe Posted June 25, 2023 Report Share Posted June 25, 2023 Hi All, I have been battling front end bulkhead rubbing on my GT6 MK3 since restoring the car. As the attached photo shows when the car is on lock the tyre is very close to the bulkhead on both sides but slightly more rubbing on passenger side. I think iv ruled every possibility out so far from. - Tub in wrong place, seems to all line up where it should. - Suspension arms are straight - shims went back in the positions they came from. Only things I changed during the resto in this area was trunnionless uprights and I changed the tyres from 165/70/13 to 175/70/13 the rims were always steel 5.5J. I think my only option now is to change the front tyres back to 165/70/13 but peoples thoughts on this would be very appreciated. I believe I will gain approx. 15mm of extra space but will there be any detrimental effect having different sizes front and back? Link to comment Share on other sites More sharing options...
cliff.b Posted June 25, 2023 Report Share Posted June 25, 2023 My Spitfire has the 185/70s it came with on the back but I have fitted 175/70s on the front and I am not aware of any issues. I would say playing around with tyre pressures had more impact than the the difference in width. Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 25, 2023 Report Share Posted June 25, 2023 this foul does seem to bug some cars with little clues to solve it unless you change the tyre pressure or weight of car you wont change the area of the footprint on the road surface regardless of tyre size Pete 1 Link to comment Share on other sites More sharing options...
Alex Lowe Posted June 25, 2023 Author Report Share Posted June 25, 2023 3 minutes ago, Pete Lewis said: this foul does seem to bug some cars with little clues to solve it unless you change the tyre pressure or weight of car you wont change the area of the footprint on the road surface regardless of tyre size Pete Adding my spare which had an original 155/13 I gained a decent amount of room so I think the 165 should do the trick. But I agree some people have no issues some do with very few solutions. Link to comment Share on other sites More sharing options...
Mark B Posted June 25, 2023 Report Share Posted June 25, 2023 This is usually caused by ride hieght/tyre combination. I would have thought 175/70 would have been ok. If the car is fitted with lowered front springs this could be the cause, and why having adjustable spring seats on the shocks is usefall. The bulk head tapers in down towards the front outrigger, so a little bit of height adjustment can make big difference with tyre to bulkhead clearance. Link to comment Share on other sites More sharing options...
Qu1ckn1ck Posted June 25, 2023 Report Share Posted June 25, 2023 4 minutes ago, Mark B said: This is usually caused by ride hieght/tyre combination. I would have thought 175/70 would have been ok. If the car is fitted with lowered front springs this could be the cause, and why having adjustable spring seats on the shocks is usefall. The bulk head tapers in down towards the front outrigger, so a little bit of height adjustment can make big difference with tyre to bulkhead clearance. That is how I eventually solved a similar problem on my GT6 ! Link to comment Share on other sites More sharing options...
Alex Lowe Posted June 25, 2023 Author Report Share Posted June 25, 2023 10 minutes ago, Mark B said: This is usually caused by ride hieght/tyre combination. I would have thought 175/70 would have been ok. If the car is fitted with lowered front springs this could be the cause, and why having adjustable spring seats on the shocks is usefall. The bulk head tapers in down towards the front outrigger, so a little bit of height adjustment can make big difference with tyre to bulkhead clearance. I thought that originally but I installed new gas shocks and road springs. Then added some spacers to raise the ride height but still having issues Link to comment Share on other sites More sharing options...
Stratton Jimmer Posted June 25, 2023 Report Share Posted June 25, 2023 My Mk3 has 165/70 front and 175/70 rear. The handling seems fine to me although my aim is to standardise on 165/70 all round. I run 25psi in every tyre. Link to comment Share on other sites More sharing options...
AlanT Posted July 4, 2023 Report Share Posted July 4, 2023 I had this problem on my Spit resto. Fitted standard springs from the most well known supplier and they are definitely lower than originals. I went back to 155s all around and, on balance, am pleased as the car is light to drive and responsive. Link to comment Share on other sites More sharing options...
Gully Posted July 5, 2023 Report Share Posted July 5, 2023 My GT6 runs 175/70 tyres on 5 inch rims all round and has no bulkhead clearance issues. Standard front springs and shocks. When QuickNick and I compared cars (when he was having his bulkhead fouling issues) we found the front of his car (ground / chassis clearance) was sitting slightly lower than mine - as he's indicated above, a slight front end lift via adjustable spring pan shocks solved the problem. Gully Link to comment Share on other sites More sharing options...
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