Triumph Sports Cars

I have Les Schwab 195 x15 Confidence All Season on my 302 conversion 4A solid axle and the car changes direction 10-15 degrees every time I hit the gas or shift
I am suspecting That the sidewalls are way too weak for the task at hand
Tires are mounted on panasport true knock off Wheels, so that is not the problem
Any suggestions?



Edited 1 time(s). Last edit at 04/07/2021 10:18AM by Triumphant4A.

Not sure if it helps but I have G Force TA drag radials on my sprite sbc conversion. To say I do spirited driving in the car is an understatement. It'll get enough traction to pull the front end high. 225/50 R15s. BF Goodrich

What width are the rims?

Does it have a limited slip?

Ivor

5.5 inch mini light style rims - still running the factory live axle, not LSD

The rims are slightly narrow for 195 tyres. Not out of range, but it would allow more distortion.

Does the squirreling still happen if you temporarily increase the inflation pressure by say 10 psi? If not, that would point to the tyres or wheel/tyre combo as being the problem.

That said, from what I can see the Les Schwab are what one might call budget tyres, and personally I would not want them on a performance car. I don't know what is generally available in the US, but over here in the UK, I would be looking to the Michelin XAS or Pirelli Cinturato CN36, both of which have progressive handling well suited to a solid-axle car.

However, just to throw in another thought, thinking back to a problem I had years ago... are you sure, really sure, that the axle U bolts are tight?

Ivor

Have you had an alignment done? I suspect the thrust angle is off. Could be caused by worn bushings.

Alignment is next on my list of to do efforts. We did a string alignment at home, but I suspect camber setting is not correct
We have replaced axle bolts and centering pins for the spring blocks
Extra 10 pounds of air reduced the squirreling but didn’t make it go away entirely
Thanks for the ideas!
I will be helping a friend complete some repairs on his 66 in a couple of weeks and plan to borrow his wheels and tires for a drive to see if it changes the behavior any.

What does it do on hard braking?
Swap your tires side for side to see if the issue changes.
I would suspect that you have a suspension issue. A worn or loose spring bushing or mount. Possibly a broken or cracked leaf?
The stock live axle uses spacers between the spring and axle. Any play in the suspension is magnified by this setup.
Even a weak shock can upset it dramatically. If you still have the lever shocks, are they working well and the links are good?
I actually like the levers. Simple, tunable and rebuildable.
If you keep the live axle I see a spring upgrade and some torque rods in your future.
Live like you mean it.
Fred

Thanks Fred - Braking is not a problem - just the on and off of throttle / shifting.
All shocks are new - levers in back spax out front.
Just received new rear leaf springs on the chance..
redrilled and repinned the spacers already
I have been looking for a good torque rod design - so far have only found those designed for the TR4 live axle - no 4A

Half the fun, right?

5.5 inch wide rim?

It says here [www.britishcarforum.com] that around 25% of TR4A production was live axle. Maybe 7,000+ cars.

Mainly US market but some have come back to the UK.
Worth getting in touch with Revington &/or CTM, they will have experience in taming the back end from their racing involvement.

[www.revingtontr.com]

[ctmengineering.co.uk]

Ivor

Had a thought over the weekend.
Is your drive shaft possibly too long and binding the rear suspension?

In drive shaft, don’t think so. Had it made to measure but not hard to check. I don’t really have a speck for how much slide it should have on the front where it engages with transmission anyone’s guess??
Took leaf springs out to replace - old but nothing visually wrong. Strangely, the poly bushings at the shackles are already distorted and ovalled out after 2-300 miles??

I have a 66 TR4A and had exactly the same problem a couple of years ago. When I bought the car it had a broken leaf spring and loose shock. I fixed that stuff and then found the car swayed every time i shifted or hit the gas pedal. I rebuilt everything on the back end and still no change I finally took my car to an old TR guru and ten minutes later on the hoist he said I can see by the oil leak between the axle tube and the differential that. the axle tube is loose due to the car being driven with the broken spring and shock. He was right of course. I replaced the rear end since the gears were noisy because of damage to the other broken parts .Problem solved. I know its a long shot with your car but it might be something to check ps Hello Fred Key nice to see you posting

Thanks,
Just got the new springs in this past weekend and am happy to report that the problem is solved!
Neither spring looks bad, so I am guessing that one has lost more spring tension than the other. Replaced all of the bushings with super poly while I was there. Gave it a quick aggressive run up the highway and enjoyed every shift and twisty.
Great suggestion on the tubes - reshimmed and sealed those earlier. Always the last thing you would suspect!