Trailing arms

[Guest Steve Raine]

Hi,

 

I am slowly restoring a 1972 TR6 and would like advice on the best method to refurbish the trailing arms.

 

I have cleaned the arms with an aluminium cleaner and they look pretty good but do I leave them in bare aluminium or coat / paint them with something?

 

Any advice from the vast experience in this forum would be much appreciated.

 

Thanks,

 

Steve

[Guest Neil Russell]

give them a very light bead blast if they are really dirty to even out the finish and clean thoroughly. That said, yours sound good enough now? If so i would just etch prime and paint silver.

 

I would not try to anodise or powder coat if I were you, since I think you will find that the coating will bubble and blow everywhere due to the porous nature of the casting.

many members have tried this at cost.

 

I would also ensure all of your threads are helicoiled with UNC threads before re-painting. It may even be worth crack testing the casting before you spend any money on it if you are not sure of its history.

 

regards

neil.

[Richard Crawley]

Do the Helicoil mod as a matter of course & check thoroughly for stress cracks (crack test if you can). After cleaning, I just used a couple of coats of clear matt, laquer on mine.

[Andy Moltu]

Why helicoil the treads if they are fine?

[Guest Neil Russell]

They are never fine Andy! In my experience they are always marginal on strip down. triumph in their infinite wisdom used a UNF thread in the casting from new. when stripped down invariably the corrosion of the steel in the aluminium casting results in the thread being damaged. as such as a matter of course you should always drill and re-thread with a UNC helicoil. I actually had to re-weld 2 of my holes prior to re-drilling and re-threading.

 

In a lot of cases trailing arms have often been re-threaded with replacement studs, which will often fit, but the tolerance is always too high which can result in a stud pulling out of the aluminium when a stress is exerted.

 

Neil.

[Richard Crawley]

Fully agree with Niel: These arms will now be at least 25 years old, possibly much more & will have been apart many times. The torque setting for the hub/back plate fixings is very low at 16lbf/ft & you can practically achieve this just by turning a ½” socket extension bar with your hand let alone using a ratchet!

Most people not using a torque wrench will tend to over tighten them with the result that even if they don’t strip the aluminum threads completely, they will be stretched & very, very tired. The Helicoil mod is cheap & will give you piece of mind that the hub wont part company & disappear into the nearest bush on a future fast corner!

[Guest Steve Raine]

Thanks for the advice guys.

 

My trailing arms have cleaned up pretty well so may try the clear laquer route.

 

I have read that the arms should be helicoiled but my studs seemed to be pretty solid, so solid in fact that I was worried that I may damage the arms trying to get the studs out.

I had thought of leaving well alone but probably not a good idea by the sounds of things!

Time to find a good engineering firm in West Yorkshire.

 

Steve

[Guest Neil Russell]

2 schools of thought steve. if they have never been apart, and you are sure then you might get away with leaving well alone. but do you have any doubts? I had 3 -4 unscrew on me when I stripped the rear arms down so the decision was made for me.

 

helicoiling shouldn't cost too much. ensure you fit UNC though and then purchase the correct replacement studs. its a long time since i did it but i think you can use a UNC steel helicoil with a UNF thread to allow the original fitment studs (its 10 years now and the car still isn't finished) 2 Houses, 3 garages, marriage etc etc.

[Richard Crawley]

you can use a UNC steel helicoil with a UNF thread to allow the original fitment studs

Preferably, use stainless steel inserts (I have a feeling these might be the standard material anyway) as they will not "fret" with the alluminium housing.