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Discussion Starter · #1 ·
Stripped threads seem to be increasingly common in the alloy trailing arm on the R56.

The bolt that holds the bottom end of the rear shock to the swingarm as well as the bolt which holds the front bush are self tapping from the factory and they have a tendency to take the threads with them if they are removed and refitted more than a few times.

I'm going to be doing a proper future proof thread repair on my own car using a solid steel threaded insert called Wurth Time-Serts but the cost of the kit is fairly eye watering.


Does anybody want me to do their swingarms while I'm at it to spread the cost at around £30 per thread repair?

Cheers,

George


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I've now swapped both mine for good used examples and fitted black series polybush bearings which has transformed the rear end

I think the issues with the trailing arms and the bolts taking the alloy away are the stupidly high torque values. I think they're around 165nm or 121ftlb which when going into the relatively soft alloy it's a recipe for disaster.

I stopped at 80ftlb on mine and believe me that's enough. Switch back to a half inch ratchet and I gave it a good pull and as quite a strong person it felt very tight. I certainly won't be loading it up with 120+ ft-lb as I'm pretty sure that's going to strip the threads again and then I'm royally screwed once again.
 

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Could I buy your old arms off you to try out the repair system?

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Would be ideal if you could do them on an exchange basis.

Take a decent sized deposit from people, send out a set of "fixed" arms, buyer sends their old ones in, you refund the deposit -££££ for your time and effort.

;)
 

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Could I buy your old arms off you to try out the repair system?

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Hey George, I'll need to check to see if my body shop still has them. Also bear in mind in order to put a nut and bolt through it I've milled away on the first arm, and then on the second failure just crushed a section flat so these are probably scrap now. Will find out at any rate if they're still there.
 

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Discussion Starter · #6 ·
Hey George, I'll need to check to see if my body shop still has them. Also bear in mind in order to put a nut and bolt through it I've milled away on the first arm, and then on the second failure just crushed a section flat so these are probably scrap now. Will find out at any rate if they're still there.
Probably not worth the effort if they've been butchered. I'll get a couple from a scrappy or there might be somebody on here with some old arms that have stripped.

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Discussion Starter · #7 ·
I think the issues with the trailing arms and the bolts taking the alloy away are the stupidly high torque values. I think they're around 165nm or 121ftlb which when going into the relatively soft alloy it's a recipe for disaster.
Maybe the 165Nm is required for initially forming the threads in the untapped hole in the factory. There might be a lower figure somewhere for refitting...

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Discussion Starter · #9 ·
I can't see what advantage this would have over a heli coil. Just seems to be a dearer system. Have any of you tried a comparison of the two methods ?
I've used helicoils in the past and they do work. I haven't used the Time-sert myself but I've spoken to engineers who use them and swear by them. The solid Time-sert is supposed to be much better for something that you're going to have off and on more than once. The bottom end of the insert is cold formed into the threads and you can use thread lock with it unlike the helicoil. It's a proper permanent repair.

I'll destroy one by torquing it to the point of failure and we can see what it will take. It will be interesting to find the limits in aluminium.

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