Erie Fred
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- Erie, Pa USofA
I'm not understanding exactly the problem.
- Thread starter Domdom
- Start date
I’ve done just that in the past.
charlysays
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- 547
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- UK, Wales
They can be really annoying to get hold of. I usually buy parts for the Mk4 golf based on whether they come with the bolts. As others have said look for a thin shank on the bolt and look up the procedure in the manual- if it's a torque plus 90 degrees etc then it's likely they're TTY since the initial torque is there to get it into the ball park so that the 90 degrees ensures it yields and stabilises the torque based on the bolt specs. Whether you can reuse them is partly down to luck. When I last did the lower control arms on the golf I read of loads of people reusing them without issues but luckily the FAG lower arms came with the bolts. So buy your parts wisely, most pics on autodoc show the bolts if they're included. The bolts can be expensive on their own.
hotponyshoes
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- Somerset. Uk
I'm not a fan of that either.
But to be fair, bolts are not readily available with a huge choice of shank lengths sp it's not allways an easy problem to avoid
Yep. And all the other bolts from engines gearboxes and diffs I've dismantled and scrapped over the years.Anyone else got a stock of saved old head bolts for that "just in case" project?
Cobbler
Codger bodger
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- Gloucestershire UK
Errr, anyone want a bucketful of odd bolts
colnerov
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- Nr Gatwick UK
Ditto, I've got a 20L drum cut in half, with Imperial in one and Metric in the other.
Me either. Thread bound bolts don't sound too clever to me. It's not the defining factor in the fatigue life of the joint, so not sure what the issue is.
It won't 'stretch at a certain torque', it will yield at a certain stress (based on the waisted diameter) and thus move from the elastic to plastic region where the stress strain curve flattens off and increasing strain doesn't increase stress (read that as clamp load) as significantly (see the bottom graph below).Aha!!! The light bulb just came on
If I understand correctly, a normal TTY bolt will stretch at a certain torque so that tightening it further (up to the point where the bolt breaks of course) doesn't actually exert any more clamping force. So it can't really be over-tightened.
This might go some way to explaining why replacing a TTY bolt with a 12.9 one is not good as the 12.9 could easily be over-tightened. This was a really confusing part for me, I couldn't fathom why a stronger bolt would (could) be undesirable.
Using TTY is intended to minimise the influence of applied torque from the equation as clamp load derived from torque is dependent on all the frictions in the joint so is inherently variable. It might also give you some tummy comfort that you don't need to get toooooo precious about the angle.
