Mk III golf suspension problem - Robble

My N reg Golf GL TDI had worn lower front suspension bushes that need replacing. I bought the complete new lower arms, pivot bolts and mounting bolts to fit them myself.
I couldn't get the bolts undone and was concerned about damaging the bolt head by putting excessive force on it so gave it to a local garage to do. They also found the bolts were very stiff, one pivot bolt in particular. They advised the thread maybe damaged and they were going to put the bolt back in, tighten it up and put a weld on the end of the bolt to stop it coming loose.
Got the car back and it seemed fine. Drove about 10 miles and started hearing clonking noises under braking and when steering. Drove back to the garage and they looked at it and said the bush had not been compressed sufficiently because the bolt wasn't tight enough as the thread in the sub-frame was damaged. Basically they said I'd need a new subframe!
I spoke to my father about it who knows more about these things than I do. We managed to convince the garage that they should get an engineer in to attempt to repair the subframe either by retapping the thead or fitting a helicoil to it. My father told them he thinks they should have done this in the first place rather than replacing a bolt that couldn't or at least wasn't tightened sufficiently and welding it in place. The bolt is tack welded so can be removed. Engineer is busy till next thursday, but is going to "asses it" then.
I'm reluctant to have a new sub frame, firstly because of the costs involved, and secondly I'm thinking if the bolts holding the subframe to the chassis are in similar condition to those on the lower arms, then I could have the same problem with threads damaged in the chassis/body!
What do you guys think about all this. Am I doing the right thing? Is the garage accountable for any of this? I understand that the bolt was very stiff and I don't think its their fault for damaging the sub frame thread, but to me the repair they attempted was a bodge that didn't work. Should I be expected to pay for it?

Mk III golf suspension problem - M.M
I'm no VW specialist but have come across this type of thing so many times on other cars.

I tend to phone the owner if I suspect some bolt/whatever may strip on the way out. Give them the choice of me taking the chance or not. Obviously you try as hard as possible to ease the fixing out without damage because usually if it strips/breaks everyone loses.

Having said that if this does happen then you then have to inform the customer of the proper way to resolve it and costs involved.

So far your guys seem to have done OK, especially as you were already aware the problem existed hence passing on the job.

But from here on they got it a bit wrong. Sadly many mechanics fail to understand engineering principles. As I'm sure you knew it doesn't matter how well the weld stops the bolt turning the fact that the thread at the main fixing point had stripped meant the design tension could never be maintained.

I don't know your subframe design well enough to say on yours but for example this can happen on Astras and one answer is to cut a hole in the subframe and then use a locking nut on the end of a slightly longer bolt. Often a patch is welded over the hole again.

This may be considered an acceptable solution but boy is it a puzzle if someone tries to get the bolt off in the future and the hidden nut just spins!

Many guys in car repairs don't understand how to tap a thread to the required standard for this loading, helicoils also can fail.

Me...well I take no chances with suspension fixings so I would be looking at a replacement subframe unless a 100% engineering solution could be found from someone I trusted.

Good luck.


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