Front caliper pin wont fully tighten - keeps turning and turning

[christdi]

Well I decided to change my front pads + discs due to the fact I was getting a bumpy braking effect (warped discs)..

I changed them over no problem, but upon tightening the top caliper pin on the passenger side it just keeps turning and turning and wont fully tighten. I tried swapping the pin with the bottom one and it does the same.

I'm guessing the thread on the brake/wheel hub is partially knackered.. the question is what should I do? The pin itself now has about a 1mm gap and seems locked in place up until this small gap..

Assuming the role of the pin here is to just keep the caliper in the correct position then once the brakes are applied the pin is irrelevant as long as the caliper is in the right place.. I've been out on a test run and the brakes seem fine.

Can I use thread-lock perhaps?

Anyone else heard of or seen this problem?

[a8 tech]

Sorry replace the hub unless you can tap a new thread which sounds unlikely and as there is no option to oversize then its a new hub and bolts

[batteryman]

Had this problem with my Golf. There are two solutions:- (i) renew the hub at about £150.00 for new or if you're lucky about £30.00 for a good one from a breaker. Don't bother changing the ABS sensor unless you have to - my mechanic reckons they usually break coming out. I was lucky and got a hub with a decent bearing. (ii) Crasher posted photos of a repair where special jigs are used to drill out the damaged thread and tap a bigger thread for a custom made insert. You may be able to find someone local who can engineer something similar or contact him if you can take it to Nottingham. Commercially available inserts won't work because there's not enough metal in the caliper carrier to use them. Crasher's repair is neat but a replacement from a breaker is probably the easiest and cheapest fix.

See my post "Front caliper carrier problem - stripped threads" dated 16/09/2008 for more info.

[producedapples]

Changed my front pads + discs this weekend, came to do the n/s and the top bolt was loose, obviously threads have been stripped, seen a post on here that its a M9 x 1.25 thread, well, ive found this... http://www.justoffbase.co.uk/M9-X-1-...raper-DHCK-MET

im guessing thats it really??

[batteryman]

I think that's the correct size but personally I wouldn't use a helicoil kit in a safety sensitive area such as a front brake caliper. I know the loads involved on these pins are low but I wouldn't take the risk myself. Crasher's repair uses a custom made shouldered bush insert - a bit like a top hat section. He line bores the original hole with a jig to keep it accurately positioned and then fits the insert - it has the correct size threaded hole for the pins, This repair looks as strong as the thread in the caliper carrier casting - I doubt a helicoil repair would be anywhere near as strong. Best solution is a hub from a scrapper - I got mine for £20.00.

[producedapples]

Thats also an option...

[producedapples]

Or even better, the caliper carrier

bolted on with 2 x 19mm bolts, surely cheaper, and more sensible??

[batteryman]

Sorry for the delay in replying to this one - been offline for a while. A replacement bolt-on caliper carrier is fine if you're lucky and your car has this feature. Mine was part of the hub casting and I had to replace the lot. I was lucky to find a good hub in a breaker's yard - one with working abs sender and bearing in good condition. They also gave me the caliper pins.

[vwcabriolet1971]

Well I decided to change my front pads + discs due to the fact I was getting a bumpy braking effect (warped discs)..

I changed them over no problem, but upon tightening the top caliper pin on the passenger side it just keeps turning and turning and wont fully tighten. I tried swapping the pin with the bottom one and it does the same.

I'm guessing the thread on the brake/wheel hub is partially knackered.. the question is what should I do? The pin itself now has about a 1mm gap and seems locked in place up until this small gap..

Assuming the role of the pin here is to just keep the caliper in the correct position then once the brakes are applied the pin is irrelevant as long as the caliper is in the right place.. I've been out on a test run and the brakes seem fine.

Can I use thread-lock perhaps?

Anyone else heard of or seen this problem?

You don't say what car is involved but if it is a MK4 Golf then a new caliper carrier is required . This is held on to the hub with 2 hex head bolts so is fairly easy to remove from your car (and a scrap car).
The replacement carrier should be thoughly cleaned before fitting , particulary the pad sliding/seating areas to remove all rust. New bolts ( from VW) are recommended and should be tightened to 125Nm (92ft.lb).
You should use 2 new caliper guide pins ( one is suspect any way ) and torque these to 28Nm (21ft.lb) . The lack of a torque wrench is the biggest reason why guide pins/ holes are stripped- the 28Nm torque is about the same as most spark plug recommended torques.
It is possible to repair the carrier stripped thread with a helicoil or insert
but it does need a jig to ensure that re-machined hole is both square to the caliper mounting face and also that the pitch of the hole is maintained.
Not realy a normal DIY job ( unless you have a M/C shop ).

Simplest/cheapest way is a visit to the scrap yard- but check part is not damaged or bent.

[producedapples]

Just had a look, mine, unfortunatley hasnt got the bolt on carrier so will be a thread repair kit for mine, there torques arent massive, and its only there to hold the caliper in place, i feel it will be fine...