1996 front pinch bolt thread

[davkyt]

The thread in the suspension foot has come out....
Is there any fix for this other than the obvious?
It's the one on th the right hand side, and the outside bolt. The inside one is fine.

[Flip]

What do you mean it 'has come out' ? (insert the obvious joke here).

The fork lower is a tapped thread so unless it was previously heli-coiled and it is the insert that has come out when you've undone the cap head pinch bolt I don't quite see what you mean

[davkyt]

The hole where the pinch bolt goes has no thread in it.
About 1\4 of a turn away from the torque wrench "click", the pressure released and the the bolt was allowed to move freely. I took the bolt out..... And the thread from inside the hole is now on the bolt

[Darren69]

Do you mean the original aluminium thread has come out with the bolt, eg stripped? I guess some Neanderthal has thought they need to be super tight and overtightened them. They only really need nipping up as they're only designed to stop the axel from turning and undoing.

[Flip]

If the thread that came out was a perfect coil it sounds like it had already been hell-coiled where someone else had previously stripped it.

If that's the case it's a simple job just to clean it up and fit a new heli-cook to repair it.

[jerry]

8ft lbs or 10nm is all the torque they need its a 6mm

[davkyt]

Yes Darren and Flip

There was a perfect coil around the bolt when I took it out

So what do I need to do to fix it?

[Luddite]

There's a really helpful step-by-step guide on fitting thread inserts in this month's Practical Sportsbikes magazine. I've sent you the relevant pages via PM. You can ignore the first six steps as the hole has already been tapped for you, although it might be a good idea to run the tap down the hole to ensure the thread is clear.

You'll need a replacement insert and insertion tool. Machine Mart do an M6 kit for £16.79, https://www.machinemart.co.uk/p/040216677/ which should do the job.

Hope that helps.

[davkyt]

Thanks luddite

[utopia]

Hold on .. are we certain here that the thread has already been helicoiled before ?
Its quite possible to pull out the entire original aluminium thread with the bolt, and it will look very similar to a helicoil insert.
I'm more inclined to think that this is what has happened.
Either way, I would still start from the beginning of the helicoil process and run the tap down the hole, even if its only to clean up the threads before fitting the insert.
But I strongly suspect that you will have to actually cut the new thread for the helicoil.
There may even be further complications if the clearance diameter of the plain half of the hole is too small to pass the helicoil tap through.
You could of course tap it from the other end but then you significantly increase the chances of the tap not going in square, as it is no longer guided by the plain section.
If it comes to threadcutting, use paraffin as a cutting fluid/lubricant on the tap, cut the chips off small and blow them clear to avoid them jamming in the new threads and ripping them.
Remember, you have one shot to do it right, or else its a new fork bottom.

If I were doing it from scratch I'd strongly consider doing a practice run on a bit of scrap aluminium first.
Either that or find a local garage that will do the work (and take the risk) for you.

When its all done and you're retightening the two bolts, nip them up very gently and gradually, moving repeatedly from one to the other as you gradually approach the clamp torque on the spindle, and remember they only need a very low torque.
Use lube on the bolts, not Loctite .. black moly grease ideally or fine grade copperslip.

Worst case scenario, as a super-bodge you could put a nut on the back. :eek:
You could at least ride it to the garage like that.

[Luddite]

Just so we can confirm what you're dealing with here, what were you left with when you removed the 'coil' from your bolt? If you can stretch it out and it breaks up, then it's a newly stripped thread. But if it's solid, like a coilbound spring, then it's a helicoil-type insert.

It's fixable either way, it's just one way is easier than the other!

[davkyt]

It was a coil that broke off in sections. So from was ppl are saying it would most probably be a freshly ruined thread?

[Flip]

Okay, get a nice little torch and have a look at where thread 'should' be in the fork leg- if looks neat and 'thread like' you have taken a heli-coil insert out. If it looks knackered then you have stripped the original thread and it will need repairing.

[Luddite]

It does sound as if you've got a stripped thread there (if you've still got the pieces, check the material. If it's steel, it's an insert; if it's aluminium, it's a stripped thread).

If you do need to drill and tap the hole and want to do it yourself, you'll need a pillar drill or at least a drill stand to ensure accuracy. If you've not got the equipment, you could try a local engineering firm who should be able to do something like this pretty cheaply.

Either way, you're going to have to remove the fork, if you haven't already done so.

As utopia said, for a temporary fix, you could fit a nut (and washer) on the end of the thread, but you'd need a longer bolt to do this.

[davkyt]

On looking there is about 1cm of thread left.... So a longer bolt might do.

If anyone has a spare, longer bolt to sell me it be awesome.... or direct me to one. I don't want to guess and knacker the remaining thread

I have some spare forks with knacked stanchions... It might be time to try and disassemble them. I don't have a bench vice tho so i might have to pop it to a garage to get the feet off.

[Mr Gazza]

It's going to be far easier, cheaper and quicker to just slip the offending fork leg out and take it to someone with a Helicoil kit.
Any self respecting fitter will have one in his toolkit.

It took my mate about 5 minutes to pop 2 Helicoils into my alternator cover for the sprocket cover screws.

Wurth do oversize ones BTW. So you can replace a knackered Helicoil with a Wurth one if needs be... But you only need a standard one.

[garry]

if anyone has the dimensions of the bolt, i may be able to help you out.

[Dirty]

Personally I'd get it properly sorted rather than rely on the last 10mm that hasn't failed yet.

[Flip]

I do quite a lot of Heli-coil-ing (if that's really a word?) at work, mostly into Aluminium heatsinks and Mould Tools for Epoxy resin for use in Electronics and if it were mine I would be tempted to run the insert tap in without drilling it out (the insert tap puts a 'mirror thread' into the metal) and then carefully run the insert in from the 'wrong way' - you have to be careful here as you're winding it in against the direction of the thread so the 'tang' is still at the correct end- if that makes sense.

The worst that will happen is that you'll have to pull the insert out and start again but it will come out like an un-coiled spring so not real bother.

If you use a set like this 'V-Coil' set on Amazon there is no tube tool like the actual Heli-coil tool (Heli-coil is a brand name like Coke is for Cola by the way) which will make sighting it going in straight a little easier.

https://www.amazon.co.uk/V-Coil-6mm-1-0-Thread-Repair/dp/B000ZEHGJY/ref=sr_1_1?ie=UTF8&qid=1488832392&sr=8-1&keywords=m6+v-coil

I would be happy to do it for you but you're miles away from the South Coast.

Personally I'd get it properly sorted rather than rely on the last 10mm that hasn't failed yet.

A thread insert will only be about that length anyway and the pinch bolts really are only doing just that- there are two on each fork lower to make sure it clamps the Axle evenly.

[Albie]

if anyone has the dimensions of the bolt, i may be able to help you out.

If they are early forks they are M8 x 35mm long caphead not M6

[Flip]

If they are early forks they are M8 x 35mm long caphead not M6

Okay then this set if they are early forks:

https://www.amazon.co.uk/PowerCoil-3521-8-00K-Thread-Repair-Kit/dp/B007R5RDI8/ref=sr_1_11?ie=UTF8&qid=1488834028&sr=8-11&keywords=m8+v-coil