Lower Yoke pinch bolts woe.

Old Bloke · Apr 13, 2013

Well, hit my first stopper on my rebuild today. Yokes have been powder coated. The lower yoke pinch bolts won't screw in. I am sure I am using exactly the same bolts that were fitted before the powder coating. I thought the problem was maybe the threads hadn't been masked/sealed, but they look clean ok but maybe a slight run of black towards the rear of the holes. I made the mistake of trying to force the bolts in, thats just damaging the threads. Could someone kindly tell me what the hole size and thread is on the lower yoke/bolt so I can check it out, and opinions on fix, would it be worth buying the correct tap to chase the thread, or is the yoke too hard? Thank you.

pete.v · Apr 13, 2013

Should be a common 3/8" - 24 tpi, common in the US anyways. The yoke will never be as hard a a fair quality tap.

Old Bloke · Apr 13, 2013

pvisseriii said:
Should be a common 3/8" - 24 tpi, common in the US anyways. The yoke will not be as hard a a fair quality tap.

Thanks for the info pvisseriii, it was the thread pitch I was not sure about.
I see a few of these taps for sale on Ebay UK, so they are available, new and used. I'll give it a shot.

Actually you might be able to give me some more help. If I am only needing to clean up the thread, which tap is best, as there are various available on Ebay, First tapered, 2nd, 3rd finishing, or does it not matter that much?

Peter

BillT · Apr 13, 2013

If you are looking to simply restore a thread that has been damaged, see if you can find a rethreading tap. If not, then a finishing tap.

Look up rethreading or thread restoring

Old Bloke · Apr 13, 2013

Stephen Hill · Apr 13, 2013

I don't think you will have much luck finding a rethreading tap. They are sold as taper, plug, or bottoming. Each has its own use, and have different number of parial threads. A plug is more general purpose, as in if you could only own one, that would be it. If you are chasing bodged internal threads, you need a taper or a plug. If the bolt threads are also bodged, you probably need a die, which also come in different flavours, including rethreading (aka chasing).

Stephen HIll
Victoria, BC

bwolfie · Apr 13, 2013

Best yet, a re threading set. Fixes threads with out removing material.

http://www.ebay.com/itm/Snap-On-RTD40-4 ... e5&vxp=mtr

kevbo82 · Apr 13, 2013

Did you do any prying to get the fork in or out? Could be the two holes are slightly misaligned and causing the bolt to cross thread. Look into the hole with no bolt in and see how the outside hole lines up with the threaded hole. Happened to me, as soon as I felt it cross threading I backed out gave it a knock with a 2x4 and ran a tap in there to clean things up

Old Bloke · Apr 14, 2013

kevbo82 said:
Did you do any prying to get the fork in or out? Could be the two holes are slightly misaligned and causing the bolt to cross thread. Look into the hole with no bolt in and see how the outside hole lines up with the threaded hole. Happened to me, as soon as I felt it cross threading I backed out gave it a knock with a 2x4 and ran a tap in there to clean things up

Thanks all again for more info.

Kevb082. Now you mention it, i've usually had to pry the" collar" apart to slide the fork leg in, and didn't have to do this. Maybe the heat during the powder coating has caused it to spring out a bit. I'll check that thanks.

doug · Apr 14, 2013

Old Bloke, you have PM.

doug · Apr 15, 2013

Hi, I got your PM today. If you want a tap, PM me an address and I will post some down to you.

splatt · Apr 15, 2013

Make sure the plain section doesn't \have a large offset build up of powder coating pushing the bolt off center

Old Bloke · Apr 15, 2013

splatt said:
Make sure the plain section doesn't \have a large offset build up of powder coating pushing the bolt off center

I'll double check that too, looked ok visually, guess it was masked/plugged ok.

Doug: Thanks for that kind offer, someone at my work has loaned me a set, so I'll try them later this week, when I get back to home.

Thanks

Old Bloke · Apr 21, 2013

Thought I'd just close the thread with the solution.

When I tried to clear the threads with the tap I noticed the tap was hooking up on the outside hole, so looked like Kevbo82's idea might be correct. "Persuaded" the clamp to be a little tighter, and the tap ran through, and took out quite a few rough bits. I could get the bolts in ok then.

Thx for all the tips, I'm going to get my own 3/8 unf tap and die now.

kevbo82 · Apr 21, 2013

we built a garage at my father in laws business and it kinda became a community tool box. we have two great tap and die sets there, which no one else seems to use so they've slowly worked their way into living in my garage until someone calls looking for them. Helped with a lot of stuff on the norton rebuild. Glad i could finally give someone a helpful suggestion on here and start paying it back!

Lower Yoke pinch bolts woe.

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