I thought I'd have a go at replacing the cylinder base and pushrod tunnel gaskets on my B33 to reduce oil leaks. One of the cylinder through bolts 66-0115 was a bit knackered so I decided to fit new ones to one side. Big mistake. As soon as I started to tighten one of the new bolts, It continued to screw into the head until the shaft hex came to the bottom of the fins. When I'd got it disassembled, I could see that the stop at the bottom of the shaft had come adrift, and fortunately it was sitting on top of the flywheel. I sent it back to Drags for replacement. Before I fitted the new bolts I decided to drill a small hole in the end and fill with weld to prevent the stops coming off again.
As soon as I started to tighten again, one of the stops again came off.
The original BSA bolts had the stop integral to the central shaft. The replacement ones have the stops screwed onto the end and unsurprisingly unscrew themselves as the bolt is screwed into the head.
Has anyone got any suggestions how to fix the stop securely to the end of the bolt so that it works as it should do?
You could try loctite thread lock that may work. I may add what a rubbish design all done on the cheap.
Thanks Idie. Having 'put it to bed' and 'slept on it', I still can't see a workable solution. Its obviously material cost vs labour cost. It looks like the stop has an M8 thread and is held by max three threads. I can't risk loctite and pulling it apart yet again and possibly losing the stop in the crankcase. So I'll fettle an old bolt to make it usable, but I'm now short of one because I gave the other the chop to investigate how it was made; making myself a mag gear puller out of the bottom socket. There's bound to be someone with a usable bolt in their scrap box having replaced them with shiny new SS ones. I've no idea who makes the SS ones or how they're constructed but I was trying to keep to original mild steel parts.
If an old one is ok send me your address. I'll post one to you. Just give me a couple of days to find them.
Pm sent
Received PM. Will look tomorrow.
I have seen the same problem on a friend's bike I worked on, the captive end just unscrewed when we tightened the head bolt and fell into the crankcase.
I have also had examples where the captive section was screwed on with a left-hand thread which at least meant it also tightened when the bolt was tightened into the head. The problem would then come when you undo the bolt!
It is just a cheap was of making these bolts and very unsatisfactory.
Can the end cap not be welded after the through bolt is assembled and any excess ground off?