Does anyone know the thread diameter and pitch for the oil pressure release valve on a 1972 t100r? I need to get a tap to clean up the threads as my release valve won't hand tighten in, and I don't want to damage the case. Thank you.
Hopefully DMadigan will notice the thread, he has a file on this kind of stuff. I would think you will have a tough time finding 1) the right size, and 2) a "bottoming" tap that will not have a long start taper. As for anything I could offer: Years ago an old timer who worked on these things himself would show me "How We did it....", and at times it was useful in a situation. He showed me a way to dress up or clean up threads in a hole using a tap as a thread chaser. I did use this method several times after and it saved my ass. First, find out thread pitch,...how many threads per inch. maybe you have a thread gage? Then find a tap you have with that same thread pitch, in a size that is smaller diameter. Using that tap as a scraping tool, lay it in the good part of the threads, and drag / scrape it into the problem area. The good threads act as a guide as you hold the "tool" down while scraping away the problem nick or cross threaded portion. It's a Bodge way to get the problem resolved, but as those old timers didn't have a lot of $$ and had the can do attitude, those methods were used when all other options dry up. And they rode the bikes........... Good luck!
thread diameter and pitch for the oil pressure release valve on a 1972 t100r? I need to get a tap to clean up the threads
'Fraid that's likely to be expensive ... Triumph deliberately chose threads that some shade-tree 'mekanik' couldn't replace the release valve with a hardware store bolt to 'improve' the oil pressure. It's a Unified Constant Pitch.
Originally Posted by flattrack500
release valve won't hand tighten in, and I don't want to damage the case.
Risking asking a stupid question, you have checked that the release valve and the case are the same thread? Triumph earlier used a 26 tpi Cycle-based thread on the oprv.
I do not have a T100R case to check. The late A65 and A75/T150/T160 have a 7/8-16 UN thread. A tap will not work unless you can grind the end up to the full diameter as they all, including a plug tap, have a lead-in with reduced diameter. One possibility, and cheaper, is to find a bolt of the same size and file slots lengthwise on the end to clean up the threads. Once a tight spot is found turn the bolt only a 1/4 or 1/8 turn and back out to check. You will want to spray brake cleaner or similar through the passages from the other end to clear any chips out.
Apologies for the slightly bum info. in my previous post, now corrected.
7/8-16 is Unified Constant Pitch - 7/8"UNF is 14 tpi, 7/8"UNEF is 20 tpi. So, as said, if a tap is available, expect to part with various upper and lower limbs for a one-off job ... Unless Dave knows of a source for 7/8"UNCP bolts?
Otoh, 3/8"UNC and 3/4"UNF are both 16 tpi; use one of those - or a thread file - in the way suggested by "KC"?