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Thread Like Summary
Beach, BILL P., Jon W. Whitley
Total Likes: 10
Original Post (Thread Starter)
by BILL P.
BILL P.
Changed the fluids and noticed someone "may" have used JB Weld in one of the sump holes. Interested in hearing a couple suggestions to repair the stripped hole.

Thanks,

Bill
Liked Replies
by Jon W. Whitley
Jon W. Whitley
Originally Posted by BILL P.
Changed the fluids and noticed someone "may" have used JB Weld in one of the sump holes. Interested in hearing a couple of suggestions to repair the stripped hole.


I would use either a Time-Sert or Heli-Coil. I lean toward Time-Sert but both will work.
2 members like this
by Gary Caines
Gary Caines
Time-Serts are fantastic. With a HeliCoil you have to be very careful how tight you torque the fastener. Time-Serts are much more durable and you can normally tighten the bolt or screw to specified torques. If possible, I would always use a Time-Sert.
2 members like this
by gunner
gunner
The sump plate is a very common area to get stripped studs and its important that they secured so that the nuts can be fully tightened.

I've use Helicoil thread repair kits over many years without problem and can recommend them, never tried the time sert version but assume its similar.

I believe the studs from 1968 are 1/4 UNC where they screw into the crankcase and the nut end is 1/4 UNF. Alternatively pre-1968 it might be 1/4 BSW/BSF, so best to check with a thread gauge.

Unless your are keen on originality, I find it easier to use a metric M6 helicoil in this area and substitute the studs for socket caps. Additionally I use an alloy sump plate with magnetic drain plug. M6 helicoils are easily available and cheap whilst imperial ones are expensive,hence my reason for using them.

This approach means the sump plate can be kept in place much longer and oil can be drained by simply undoing the drain bolt. The magnet picks up any ferrous material and is usually covered in a kind of grey sludge which shows its doing its job.
1 member likes this
by PFribley
PFribley
Time-sert is more reliable!!
1 member likes this
by gunner
gunner
Hi Allen, yes it does seem strange that SRM sell their alloy sump plate with only one size of socket cap.

However, I was looking at the part numbers of the studs and crossed referenced them with the list of threads for each nut/bolt on BSA's Triumph's etc. I have a copy of this list on my PC as the website which hosted it closed a while back, but I believe its available again and was mentioned on this site, but I cant find it.

Anyway the list mentions the following:-
- for bikes starting in 1970, the stud is part no 14-1401, the thread cross reference says its - UNC/UNF 1/4" 20/28 threads, 1" length
- for bikes up to the crossover year 1969, the stud is part no 31-0222 - BSW/BSF 1/4" 20/26 threads, 7/8" length

So the thread in the crankcase is either BSW (pre 1970) or UNC (1970 onward). I can imagine that trying to screw a UNC stud into BSW hole might be difficult and even though they are both 20 TPI the thread form is different.

The reason SRM supply socket caps may be that it makes the job easier when screwing into a BSW thread, otherwise vise grips may be needed to screw the stud in.
1 member likes this
by Beach
Beach
I just a helicoil to redo thread for stud that holds stator, 5/16-22. Would normally use timsert but don't make in British sizes. Had to flush tang out of crankcase with kerosene dumped in thru pushrod cavity. Worked fine.
1 member likes this
by NickL
NickL
The early ones were whitworth into the cases not bsf.
UNC goes into them with no problems, just a different thread angle.
Helicoils are fine into the holes, either unc or metric.Then allen
screws will last a lifetime.
1 member likes this
by Allan G
Allan G
Originally Posted by gunner
Hi Allen, yes it does seem strange that SRM sell their alloy sump plate with only one size of socket cap.

However, I was looking at the part numbers of the studs and crossed referenced them with the list of threads for each nut/bolt on BSA's Triumph's etc. I have a copy of this list on my PC as the website which hosted it closed a while back, but I believe its available again and was mentioned on this site, but I cant find it.

Anyway the list mentions the following:-
- for bikes starting in 1970, the stud is part no 14-1401, the thread cross reference says its - UNC/UNF 1/4" 20/28 threads, 1" length
- for bikes up to the crossover year 1969, the stud is part no 31-0222 - BSW/BSF 1/4" 20/26 threads, 7/8" length

So the thread in the crankcase is either BSW (pre 1970) or UNC (1970 onward). I can imagine that trying to screw a UNC stud into BSW hole might be difficult and even though they are both 20 TPI the thread form is different.

The reason SRM supply socket caps may be that it makes the job easier when screwing into a BSW thread, otherwise vise grips may be needed to screw the stud in.

You learn something new everyday.
I haven’t looked in the 69 parts book for a while, and know most studs and threads are unf/UNC I’m quite surprised the sump cover is British thread and BSW at that. Also that probably does answer the SRM screw question, they always seem tight when threading into a set of cases so I prefer not to use them and stick with studs and use lock nuts
1 member likes this
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