Sump Plate - loose studs & sealing

[hoogerbooger]

Two of the studs unscrewed when I removed the sump plate to drain the oil.

Should I be installing the studs first & using some form of locking compound to prevent them coming out again next time? or just use the nut on it to screw back in as if it were a bolt.

I have no locking compounds so wot would be good

(Re the paper gaskets: was just going to use grease)

[A10 JWO]

I would just clean them up and pop them back in. You obviously had a tight fit. If it's not broke, don't spend more money. I use the blue jointing compound, only because I have some.

[AWJDThumper]

Either use thread lock or lock two nuts on the end of the stud to enable you to screw the studs in tight into the crankcase. If you don't, they will just come loose again and eventually wear out the thread in the soft crankcase metal;.

[hoogerbooger]

The studs I have are too short to seat. (didn't realise until non threaded section started disappearing ! - so may have a bit of damaged thread now)

stud holes are 1" deep. Stud width appears to be 1/4" ..but I have no idea on what the right thread is . Can anyone confirm on the right studs to get for my B40F ?

I found this link but the non-threaded section looks too short if it needs to match the sump plate thickness ( i.e sump plate + sump filter + 2 paper gaskets = total of 3/16")

https://www.britishbikebits.com/stud-1-4-unf-unc-x-1#.WuEBb9TwbMw


Also should nylock nuts and normal washers be sufficient - or is there a need for a spring washer as well ?

[AWJDThumper]

I think the correct ones are shown below with 1/4" BSW thread into the engine and 1/4" BSF for the nut. Nowadays using a plain washer and Nyloc nut is probably best. If the threaded hole in the engine appears to be too deep, insert studs up to plain section and use a Loctite thread and stud lock to fix in place. If a thread is damaged then you will need repair with a Helicoil.

[ROYC]

I made my own studs from ¼whit bolts.
I cut the hex head off and ran a ¼bsf die down the plain part of the bolt.

[AWJDThumper]

Sorry, missed off the link to the studs:

https://www.feked.com/bsa-engine-stud-31-222.html

[ROYC]

Sorry, missed off the link to the studs:

https://www.feked.com/bsa-engine-stud-31-222.html

Those are only 1" (25mm) too short if you have a thick aluminium sump plate.

[AWJDThumper]

These are longer and may be ok:

https://www.ebay.ie/itm/BSA-Sump-Filter-Plate-Stainless-Steel-Studs-Long-for-alloy-finned-sump-plate-/162986716380?hash=item25f2c3ecdc

[hoogerbooger]

agree. these look like the ones I have and 1/4" too short on the engine side.

To my great annoyance, I have lost 1/4" of thread on one hole ..leaving 3/4" of thread not damaged. I'm presuming that's enough to fix studs without loctite ...if I can find a stud that is 1" .

If anyone know of a source of studs that are 1" engine side....I'd be grateful to know.

the last post link is only half inch engine side...but thank you for posting.

red locktite and (the Granville Bearing and Studlock that I have) say they are permanent...but looks like you should be able to double nut to extract the stud later. But what about the set threadlock left in the stud holes ? is this not going to be a problem to later fitting new studs ?

having messed up once it would be good to avoid exacerbating the problem

[MALCOLM.JOHNSON]

1/4 inch BSW threads are the same pitch as 1/4 inch UNC, except that the former has a thread angle of 55 degrees and the latter 60 degrees. Which makes the use of UNC useful when dealing with worn BSW thread holes, which is often the case. Are you sure the thread in your stud hole goes right the way in to an inch deep - it is rare that they cut the thread that deep even if the hole is that depth.  If the thread is that deep, then for simplicity in your case, buy a UNC allen set screw of the required length using a spring washer under the head, making sure that it will not bottom out AND do not over tighten - just use a couple of fingers on the allen key. At most auto jumbles you can buy taps that are good enough to clean threads out in alloy very cheaply. If you have 1/4, 5/16 and 3/8 taps in BSW for studs or in UNC for allen set screws you will meet most situations. When I re-build an engine or gearbox I ALWAYS remove all studs and gently file flat the inevitable raised lip around the holes, for a better gasket face. I also ALWAYS clean out thread holes with a suitable hand held drill bit to remove all traces of gasket glue and then clean the thread with a suitable tap. I have lost count of thread holes AND casings, found burst open by hydraulics involving Hermatite or similar that I have found needing serious attention.

[hoogerbooger]

Have rechecked the two open stud holes.  One is one inch deep and blind. can't tell if it's threaded to the top. This one not knackered.

However the one I've knackered is open and 3/4" deep - seemingly threaded to the end. So 1/2" of thread left ( plus now - as you highlight I have a surface bur to carefully remove)

I had presumed studs always  go into a blind hole and were tightened into a blind end. I'm not sure how they wouldn't shake loose if they didn't.... unless thread locker is used. Wish I'd done a bit more checking.

The studs I have seem in ok condition and have 3/4" of thread. Reckon that's enough to threadlock in place  ?? (having removed the surface bur on sump plate mating face )

Let me know  if  this is not likely to be sufficient  - with  1/4" at the plate end now enlarged and threadless

I have no taps or experience of using these  ( nor a Helicoil kit). So I'm hoping threadlock will do for now.....although if this fails using one of these approaches  looks like it'll be needed.

[MALCOLM.JOHNSON]

If you have 1/2 inch of good thread, then that will be plenty, but clean the thread to get rid of all traces of oil, otherwise threadlock will be a waste of time. Similarly wire brush the male threads. I usually give the threads a squirt of carb cleaner and blow off with an airline before using threadlock. Test screw in first by hand to the depth you require and then follow with threadlock and leave to set before final assembly. Finally do not use big socket sets to tighten small nuts. For 1/4 bolts and studs into alloy, need little more than a 4 to 5 inch spanner !!!!  Good luck.

[hoogerbooger]

Still having problems with studs. Thread locker not really working & I'm a bit worried when I put the nyloc nuts on they'll start moving the studs...as they were undoing them after leaving the thread lock to set for 2 days ( when the official setting time is 45mins)

Should standard nuts & spring washers be ok  to seal & stay sealed ?

as I'm presuming they're less likely to turn the studs. (I've checked and straightened the sump plate and filter - sump casing looks straight/level)

(the 2nd attempt with thread lock on the damaged hole was strong enough &  I could undo the nut on it. Had 2 attempts on the other lose stud and it just comes out . So have just had a 3rd attempt with no nut on it gripping with mole grips on non threaded bit... but now need to put nuts on with out dislodging/winding studs in)

(I did my best to clean out the case holes with carb cleaner & screwing in the stud a couple of times carefully. Cleaned up the studs with carb cleaner and wire brush....... no air line, so used track stand pump and football inflator nozle.  I thought I had blown out the carb cleaner and left it long enough to evaporate. not sure if it's dirt, residual carb cleaner or worn threads causing the problem)

[AWJDThumper]

Which thread lock are you using since they come in different strengths? It's best to lock them firmly in place otherwise you run the risk of eventually wearing out the threads in the soft aluminium crankcase.