Author Topic: Question regarding barrel studs  (Read 2468 times)

Online orabanda

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Question regarding barrel studs
« on: 23.11. 2008 01:24 »
Hi All,
I have an RGS replica, built up from a Super Rocket (like most, I guess).
The engine no is DA10SR245

The barrel studs are unlike any I have seen in any other A10 engine.

http://i302.photobucket.com/albums/nn82/orabanda/IMG_0741.jpg

All of them (except the two rear ones) are stepped, and have a much larger thread on the portion screwed into the crank case(s).

Is this a BSA factory design, or has someone done a bodge?

Regards,

Richard

Online trevinoz

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Re: Question regarding barrel studs
« Reply #1 on: 23.11. 2008 02:15 »
Richard, I would bet someone has bodgied them. The rear one looks correct. The studs should have a Whitworth thread in the case and Cycle through the barrel base.
   Trev.

Online RichardL

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Re: Question regarding barrel studs
« Reply #2 on: 23.11. 2008 02:41 »
The good news is that it appears to be quality work. It looks as though the bodger (here, not really a bad name) had some contiuous-thread rod or cut-off bolts to use and made inserts robust enough to grasp while threading the inner and outer diameters. This is my only thought as to why they chose to go so far oversized in making their custom studs/inserts, versus using about half the step of what is showing or, even, helicoils.

Richard L.
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Online orabanda

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Re: Question regarding barrel studs
« Reply #3 on: 23.11. 2008 05:21 »
Trev,
Richard,

Thanks for your feedback.
I agree that it has been quality work. The first indication of that to me, is that the barrel firs perfectly over them all. If any had been positioned "off" the centre of the original studs (not hard to do) then it would have been difficult to fit.

The only issue I had after start-up, was an oil leak from the base gasket.
 
This was caused because several of the studs were below the surface by 0.010" or more, and therefore there was very little contact surface for the gasket.

I had to remove the barrel (when this photo was taken) and used Devcon to fill above the stud shoulder. I then filed / stoned the filler down until there was a continuous flat surface.

Good result; no more leaks!

Regards,

Richard

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Re: Question regarding barrel studs
« Reply #4 on: 23.11. 2008 08:35 »
I reckon the work has been very nicely done too, but has to be said there's precious little casting left on the inside sides from what I can see. A millimetre or so, assuming the tops on show represent the true major diameter of the parts?  Maybe his barrels flew off some time in the distant past, ref other war stories hereabouts, and that's why he had to make the stepped bits so wide.
I'm far from against these quali-bodges - I have often had to resort to similar to get round problems quickly, effectively and at nil cost. But I think I'd have hesitated here, given the lack of meat and that it's soft. Not sure what the engineering rules are concerning the minimum amount of material to be left outboard of a threaded hole of given size in any given material, but there'll be some for sure. This has to be close. Still, he seems to have got away with it. Hope it holds together with RGS style horses leaping around. Suggest Forth (or should I say Sydney Harbour) Bridge parts for the head steady!
Bill

Offline LJ.

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Re: Question regarding barrel studs
« Reply #5 on: 23.11. 2008 11:11 »
Difficult to call this bit of quality workmanship a 'bodge' I think congrats are in order here towards the so called 'bodger' in the way that he has kept another crankcase on the road and not resigned to the scrap heap. I don't think there were/are any alternatives to what he had done. As with...
Quote
given the lack of meat and that it's soft.
It's now up to the rider to go easy with the engine and it's likely weaker holding and I'm sure he will being an enthusiast of BSA motorcycles. (by the way welcome to the forum Richard [Orabanda] )   *smile*
Ride Safely Lads! LJ.
**********************
1940 BSA M20 500cc Girder/Rigid- (SOLD)
1947 BSA M21 600cc Girder/Rigid-Green
1949 BSA A7   500cc Girder/Plunger Star Twin-(SOLD)
1953 BSA B33  500cc Teles/Plunger-Maroon
1961 BSA A10  650cc Golden Flash-Blue
1961 BSA A10  650cc Golden Flash-Red

Online orabanda

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Re: Question regarding barrel studs
« Reply #6 on: 23.11. 2008 13:04 »
LJ,
Thanks for the welcome!
Having seen the job first hand, I am comfortable with it lasting. It is possible (perhaps likely) that the stud size in the housing is not as large as what we can see. The largest diam is likely to be a shoulder, and the thread on the other end is possibly, say, 7/16". However, I did not risk removing a stud to find out.

Let sleeping dogs lie....

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Regards,

Richard