Britbike forum Forums British Motorcycle specific Brands Bsa bulletin board A65: another oil pressure thread....

Paul
Good going.
Sounds like you might be really onto it.
Cheering for you

>>sb

Maybe hold off on the goop and shim thing until Rich wakes up and walks you through this procedure...

ok, so i changed course a little. i decided the sealer fix was a little too half-assed, so i surfaced the faces of the gears .0005" at a time, until they were no longer contacting the end plate. i'd estimate that i took about .0008" off total, and probably have about .0002" between the gear ends and end plate. probably not enough to worry about leakage around them.

the middle section is another story all together though... i can't surface the gear that turns the tach drive, because it is permanently mated to its shaft. the dye shows that it is barely contacting, and the lower gear quite a bit more. i'm going to try different thickness gaskets first and see if i can free it up. i figure the gasket and sealer will help prevent leaks anyway.

i'll report back when i get more done, but i'm done at the workshop for the night.

almost done anyway...

i used butcher paper for the gasket, which compresses to about .001", and the pump turns freely now with the bolts tightened all the way! i'm going to seal it up now with some threebond 1194 and call it a night. more results tomorrow hopefully.

Paul sez:

"strange design that has the gears turning on the face of the endplate like this..."

Not strange so much as about basic design of a gear pump you will ever see. There is nothing in there that is not needed.

Based on the rest of the thread, looks like you have skimmed the gears to get clearance. The drive gear on the supply side can be tweaked for length if you have a lathe, patience, and time. Or use a flat plate with a hole in it, some valve grinding compound and time Not that I have done anything like that

Since my supply of pumps have gone up over the years, I tend to mix and match to get gear lengths correct when I can.

Did you pack it with light grease so it primes on start up?

I think that the lapping gears and plates is necessary. You have no way of knowing if the pump is completely original. I use a heavy assembly oil on the pump as it mixes with the oil well. Also a little compressed air with an air wand sealed with a rag in the tank will flood the inlet immediately. I also prime the whole system by spinning the pump or kicking the motor over (plugs removed) till I see the oil coming out of the rod bearing.

Mr Mikew

maybe i should clarify: it's not that it's strange, so much as that it's as crude as much of the other engineering in the engine. i thought of another solution last night lying in bed: a teflon plate cut to size to fit between the pump body and the endplate, so the gears could contact it fully, but have little friction.

i use assembly lube instead of light grease, as it's designed to dissolve in engine oil, which grease is not.

Glad you found the source of the problem, it was fortunate that you have a late model with a low oil pressure switch. Too many BSA engines have died from the same problem yours experienced.
Crappy materials and less than ideal volume, combined with amateur mechanics who tend to over tighten the nuts to the point of warping components are the cause. It is rare that a 40 year old pump does not need attention!
If this isn't a wake up call to those rebuilding a BSA I don't know what is.
Once the engine cases are together the pump and the sump plate are on, install the lines on a clean oil tank,(this can be done on the bench) and turn the pump with a drill. If all is good, continue the assembly, if not, it is better to find the problem at this stage. Thanks for posting and enjoy your BSA. Rick

thanks, rick.

today i installed the pump, tested it, and found it still leaking at the joint between the two halves. i was trying to avoid surfacing these faces because of the difficulty of adjusting the depth of the gear that is mated to its shaft, but i guess it was inevitable. i surfaced both halves on the belt sander, then sanded with 320 and 600 grit sandpaper until they were flat and smooth. the lower gear was easy enough to address: using a feeler gauge i found it .003" proud of the surface. i measured it with the micrometer, tightened it up .0035", and sanded the face of the gear until it fit snugly in the micrometer.

to dress the upper gear, i drilled a hole in a piece of 1/4" steel plate, sanded the area around the hole flat, and chucked the shaft/gear up in a drill. i attempted to use sandpaper with a hole punched out to take material off of the face by inserting the shaft into the hole and spinning the drill, but i think i'll have to use lapping compound as it was not working very well. if i have to, i'll hand file the back side of the gear down until i have clearance from the pump body.

anyway, if this works i'll post pics as this is obviously a problem that needs to be addressed by many A65 owners.

Borderline offensive message warning against extreme technique removed by EWebster.

?? huh? just what are my worries, then? you might have piped in a little earlier if you have some helpful advice. and yes, "flat" is relative to the flatness and trueness of the other mating face. if the joint is seeping oil very quickly while the 20W oil is cold and the pump is being driven very slowly with a drill, i'm pretty sure hot oil at high RPMs will leak much worse, and can likely explain much of my low pressure problems i've been having. maybe you can suggest a better way to eliminate the seepage and explain the low pressure problem though... please do.

anyway, not really sure what you're implying with that link. my surfacing using a stationary belt sander is akin to a jury-rigged homemade table saw? are .0001" micrometers not accurate enough or something? i can tell you this, some of the factory "machining" in this engine looks like it was done drunk in the workshop you posted... there is certainly room for improvement and accuracy from stock in many areas.

funny picture though. don't know if you're trying to be a dick, or just playing around... the internet doesn't translate sarcasm well. with all due respect and appreciation to all that have helped here, i still don't have a definitive solution, so you'll have to excuse me if i take your particular opinion with a grain of salt.

Lapping plates and gears on these types of pumps was common in industry especially if parts were mixed. Our pumps were "billet" type, sandwiched together, which made lapping ideal, and that's how we repaired them. I have always felt the BSA pumps were "Chintzy" in design and manufacture. It is obvious to me that when torqing the pump you can cause deformation which binds the pump. The pump should be able to be torqued to reasonable levels and pinned in position so it does not move. In my mind the lube system was the nemesis of BSA's plain bearing motors. The pump is likely marginal on volume and less than that on reliability. I wish I had the opportunity to see some of the aftermarket pumps and I think you are "right on" with your concern about "oil pressure".

We have all learned a lot at your expense from this thread, Paul, and I hope you fix it up so as to have good oil pressure.

Mr Mike

The reason one would use a lapping compound on a flat hard surface like a glass plate is because one doesn't have a surface grinder.
Use of any sand or emery paper isn't ever as 'flat' as lapping on a hard surface because paper has thickness and the parts can be rocked yes, slightly, but rocked, and they are no longer have parallel surfaces, and hand lapping can't fix that.
Your use of a belt sander is nowhere near the standard of 'flat' you should be trying for, imo. Now, maybe that standard doesn't have to be reached here, as you may have improved the fit enough to have a good enough pump.

Ideally a surface grinder in a machine shop would be perhaps best, but hand lapping on a hard flat surface could work well enough.

And maybe the belt sander is flat, but I would say that the part is going to drag into it and the surfaces will not be parallel....or flat. That's my 2 cents, hope I'm wrong, but I wouldn't trust it. You can still lap the part to be thinner, and maybe that will be good enough, but you can't trust the surfaces of the gear to be parallel tho. If it works, great. Now you know how to test it...

A new cast iron pump from SRM is a couple of hundred dollars, many have liked them, many have made the pot ,metal body originals work. I'd be trying to fix mine hoping for a winning lottery ticket.

Good luck, you'll get it right..

I thought you might be joking around with the belt sander thing. Okay, so maybe not.

The pump is soft alloy, it would only take a few strokes against the paper to show up surface irregularities and remedy them.

If extreme techniques were used in fitting up your crank bushing or rod bearings there is no telling where this problem lies.

It only takes a small amount of extra clearance to lose "pressure" at those bearings. Only you know those numbers.
Controversy is what powers these bulletin boards so don't be too offended, someone will hop in here soon to give you the answers. Best of luck.

keep in mind the type of tools and material burt monroe worked with.. i'm hardly a burt monroe, but my point is that there are many ways to do something right, and careful attention to what you're doing is paramount. i realize that a belt sander is not the ideal way to surface something, but i was measuring carefully, and it is as true and square as it ever was. the belt sander was used just to get over .001" and then i took anything else off and finished with sandpaper laid flat on a very flat surface.

to state again, all bushing clearances were done to BSA spec by a very knowledgeable and competent machinist who spend over 50 years building engines and racing. i know for a fact no "extreme techniques" were used. EWebster- it's not controversy i'm afraid of if it's helpful, it's useless poking and banter that i've seen before on this board.

thanks again guys... we'll see what happens when i get to the workshop tonight.

arrrrrrrrrgh! i was putting the pump back together after very carefully cleaning everything out and stuffing the passageways with assembly lube (redline cam lube is thick enough to stay put), and the threads on the last bolt hole just pulled right out.

dammit, now i have to helicoil the thing, which won't be easy, given the proximity of the worm gear housing to the back end of the threads. the saga continues...

wish santa would appear in my living room with a beautiful SRM pump and i could just get on with riding the damn thing. oh well, in the meantime pictures of the steed:






eh, and while i'm at it, my "modern" bike:

Gees Paul, Somebody must have parked their BSA exactly where your Honda is 'cause I see 4 spots of oil under the Honda and everyone knows Honda's don't leak. Ha! Nice Bike. I think I was lucky with my original 66 A65L pump in that it makes good pressure. I did nothing special except a little lapping and it turned out OK. You will feel the slight pulsing of the teeth as they engage/disengage. My bearing clearances were all at .0015".....checked and double checked.

Sorry about the pulled thread. It happens. Are your studs 1/4 SAE threads or the earlier Whitworth?

Mr Mike

Don't know what thread pitch they are yet, but I'm hoping it'll be SAE since it's a '71. I have an appropriate helicoil I believe, but I worry about drilling that hole larger, and welding it shut and redrill/tapping probably won't do the pump and favors with distortion being a possibility.

well, i hate to admit it but i may be throwing in the towel and selling some things to fund an SRM pump. the pump no longer leaks at any of the joints, but the indicated running pressures are no better, and are strangely different. the pressures seems to rise and fall more closely to the RPMs (1000 RPM= 10PSI, 3000RPM= 30 PSI), but the light still flickers at idle and the pressure drops considerably when warm. i suspect i may have dressed the gear faces down a little too far and oil may be leaking around them thus causing the pump to produce lower pressures... or it could have not been the pump to begin with. the gears are within .0002" of the surfaces they contact, but i don't know what else to blame.

back to the drawing board...

Paul,
I have heard the merits of the SRM pump but have never seen even a picture of one. Are they billet type or do they have cast housings? I think you are doing the right thing. Your thread is not unlike many others on this subject. I think British Cycle supply may deal with some SRM parts, but you can e-mail SRM and they will get back to you.

Good luck Paul,

Mr Mike

yes, they are billet. very pretty. i've seen them at british cycle supply.. seems to be the cheapest source. if anyone knows somewhere cheaper, please let me know.

Ed V does just the bodies, you fit your old gears, cheaper than the SRM plus being in the US better for support.

When I rebuild a pump I get the clearance close to nil, and then spin the pump with a lathe chuck and feed it with oil to free the inital stiffness off, only takes 5/10 mins at 300rpm.

Where do I find his bodies?

Another possible cause may be the wrong spring pushing the anti wet sump ball against the pump. The original spring has thin gauge wire (about 18 thou diameter) and is easily lost by home mechanics who replace them with a heavier spring, usually a spring from a pre 1970 pressure relief valve. I seen heavier than stock spings may cause problems similar to yours. Failing that, I would think their is a excessive clearance on the rods or main bush before I would suspect the pump. I would also check the oil flow to the pump for restrictions. Rick

Paul:
If you are still trying to fix the end plate with stripped threads (if I understood the posts correctly) what you could do is get a peice of "01 GAUGE PLATE". And make a new one, in its unhardened state it is drill and tapable and will be gaurenteed flat to tool making specs. It comes in 12" long peices and isnt that expencive.

Its realy good material and as tuff as. You wont strip a thread in that stuff.