Britbike forum Forums British Motorcycle specific Brands Bsa bulletin board 61 Goldenflash primary oil leak.

Kind of a long story but I'm working on a 1961 Golden Flash 650 for a friend of a friend. The owner is a 86 year old gent that supposedly had this bike restored long ago and only rode it 15 miles. It then sat in his garage for a long time. He didn't remember how long but the tires were 30 years old. I have been going through this bike for a while now and finally rode it, maybe a couple of minutes, set it on the side stand and right away oil was dripping from the primary cover. Looking under it I could see a trail of oil coming from the backside of the inner primary cover.

I took the outer cover off to inspect everything before I ran the engine and everything appeared good but there was almost no oil in the primary area.
I resealed the case added oil and it sat for weeks like that with no leaks while I went through the carb and the gas tank was a mess.
After the short ride and the leak, I took the primary apart again removed the clutch to see how they seal around the clutch hub.
Was surprised to see the lack of a true seal there.
Everything appears to be in good condition.
Is there something I'm missing here?

Would appreciate any help on this.

Thanks.

Ed

"I resealed the case added oil and it sat for weeks "

what did you reseal it with ?

Are you sure it is the primary and not the engine breather
If it was a real restoration then the primary has a breather on one of the top bolts that drips any condensed oil onto the chain which is intentional
Then there is the sliding plate which alway leaks
They leaked when new
Been lots of work arounds to stop this
Finally there is the counter shaft bush which is OEM is split so it leaks gearbox oil.
Fen new there was a felt washer there to adsorb this oil .
Best trick is to use 3 different coloured oils in the primry ( Pink ATF ) engine ( will go black ) & Gearbox (blue or purple )

Lots of good info there Trevor. That is what I need to know as I'm not familiar with these bikes.
The sliding plate arrangement is interesting.
The reason I suspected primary oil leak is it was empty when I got the bike and the oil leaking out now
is light oil like what I filled it with.
Am I correct in thinking the oil drain on the bottom of the primary case has a small hollow tube connected to it with a small tapered
plug. The only function I could see for this is a oil level indicator. I filled the case until oil dripped out of this, about 8 oz, is that correct?
I don't have any manuals on this bike.
Like I stated I don"t really see anything out of place and it seems like the leak is around the clutch hub at the sliding plate.
After seeing how that is made, I don't know how it couldn't leak some.
It would have to be coated with oil or I would think it would seize.
I have never seen anything like it.
Thanks again I really appreciate it.
Ed

That's basically correct. It is a scroll type seal that can only "encourage" the oil to stay inside due to the rotation of the "thread" on the shaft, or seal collar. When everything is new and fresh, it works pretty well.

Having said that, the parts do wear and the leaks get worse. The thread gets worn off the removable seal collar and the hole in the sliding plate gets worn larger also. The combination equals bigger leaks. How tight a fit is the seal collar in the sliding plate? if it's sloppy, replacement parts might be needed.

Also, there are modifications out there that fit a modern sealed ball bearing in place of the scroll setup that can be really effective. If you are a machinist, doing such a mod might be the way forward.

Best of luck with it.

There was some scroll seals on the market at one point that had the scroll the wrong way, so it threw oil out and not throw it back in.

but that was within the last 20 years. Not 30….

Hi Ed,
Check the fit of the scroll in the sliding plate, Beware the pattern sliding plates are CRAP!
As well as not fitting close to the scroll the two parts riveted together are not sealed so oil leaks down between them instead of running around the lip to fall to the bottom of the case, A lot of the large felt seals are useless too. A soft rubber seal is or was available.. Some discussion on this thread, https://www.a7a10.net/forum/index.php?topic=13429.0

Running the bike on the side stand is not a good idea, the gear oil will pee out between the shaft and bushes (check the fit here)
A gearbox nut with seal is available from SRM Engineering, a very good mod
Adding a plate with proper seal will necessitate fitting a breather to the case to prevent pressure build up

John

BSA didn't produce workshop manuals as such at that stage, but had parts books and a quite extensive series of service sheets.

A number of the site sponsors have reproductions available, and "Kim the CD Man" has a DVD with most of the post-War parts manuals, service sheets and workshop manuals. Some of the site sponsors carry that, and it used to be available through Britbike.

A great online resource is https://bsa-info.nz, which has quite a lot of BSA technical material available for download.
Classic British Spares, and possibly other site sponsors, has parts books available online as well.

It's somewhat of a mixed blessing. It's great to have the material so readily available, but I really miss the original factory manuals and the later reprints from John Nelson's company.

Don't underestimate scrolls!
If the fits are correct they can be very effective. This is the oil pump off my GM engine, a simple alloy block with a scroll cut in the bore, It fits over the crank and is prevented from rotating and is below the oil level. Crank rotation pulls oil through the scroll, into the crank via a drilling to feed the big end
20200817_151948 by Sigma Projects, on Flickr

20200817_152018 by Sigma Projects, on Flickr

Morning guys.

Had a bit of time to work on the bike yesterday and removed the inner primary case.
I'm not impressed with the quality of work of the person that supposedly restored this BSA.
I think the biggest problem is the holes in the case for the sliding plate retaining pins are worn.
The front hole has almost .040 clearance and the rear is close to that.
There is about .019 clearance between the clutch hub scroll and the inside of the sliding plate.
The retaining pins for the sliding plate look a bit hammered as well.and he had some form of crude washer on the rear bolt
I'm guessing to get the sliding plate tight against the felt ring.
Do you guys know what the clearance is suppose to be on the sliding plate to the clutch hub?

Not sure how I'm going to repair the case holes.yet.
I could either weld them shut and re-machine or sleeve the case but it may be too thin for that.
I don't like how the pins are retained by cotter pins.
They can be rotated when assembled and just leaves an area for leakage.
I wold post some pictures if I could figure out how to download images from my computer.

Any thoughts on this?

Thanks again for your help.

Ed

Originally the sliding plate was retained by thin headed shouldered bolts inside the primary and thin nuts and lock washers behind. No cotter pins! Sounds like someone got creative/desperate with the hardware.


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Received the new sliding plate and bolts today that I ordered from Donaldson Cycle.
The new sliding plate has .035 more clearance around the clutch hub than the old one and
the old one had .019 clearance. How in the world is that going to keep oil in?
Do you guy's have ant idea what that clearance is supposed to be?
I just don't see how this could work.

Thanks.

Ed

Hi Ed,
I did warn you that the pattern sliding plates are crap!!
If you have machining facilities you could do as I did, machining up a new round section and riveting that to the sliding part
I made the sealing section wider and added a rebate on the inner face to accept a quad ring, this runs on the plain section inside the scroll. I sealed the joint between the parts with Hylomar

Alternatively a sliding plate from Phil Pearson Junior or Dave Flintoft with inbuilt seal which I think may require a modification to the shaft adaptor ???

Have a read of this thread on the A10 forum, where the foam large seal is also mentioned

https://www.a7a10.net/forum/index.php?topic=11845.15

John

This is going from fuzzy memory using a NOS plate and scroll a few years back. The fit was quite tight such that various high spots actually made contact when trial fitted together. It wasn't enough to stop the scroll from rotating but it was close. Since neither plate nor scroll are particularly precise to begin with, I assembled it as it was and let it wear in. That particular bike is relatively oil tight for a pre-unit BSA.

Thanks for the info guy's. You were right John the aftermarket parts are crap.
I just ordered some quad rings and will machine an adapter to install it.
Did you have to vent the case after you sealed it

Ed

Hi Ed,
Yes I had to ad a breather, before I fitted one it peed oil out when the engine heated up
I used a SS brake pipe banjo and tube bolted through the filler cap, over the top of the case and down towards the rear sprocket

John