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1929 Sloper oil feed to big end question

Posted By: jemsk

1929 Sloper oil feed to big end question - 09/06/14 5:54 am

I'm rebuilding a 1929 350cc L-29 Sloper. Most of it is back together but I have a concern about the big end oil feed. There is a bronze bush in the timing cover that fits over a threaded shaft/stud on the end of the crankshaft. The bush is fed with oil direct from the oil pump.

My concern is whether there is something needed to improve the seal between the bush and the threaded shaft to minimise oil leakage? I've made a felt oil seal that bears against the end of the bush but I'm not sure if this is part of the original design. The end of the shaft has a small indentation and I wonder if there is some sort of jet intended to fit in here - maybe something spring loaded that fits within the bush. I've scoured the parts manuals and can't find anything that I'm missing from my engine. If anyone on here knows for sure how this seal is made I'd be very grateful for a reply as it may set my mind at rest about the nature of the oil feed.

Here are some pics showing the stud/shaft, the bronze bush in the timing cover and my attempt at a felt seal:

[Linked Image]

[Linked Image]

[Linked Image]
Posted By: Elijah

Re: 1929 Sloper oil feed to big end question - 09/06/14 6:26 am

There is no way a threaded shaft should ever run in a bronze bush !!
Looks like a home brewed "repair" to the end of the crankshaft.
Something seriously wrong here .....
Posted By: LarryLebel

Re: 1929 Sloper oil feed to big end question - 09/06/14 11:00 am

The gear on the shaft just looks like an idler gear to me. Are you sure the shaft actually turns? Or are you just trying to seal the gap between the nut and the bushing to keep oil from leaking into the cavity?
Posted By: downhere

Re: 1929 Sloper oil feed to big end question - 09/06/14 7:07 pm

That felt will get shredded in no time. Stop! Wait for someone here to help you.
Posted By: jemsk

Re: 1929 Sloper oil feed to big end question - 09/07/14 2:42 pm

The shaft definitely turns - the threaded portion is for the nut that holds the crankshaft timing gear in place. It's a running fit in the bronze bush. You can see in the pic that the thread form itself is flattened off where the shaft fits within the bush but the interior of the bush is not scored, so I don't think this flattening is due to wear, I think it is how it was designed and made. I don't think it is a repair or bodge of any sort. I take your point though about the felt probably not lasting long on the thread.

Here's a picture from the 1929 catalogue showing a cross-section of the Sloper engine. The bit I'm asking about is labelled 'K'. There's no felt seal visible in this picture but it isn't an engineering drawing, hence my question to anyone who has first-hand knowledge of this engine.

[Linked Image]
Posted By: triton thrasher

Re: 1929 Sloper oil feed to big end question - 09/07/14 2:56 pm

If that was a plain shaft, running in that bush, it would be a normal end feed design.

In fact:

[Linked Image]


http://www.motomaniastore.com/parts/details/bsa-sloper-500ohv-1930-crankshaft-911
Posted By: triton thrasher

Re: 1929 Sloper oil feed to big end question - 09/07/14 3:10 pm

The shaft threads for the nut were stripped, so Mr Bodger cut a smaller diameter thread all the way along it.

Look for another crankpin or whole crank assembly to buy, or investigate getting the pin removed, built up and re-machined.
Posted By: downhere

Re: 1929 Sloper oil feed to big end question - 09/07/14 6:14 pm

Mr Bodge was hung over that day!! I suppose you could turn the thread down and make a smaller bush?
Posted By: jemsk

Re: 1929 Sloper oil feed to big end question - 09/08/14 4:48 am

Originally Posted by triton thrasher
The shaft threads for the nut were stripped, so Mr Bodger cut a smaller diameter thread all the way along it.

Look for another crankpin or whole crank assembly to buy, or investigate getting the pin removed, built up and re-machined.


Thanks! At least I know now what it should be like, although it looks like a major job to fix the problem. The 350cc engine that I have has a different stroke to the 500, so a replacement 500 crank won't work - I'd need barrel and head too.
Posted By: kommando

Re: 1929 Sloper oil feed to big end question - 09/08/14 7:13 am

Look up speedi sleeve, this may be an option for you.

http://www.skf.com/group/products/s...ear-sleeves/skf-speedi-sleeve/index.html
Posted By: LarryLebel

Re: 1929 Sloper oil feed to big end question - 09/08/14 11:42 am

The sleeve is to "stop shaft whip" according to the manual, so there's no big load on it. You might get away with it the way it is.
Posted By: Elijah

Re: 1929 Sloper oil feed to big end question - 09/08/14 12:05 pm

The mainshafts are pressed into the flywheels & riveted in place. There is a flange on the inside.
I had a new drive side mainshaft made for my 1935 BSA W35/7.
You have to buy quite a large diameter piece of EN36B because of the diameter of the inboard flange.
The flange was something like 2 " in diameter , shaft 3/4 " if I remember correctly.
I machined it roughly to size on the Colchester Student lathe at work & then took it to a retired tool & die maker to finish it off.

Elijah.
Posted By: downhere

Re: 1929 Sloper oil feed to big end question - 09/08/14 7:23 pm

Kommando has the other alternative. Any engineering shop could grind it down and fit a sleeve. getting the shaft out and built up and refitting would be unnecessary
Posted By: BSA_WM20

Re: 1929 Sloper oil feed to big end question - 09/09/14 5:43 am

And a slightly different variation on the same theme.
Make up a sleeve nut to fit over the threaded section with an Id to run in the bush.
If you have access to a lathe easy job provided ther will be sifficient wall thickness.
Posted By: jemsk

Re: 1929 Sloper oil feed to big end question - 09/09/14 7:02 am

Originally Posted by kommando
Look up speedi sleeve, this may be an option for you.

http://www.skf.com/group/products/s...ear-sleeves/skf-speedi-sleeve/index.html


That looks to be a good idea. I need to accurately check the OD of the shaft and the ID of the bush. If they're a close match then I'll probably leave it as is - I believe the engine has been running in the past with this bodge. The shaft runs inside the bush for a fair distance so if the diameters are close then I don't think that much oil will be lost down the shallow thread instead of passing into the crankshaft.

The oil feed is adjustable, and the manuals refer to setting the pump so that a puff of blue smoke is seen when the throttle is opened. This should give me some leeway too. I've got a 1930 250cc BSA with the same arrangement as the Sloper so I have a bit of experience with the oiling system.

Thank you to everyone who has taken the time to reply.
Posted By: downhere

Re: 1929 Sloper oil feed to big end question - 09/09/14 6:44 pm

Seems you're determined to stick to the bodge to avoid pulling it apart.
Posted By: jemsk

Re: 1929 Sloper oil feed to big end question - 09/22/14 1:22 pm

Originally Posted by downhere
Seems you're determined to stick to the bodge to avoid pulling it apart.


Yup. The engine has been running with this bodge. I will ride it perhaps 400 miles per year max. If it fails (and I don't believe it will) I'll fix it then. In the meantime I'll be riding the bike, rather than having it strewn in bits for another xx months or years. I also use as many of the original fasteners and other components as I possibly can. I could replace old slightly chewed fasteners with new stainless ones - but this bike is 85 years old and I want it to look that way. Same applies to this bodge - it's part of the history of the bike.
Posted By: downhere

Re: 1929 Sloper oil feed to big end question - 09/22/14 7:26 pm

Well don't come back here whingeing when your bigend turns to dust!
Posted By: triton thrasher

Re: 1929 Sloper oil feed to big end question - 09/23/14 3:33 am

By all means come back here with any future problems!

I hope they don't include destroyed 1929 crankshaft, conrod and crankcases and even piston and barrel.

Putting that lot back on the road is like refurbishing everything in your house except the roof. If there's one part of a bike that should not be compromised, it's the oil supply to the big end.
Posted By: craig

Re: 1929 Sloper oil feed to big end question - 09/23/14 4:46 am

does seam a pity and this is a easy fix , pm me if you want it done
Posted By: kommando

Re: 1929 Sloper oil feed to big end question - 09/23/14 5:50 am

I would fix it but as its a roller bearing big end it needs no oil pressure just a small flow of oil so that should not be affected, its the piston that is more likely to suffer from lack of oil splash from the big end.
Posted By: triton thrasher

Re: 1929 Sloper oil feed to big end question - 09/23/14 6:13 am

I doubt that shaft's ability to ensure that even a dribble of oil always reaches the big end.
Posted By: kommando

Re: 1929 Sloper oil feed to big end question - 09/23/14 6:20 am

You can accidentally leave out the oil pump seal on a Norton oil pump, as long as the pump floods the entry to the crank then the centripetal force from the oil at the big end will drag oil through the crank and give a supply enough for the engine not to seize in the short term. This is a similar situation and the engine will survive in the short term but its not something you plan to do and needs fixing ASAP.
Posted By: craig

Re: 1929 Sloper oil feed to big end question - 09/23/14 6:25 am

it may also force oil into the mag with to much in the timing area , I would also fix as its not how BSA intended it to be
Posted By: tzrewinds

Re: 1929 Sloper oil feed to big end question - 01/02/15 3:37 pm


I use a leather seal on my sloper, having remade that bronze bush to be a snug free-running fit. But I agree with you.. yours will probably run perfectly fine as is, even with that thread on the quill. (At least the spiral tends to push the oil back in to the bush eh!)
I attach a photo of the bsa assembly drawing which shows the seal.

with the original felt seal that i removed from the engine when I rebuilt it, or my leather seal, I found the seal snags on the timing gear nut and so spins with the crank and polishes the concave bush, rather than becoming shredded. After around 1500 miles the oil pressure on my tank-mounted gauge drops from 3 to 1 PSI as the seal eases off. But after 4000 miles i had good compression but rebuilt with a high compression piston & barrel and new seal on the crank anyway. All was still otherwise good at 4000 miles including the bore and the new Alpha big end.

I know the oil gets to the bore from that blue haze that the handbook describes. I have my oil knob open just 3 flats (1/2 turn from fully shut). It took me quite a while to find the confidence to turn it that low... But I have undertaken regular long motorway journeys with full camping gear like this (e.g 2014 John Bull, BSAOC Summercamp in Belgium etc).

I think the only downside maybe something I experienced when first running in with the knob open 3-5 turns, i.e the timing side will tend to fill more than it need do, So oil can get past the cam followers and even fill the push rod tubes (I sealed my telescopic push rod tubes with leather seals only to have the oil then rise to the rocker box!).. If you don't have a felt seal in the taper behind the Magneto timing gear, it might exit also between Timing chest and Mag... However... just closing down the oil supply solved all that.

I use Morris Golden Film SAE 40 mostly. It revs more freely than SAE50 but using SAE50 on the 400 mile summercamp trip I only used 1.5 litres of oil. These bikes original pistons have no Oil ring of course, and there is no engine breathing, so I was quite pleased at that.

[Linked Image]

Posted By: jemsk

Re: 1929 Sloper oil feed to big end question - 04/18/16 1:23 pm

Thanks very much tzrewinds, this is very useful info. I haven't visited here for quite some time as several of the earlier replies seem to be from people who have no first hand knowledge of early BSA engines but just want to pass critical comment
Posted By: chaterlea25

Re: 1929 Sloper oil feed to big end question - 04/18/16 5:50 pm

Hi,
Quote
These bikes original pistons have no Oil ring of course, and there is no engine breathing,


Theres a drilling through the drive side mainshaft and out through the cush drive assembly to vent and lube the cush drive
I'm not very familiar with the sloper engines but have a couple of earlier L vertical engines, theres a breather on the drive side of the crankcase on these
I have rebuilt Blue star and Empire Star engines , but cannot remember the breathing arrangements
When the crankcase contains the oil reservoir theres more volume to accomodate crankcase pressure, but there has to be an outlet somewhere, theres no "seal" on the drive side bearing just a felt washer on some models which will also vent
The mid thirties BSA's have a spring loaded bronze plunger up against the mainshafts female taper end

The slopers were as far as I know the first BSA's to have an oil feed to the bigend, before that oil was just drippled into the crankcase and left to find its own way to the bearings and bushes
This was a common feature on most of the vintage era bike engines

Ariel engines have a small diamater quill sticking into the mainshaft end, no seal involved, centrifugal force sucks the oil to the bigend

Regards
John

Posted By: Art_Wozniak

Re: 1929 Sloper oil feed to big end question - 09/14/18 10:07 pm

Hello, I have a BSA Sloper 500 OHV 1931. I was wondering how many a turn should I go for with the oil pressure screw? Can it be that too much pressure can cause a bit of oil getting into the cylinder head area?
Posted By: koan58

Re: 1929 Sloper oil feed to big end question - 09/15/18 1:07 am

From your pics, that shaft looks rough in all respects, not only does it have a partial thread on it, but the flats on the threads and the centre bore at the end look very rough. I really don't think those are original.
I have no doubt that the original shaft would have been a smooth and close fit to the bush. In which case it would work perfectly well for the B/E supply, as it does successfully in many designs.
I am more familiar with the similar setup in pre-unit Triumphs, which have a relatively high capacity pump. In your case, with a fairly small delivery pump to a roller B/E, I find it meaningless to speak "oil pressure on my tank-mounted gauge drops from 3 to 1 PSI as the seal eases off". I really cannot see the pump generating any significant pressure, with a "seal" between nut and bush or not.
What is that seal between nut and bush? It is not evident in the diagram kindly posted. All I can see is a concavity of the bush face. That is curious though, anyone know the reason for it?
"(At least the spiral tends to push the oil back in to the bush eh!)"
As best I can see, it's a left hand thread on that shaft. I don't know if the engine runs "backwards", but if not, then not so, so the thread had a tendency to divert the oil flow from the supply to the timing case.
With a small delivery pump, this is not good.
Kom's mechanism is fine with full flow, but in this system there are air gaps. The air will so easily escape via the clearances and threads.
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