I built an engine for my '27 Chummy last year and it has been performing well, completing about 750 miles in the last 12 months. Only problem is that it leaks rather a lot of oil, with the oil coming out of the clutch pit drain hole. I got around to taking the engine out at the weekend and stripped the clutch and flywheel off. The oil is definitely coming out of the rear main; you can see the trail where it is running down the case.




I haven't stripped any further at this stage but I'm not sure whether the rear main housing closing (tin) plate is correctly assembled. It was like this when I originally stripped the engine but now, I'm thinking that perhaps it was on back to front, i.e. it should have the recess pressing in on the felt. What do you guys think??

Location: North Wiltshire

Tim, it looks the right way round to me. (If you reversed it, the lip on the circumference would not sit around the rear main carrier)

There should be a bearing plate (similar to that found in the rear hub) between the felt and the bearing.

FWIW I have recently rebuilt a mag engine with the correct felt seal and it too leaks like a sieve. It is possible to fit a sleeve on the flywheel to accept a nylon seal and machine the inner face of the bearing housing to fit. Drilling a drain hole as in the coil engines might help but not sure if that alone would solve all the problem.

Let me know what works for you as I am still pondering options

Location: Farnham

Hi David, yes, there's a plain steel plate between the bearing and felt and a wiggly washer that sits between the flywheel and bearing - most of the drawings don't show that bit and I don't know what it's for either!

Strange thing is that I renewed the rear main on the previous engine, with a new Seven Workshop felt and it didn't leak (well, not appreciably anyhow). That engine didn't have the wiggly washer.......

Location: North Wiltshire

You are lucky to have the wiggly washer, a lot have been lost or disappeared. (the correct name for it escapes me at the moment, but I think it is wavy washer)
It is there to act as a distance piece between bearing and flywheel boss. It nips up the bearing whilst still allowing the flywheel fully up the taper.

Location: Farnham

Tim, I don't know if you can get one for a 1 1/8th crank but on my Ruby with the 1 5/16th crank I got from a cherished supplier a new rear bearing seal plate that takes a modern lip seal. Since I fitted it 3 years ago I have had no oil leakage from the main rear

John Mason
Robin Hood County

Location: Nottinghamshire

Hi John, I'm afraid that the bent wire crank and flywheel are substantially different in dimensions, so the option of a lip seal is not available, at least not without a lot of re-engineering.

Location: North Wiltshire

Hi David, yes the "Wiggly washer" is in fact the "Flywheel distance piece" BB14, according to my '28 parts list. Still beats me as to why it's necessary though.....

Location: North Wiltshire

Like Austin in the shed, I have successfully fitted a lip seal to the 1 1/8" crank. Hope this helps, Regards, Robert.

Location: Deepest darkest Kent.

Tim,

"Hi David, yes the "Wiggly washer" is in fact the "Flywheel distance piece" BB14, according to my '28 parts list. Still beats me as to why it's necessary though....."

This wave washer Flywheel Distance Piece, along with some shims for the front bearings, seem to vanish when the heavy shaft is introduced - I expect it was found to be of absolutely no use in retaining the rear bearing.

Regarding the felt assembly the inner small 'felt plate' BB8 must of course be placed with the offset away from the bearing inner ring.
Felt Seals are the very devil to fit correctly - too tight and you cannot assemble the flywheel properly, too loose and they don't seal!

Tony.

Location: Malvern, Melbourne, Australia.

Location: Farnham

Hi,

Any more details on fitting a lip seal? The kits available seem to be for 1 5/16 cranks, not 1 1/8.

Thanks

TR

Location: North Wiltshire

I got a 1-1/8" seal kit from A7Components

Location: Melrose, Scottish Borders

Good evening David,
It was a long time ago when I fitted the lip seal.
The engine is now under the bench.
I could pull the flywheel off to reacquaint myself with the modifications done, if it is of any help.

Location: Deepest darkest Kent.

Thank you Robert, I would be very grateful.

Location: Farnham

Thanks Jim. I was unaware that A7 Components are listing a seal, suitable for the small crank, however no plate is catalogued to retain it! A phone call to David Cochrane should reveal all.

Could be an opportunity to crank up the Colchester Bantam to make one, if only I can find the time.

Location: North Wiltshire

As far as I remember it fits into the cover for 1 1-5/16" crank, the seal being big enough to fill the gap.
The Main bearing carries needs a rebate machining for the aluminium carrier locating ring.

Location: Melrose, Scottish Borders

I spoke to David regarding this. The later seal cover is used but the rear bearing housing has to be removed and machined to accept it. Also the retaining bolts will have to have their reduced to clear the flywheel. Hope that helps.

Adrian.

Location: New Forest

Adrian to the best of my recall it wasnt me. Another David perhaps?

Location: Farnham

I fitted a lip seal to my Chummy last year. My engineering talents leave much to be desired but the following worked OK. I bought a lip seal plate for the later crank from 7 Workshop at Beaulieu and sourced an appropriate lip seal. Not having the facility to machine out the bearing carrier I removed the lip from the front of the plate to allow it to fit up to the rear of the crankcase. I then used a narrow (I think 10mm) lip seal in the reduced depth of carrier. Hope that makes sense. No oil leaks during the years use. Crude but effective.

Gordon

Very interesting thank you Gordon. Can you recall whether you:

1: Refitted the steel plate (that normally sits between felt and bearing), and

2: Fitted a sleeve of some sort on the flywheel boss?

Location: Farnham

David

I did not use the plate which sits between the bearing and the felt as I did not see it served any purpose. I found a lip seal with an outer diameter to fit the plate and an inner to fit on the flywheel boss. I did not put a sleeve on the flywheel as the boss seemed to have a good surface to run in the lip seal. If you visit Simply Bearings web site you can select seals by the Outer, Inner diameters and Width. I think I used a 10mm wide seal sat flush with the flywheel end of the plate.

Gordon

Location: North Hampshire

Thanks Gordon

Location: Farnham

Don’t you just hate it on a forum, when a technical question is asked but we don’t get the final resolution?
So here is the answer to my oil leaking problem, at least as far as it goes.....
I took the felt seal out of the engine and the first thing I noticed was that the four bolts (5/16 BSF) holding the rear main housing and plate were not tight. The rear main bearing housing was quite rough and the result of these two items was that oil had been leaking past the outer gasket and this may be the cause of the problem I was seeing, i.e. a pool of oil, 2 or 3 inches across under the car after a run. However, the rear main was tight on the crankshaft, which dispelled another of my worries about this engine.
A phone call to David Cochrane cleared up the situation on lip seals. The first thing to note is that the 1 1/8” rear main bearing housing and the 1 5/16” rear main bearing housing are not the same. The former is designed to house a bearing (RMS11, MRJ 1 1/8) which has an outside diameter of 2 13/16” and the latter houses a bearing (MRJ 1 ¼), ) which has an outside diameter of 3 1/8”. Although the outside diameters of the housings are the same at 3 25/64”, the bore is quite different; in fact the later housing is 5/16” wider on the bore diameter.


The lip seal plate is made with a register and this is necessary to centralise the seal, otherwise it can be pushed in one direction or another, causing premature failure. The plate is made with the register of only one diameter, 3 1/8”, for the 1 5/16” engine. A plate suitable for the early engine is not currently manufactured. However, there are two possibilities:
a) Machine the register on the lip seal plate to 2 13/16” (actually a bit bigger as the area where the felt seal fits is slightly oversize)
b) Machine the bearing housing to 3 1/8”, to form a small recess to accommodate the register on the later lip seal plate.
In fact, only b) above is viable, because there is not really enough material on the plate to allow it to be machined to the required dimension.


So, I set up the rear main housing on the Colchester Bantam and lightly took out the required amount of material from the bore.



Because the lip seal plate is thicker than the original tin cover plate, the retaining bolts must be faced off so that they don’t contact the flywheel. I thought of using the later bolts, only to remember that they are 5/16 BSW, not BSF!

One of the issues I have with the use of modern type lip seals is that the components in an Austin 7 (with the exception of the half shaft inner (gear) ends) are not designed to use them. Lip seals should always be used on a hardened steel surface; if used on a mild, unhardened surface, they will quickly wear a groove and become ineffective. Of course, today most people don’t do huge mileages in their Austin 7, but I suspect that the lip seal would begin to wear a groove on the flywheel boss within 20,000 miles. Also, my flywheel is a bit knadgered and doesn’t provide a good surface for the lip seal.

So, I decided to use a SKF “Speedi-Sleeve”. These are in metric denominations but there is, conveniently, a 41.2 – 41.35mm option, which equates to the boss diameter of 41.275mm or 1 5/8”.
http://www.ebay.co.uk/itm/131042491504?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
Speedi-Sleeve part number was 19166. These sleeves are just hammered over the shaft (or boss in this case). The top hat “brim” section can then be removed, leaving a band of hard steel of very minimal diameter for the oil seal to run on.


Perfect! Picture also shows the “wiggly washer” I spoke of earlier. I have decided it’s there to stop the rear main inner from wandering about.....
Final check to see that the bolts are well clear of the flywheel and the seal is seated correctly.

Engine goes back in Friday and we’ll see if the leak is fixed. Here’s hoping........

Location: North Wiltshire

Blimey Tim you didnt hang about! I wont get the opportunity to get my engine out to fix until September but all carefully noted.

Thank you for sharing this

Location: Farnham

Location: North Wiltshire

Very neat solution Tim - love it :)

Tim,

Excellent work- a proper job well done. Thanks.

Tony.

Location: Malvern, Melbourne, Australia.

Hi Tim
Great job. I am doing the same conversion and have a query about the Speedi-Sleeve. In your desctiption you quote the part number as 19166 but the Ebay listing is for 99161. Could you confirm which is correct.
Many thanks.
Adrian.

Location: New forest

Tim,

probably too late for you but, following advice from Dave Mann many years ago, I also line the lip seal with high temperature blue grease which ensures an oil tight seal.

Hi Adrian,

My dyslexia I'm afraid! Correct number for the Speedi-Sleeve for the early flywheel is 99161.

There will be an equivalent for the 1 5/16" flywheel but I haven't been there yet.

Thanks

TR

Ruairidh, yes I did line the sleeve with HMP grease but it wasn't blue

Location: North Wiltshire

Thanks Tim for the sleeve update.
I have completed the machining and now just waiting for the sleeve to arrive.

Adrian.

Location: The New Forest