Fitting lip seal to smooth case gearbox front plate.

[philthehill]

The original 803cc/948cc gearbox front plate (Pt No: 2A3087) which had been fitted with a lip seal was damaged when a friend was making up a 803cc/948cc gearbox combination.
To help out I volunteered to machine a good front 803cc/9048cc plate to enable the existing (or new) lip seal to be fitted and this is the process undertaken.
The gearbox front plate was held against the face plate of the lathe and a revolving centre pushed into the scroll hole so as to keep the scroll hole central. The gearbox front plate was then bolted to the lathe face plate ready for the boring bar to open up the scroll hole to the accommodate the lip seal.
The seal being used is not dimensionally the same as the ESM seal but the same process can be used.
Further commentary and pictures to follow as the job progresses.

[oliver90owner]

Phil,

What swing over the bed is required? My lathe is only 5 1/8” centre height, so could I do it this way, or would my milling machine need to be used for the job?

RAB

[philthehill]

RAB
You will need a 8" swing so your lathe should be suitable.

The front plate has now been line bored and the original seal fitted.

I would advise do not face the front of the scroll tube until you have tried the lip seal in the machined front plate.
The lack of a back stop for the seal makes the depth of the hole for the seal crucial.
Whilst both plates have the same part number they are slightly different in metal thickness in the area of the scroll tube (possibly different manufacturers) so go steady with the machining or you may be caught out.

The seal I have fitted was extracted from the damaged front plate and although the machined hole in the new front plate is several thou smaller in internal diameter the seal is not as secure as I would like it to be - so if the old seal is re-used I will secure with a liquid lock and seal or similar.
If I can obtain a new seal I believe that the new seal will be a better interference fit in the hole.

Make sure that you leave enough clearance to enable the clutch release fork mounting to pass the compound carriage assy.

I hope that the above is of use to those thinking of replacing the scroll oil return with a lip seal.

I have ordered a new seal which is of the same measurements as originally fitted which is TTO CO185 4 VC 23 30 4

http://www.ebay.co.uk/itm/23x30x4mm-Nit ... 2749.l2649

Phil

For those that may be interested the lathe (Aster) being used was made circa 1895/96 but is still in excellent condition and is still well within accepted tolerances. A useful feature of the lathe is that it is capable of a 16" swing when the front part of the bed is removed.
The full history of this lathe is known and it has featured in the Model Engineer magazine on two occasions.

[Declan_Burns]

Very impressive Phil!
Regards
Declan

[philthehill]

Thank you Declan.
Regards
Phil

Further to above I have ordered a seal which is the same size as the ESM seal 23mm x 35mm x 7mm and I will see If I can open up the original damaged front plate to accommodate.

http://www.ebay.co.uk/itm/23x35x7mm-Nit ... 2749.l2649

[Pucketsport]

Great info Phil, I will be attempting this in the next day or two. Am I understanding correctly that the depth of the machined hole is the full thickness of the casing ? So no lip on the inside for the seal to press up against ? If so what thickness are you seeing typically ? Also if the OD of the seal is specified as 35mm what interference fit should I machine the hole to ?
Thanks

[philthehill]

The hole for the new seal goes all the way through with no backstop for the seal so in reality the seal can be pressed right through.
The thickness of the alloy is between 4mm and 7mm in the area of the scroll tube after machining.
As I pointed out above I would not face off the front plate until you are certain that the side of the seal is fully gripped by the sides of the new hole. You may have to adjust the fore and aft position of the seal in the front plate to suit. I am sure it will become obvious as you work through the process.
As regards the interference fit - I would open out the hole to 34mm as a start and see what the fit of the seal is like. The depth of the rubber coating on the seal will have a bearing on the interference grip. I would then open up the hole gradually until you have a good interference fit between seal and front plate that you are happy with.
I would use a lock and seal compound to ensure that the seal is held in the front plate.
Phil

[philthehill]

Pucketsport

I have just finished machining out the scroll hole in the 2nd plate (damaged) plate to 34.2mm for the 35mm O.D. lip seal (I will not open out the hole any more until I have the new 35mm lip seal). The depth/thickness of alloy at 34.2mm hole diameter and which to hold the seal in place is 5mm. I do not think that that will change either way even with a slight increase in hole dia towards 35mm.
Whilst I am of the opinion that the depth/thickness of alloy will contain and hold the 23mm x 35mm x 7mm seal with a 1mm protrusion of the seal fore and aft my preference would be to fit the 23mm x 30 x 4mm lip seal which listed above and has a link to a supplier.
Therefore I would advise that you machine for the 30mm O.D. lip seal in the first instance.

Phil

[philthehill]

The front scroll hole opened up to 34.2mm I.D.
The seal holding face is 5mm deep.

[philthehill]

The two new seals came this morning.

Firstly the new plate and the 30mm O.D. Seal...............

The bored hole in the new plate is 29.90mm I.D. . The new 30mm O.D. seal is 30.17mm O.D. - so 0.27mm interference fit.
Where as I thought previously that the old 30mm seal was not as secure as I would have liked I had to use the press to remove the old seal from the new front plate, so the interference fit is adequate.
The I.D. of the seal hole in the damaged plate was 30.01mm and the seal was held secure.
The O.D. of the old 30mm seal is 30.11 so only 0.10mm interference fit

Secondly the damaged plate and the 35mm O.D. Seal..........

The current bored hole in the damaged plate is 34.2mm I.D. . The new 35mm O.D. seal is 35.2mm O.D. - so 1.00mm interference fit.
I will take a little more out of the centre of the damaged plate to get a similar interference as the 30mm O.D. seal.

Pucketsport
You should now have enough details to enable you to carry out the task of fitting a lip seal to the 803cc/948cc gearbox front plate.
Good luck
Phil

[Pucketsport]

Perfect thanks very much Phil, armed with this info I will machine my casing accordingly. No harm in using a seal locking compound as well for a belts and braces approach I guess. Is there any particular brand of seal locking compound you recommend ?

[philthehill]

I have no particular brand preference other than making sure that it will do as it says on the packaging.

[philthehill]

Bored out the front plate to 34.9mm and fitted the seal.
I had to increase the size of the hole for this particular seal as the rubber covering is quite thick and would not tolerate the same interference fit as the 30mm lip seal. I was concerned that the rubber would tear so I would advise that the interference is adjusted to suit the particular seal being used.
The 7mm deep seal was pressed in and centralised so as to give 1mm protrusion fore and aft.
Having now fitted both sizes of seal my preference is still to use the 30mm O.D. lip seal.
The fitment of the 30mm O.D. seal is a known entity as it was removed from a working gearbox but when fitting the 35mm seal it must be ensured that there is adequate clearance between the seal and the nut holding the first motion shaft bearing/lock washer in place.

[Declan_Burns]

There is a cover available in Oz on an exchange basis but I don't know for what gearbox. The postage would be the downside.
http://www.spriteparts.com.au/shop/perf ... platewithr
Regards
Declan

[philthehill]

Declan
Many thanks for the link.
If I read the part number on the front cover in the link correctly it reads 22G118 which according to the chart below (which I believe was put together by Islip Minor) is fitted to the 1098cc gearbox.
The plate (Pt No/casting number:- 2A3087 which is an old BMC Pt No:) (new BMC Pt No: 22A224 & confirmed from BMC Pts List)) I have modified was removed from a 948cc gearbox.
Whilst I have identified that ESM do a 1098cc front plate (no casting number but ESM Pt No: 10G132) with lip seal http://www.morrisminorspares.com/gearbo ... ew-p830915 I have been unable to find a supplier for a modified 948cc front plate and that was the main reason to replicate the damaged front plate.
The ESM front plate is a new (non BMC ) casting and the seal carrier part is revised in that it has a different and thicker casting around the seal and has a back stop for the seal.
The 948cc plate modification may have been done by the person from whom the gearbox was purchased and who lives in Somerset.
If he is reading this he may like to comment.
The 22G118 front plate in your link appears to have been machined in a similar manner to my 948cc front plate i.e. BMC front plate and machined right through with no seal backstop.
Phil