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Rear gearbox seal
Posted: Thu May 04, 2023 9:54 am
by Classiccars
Is it possible to replace the rear gearbox seal while changing the clutch or are there further parts to remove plese
Re: Rear gearbox seal
Posted: Thu May 04, 2023 10:11 am
by les
Yes, once you remove the gearbox you can remove the cap with seal at the tail end, it might be crimped in a couple of places to hold in place.
Re: Rear gearbox seal
Posted: Thu May 04, 2023 6:50 pm
by Classiccars
Thank you.Hopefully the crimped part is reusable so will order a seal if we have the clutch out.
Re: Rear gearbox seal
Posted: Thu May 04, 2023 8:15 pm
by philthehill
There is no reusable crimp.
Once the seal and housing is removed from the gearbox tail shaft housing it is disposed of as scrap.
The new seal & housing is fitted/knocked onto the tail shaft housing of the gearbox and when fully home the front edge of the seal housing is knocked down into the retention groove of the tail shaft housing of the gearbox in at least three places.
Re: Rear gearbox seal
Posted: Thu May 04, 2023 8:18 pm
by les
The crimped part contains the seal, and is discarded, and replaced with the new part containing the new seal.
Re: Rear gearbox seal
Posted: Thu May 04, 2023 8:19 pm
by les
Oops, beat me to it Phil, however your explanation is clearer than mine !!
Re: Rear gearbox seal
Posted: Thu May 04, 2023 8:44 pm
by philthehill
Thank you Les.
Relative to this thread - I was at an autojumble a while back and spotted the special tool - gearbox rear oil seal remover (basic tool) Pt No: 18G 389 and Pt No: 18G 389A gearbox rear oil seal remover adapter for removing the tail shaft seal housing as fitted to the Morris Minor gearbox.
The seller did not appear to know what it was for so I quickly snapped it up. It also came with the adapter for the BMC 'B' Series gearbox.
Having the special tool means that the tail shaft seal can be removed very quickly and easily.
It does pay to keep your eyes peeled.
Sometimes I do have a bit of luck.
Phil
Re: Rear gearbox seal
Posted: Thu May 04, 2023 9:57 pm
by les
I was going to ask for a photo but found this.

- IMG_3008.png (2.03 MiB) Viewed 1889 times
Re: Rear gearbox seal
Posted: Thu May 04, 2023 11:15 pm
by StillGotMy1stCar
I might be wrong but I think Classicars has mentioned in another post that it has a Type 9 gearbox fitted?
Re: Rear gearbox seal
Posted: Fri May 05, 2023 12:04 am
by les
Now you mention it, yes you’re right, although he didn’t sound too sure if it was a type 9, he was mistaken about the size of the engine initially so perhaps the gearbox is actually from a Minor. It’s difficult to advise without certainty.
Re: Rear gearbox seal
Posted: Fri May 05, 2023 9:46 am
by philthehill
The gearbox of what ever type is not Minor as the bell housing is not Minor.
It looks to be an adapter bell housing bolted onto the front of the gearbox.
If it is as I suspect a type 9 gearbox replacement of the tail shaft seal is easily accomplished.
Here is some useful type 9 information:-
https://www.gbsportscar.com/TVR%20Body% ... manual.pdf
Re: Rear gearbox seal
Posted: Fri May 05, 2023 7:04 pm
by Classiccars
Thank you gents read with interest.My gearbox is indeed the type 9 5 speed with the 1275 marina engine.As it is looking as if I will need to change the seal and clutch is it possible to advise a for sale seal and clutch replacement as won't be able to go any further without these.Not much point having a rebuilt engine on a car that can't be used.Your help is appreciated as always.If I purchase the wrong parts that's on me but at least I have to try.
Re: Rear gearbox seal
Posted: Fri May 05, 2023 9:02 pm
by philthehill
Re: Rear gearbox seal
Posted: Sat May 06, 2023 9:09 am
by Classiccars
Very kind thanks
Re: Rear gearbox seal
Posted: Sat May 06, 2023 9:12 am
by Classiccars
Can you also please advise on the earlier part of the post.Regarding somewhere that any oil leak to the bell housing would be let out through an opening stopping it resting inside .
Re: Rear gearbox seal
Posted: Sat May 06, 2023 10:14 am
by JOWETTJAVELIN
Hang on, is it leaking from the engine or prop shaft side of the gearbox, or both?
Re: Rear gearbox seal
Posted: Sat May 06, 2023 2:47 pm
by philthehill
Most bell housings including the adapter bell housing have a drain hole in the lower part of the adapter bell housing so to allow any oil to escape.
If there is no hole in the lowest part of your bell you can carefully drill a 1/4" hole through the alloy casing at its lowest part.
Re: Rear gearbox seal
Posted: Sat May 06, 2023 6:26 pm
by Classiccars
Thanks very much
Re: Rear gearbox seal
Posted: Sat May 06, 2023 6:36 pm
by Classiccars
Clutch plate will.not fir 1275 so I will have yo call them.Woukd you think the clutch bearing would be affected by any oil or would it not be affected like a clutch plate would.
Re: Rear gearbox seal
Posted: Sat May 06, 2023 7:16 pm
by philthehill
Could you please enlarge on why the clutch (centre?) plate will not fit.
A photo of the clutch centre (driven) plate as removed would be appreciated.
The Ford centre plate has to be used with the type 9 gearbox. A BMC centre plate will not fit as the splines are too coarse.
The clutch release carbon thrust whilst it can be covered in oil does not make the clutch slip. Oil on the centre plate will allow the clutch to slip.
I would replace the clutch release carbon thrust as a matter of course.