Gasket twixt back brake backplate and axle case flange

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Dave Wheatley
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Gasket twixt back brake backplate and axle case flange

Post by Dave Wheatley » Sun Apr 26, 2020 1:55 pm

Replaced the oil seal on the semi floating axle rear hub,incidenally a very simple job, and there is still a slight leak, but closer examination revealed that the leak looks to becoming from between the backplate and axle case flange.
I tightened the 4 securing nuts a bit, they were already tight.
None of the axle drawings that I have show any gasket.
So a bit more dismantling needed.
Can anybody tell me if the brake back plate can be removed without dismanting the shoes apart from undoing the brake pipe at the wheel cylinder, and the handbrake connection.
I suppose that a gasket or not will be revealed and if there is one should be easy to make a new one.
1978 MGB GT
1931 Austin 7 RM
1955 Standard 10
1972 Ford Cortina
No modern!

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Paul Scott
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Re: Gasket twixt back brake backplate and axle case flange

Post by Paul Scott » Sun Apr 26, 2020 2:24 pm

This might help Dave,

But it does not show a gasket as you say.

https://www.youtube.com/watch?v=IA1XTlKidao

Regards
Paul
1975 MGB Roadster
Webguru for MGB Register

Ian Fozzard
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Re: Gasket twixt back brake backplate and axle case flange

Post by Ian Fozzard » Sun Apr 26, 2020 3:42 pm

Dave, from memory:

The back plate complete with shoes etc. should just lift off.

Check the mating surfaces of the two halves of the bearing retainer - they may have burrs or may not be completely flat. Can be lapped if not perfect but be very careful with any lapping paste if used. I think a smear of blue hylomar on the faces would secure a good seal.

The cone on which the oil seal sits needs to be perfect it can be worn or damaged. The fit of the bearing in the housing also needs to be perfect, blue hylomar may be helpful here to ensure it is oil tight.

Other contributors may have different advice of course😁!

Ian F
1972 BGT, Blaze, Navy trim, recessed grill
1961 Midget, 948cc, Clipper Blue, Blue trim and weather gear

Dave Wheatley
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Re: Gasket twixt back brake backplate and axle case flange

Post by Dave Wheatley » Sun Apr 26, 2020 5:38 pm

Ta Paul and Ian.

The man in the video is a bit of hammer and chisel man, but the detail is there. Looks like a simple job to dismantle.

Very kind of MG to allow the backplate to come off without dismantling shoes and springs!

Hopefully no surface damage.
1978 MGB GT
1931 Austin 7 RM
1955 Standard 10
1972 Ford Cortina
No modern!

Ian Fozzard
Posts: 370
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Forename: Ian
Surname: Fozzard

Re: Gasket twixt back brake backplate and axle case flange

Post by Ian Fozzard » Sun Apr 26, 2020 5:44 pm

Hammer and chisel is exactly the technique to raise a few burrs on the bearing retainer edges!!!

Ian F
1972 BGT, Blaze, Navy trim, recessed grill
1961 Midget, 948cc, Clipper Blue, Blue trim and weather gear

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Michael Barclay
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Re: Gasket twixt back brake backplate and axle case flange

Post by Michael Barclay » Sun Apr 26, 2020 6:06 pm

Hi Dave
I did this job on my car last year when changing the rear bearing. I think Ian has answered most of your questions. The back plate can be removed complete with shoes. Just disconnect the brake pipe at the back of the wheel cylinder then undo the 4 retaining nuts and bolts and it should lift clean away. The oil seal should be a snug fit in the retainer. There is no gasket between the retainer and axle hub. As Ian says check the cone for any wear or ridges as these will be sure to cause a leak. The other question is where you got the oil seal from? My experience of aftermarket parts from the likes of Moss is not good. I could not fix a leak on my timing chain cover until I fitted an original Rover /Leyland seal. I suspect you seal is not “gripping” the cone enough to form a decent seal. Have a look on the well known auction site, there are some original Rover seals for sale for reasonable money.
Best regards
Mike Barclay

Dave Wheatley
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Re: Gasket twixt back brake backplate and axle case flange

Post by Dave Wheatley » Mon Apr 27, 2020 9:08 am

Hi Michael. when I first noticed the leak, all I could see was a droplet of obviously hypoid oil hanging fro the bottom of the backplate, as well as a smattering on the wheel and tyre, so I assumed it was the oil seal.
After fitting a new seal I noticed the droplet still there, and after a close examination established that the drip had come from somewhere between the backplate and axle flange. Oil seal did come from Moss or the Hive.
Talking of oilseals, you used to be able to obtain oilseals with 2 or even 3 contact rings. I will try to locate one of these for the next replacement.

Can any body tell me the size of the oil seal,inches or mm please?
Last edited by Dave Wheatley on Mon Apr 27, 2020 10:06 am, edited 1 time in total.
1978 MGB GT
1931 Austin 7 RM
1955 Standard 10
1972 Ford Cortina
No modern!

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Michael Barclay
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Re: Gasket twixt back brake backplate and axle case flange

Post by Michael Barclay » Mon Apr 27, 2020 9:55 am

Hello Dave
From your description this suggests the seal is not sealing on the tapered collar. You could confirm this my briefly assembling everything without the back plate in place. This will give you a clearer view of where the leak is. Again I would carefully examine the tapered collar for marks ridges. Also with just the collar fitted into the seal look to see how the lips of the seal grip the collar. Again I canno reiterate using a good quality seal. I have a new seal which I believe to be genuine Leyland. If you send me you address via the private message link I will send it to you.
Best regards
Mike Barclay

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