MG Motorsports Forum

My race car seems to push out rear double bearing hub seals quite often. I need advice on a better way to vent the rear axle in order to reduce pressure. Any tips?

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1965 MGB Roadster
1967 Austin Healey Sprite Vintage Race Car

Does it have any vent now, the stock axle came with a vent. Lots of racers will run a open hose there to a vented catch can. A working vent is necessary, even on a street car.

This is the stock vent, and it does a pretty good job in most cases. https://mossmotors.com/267-040-breather

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Hap Waldrop
Acme Speed Shop
864-370-3000
Website: www.acmespeedshop.com
hapwaldrop@acmespeedshop.com

Hap,

I am using a braided line from the stock vent hole location to the trunk area with a bulkhead fitting, and then a rubber hose to a vented catch can attached to the roll bar.

I was just wondering if going to a larger diameter or dual vent locations would relieve more pressure.

Thoughts?

Tom

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1965 MGB Roadster
1967 Austin Healey Sprite Vintage Race Car



Edited 1 time(s). Last edit at 2024-04-22 08:59 AM by Midwest.MG.

I can’t imagine that the diff builds up enough pressure to actually push the hub seals out if you have the original single vent. Sounds like another problem.
Possibilities
Are you using a “good” seal? I know that SKF seals are good. Someone recently had a problem with the rear hubs on a street Big Healey and the seal actually would fall out if the hub was inverted.
Where is the seal riding on the housing end? When I first started Billy recommended that I use such and such SKF seal that was only 1/8 thick. I was driving it in until it bottomed on the bearing which left about 1/8 of the hub outside of the seal. The hubs leaked ALL of the time. I finally took the entire axle housing to a good machinist that I knew to see if there was any underlying wear. He measured everything and found that the end of the housing has a slight taper. I started installing the seal just flush with the double bearing housing and like magic no more leaks. I was pushing the seal down to a point that there was insufficient pressure on the seal.

John

Thanks John. I am using SKF 17707 into a Spridgetmania WC1200 steel billet rear hub. It rests very slightly above the housing (near flush). It doesn't just start leaking. The pressure eventually pushes it out of the housing. I turn the engine 8,000+ RPMs. I am just wondering if the axle needs a larger vent or one on both sides of the differential.

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1965 MGB Roadster
1967 Austin Healey Sprite Vintage Race Car

It has been a few yeas since I raced a Midget, but I remember the Winner Circle rear hub as well the one batch we made had a inner seal that was below the inner edge of the hub and then we used a big cirlclip to retain the hub seal.I remember we had the machine the thickness of that circlip to make it all fit. I am sure my friend Mike Miller will be along, and can tell you all you everything you ever wanted to know about rear double bearing hubs.

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Hap Waldrop
Acme Speed Shop
864-370-3000
Website: www.acmespeedshop.com
hapwaldrop@acmespeedshop.com

This is what it is doing…I wonder what those tiny threaded holes are for in the hub? Do you think little studs would hold the seal in place?

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1965 MGB Roadster
1967 Austin Healey Sprite Vintage Race Car

My guess, To help retain the seal, with some sort of short set screw, I seem to remember some being made like that. I also remember getting the right seal was a little iffy, and sometimes hard to find. Some of the seal would sit proud as your's does, and some were not as tall, and set down in the hub, enough for use to a big circlip there. In my mind, it is like you have, the wrong, taller seal. Mike and Klaus would know for sure the right seal to get. Email Mike, if he does not see this, here's his email, miller64fp@hotmail.com

Mike is a walking, talking Midget racing encyclopedia, he can fill in the blanks, or might even have some of the correct seal seals.

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Hap Waldrop
Acme Speed Shop
864-370-3000
Website: www.acmespeedshop.com
hapwaldrop@acmespeedshop.com

Thanks for all of your help Hap. When the seal is installed, it is actually near flush. When pressure builds in the rear axle, it eventually pops out like you see in the picture.

I agree with you that small set screws gently snug against the seal might solve the issue. I will check with Spridgetmania tomorrow and see if that is how it was designed. It certainly did not come with any that I saw in the box.

I appreciate your help. Getting tired of repairing this between sessions at the track.

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1965 MGB Roadster
1967 Austin Healey Sprite Vintage Race Car

I can't believe pressure is forcing the seal out unless your vent is totally 100% plugged. Just my opinion, but I think the seals are just walking out when you run the car. If the hubs came with three threaded holes I'm pretty sure set screws should be installed.

Greatly appreciated Rick. I agree with you 100%. Hope to spend time with you at Gingerman.

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1965 MGB Roadster
1967 Austin Healey Sprite Vintage Race Car

I spoke with Spridgetmania and the problem is now solved. The threaded holes in the hub were supposed to have tiny set screws in them to hold the seal in place. They are expediting a shipment to me.

Thanks to all for talking me through potential solutions. Greatly appreciated.

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1965 MGB Roadster
1967 Austin Healey Sprite Vintage Race Car

Maybe add some Loctite sleeve retainer also when you install the new seals.

Make a tattle tail anemometer and hook it up to the rear axle. I would be looking at
foaming of the fluid as a problem if the seal fits snug and comes out.

Good idea. Thank you.

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1965 MGB Roadster
1967 Austin Healey Sprite Vintage Race Car