MTFCA Forum

Hello everyone,

A while ago I installed a new neoprene half shaft inner oil seal on my 1915 tourer. I installed it as per recommended, having wrapped tape around the keyway, apply grease etc so as not to damage the seal.

All was well at first, but after about 100 miles the oil seal is leaking again, not as bad as before but still a bit of a nuisance.

Would anyone have any suggestions as to what could be the cause of this?

Any help would be greatly appreciated.

Many Thanks
George

Did you apply a thin layer of oil-resistant black RTV around the edge of the metal flange prior to inserting the seal? And thoroughly clean the shaft tube lip which it will be pressed against? Doing that helps keep the seal from rotating along the shaft as well as extra sealing against oil seeping around the new seal.

I see that your car is a 1915 speedster, does it have a pre 1919 rear axel with the fill plug on the axel center line ? It is easy to over fill these axles, the gear oil should be about 3/4 inch below the bottom of the fill plug. If you don’t have a Ruckstell you can run the modern type replacement 600 wt gear lube that the Model T & A venders sell, that is thicker than the 140 wt gear lube like a Ruckstell would use. What type outer seals do you have, modern or felt, and did you install the stock thinner felt seal in the rear hub, many people leave these out ?

I have spoke of this problem before. The inner neoprene oil seals fit too tight on the shaft. They were designed for a much smaller shaft. (Chrysler CV joint I believe) The tight fit grabs & shreds itself. I have yet to find an unmodified one still in tact even after a few miles.
Here's what I do. Stretch the seal on an axle shaft stub & turn in a lathe. With a sharp utility knife blade, cut the seal @ about where the bead is molded into the seal. This makes the seal hole larger, removing the excess pressure fit that grabs & destroys itself.

speedytinc wrote: ↑

Sat Oct 22, 2022 9:05 pm

The inner neoprene oil seals fit too tight on the shaft. They were designed for a much smaller shaft. (Chrysler CV joint I believe) The tight fit grabs & shreds itself.

Interesting to know. I always thought they were too tight. I've had limited success with these seals. One one side never had a problem, but the other always leaks despite sealing the flange with silicone. I'm going to try the thick felt seals which get pushed down the axle behind the Hyatt bearing next.

I would be interested to know from Mark Chaffin as to the genesis of the seal. I recall that Chaffins had them made, and at one time, were unavailable and then reissued in a very slightly different configuration. That does not comport with a story of them being from another modern car.

JohnH wrote: ↑

Sun Oct 23, 2022 7:02 pm

speedytinc wrote: ↑

Sat Oct 22, 2022 9:05 pm

The inner neoprene oil seals fit too tight on the shaft. They were designed for a much smaller shaft. (Chrysler CV joint I believe) The tight fit grabs & shreds itself.

Interesting to know. I always thought they were too tight. I've had limited success with these seals. One one side never had a problem, but the other always leaks despite sealing the flange with silicone. I'm going to try the thick felt seals which get pushed down the axle behind the Hyatt bearing next.

I still use them in modified form. They seal very well. I would not change to a different type of seal. I do glue them in around the edge with ultra black.
I would bet if you look @ the side thats not leaking, the seal is still shredded. The fact that you dont think it leaks may be it hasnt gotten bad enough to see yet.
As I said, I have never serviced a rear end where an unmodified seal was not shredded or cam unglued from the steel washer. We're talking a dozen or so. That was another issue. Some were not glued well enough to the washer.

Thank you all for your detailed replies, it is very much appreciated.

I did use some black rtv around the flange and did clean the lip, however, is there anything in particular you use to clean the lip with?

I apologise for my lack of clarity, the car I am currently working on is my 1915 tourer, I need to update my profile as it has my first model T listed, which was a 1915 speedster. My tourer has the pre 1919 axle and no ruckstell- I might try that axle oil once I have replaced oil seal again. I have the felt outer seals in the hub, I am 99% sure that I installed both but now that has got me thinking! Are the modern seals in the outer hub a big improvement?

It is interesting to read about the modification to the modern inner seals, this is something I will try when I install the new seals, I did think it was very tight at the time.

Many Thanks again for all of your help

George

Always lube the inner seal rubber of a new seal Don't install it dry. bobt

bobt wrote: ↑

Mon Oct 24, 2022 6:55 am

Always lube the inner seal rubber of a new seal Don't install it dry. bobt

Oil doesnt help for long. They just fail a few revolutions less.

speedytinc wrote: ↑

Mon Oct 24, 2022 8:23 am

bobt wrote: ↑

Mon Oct 24, 2022 6:55 am

Always lube the inner seal rubber of a new seal Don't install it dry. bobt

Oil doesnt help for long. They just fail a few revolutions less.

Ha ha, ur probly right, but it makes us feel good!

George, as for cleaning the inner lip, I've used mostly lacquer thinner, my "elixir"..ha ha, but have also sprayed Brake Kleen up in there too, to make sure it is totally clean and dry and I mean totally. I use a fairly generous smear of the RTV around it, maybe that's why I've been lucky as far as no problems? Or the seals I've had weren't that tight, as I recall, they didn't "fight me" much putting them on.

Not just any RTV. Stephen Heatherly told me about this. He says it cured the problem for him.

If you are running a cartridge bearing on the pinion, it seals the path that internal pressure from heat has out of the rear diff. I have installed a vent on the axle tube and have had no problems with seal leakage.

I've tried that gear oil gasket maker - still have a "drip" !