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Ferret fluid flywheel seal.
   (Ver 1)

 

Richard F. in England spent the majority of his military career working on wheeled armour, mostly the Ferret/Saracen/Saladin series but also the latter Fox. In this article he gives a brief rundown on the fluid flywheel.

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1/ Did you have to top up the flywheel with about 4 pints of oil (2 quarts)? (I know there is a small difference between US and British pints but this is near enough)
2/ Has the leak been noticable before, or suddenly happened?

My guess is that the seal is cooked, if the level has not been checked for some time and the leak has been gradual, it would come to the point where the oil would be worked so hard it was overheating and would cook the seal. Of course it can leak from the outer flange, filler plugs or a cracked cover. If it were the seal you would end up with it being about half full, that is why I asked how much oil you put in. Not a great problem to access, leave the engine in, just pull the gearbox away from the engine.......after removing all the seats and tinwork, front propshafts, etc. If it is a Mk1, lift the box out, on a Mk2 you would have to take of the turret if you wanted the box right out, but pulling it back can give sufficient room. You may well see if the seal is leaking from the tell tale streaks from it. Knock back the lock tabs on the seal carrier and remove the bolts. There are tapped holes to extract the seal carrier, cannot remember off hand if they are threaded National Fine or National Course, it will be one of these. It will help if you can look at the EMER worksop repair manual to give you an idea what its like. I think you can access an Australian version on the Ferret website. I always pressure test the flywheel to check for leaks elsewhere, using another filler plug with a guage and tyre valve attached, just in case it is leaking somewhere else as well. Just had a thought, the last one I did, on a Saracen, the guy had boiled the flywheel dry and the inner driven member had expanded and siezed in the outer casing. You can check it is rotating free once the seal is removed. Best of luck with it.
regards,
Richard F.

I found a seal available in the U.S. which worked extremely well with my ferret's fluid coupling. I got it through my John Deere tractor dealer and it was the least expensive of the seals I tried. It is a double wall seal and is made of longlife material, so it is more durable than the original.
Specifically it is part number: AT52447 (John Deere) It is the equivalent of the CR 17395 except it has a double wall making it stronger. I paid $5.41 for it. I tried the CR 17387 but it did not work for me. (Courtesy of Ross R. - USA)

I have been told that there are NAPA kits that are the equivalent to the rebuild kits. The information that I have is as follows: (Please note that I have no actual first hand knowledge as I have not used these parts);

Whilst on the subject of seals:

Master cylinder rebuild kit: NAPA part 214

Wheel cylinder rebuild kit: NAPA part 152

This I can tell you: If this info is correct the kits will be reasonably priced and universally available.

My thanks to Richard and Ross.

 

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