727 to propshaft oil leak

witorque · Post by **witorque** » Mon Jul 04, 11 7:56 pm

The auto rear oil seal on our 72 Challenger 340 has started to leak after around around 2500 miles. I noticed the prop can be wriggled around in the casing, maybe beyond what the seal should cope with?
Prop measures 1.682" - no significant wear steps
Nominal size is probably 1.6875 = 1 11/16"
Clearance is going tp be at least .0055" if the bush is on nominal size.
Is this sort of clearance normal? I would have thought 3 thou would be enough?
I'll have to check if Alders replaced the rear casing bush as a matter of course.

Dave999 · Post by **Dave999** » Tue Jul 05, 11 10:01 am

isn't there supposed to be a massive rubbery seal??

Dave

witorque · Post by **witorque** » Tue Jul 05, 11 11:08 am

There is a metal cased lipped rubber seal, which is flanged
Ive pulled out the existing one which is barely worn
I'm inclined to think that the prop yolk has been made undersize which is causing premature leakage- too much movement of the prop within the seal...

Dave999 · Post by **Dave999** » Tue Jul 05, 11 12:58 pm

odd

very odd

ive never paid much attention

just polled out the yoke and stuffed something in to stop oil coming out

then replaced....

i.e no real care and attention....

maybe i should be more careful

mines manual same yoke as 904

Dave

Anonymous · Post by **Anonymous** » Sat Jul 16, 11 4:44 pm

Hi Wi,

Looks like Alders didn't replace the tailshaft bush in the Mas67 trans either?
Not sure if this was a normal service routine in the past, but it sure should be now, after 100,000 plus miles and 44years of of use.

Seems wear in this bush throws out the prop balance too???

Its getting real hard to find a good transmission/propshaft shop in the South East?

Bacca.