A Leak

[Otto Man]

OK everything is fine
And I notice gear oil dripping from what looks like the inboard right side of the rear end. What leaks from there??? Two Tablespoons of oil on the floor.
I have not crawled under there yet, but what COULD leak there?
Man does that stuff stink............
Chris
Any thoughts?

[KevinK]

leak

If it's behind the brakes at the end of the axle tube, then you have a leaky axle seal and possibly a bad axle bearing. Sometimes the shaft must be replaced. If it's near the differential housing, I don't think there is much you can do unless it is the vent hose.

[kiwi]

Stink?

Def old original rear end fluid............Axle seal most likely like said.........

[Ken Potter]

I'd have to go look but I think the axle vent tube / hose is on that side on SVO's? Been making any real hard left turns?

[Otto Man]

OK, I crawled under the beast (man is it hot and muggy in my garage today) and looked around. No more drips, the whole rear end assembly is dry but the floor board (or whatever you want to call it) has gear oil in the area directly above the front of the differential housing/back end of drive shaft.
The fluid is 30,000 miles old and quite clear.
See pic.
Any ideas?
And is the little rubber cap on top of the right axle housing next to the differential the vent? It's dry there.
Thanks,
Chris

[Pat_in_L.A.]

That's most likely the pinion seal leaking. Not a terribly expensive part, but you need to check for any free play (in Georgia they call it "slop") in the pinion assembly. If there is excessive free play, the pinion spacer has crushed too far and needs to be replaced. This would require more work than a simple pinion seal replacement, but catching it early will save a lot of money and a ruined ring and pinion. If it's just a leaky seal I'm sure that you can take care of it yourself with only minor drama and enough beer nearby.

[Otto Man]

Thanks Pat,
That's kinda what I figured would be the verdict. Now just a couple questions:
Is it true I cannot get at the seal from the "front", and I must take the gears out and push it out from "behind"?
And
At about 40,000 miles I developed a sort of wum wum wum sound from the rear end on slow turns (like in parking garages) and was told this is normal, just put in this anti-noise additive in the rear. Do I need to do that again when I put it back together? Or is there some hidden reason (problem) why the rear ends make that noise after time?
Chris

[KevinK]

When I replaced the drive shaft, I checked the pinion nut and it was loose. I tightened it fairly tight with a 1/2 drive ratchet but I never loked into the torque spec. For some reason I thought it should be 2-300 ftlbs. Look up the spec first but mine seemed to stop leaking.

[SVOeric]

if you are saying 200-300 FT LB -- that is too tight

I can't remember (without my book in front of me), but this is one of the major adjustments for the rear-end --

[Pat_in_L.A.]

From The FORD Factory Shop Manual

To tighten the flange nut:
"Minimum torque required to tighten pinion flange nut to obtain correct pinion bearing preload: 170 lbs-ft."

Pinion Bearing Preload:
"(Collapsible Spacer (with oil seal):
Original bearings: 8 to 14 lb-ft.
New bearings: 16-29 lb-ft."

The book also mentions shims available, but I wouldn't trust the shims (I've seen shims self destruct, and once the crush spacer has been used it only gets weaker. They are too thin to take the loads involved without spitting themselves into oblivion).

If you have unlimited time and a machinist friend, what you can do is to assemble the diff with a new crush spacer as per factory spec. Then disassemble it and have the machinist duplicate the spacer length and inside diameter, with a larger outside diameter that still fits the confines of the location. This obviates the necessity for any crush spacer in the future. My reasoning is that if they "crush" with 170 lb/ft when assembling them, what the heck lb/ft will the parts see when you dump the clutch when you're really exercising your car? (The trans is rated to 250 lb/ft for a car in stock form, so think about that!)

Basic observation dictates that if you have any pinion free play, then it is out of spec. Period.

Regarding the diff oil additive and chirping in parking lot situations: Now is the time to drain, refill and inspect the diff with the proper gear lube and friction modifier anyways.

WOW! not a bad post for being up for 20 hours and three beers.

Make that four beers.

[Eyelawdoc]

Pat, you need to get some rest! ...Or have another beer!

[Otto Man]

This is beginning to sound like something I'll let my local Ford Service Department tackle, unless you folks think it's beyond they're ability. In which case I'm up for suggestions; gas station, private garage? The local Midas has a Manager who is a Mustang nut and knows GT’s very well and he said he could take care of it?
Chris

[Pat_in_L.A.]

If there's no "slop" then just replace the pinion seal and re torque the flange nut to 170 lb/ft. most 1/2 inch impacts will not produce that much force, so you need the proper torque wrench.

[Otto Man]

Pat
Can you better define "slop".
I don't think I want to mess with this one!
Chris

[Pat_in_L.A.]

Originally posted by Pat_in_L.A.
... but you need to check for any free play (in Georgia they call it "slop") in the pinion assembly. If there is excessive free play, the pinion spacer has crushed too far and needs to be replaced.