rear end leak

[jpaz]

Hey guys I noticed that I have a rear end leak. Its coming from the inside of the pinion yoke flange, where the nut attaches it to the pinion shaft. It also has quite a bit of play to it, I can move it up and down or side to side. No leak at the dust cover only where the nut is.

I didn't notice anything wrong the last time I drove it last fall. I never noticed a leak there either, and I clean and inspect the underside of my car on a regular basis.

Some details about car: 72 Mach 1 Q code w/c6 trans, 9in rear w/3.25 gears. The car was restored about 7-8 years ago & I bought it from the guy that did the restoration. It is mostly stock with a few engine upgrades, but nothing wild.

I've never done any rear end work, so not sure what to do. I think the minimum torque on that nut is 170 ft. pounds & my torque wrench only goes up to 150. Plus, I have a bum left arm, so I don't even know if I can tighten that nut enough.

Any suggestions would be greatly appreciated, thank's!

                                                                          John

 

[Bentworker]

Well the good news is you won't have to torque anything to 170 foot pounds.

The bad news is that you need to pull your axleshafts and remove the third member.

If you can move the pinion around that is BAD. Your pinion bearings are most likely bad (and maybe more). Your pinion is mainly supported by two opposing tapered roller bearings (there is a third straight roller bearing on the nose of the pinion too). These two opposing bearings are supposed to have "preload" which basically means there is enough compression on the two roller bearings that they don't spin freely. The preload measurement is measured in inch pounds. Too little preload and your pinion will deflect or move under load and destroy your gears. Too much preload and the bearing will be overloaded causing heat and failure.

The amount of preload is controlled by one of two things.

1) A crush sleeve

2) shims

Between the inner races of the two opposing tapered roller bearings there is a crush sleeve or shims. With a crush sleeve the pinion nut is tightened in small increments until the two opposing races have enough pressure on them to require the force specified (in inch pounds) to turn the pinion. With shims the assembly is put together, the pinion nut is torqued to a fixed value, then the rotational force to turn the pinion in checked in inch pounds. If it is out of spec it must be pulled back apart and more shims added to lower preload or to raise preload shims must be added.

With a shim type setup you can remove and install the yoke and the preload will stay the same. You can replace pinion seals with no issue.

With a crush sleeve type removing and installing the yoke to install a seal requires a lot of tools. Basically to do it right you have to break it down and put a new crush sleeve in it. I think a lot of folks do the job and torque the yoke down on the old crush sleeve, don't check preload and call it good. That basically turns your rear end into a time bomb.

Pull it and find a trustworthy gear shop locally or ship it off. Here is a link to a shipping case. http://pitstopusa.com/i-5060395-jaz-products-protecto-i-ford-9-third-member-case.html

Hopefully it did not get run long enough in it's current condition to ruin the ring and pinion.

You could also just swap the entire third member with one from strange or the vendor of your choice and keep the stock one on a shelf.

 

[Don C]

I had the same situation when I bought mine, leaking, loose bearings, and loose pinion nut. I believe it was an incorrectly installed crush sleeve that caused the problem. I removed the nut, the seal, and the old crush sleeve, replaced them with new components, torqued to specs, met the preload specs, and it's been OK since. And, yes, you'll need a new torque wrench, and yes, it's not easy to get that nut torqued down from under the car, with the car on jack stands, very difficult to get the right angle to get the leverage needed.

 

[jpaz]

Thanks for all the great info guys! I think I will be taking my car to the shop to get checked out and fixed. I hate to have to, but I don't think I can handle this on my own.

I live in the Detroit area and there is a place called the Ring & Pinion Shop. They have been in business for over 40 years, so I think that's where I'll take it.

I actually just talked with the guy who restored my car & it sounds like he just reused the old crush sleeve & only put a new seal in. I better have the pros fix it.

 

[Bentworker]

Thanks for all the great info guys! I think I will be taking my car to the shop to get checked out and fixed. I hate to have to, but I don't think I can handle this on my own.

I live in the Detroit area and there is a place called the Ring & Pinion Shop. They have been in business for over 40 years, so I think that's where I'll take it.

I actually just talked with the guy who restored my car & it sounds like he just reused the old crush sleeve & only put a new seal in. I better have the pros fix it.

Excellent.

 

[jpaz]

Bentworker, I'm sure your right about the ticking time bomb. I don't want that to happen.

I have been actually thinking about changing the gears & maybe putting a posi in it. (Might have to anyway)

Right now it's an open diff w/3.25 gears cause its an A/C car. Thought about just going up to 3.50. Would that be ok with the A/C?

Sure would be nice to have it a bit better off the line & still be able to drive on freeway too. I only drive this car in the summer, so it is not a daily driver.

 

[Bentworker]

I don't know about AC. Can the compressor be damaged from high rpm or something?

What diameter tires are you running? Personally I have a truetrac and 3.50 gears, but since my car is still a pile of parts I have not run them yet.

 

[jpaz]

I know that any car with A/C no matter what engine, the highest ratio you could get was 3.25. So I guess Ford was worried about the compressors spinning to fast maybe but not really sure.

I have P235/60R15's so I know the tires and wheels are larger than stock which means everything is spinning slower.

It should be ok, I think. My speedometer reads about 5 mph slower than actual speed.

That was exactly what I want to get, a TrueTrac w/3.50 gears.

 

[Don C]

The difference between 3.25 and 3.50 gears would be less than 200 RPMs at 60 mph if the tires were the same size before and after the change.

You can use the spreadsheet here to play around with tire sizes and gear ratios

https://www.7173mustangs.com/thread-tire-sizes--11566?pid=115406#pid115406

And, if you still need to change your speedometer gear to correct your speedometer you can use this spreadsheet

https://www.7173mustangs.com/thread-speedometer-gears?pid=163384#pid163384

 

[jpaz]

Thanks Don! I should be fine with the 3.50's then. 

Now I just have to decide for sure about the posi. I'm thinking I might as well since I'm gonna have a little more gear.

 

[Don C]

I agree, now is the time to get it put in. It's a lot more fun to make two black stripes on the road than just one.

 

[mjlan]

If you are talking about the shop on Walton in Waterford I have also heard they are the go-to around here.

I have a third member they did in my Galaxie and it seems fine.

 

[jpaz]

No, I mean the Ring & Pinion Shop (this is their actual name) at 12 & Grossebeck in Clinton Twp. They are the go to rear end shop in SE Michigan.

Have never heard about the one in Waterford. Great info incase I hear different.

 

[jpaz]

Actually the Ring & Shop is on Grosebeck just south of 16 mile.

I talked to them and they quoted me right in-between my guesstimate. Gonna try to get it there this week. 1350 for gear change, truetrac posi, and of course all the bearings & seals installed out the door.

Still kind of thinking if I want more gear than a 3.50, maybe 3.70? My car has a/c so not sure if I can go that low.

Does anyone out there have a 3.70 with a/c?

 

[Bentworker]

How much freeway driving do you do? What is the speed limit like in your neck of the woods? This stuff should play into your decision too. Maybe a future OD transmission?

 

[73pony]

I am running 3.70 gears but also swapped out the fmx for a T5 and pulled the non working AC.

Originally had FMX with 2.75 open. Dog, my old beat up 94 Dakota had more nuts.

Swapped in the T5 and ran with the 2.75 open. Much more fun but had issues with rear end anyhow so time for a switch.

Switch to 3.70 truetrac. That with the T5 and WOW, completely different car.

I would be concerned if running with no OD and you do much highway driving though.

 

[Don C]

I have 3.73 and a C-6 and while it is a lot of fun around town I wouldn't want to go more than a couple of miles on the freeway.

The only time you would have to be concerned about the a/c compressor is on long runs on the highway. Turn the a/c off and roll down the window.

 

[jpaz]

I live in the Detroit area and do run the freeways on an occasion to go to car shows. Once or twice a year I go up north to my cottage, which is a 3 hour drive, but not all freeway. I mostly run around town here.

I don't have the a/c working at this time, but plan to soon. So I guess I should just go with the 3.50 gears and be happy, which I'm sure I will.

Ok thanks guys, you've helped me make up my mind.

 

[Don C]

Or, go with the 3.70 gear and an overdrive transmission.