Ford 9" Pinion Seal leaking

[viven44]

The pinion seal on my 78 Bronco's 9 inch rear end is leaking profusely. I am quite sure the pinion bearing preload is not sufficient and there is too much play in the bearing which is why it is leaking.

I have no idea if what is inside is a crush sleeve or solid spacer setting the pre-load.

I've ordered a "Stainless Steel Pinion Yoke Wrench" Jig to hold the yoke while adjusting the pinion nut

My plan is to pull the pinion housing/pinion gear and install new crush sleeve, set the preload, install new seal, install the pinion housing back and hopefully call it a day. If the housing is shimmed, my plan is to put it back the way I found it with the same shimming. Looking for best course of action/suggestions.

[ArdWrknTrk]

I would send you my 3' Horrid Fate pipe wrench, but it would cost you 3x more than buying one new in Dallas. 🙃

[85lebaront2]

Depending on the gear ratio you may need to be sure it is still indexed to the ring gear correctly.

Ford had three different classes of ring and pinion, hunting where every tooth on the pinion hits every tooth on the ring gear 3.89:1 was a good example, it was actually 3.888888 as far as you want to go :1, non-hunting, 3.00:1 is a non-hunting set where every tooth on the pinion hits the same 3 teeth on the ring gear, and partial non-hunting where there is a cyclic pattern and every pinion tooth hits the same group of ring gear teeth.

If you have a hunting set, then it doesn't matter where the pinion teeth land, the set is already run in, if you have a non-hunting or partial non-hunting and get the gears "out of time" you will probably have a lot of noise and may end up destroying the gear set.

[ArdWrknTrk]

These are the Pearl's of wisdom I've come to expect of this forum!

Thank you, Sir!

[mat in tn]

i re read this three times. I believe this explains this in as simple of a way possible. although I have not heard it referred to as "hunting". maybe that is my daily "learn". I call it sync because it makes sense to me.

[85lebaront2]

The terms I used are right out of my 1964 Falcon/Comet FSM where I first learned about Ford rear ends (Falcon had the 260 V8 and an 8" rear end).

[viven44]

Thanks Jim!! Did you mean that the pipe wrench could be used to hold the Yoke ? If so, the Jig I ordered would do the job, but I do have one of those wrenches already

Thanks Bill! I had no idea about hunting vs. non/partial-hunting. I have the H2B Limited Slip axle with 3.5 gear ratio. Curious to know what that axle ratio is considered.

[ArdWrknTrk]

These are the terms I've always known... 🤷‍♂️

[viven44]

OK I found 3.5 is semi-hunting

https://www.diyford.com/ford-axle-ring-pinion-assembly-guide/

I guess I am supposed to find timing marks on the gears... but they don't always have one?  

[85lebaront2]

They may or may not, but, brake cleaner or similar to de-oil the pinion and ring gear where they mesh and use a paint daub or grease pencil, even a crayon and mark one pinion tooth and the flanking ring gear teeth.

You will have to pull the hogshead out of the axle to do this.

[ArdWrknTrk]

The Ford 9" is one of the simplest rear ends to set up... ever!

[85lebaront2]

Here is what the pattern on my best friend's 3.73 10.25" looked like:
Drive side:

Coast side:

[viven44]

OK thank you. I just want to make sure I understand. I am just a guy that has learned enough to put things back just the way I took them apart.. so far (Green to Green at all cost )

What you are recommending here is
1) to ensure with paint that the pattern on the ring gear looks like a 'football' to ensure pinion depth is correct.
2) Timing???

I still worry that I have not understood the concept of hunting and timing well.

My understanding (so far) is that all teeth are the same size on Ring/Pinion so ideally they are able to ride any which way. But on gear ratios that are non or partial-hunting, there is a certain wear pattern / marriage made on certain gear tooth combinations over time that requires you to keep them married forever.

Currently I do not have any noises or anything else acting up on the rear end so I assume the ring and pinion are happy together.

Now if there are no timing marks, Can I possibly mark the pinion 'shaft' / pinion housing / ring gear housing / ring gear so I can put back the pinion gear exactly the way I pulled it out ?

Edit: Dumb question. Can I replace the crush sleeve without removing the pinion gear housing/assembly? Looks like if I pull the seal and the front bearing, the crush sleeve should come out... If so, maybe that's all that's needed for now.

[85pig]

Thank you.  In the process of starting to rebuild two 9" limited slip diffs, and never knew about the "timing" of certain gears mentioned in that article.  I'll look for marks on mine - both 3.50s.  

[viven44]

Keep us posted on how that goes!!

I wish I had the time to do a full rebuild. I have many other things to be addressed on the Bronco, including brand new carpet, upholstery, air conditioning, brakes.  The bronco should lead a low-rpm peaceful life, going to grocery stores, workplace, school drop-offs so I think I will get by for now if I can address this leak.

[viven44]

Took out the Yoke. Good news is the preload seemed to be in spec. About ~15 in lbs and no play. Front bearing came out and looked really good.

The yoke shaft is all scored up and the old seal looks jacked up. I don’t know what could explain that seal deformation.

[mat in tn]

the seal also looks split in one picture. but the yoke looks to be grooved. is there a yoke repair sleeve available or possibly a new yoke?  a new seal may not mate to a grooved yoke.

[viven44]

These 2 look like good options

Sleeve

https://www.rockauto.com/en/moreinfo.php?pk=257669&cc=1105614&pt=13976&jsn=985&optionchoice=0-0-1-1

Yoke (I need to confirm my U joints are 1310)
This is literally the only one I've found that looks like mine!!

https://shop.broncograveyard.com/Ford-9-Inch-Pinion-Yoke-1310-Flange/productinfo/22280/

[mat in tn]

the yoke does seem reasonable but I have used seal sleeves with excellent results and may very well be using another soon as my 8.8 seems to be weeping and I'm considering changing gears at the same time.

[viven44]

I just ordered the sleeve on Amazon as it will get here pretty quickly.. Rockauto's shipping usually kills it for me.

I agree that Yoke is priced well.

It's amazing metal can be pitted like that from friction/heat.

The previous owner (kid) went mudding a couple of times. I am sure the seal took a beating then.