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8.8 differential

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jdavidsmi

8.8 differential

While I was waiting for the battery to charge, see the on going electrical issue thread. I thought now would be a good time to replace the leaking pinion seal.

Once I removed the pinion nut the yoke could be pulled off with my hand. Is that normal? I thought it should have been a lot tighter.

Both the yoke and pinion have 30 splines

Also in 84 was a flange was used instead of the yoke? I have seen pictures of both, but no clue as to when each application was used.

last question is, if the axle vent is plugged, would or could this cause the seal to start leaking? the seal I replaced looked almost brand new.

David,
1984 F150 LX, 4x4 117 wheel base, Engine Code "F" = 302, 5.0 2/B,
Transmission code "A" = 4sp manual New Process model 435
Axle code "19" = 3.55 (ford 8.8) manf. 08/1983, in Norfolk
DSO code "21" AtlantaFactory Air Conditioner, Dash with Gauges
1990 Goldwing 1500
1986 F150 XLT, short bed, 5.0 automatic
2004 F53 Fleetwood Terra motor home
2017 Chevrolet Traverse
Home town Viola Tennessee

Gary Lewis

Re: 8.8 differential

Administrator

The seal should be a press-fit. And a plugged vent will cause a leak somewhere. Either of the axle seals or the pinion seal, or all of them.

I'll have to check on the flange question later.

Gary, AKA "Gary fellow": Profile

Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker & 10.25 Sterling/Trutrac, Blue Top & Borgeson, & EEC-V MAF/SEFI

jdavidsmi

Re: 8.8 differential

Thanks, while I'm at the parts store I will pick up a new one, fast and easy fix.

PetesPonies

Re: 8.8 differential

Most times the yoke is much tighter, but if the splines look good, just feel lucky.

Pete's Ponies
Mustang RUSToration & Performance

1982 F100 Flareside
1983 Bronco

Gary Lewis

Re: 8.8 differential

Administrator

In reply to this post by jdavidsmi

I'm not sure I understand the "flange" vs "yoke" question, but it isn't something I can answer from the catalog. That's because Ford calls it a flange, with the generic part # of 4851. So, whatever goes there is called a "flange" in the catalog even when most of us would call it a "yoke".

Gary, AKA "Gary fellow": Profile

Nothing Special

Re: 8.8 differential

Some diffs (and transfer cases) have one side of the U-joint yoke as a part of the piece that is splined to the pinion shaft (output shaft for a t.case). Then you use U-bolts to attach a single Cardan U-joint (or 4 bolts to attach a double-Cardan) to the yoke.

Others have a flat flange splined to the pinion shaft. In that case the U-joint yoke will have a corresponding flat flange that attaches to the flange on the diff with (I think) 4 bolts. Those U-joints have all 4 caps pressed into the yokes (like a front axle U-joint) rather than having U-bolts.

I can't say I'm 100% sure, but I thought Ford stayed with yokes well past 1984.

Bob
Sorry, no '80 - '86 Ford trucks
"Oswald": 1997 F-250HD crew cab short box, 460, E4OD, 4.10 gears
"Pluto": 1971 Bronco, 302, NV3550 5 speed, Atlas 4.3:1 transfer case, 33" tires
"the motorhome": 2015 E-450-based 28' class C motorhome, 6.8L V-10
"the Dodge": 2007 Dodge 2500, 6.7L Cummins

Gary Lewis

Re: 8.8 differential

Administrator

Thanks for the explanation. I kinda thought that was the case. But it didn’t matter as far as the catalog is concerned as both are called a “flange” by Ford.

Gary, AKA "Gary fellow": Profile

jdavidsmi

Re: 8.8 differential

This is what I called the yoke
yoke from the 84

And this is what I called a flange
picture of flange from fourwheeler website

I hope its ok I got the flange picture from the fourwheeling website.

Gary Lewis

Re: 8.8 differential

Administrator

Absolutely ok to find pics elsewhere and share them here. I do it all the time.

And, that's what I assumed you meant by "flange" and "yoke", but wasn't sure. Unfortunately, w/o part numbers I can't tell when one was used vs the other as Ford calls both of them a "flange".

Gary, AKA "Gary fellow": Profile

PetesPonies

Re: 8.8 differential

Yes, the 8.8 uses a different driveshaft attachment as shown in the pics.

Pete's Ponies
Mustang RUSToration & Performance

1982 F100 Flareside
1983 Bronco

Bruno2

Re: 8.8 differential

How tight the pinion nut is has everything to do with your pre load. If it was hand tight that probably means your bearings are out of tolerance and may be needing a rebuild pretty soon. Also, whenever the pinion seal goes bad is tell tale signs of the bearings having a lot of play in them causing the shaft to woller the seal out.

Whitey: 1996 F 250 XL CCLB 4X4 7.3 DI ZF5 (The Work Horse) Lots of power mods
Whitey Jr: AKA Jr 1982 F 150 CCLB 4X4 351W C6 (Jr Work Horse) respectable power, but not over the top
The Bronco: 1987 Bronco XLT 351W C6 (needs work) Lots of off road mods and plenty of power mods
The Dodge: 2006 Ram 2500 CCSB 4X4 5.9 HO Cummins (The reliable ride that cant keep an AC in itself) (5th AC go around almost complete)