I'm hoping to reduce the play in my 87 f250's sterling 10.25 yoke (companion flange) by tightening the pinion nut and replacing the seal.
I have some spec's for 160 ft lbs and 8-14 in lbs for the rotation preload (axleshafts removed). I'm trying to avoid a $950 trip to the shop. The yoke is loose side to side,but I'n not hearing any noise from the ring/pinion.
Any advise welcomed.
Thanks, Mike

 

Another stumbling block: The companion flange on my truck doesn't look like the one in my repair manual. The one they show has a wide flat flange with numerous holes. Mine is much smaller diameter with no holes, but instead has shallow spines on the outside. With the wider flange you can use a screwdriver in one of the holes to hold the flange while you tighten the pinion nut. On mine it seems like you would need a special tool or else a large pipe wrench to hold it.
Mike

 

I hope you get some answers as my pinion seal leaks pretty bad and I need to replace it.

 

I have worn out several yokes on the rear axle.

The yoke metal is rather soft, the splines stretch and let the yoke move.
When this happens, the lube is actually going between the pinion shaft and the yoke, not through the seal.

Don't know if that was a design consideration, but I have never had to replace internal axle parts except for when I tried running a locker.

Yes I have even twisted the yoke off the pinion shaft, but the internal parts were still OK.

I would much rather replace a yoke than a ring gear and pinion.

 

Dave, I did a search and found your post about the pinion nut being loose sometimes. Mine only had about 30ft lbs of tork. I tightened it up to about(couldn't find my good tork wrench, used an old one) 150ft lbs.
I didn't do the no load torq testing for 8-14 lbs preload as I didn't have time to pull the axleshafts. Neither Napa nor Autozone had crush shims in stock.
I'm hoping that since I didn't tork the nut to 160 per spec at least the preload won't be too tight.
Thanks,
Mike

 

That's good to know! I never would have checked for that and after the second pinion seal leaked I'd have had a cussing tantrum that would make a sailor blush. I HATE having to do the same job two-three times.

 

As I was torqing the pinion nut, it almost seemed, at about 150 lbs, to slip a bit, like when a nut rounds off. I wonder if this was the yoke spine slipping over the pinion shaft? Hard to imagine that, though.
I still would like to know what caused the nut to loosen in the first place?
I replaced the universals about 10,000 mi ago. I just finished a 20,000 mi voyage with 3,000 lb camper, primarily on rough steep backcountry roads.
mike

 

I am getting an older, fairly small camper shortly. I have hauled a large camper on a Dodge with Firestone air bags and 19.5" wheels.
Questions:
Is you truck a 250 or 350, SRW or dually, air bags?
I don't know if I want to go to the trouble of putting airbags on my F-350.
How'd you rig do for you?

 

If the splines are worn like Dave S was talking about, then it will probably loosen up again. The splines need to be tight to transfer the torque of the driveshaft turning to the pinion shaft. If the splines have play, then the yoke and nut will move just a little bit each time you take off, and then move a little bit the other way when you decelerate. Over time, this loosens the nut.

I just had the same problem with the f350 chassis cab I was working on. I thought the seal was bad, but the yoke was loose. Being suspicious, I pulled the yoke completely out, and could see the splines in the id of the yoke were worn. Unfortunately, the guy who owned the truck did not want to buy a new one, but wanted to tighten the old one up. I put my inpact wrench on high and cranked it down, and so far it;s holding, but I expect it to work loose again.

 

Thanks Franklin,
Did you do any of those pre-load checks with the axleshafts out? I didn't pull them out because I didn't want to have to replace the seals. I've since learned you can just put some silicone on them, so I'll probably pull them and do it right.
Mike

 

Dodge,
I have an 87 f250 srw. I just added a heavy duty (1") swaybar. It worked fine. There are some threads about using airbags in the archives. I recall they were good for levelling but not so good for sway problems.
Mike

 

The Firestone bags I used REALLY helped with sway. That's my experience anyway.
Mostly I was interested in what your set-up was, THANKS!

 

I bought a 91 F250 SRW 4X4 7.3 earlier this year and in the course of hunting down driveline vibes I noticed the rear pinion nut was loose. My research (talking to personally known and respected Ford mechanic) revealed this is somewhat common and when a truck is brought in with loose pinion nut, or leaking rear seal, the shop does not remove the axles to check pinion preload. They simply torque the pinion nut back up to 150-200 ft lbs which is less than what is required to crush the sleeve. At worst this results in a pinion preload microscopically less than spec, but insignificant. This is what I did.

I also experienced the slipping you describe but if you look at the pinion nut it has some ridges on the mating surface - it is those ridges bumping in and out of the corresponding grooves, so nothing to worry about there. I freaked out at first as well - thought I had stripped the pinion or nut.

 

You have a 1000lb impact wrench under the hood. That vibration is know to loosten many items. (including my marbles)

 

Thanks Fuzzy,
That's just what I wanted to hear. Before I got your post, I did check with my shop and explained all this to them. They also said to just keep checking it for looseness and as long as there was some little slack in the pinion/ring it was probably fine. The fourwheeler mag article talked about applying some silicone to the yoke "mating surface" before reinserting it.
Thanks to all for the help.
Mike