8.8 cross-pin bolts?

[MAKG]

OK, got this all apart and partly back together.

The cross-pin bolt looked EXACTLY like Evan's picture. It broke right at the last thread, apparently many years ago (the broken part was not at all fresh steel, and the bolt felt normal coming out, not like it was twisting off). The Fabbri Associates kit took it right out, with the exception that the drill bit is a little too long and the rear stabilizer bar had to come out to accomodate that. It may be far less of an issue on a spring-over axle.

The axle bearings looked good -- the axle shafts are less than perfect (some dull discoloration -- not the bright shiny polish I'd like to see), but don't appear to be pitted at all. The companion flange was not floppy BUT the nut wasn't nearly as tight as it should have been (no more than 40 ft-lbs to remove) and the pinion just fell out of the diff. No press fit onto the front bearing. The bearings LOOKED good, but I think the front bearing has been spinning due to the loose fit. I opted to replace it ($15 for Timken). The new bearing had a nice interference fit; it could be felt pressing in as the nut was tightened.

Questions:

1. I had an unbalanced driveshaft; it has since (and recently) been balanced. That did not make the noise go away, but it did take away most of the shake that had accompanied it. The noise now sounds more like a speed-dependent rubbing sound than a grumbling (I think I was hearing the driveshaft shake). There was SOME shaking still, but much less. Does the front pinion bearing sound plausible for this?

2. I had an extra piece at the end of the day (this does NOT happen often). It's the thin spacer between the companion flange and the bearing. I suspect I know the answer, but I can hope anyway -- do I need to pull the flange and seal off or can I put this thing in the small parts box for the gear swap I'll eventually do (it will be some time)? What purpose does it serve? Oiling? The space was taken up by the crush washer.

3. I had one new bearing and one old bearing. Which preload spec should I use? I opted to the low side of the new spec. It's set at 20 inch lbs rotating now. Is this too tight?

Thanks a bunch, guys.

PS: you guys may enjoy this. My son just told my wife that he pees gear oil (it's synthetic Mobil 1 and it still looked rather yellow).

 

[rickcdewitt]

commentary underlined in quote

Questions:

1. I had an unbalanced driveshaft; it has since (and recently) been balanced. That did not make the noise go away, but it did take away most of the shake that had accompanied it. The noise now sounds more like a speed-dependent rubbing sound than a grumbling (I think I was hearing the driveshaft shake). There was SOME shaking still, but much less. Does the front pinion bearing sound plausible for this?

maybe,my pinion bearings made a speed dependant squeak when the crush sleeve or nut came loose,its possible the bad driveshaft caused your problems.if its still shaking i'de be looking at that driveshaft or your tires

2. I had an extra piece at the end of the day (this does NOT happen often). It's the thin spacer between the companion flange and the bearing. I suspect I know the answer, but I can hope anyway -- do I need to pull the flange and seal off or can I put this thing in the small parts box for the gear swap I'll eventually do (it will be some time)? What purpose does it serve? Oiling? The space was taken up by the crush washer.

time to take it back apart,thats your oil slinger

3. I had one new bearing and one old bearing. Which preload spec should I use? I opted to the low side of the new spec. It's set at 20 inch lbs rotating now. Is this too tight?

my alldata shows 17 as the low side of new.but the front pinion bearing shoulden't be press fit like you said,only the rear bearing.the pinion nut and crush sleeve hold the inner race from spinning.the pinion is supposed to fall out so i wonder if your bearing setup is kosher.

Thanks a bunch, guys.

PS: you guys may enjoy this. My son just told my wife that he pees gear oil (it's synthetic Mobil 1 and it still looked rather yellow).

classic

 

[MAKG]

Thanks. I strongly suspected #2. Ford isn't in the habit of installing unneeded parts. Dagnabit.

FYI, the shop manual says 160 ft lbs on the pinion nut, then check preload and tighten as needed. If it's high, replace the crush sleeve. That's a bit different from the 1986 7.5; it says just replace the crush sleeve.

As for the press fit, two other front pinion bearings did not slide on (I tried it at the auto parts store), and the 1986 7.5 I mentioned had to be banged out with a hammer.

 

[Evan]

That bearing preload spec is referring to the rear (closest to the gear) bearing. So if you're reusing that bearing you'd use the old spec.

Also, it seems to me that this spec is the most forgiving when it comes to gear setup.

 

[Danger06Ranger]

Guess I've been lucky so far, I haven't broken a pin bolt yet.

 

[c_note]

if you heat it up, you may be able to just back it out with a scibe by pushing on it in a counter-clockwise motion.

 

[MAKG]

I'm sure, but that drill guide and EZ Out really made it easy. There wasn't much holding it in; it was just a matter of getting ahold of it.

 

[rickcdewitt]

FYI, the shop manual says 160 ft lbs on the pinion nut, then check preload and tighten as needed. If it's high, replace the crush sleeve. That's a bit different from the 1986 7.5; it says just replace the crush sleeve.

funny i saw that spec when looking up the bearing preload.but not needed for me.the crush sleeve eliminator i used just gets torqued to 180lb/ft and all done.not that i would use it any way.just tighten it and check the bearing slop continuously until its close.then go a little at a time till your inch pound wrench is happy.

strange about the bearing.all three pinions(i geared it twice) that i've had in my housing were loose fit.and my bro's heep when we set it up.

good luck

 

[MAKG]

OK, now I'm pissed off.

The noise I was chasing had quieted down substantially, BUT IT IS NOT GONE.

Furthermore, now it seems to be quite a bit worse in hard high-speed turns (but not easy turns), which suggests to me something attached to brake rotors. It's also more noticeable coasting, which suggest it CAN'T be the front. WTF? I think I've ruled out the manual hubs (there is a bearing up there that spins when unlocked), because putting it in 4WD doesn't change a dang thing. I wonder if I might be dragging the front driveline along. I suppose I can try putting the auto hubs back on (still got 'em).

I'm confused. Any ideas?

 

[Evan]

OK, now I'm pissed off.

The noise I was chasing had quieted down substantially, BUT IT IS NOT GONE.

Furthermore, now it seems to be quite a bit worse in hard high-speed turns (but not easy turns), which suggests to me something attached to brake rotors. It's also more noticeable coasting, which suggest it CAN'T be the front. WTF? I think I've ruled out the manual hubs (there is a bearing up there that spins when unlocked), because putting it in 4WD doesn't change a dang thing. I wonder if I might be dragging the front driveline along. I suppose I can try putting the auto hubs back on (still got 'em).

I'm confused. Any ideas?

Transfer case output bearing?? Worn slip yoke on the rear driveshaft maybe?

If you crawl under the truck and can freely rotate the front driveshaft, the front driveline shouldn't be getting dragged along at any substantial speed when driving.

 

[MAKG]

The driveshaft slip yoke is known to be a moderate problem; the driveline shop greased the heck out of it and it didn't change anything.

These guys have a rep locally (the proprietor is a significant Jeep fabricator, and has some rather interesting and sophisticated articles on the Web on driveline angles), so I took their advice that the driveshaft had some miles left on it. Perhaps they were wrong? How would one independently check this? All the local shops outsource to these guys.

But I don't see how turns affect the driveshaft or transfer case. I do see how a rotating front driveline could see turns, though (U-joints).

Something else I should mention is that there is some tire wear I don't understand. The tires have some 50,000 miles on them; they are BFG Duellers, 31x10.50. The outer rows of tread seem to stand up further -- and discontinuously -- from the inner ones. I don't understand how the tire could wear that way. It doesn't look at all like overinflation wear.

 

[Evan]

The driveshaft slip yoke is known to be a moderate problem; the driveline shop greased the heck out of it and it didn't change anything.

These guys have a rep locally (the proprietor is a significant Jeep fabricator, and has some rather interesting and sophisticated articles on the Web on driveline angles), so I took their advice that the driveshaft had some miles left on it. Perhaps they were wrong? How would one independently check this? All the local shops outsource to these guys.

But I don't see how turns affect the driveshaft or transfer case. I do see how a rotating front driveline could see turns, though (U-joints).

Something else I should mention is that there is some tire wear I don't understand. The tires have some 50,000 miles on them; they are BFG Duellers, 31x10.50. The outer rows of tread seem to stand up further -- and discontinuously -- from the inner ones. I don't understand how the tire could wear that way. It doesn't look at all like overinflation wear.

Turns affect the driveshaft and transfer case because the housing is not centered on our rear ends. So when you turn and load one side of the suspension and unload the other, the u-joint angle will change.

I don't know how to check a slip yoke. Maybe use a dial indicator to measure lateral play. But I have no idea what the spec would be.

Do you have pics of the tire wear?

 

[MAKG]

I don't think the wear will show up well on a photo.

If what you're saying is right, removing the rear swaybar ought to make it substantially worse, right?

It's a fairly long driveshaft; I don't see how the modest changes in angle described here can matter. It would need several degrees, wouldn't it?

 

[Evan]

I don't think the wear will show up well on a photo.

If what you're saying is right, removing the rear swaybar ought to make it substantially worse, right?

It's a fairly long driveshaft; I don't see how the modest changes in angle described here can matter. It would need several degrees, wouldn't it?

I have found that when it comes to bearings, very moderate changes in load direction can make a big difference with the noise being produced.

Anyway, if you had your shaft checked out by a good driveline shop, I'd say it's safe to assume that's good. And if your bearing is bad in the rear of the t-case it's almost always accompanied by leaking ATF at the rear seal. So it should be easy for you to confirm or eliminate that possibility.

You're almost getting to the "drive it until it breaks or gets really bad" tactic, as this noise seems tricky as hell to pinpoint. Not the best way to find out what the problem is though...

 

[MAKG]

It did seem to show up for the first time around when I did the manual hub swap. So for a while, I chased the front end around, and thought I had ruled it a coincidence.

Another test I did that would seem to rule out the transfer case and driveshaft (and which is why I went after the rear end) was to remove the rear driveshaft and drive it around in front wheel drive. The noise was completely unchanged.

Of course, it would also be unchanged with any problem in the front end except the manual hubs. Manual hubs are immobilized when locked.

I really hate to drive it until it breaks, since some noise problems can get dangerous under those circumstances (especially wheel bearings).

Is it worth it to zip tie the front driveshaft around the diff through the front U-joint, to guarantee it won't rotate (or will break the zip tie)? Or just go replacing wheel bearings and brake rotors willy-nilly? I hate the throw-parts-at-it solution, but not as much as the let-it-break solution.