Pinion bearing preload is a no-go

[SquareRoot]

Replacing all seals in the 14 bolt ff today. Since I'm not replacing the gears or anything (except that obnoxious Detroit locker) I'm reusing what's currently there. Before I took the yoke off I marked it's alignment and used my inch pound beam torque wrench to check the pinion preload. Ha, it's ZERO! It's tight, smooth and no play but there's no bearing drag. I'm guessing the gearset takes a set over time and the pre-load goes away as things wear in?

So the question is, do I put it back to zero with no slop or add a few inch pounds?

 

[Mr Clean]

Man that is a great question. I have been doing a bunch of reading on the 14 bolt, Since I'm completely rebuilding mine. Every thing I have read says pinion preload should be around 25 inch pounds, give or take a pound either way. Having zero, I don't think is good. Sounds like you don't have a crush sleeve.

 

[CalSgt]

I'm guessing the gearset takes a set over time and the pre-load goes away as things wear in?

So the question is, do I put it back to zero with no slop or add a few inch pounds?

My dad and I were talking about this the other day, he said it seemed like anything with some miles on it would almost always be at zero. I think you are right about the bearing sets wearing in together. I would reassemble at a just few inch pounds if reusing the crush collar or set to spec if using a new one.

 

[Turbo4whl]

^^^ What Casey said, just a few in-lbs on used bearings.

 

[Mr Clean]

@CalSgt makes a good point, everything I have been reading is on setting pinion preload, with new bearings. Might ask @Vbb199 he seems very knowledgeable on rear ends.

 

[Mr Clean]

^^^ What Casey said, just a few in-lbs on used bearings.

Wouldn't you get a couple of inch lbs just from the new seal?

 

[CalSgt]

Wouldn't you get a couple of inch lbs just from the new seal?

I suppose its possible but not that I have noticed in that last few I've assembled.

 

[Mr Clean]

I suppose its possible but not that I have noticed in that last few I've assembled.

The only reason I asked that, is all the info I have read, and videos watched. It all said to set pre-load around 23-24 inch lbs with out the seal, and you'll end up with 25-26 inch lbs after installing the seal. I'm strictly going on what I have read, I have never rebuild a rear end. My 14 bolt is my first. Hell right know I'm reading about pinion angle and what shims I'm going to need...Lots of info for Jeeps, not much for our trucks...

 

[SquareRoot]

Good points. I think I'll screw the nut on 14.5 turns and line up my punch marks. I'll check pre-load and should see some difference from the new seal. Then I'll add 5 inch pounds and call it good.

 

[SquareRoot]

Wouldn't you get a couple of inch lbs just from the new seal?

Yes, but that wouldn't count towards bearing preload.

 

[Turbo4whl]

@CalSgt makes a good point, everything I have been reading is on setting pinion preload, with new bearings. Might ask @Vbb199 he seems very knowledgeable on rear ends.

Hey Shawn, I have some experience on spiral bevel gears. Many different brands and sizes. The one thing they all have in common, new bearing and races get one preload spec and used, (run in bearings) get less preload.

I did not throw out a preload number because this lower spec will be in any good repair manual, like a factory manual. Directions that may be with aftermarket parts you buy are always assuming you are assembling all new parts.

If you want a ballpark number, run in bearings, 1/3 the new bearing preload.

 

[Vbb199]

A 14b ff is to have
25-45 in/lb on new bearings
10-20 in/lb on old bearings
.003-.010 gearlash
175 ft lbs on ring gear bolts
150 ft lbs on bearing caps

A seal adds little to no drag, if anything an inch or two preload drag. I setup my axle BEFORE I put the seal in and lightly oil the bearings, so when I'm torque the pinion back down, I'm not having to factor in the withs and withouts

Second, i hope you aren't reusing the crush sleeve ?

Now that you've removed the pinion, youll need a new one, and now that you need a new one, that dotted marking will now be semi accurate.

Last time a 14b ff crush sleeve was torqued, it took putting the axle itself down on the ground, with a big ass breaker bar to smash it


Unlike a lighter duty axle like a 10 bolt, you can hit the crush sleeve torque with an impact and trigger bump it into spec, check, bump, check.
You can watch it move in 1-2 in/lbs each time

Oh, and if you overshoot the preload with a new crush sleeve, you can't back it off and start over. Sleeve is ruined.

 

[Vbb199]

Oh I noticed you said you'd be dropping the Detroit.

Remember after you change carriers you will need to reset your gear lash if anything.

Pinion depth shouldn't need changed unless the carrier journal's are like way out of concentricity to the ring gear

I'm anal and check everything on my setup.
Carrier thrust , concentricity, flatness of the gear face in relation to the bearing axis... yea

 

[Mr Clean]

Hey Shawn, I have some experience on spiral bevel gears. Many different brands and sizes. The one thing they all have in common, new bearing and races get one preload spec and used, (run in bearings) get less preload.

I did not throw out a preload number because this lower spec will be in any good repair manual, like a factory manual. Directions that may be with aftermarket parts you buy are always assuming you are assembling all new parts.

If you want a ballpark number, run in bearings, 1/3 the new bearing preload.

Wayne, I didn't mean to exclude you, I don't know what you do for a living, or what you have done. I only mentioned Vince because he has be posting pics and talking about rear ends. I have learned a few things from his posts, of what to do, and what not to do...LOL

I have never rebuilt a rear end, changing oil in one was as far as my knowledge went. Until I started rebuilding the 14 bolt I'm currently working on. I do believe it was you that told me about the Speedi Sleeve. Once I get my brake line tabs welded on, hopefully the rear end will get finished. I now have all the tools...(I think) to finish it up. I'm sure I'll have more questions. I have been posting in my build thread on all my updates. Just seems pointless to post in a bunch of different threads. No one really seemed to know about Torq lockers, by the lack of answers I got...LOL. So I'll be the guinea pig and let everyone know.

 

[SquareRoot]

@Vbb199

Yup, reusing the existing crush sleeve. Not breaking the pinion carrier down just to change the seal. I can't logically understand why the sleeve would need changed if all you're doing is pulling the yoke off and putting it back on to the exact same torque. And changing the locker for open gears doesn't affect the backlash if you put it back to the exact same setting. In the future when I get around to putting in an air locker or LS, I'll use a cruse sleeve eliminator kit and check all the silly stuff.