How to measure pinion bearing preload?

[fwdjunky]

Ok, first of all I'm new to this forum so Hello to all! This place has been a gold mine of info for me and I've been lurking here for about 2 months now.

So here's my question. I have a late 99 F350 4WD crew cab short bed. The rear pinion seal is leaking and needs to be replaced. Following the rule of "search more, ask less" I have spent about an hour looking this up. I've found the used bearing preload range (8-15 inch pounds), but I can't figure for the life of me how to measure that with the carrier still installed. I've done ring and pinion installs, ARB air locker installs, but for some reason this is just not making sense. The only thing I can think to do is measure the torque required to spin the pinion before I pull the pinion nut and then match it when I install the new nut. Anyone have a better method? I hope I'm just having a stupid moment here and this is a lot more simple than I am making it.

Thanks!

Rich

[owtcast]

Ok, are you needing to know this value so you can get the correct pinion shims put back in there? You are correct on not being able to measure the preload with the carrier installed... unless there is some other set of values that take the friction of the carrier gear and bearings into consideration. It seems you could measure the preload shims and the thickness of the bearing, add them up and replace with new shims of the same size. After all, that is the way it was set up when new and everything was "fresh". I would definately contact a "rear-end specialists" to confirm though. I'm more of a "top end" kind of guy so take this with a grain of salt.

I'm guessing your diff. is like the Dana setups...

[owtcast]

I think I just realized what you were asking. You need to know how much torque to put on the new pinion nut?? right?

[fwdjunky]

[quote=owtcast;352574]Ok, are you needing to know this value so you can get the correct pinion shims put back in there? You are correct on not being able to measure the preload with the carrier installed... unless there is some other set of values that take the friction of the carrier gear and bearings into consideration. It seems you could measure the preload shims and the thickness of the bearing, add them up and replace with new shims of the same size. After all, that is the way it was set up when new and everything was "fresh". I would definately contact a "rear-end specialists" to confirm though. I'm more of a "top end" kind of guy so take this with a grain of salt.

The Sterling 10.5 uses a crush sleave to set the pinion preload instead of shims like a dana, so the amount of torque required on the pinion nut can vary. It's not like a dana set up where you use shims to set the preload and the torque on the nut is always the same value (175 ft/lbs for a D60 if I remember correctly). Anyway, I'm just pulling the pinion yoke and replacing the seal behind it and I can't figure how to measure the preload when I re-install the pinion nut. I'm thinking its going to end up being done by feel instead of by measurement and that has me a little worried. Thanks for the quick response, you pretty much confirmed what I was thinking, that there is really no way to do this correctly without pulling the carrier out.

[2KPSD]

First off I have never done a pinion seal on a ford. I used to work in a GM garage. But I have done them on many GMs and a coupld Jeeps.

On every one I have ever done I mark the nut, the pinion shaft, and the housing at the same point so when I tighten everything up, those lines match up. I also count the number of threads showing between the nut and the end of the pinion shaft and note if there is half of the thread showing or the whole thread. You will also notice you are getting close because when you reach that point, the nut will be very hard to turn by hand. I use impacts to remove and install if I don't have the yold holder and my breaker bar.

I know this isn't the 100% correct way to do it but I have never had one come back.

Just my $.02

[owtcast]

Travis makes a valid point. At least it will be back where it was to start with. I would probably go an extra 1/8th turn to compensate for wear, but that's just me. You are putting a new crush sleeve on it, right?

[sgleshot]

that is the correct used bearing preload. you will want to use a dial style inch pount torque wrench. now the key is that it is 15-18 inch pounds once the pinion is spinning, not the required effort to get the pinion moving. I'm attaching pics of what I use, I have setup many different rear ends. And just a word of caution, if you to the extra little pit of torque just to be sure you will wind up burning out the bearings. The bearings have seated in a certain way, if you put more torque on them than what is necessary you will wind up taking everything back apart to put new stuff in. The way I would do it is take a reading of the bearing pre-load before you pull the yoke off, keep in mind that that reading is without the differential in there. record your reading that you get before disassembly, then just match it within 2-3 inch pounds after re-assembled. there will be a touch more drag once the new seal is installed. When you go to re-install the pinion nut your going to wind up snugging it down little by little to be sure not to overload the setup.

[sgleshot]

Sorry forgot the pics of the wrench.

Attached Images

	wrench1.jpg (26.5 KB, 4 views)
	wrench2.jpg (39.8 KB, 4 views)

[fwdjunky]

Thanks for all the help guys. I kind of figured it was going to be a "put it back the way you found it" thing unless I pulled the carrier. I'm going to chance it and set it back as close to what it was before I took it apart. I know the RIGHT way to do it would be to pull the carrier and install a new crush sleave and then reset the preload with the inch pound torque wrench, but I have spoken to several people who have cheated and done fine. That probably means I'll be rebuilding the rear end nex month...