Pinion shaft bearing torque

T

Tubby

Senior Member
I am now set to reassemble my 39 differential. I have done a lot info gathering and have found differing requirements for the pinion shaft bearing torque requirement. The 39/40 Engine and Chassis Repair manual says use 15lbs (but this setting might be unique to the tool that is being used). Vern Tardel's Banjo-Differential book says to use 15 foot pounds. Many of the post here and on that HAMB say 15 inch pounds.
My guess is that 15 inch pounds sounds correct, anyone care to comment? By the way, is this measurement taken with a unlubricated bearing, with diff oil, or grease?
 
The hi-tech method I use is to assemble the pinion etc into the housing. Mount the pinion in a vice vertically with the pinion sticking up above vice. Using both hands, one each side of the banjo, spin the banjo as hard and fast as you can. It should only rotate between 1/2 to one full turn.
 
None of the Ford pinion bearing adjustments are in Ft/Lb. All are inch/Lb. The Ford Spec. calls for 12-17"/#. Ford Spec Dec. 29, 1939 page S-4000.
You do not have to add lube to the bearing while adjusting but if you wish go ahead it should not effect the adjustment very much. It may make it smoother and messier to handle after lubing. Take your measurement while the bearing is turning. It may take slightly more torque to get it to start moving.
 
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As a side note, I did the same job recently and was happy with the tightening method I used to lock the two nuts together. I then acquired two open end wrenches the right size and ground one down to fit the inner nut. I was surprised at how far the outer nut turned once a proper torque was able to be applied. The preload then ended up higher than I wanted, so had to loosen both nuts slightly, and retighten fully and recheck the preload.

Just something to watch out for.

Mart.
 
I use light oil on the bearing surfaces during pre-load adjustments. 3 in 1 is good. I don't think I would go over 15 In/Lb for pre-load on new bearings.
 
I always use at least some light oil on the pinion bearings before setting preload. I would not want to set PL torque on dry tapered roller bearings.
 
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Here are all the '28-48 numbers from various ages of service bulletin. Note that the '28-32 numbers were changed in later bulletins! I got tired of looking this stuff up and got it all together. Good instructions on overhaul were in the Bulletins 1933 and 1938. There were also Model A instructions, but those bulletins are out on loan right now. Ford introduced the tool for measuring pinion bearing torque during 1934.

Pinion bearing torque: Model A-B type rear, 1928-1932, originally 35—47 inch pounds, later spec for A-B 15-20, Model 18 type 1932-1934, 20-25 inch pounds, 12-16 later rear 1935-1948 spec!
 
It's as if they were more concerned about pre-load on the pinions that didn't have tip bearing support. Once they redesigned for the pinion shaft tip support bearing, they didn't need to worry as much about the pre-load.

When those first Mercury cars came out in 1939, they were worried about the drive shaft to pinion spline coupler so they did away with it. It didn't take them long to bring it back though. I bet the mechanics cussed them for that. Setting up pre-load with that long shaft would have been a b!tch.
 
And...Ford stopped servicing the one-piece units, and sold Ford R&P's with a special length driveshaft as a kit for the '39-40 Mercs that could not be serviced with a standard Ford shaft. Parts men must have been complaining about those things sticking out og the R&P shelf...
 
I reassembled a '48 rear with an aftermarket ring and pinion set. I didn't realize it at the time, but both the inner AND outer bearings were a press fit onto the pinion. The outer bearing is supposed to be a SLIP fit on the pinion. With it being a press fit, I would tighten the nut and the preload would be too light. I'd tighten it a bit more and the outer bearing would "jump" a bit, making the preload too tight. I finally got it right but it took some doing. I should have used some wet / dry paper to take a bit off the outer half of the pinion shaft so that the outer bearing could have been tightened in a controlled manner.
 
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PeteVS said:
I reassembled a '48 rear with an aftermarket ring and pinion set. I didn't realized it at the time, but both the inner AND outer bearings were a press fit onto the pinion. The outer bearing is supposed to be a SLIP fit on the pinion. With it being a press fit, I would tighten the nut and the preload would be too light. I'd tighten it a bit more and the outer bearing would "jump" a bit, making the preload too tight. I finally got it right but it took some doing. I should have used some wet / dry paper to take a bit off the outer half of the pinion shaft so that the outer bearing could have been tightened in a controlled manner.
Click to expand...

I've ran into this also. I always use some Emory cloth and polish the outer half of the pinion and the bearing inner surface. I've have some military surplus bearings that were stamped with a "P" indicating that bearing goes to the pinion side.
 
I seen in the October 1936 Service Bulletins
Ford designated the use of bearings stamped "P"
to be used next to the drive pinion.
Same bearing numbers 48-4621 just one has the P
and the ones that don't to be used on the forward end of the pinion gear.
 
PeteVS said:
I reassembled a '48 rear with an aftermarket ring and pinion set. I didn't realize it at the time, but both the inner AND outer bearings were a press fit onto the pinion. The outer bearing is supposed to be a SLIP fit on the pinion. With it being a press fit, I would tighten the nut and the preload would be too light. I'd tighten it a bit more and the outer bearing would "jump" a bit, making the preload too tight. I finally got it right but it took some doing. I should have used some wet / dry paper to take a bit off the outer half of the pinion shaft so that the outer bearing could have been tightened in a controlled manner.
Click to expand...

This was a characteristic of the Italian made R&P sets. I have one of these sets too and it is way to tight. They should be a zero fit where it can be driven on without a lot of force but tight enough that the inner race will have no play.
 
You tighten the big nut until you can turn the gear with a rag on the teeth
but can not turn it with your bare hand. G.M.
 
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