Setting carrier bearing preload [diff] ?

[Talkwrench]

Can some give me a starting point? I'm about to start the first step of re-assembly of my 37 -40 diff. when putting the "carrier" set in how many gaskets should I start with and is it best to add or remove from just one side [which?] also do I just lightly oil the bearings too?

 

[37fordtruckguy]

It been a coupe of years since I did mine. Though you should start with the driver side first, that will changing the pinion and ring gear lash with the correct size gasket. Thats why they usually give you more than one. Then move to the Passenger side, having different thickness of gaskets is what changes the drag. Depending on how much drag and clearance is needed you may need to use more than one gasket to achieve the proper clearance.

 

[NormC]

When I rebuilt my Banjo, I used Timken bearings. I did not measure these before installation assuming that they would be the exact height as original, but I would have to say they where not. Recalling from memory, my total stack of shims was around .030 to .032, which was greater than factory specifications. I assembled the carrier and both bells without the banjo installed and took an average of the span between the bells at the bolt flanges, X dimension. Then measured the thickness of the banjo between the bell mating surfaces, Y dimension. X-Y=Shim thickness. I reduced that amount by .002. I started with the shims as equal as possible for both sides of the bells(50% each side). I used a piece of rope with knots placed in the spider gears to lock them up for the torque check. Reassemble with the banjo installed, heavy on the oil on the bearings and races. A socket on the axle nut with a dial torque wrench will let check the pre-load on the bearings, from memory, 12-15 in lbs of torque to spin. adjust the shims from one side to the other to achieve the desired torque. Good Luck. You will assemble and take apart and reassemble many times.

 

[Binx]

This is a good how-to but the photo are missing...

http://www.jalopyjournal.com/forum/threads/chassis-assembling-a-40-ford-rear-axle.61502/

Lonnie

 

[Talkwrench]

It didnt work Lonnie , but I think I've seen what you where trying to post.
Anyhoo, I followed the ' Endy' instructions written for an A model but roughly the same. I used no gaskets to the right side and just selected three varying thickness gaskets and I nailed it first time.
Next pinion preload.... May just ask on another post.

 

[Bob C]

This link is to a good article on rebuilding a Model A rear
axle but most of the information should apply to yours.
http://www.ocmafc.org/techarticles/Tom Endy's Special Topics/Differential Seminar - Re-Edited.pdf

Bob

 

[supereal]

The "preload" refers to the pinion. We used a KRW scale "back in the day". Now I set the pinion up for a heavy drag, but not enough to prevent turning the pinion by hand. The setting of the ring gear is to provide the correct gear mesh, not preload. To do it correctly, you need good instructions.

 

[PeteVS]

I did one a couple of years ago, and as I recall, I did it in three steps. First, using a bare banjo casting, I found the total amount of gaskets necessary to get proper preload on the carrier bearings. Second, I set the pinion preload. Third, I assembled the carrier assembly and axle housings to the banjo and found how the gaskets from the first step had to be distributed, left and right, to get the proper ring and pinion backlash.

PS: Forgot to mention that I was assembling with new repro gears. The pinion has two bearings, the inner and outer. The inner gear gets pressed on. The outer gear should be a "tight slip fit" but the pinion shaft was machined the same diameter full length. Thus, when I was setting the pinion preload, it would be loose. I would tighten the nut a bit without any movement of the bearing. I'd then tighten a bit more, no movement. Then, I'd go a bit more and the bearing would jump making the preload too tight. I did it over and over before I got it right. I should have taken a tiny bit off the outer half of the pinion shaft. That would have made it a lot easier.

 

[Brian]

PeteVS's method is the way to go; to set the pinion preload, assemble pinion assembly into banjo, hold splined end of pinion upright in a vice and spin the banjo as hard and as fast as you can. It will do less than one revolution when preload is correct.