BillB 2/23/00 - 8:54:20 AM
Rear end bearings
I'm replacing the tapered bearings and races that the rear axle housings suspend on each side of the the ring gear. Any suggestions on what and how to set the bearing preload other than by braille? I've ordered a gasket set that has a few different thicknesses of ring housing gaskets and would think little or no end play would be correct. Anything more exact would be appreciated.

mr bill: 2/23/00 - 10:46:09 AM
RE: Rear end bearings
These are the instructions that I have from my repair book for a pre '49 rear end.

"Bolt the right axle housing to the differential housing using an .008" to .010" housing gasket. Install differential and axle assembly into the left axle housing, and assemble this to the differential housing using the same thickness gasket.

Two people are required to check the preload on differential bearings which should be performed at this stage. Each must grasp an axle shaft and turn it in the same direction and at the same speed. If carrier bearings are correctly adjusted a heavy drag will be felt. If drag is only light (there will always be some drag because of the preload on the pinion bearings), separate the right axle housing from the differential housing and change the gasket to a thinner one (.004" to .005"). Recheck as before.

After carrier bearings are checked, the backlash between the ring gear and pinion should be checked.Mount a dial indicator so that the movement of the splines of the pinion shaft can be measured. Rotate pinion shaft back and forth and observe indicator. Backlash should be .003" to .008". If it is less than .003", place a thicker gasket between the left axle housing and the differential housing, and if more than .008", use a thinner gasket at the same joint. Note: In order to preserve the differential carrier bearing adjustment, whatever gasket thickness is added at the left housing joint, the same amount must be removed from the right housing joint, likewise, if gasket thickness is reduced at the left housing joint, it must be increased at the right housing joint by the same amount."

Hope this helps, Have fun. mr bill

JWL: 2/23/00 - 10:50:56 AM
RE: Rear end bearings
Yes, there must be preload on the tapered bearings. The normal practice is no less than .002 and no more than .004. Be certain you are rotating both axles when ''feeling'' the preload.


An addendum from Bob Hall:: 2/05/02

Subject: Setting up pre-49 Carrier Bearing Preload

The reason for the following 'offering' is because I feel that carrier preload cannot be adequately set, or 'felt', with the 'other' procedure. I do not mean to imply that the 'other' way will not work. I am simply suggesting that carrier bearing preload might be set first, and in a manner consistent with trade practice for ANY bearing setup, allowing intimate 'feel', or even 'measured' preload. When I refer to the 'other' method, I am referring to the method where TWO people are required to rotate the axles at the same time, and feel carrier preload, combined (and masked) with pinion preload, gear drag, and perhaps axle drag.

I do not take credit for this procedure, as I have obtained this information from professional rebuilders. It's being passed on, as info only.

Some EFV8 repairmen charge a substantial amount to set up a rear-end. One reason is that it takes a fair amount of time, following this procedure. The trade-off, and benefit, of this procedure, is that you will have confidence that carrier bearing preload is correct.

The bottom line, and the short version, is to set the carrier bearing preload FIRST, without being distracted by any other parts in the assembly. Here's how:

Determine the banjo gasket-pack, FIRST. You can use the actual banjo center, or another spare (empty) banjo center, for gasket selection. With the banjo center empty (no pinion), assemble the carrier and ring gear, and two axle housings (the actual ones you will use). No axles are installed at this point. Support the axle housing vertically. Install the 'top' axle housing with an assortment of gaskets. All the gaskets can go to one side, for this 'gasket-selection'. I prefer to do this 'fat', meaning, with enough gaskets for the carrier to be loose. If desired, rig a way to read carrier looseness with a dial indicator. If working by hand (no indicator), feel looseness of carrier (through pinion hole, touching the ring gear). Remove gaskets, until all looseness is gone, and the specified preload is established. At this point, you will be able to rotate the ring gear with your fingers (through the pinion hole), and feel the actual carrier preload (without being masked, as with the 'other' assembly technique). You can even apply a 'fish-scale', with a string, fish line, or light wire, through the pinion hole, hooked to a ring gear tooth, if you wish to use the procedure outlined in many rear axle assembly manuals. With practice, this is unnecessary, but might be useful for a novice.

An alternate method to that described in the previous paragraph: With axle housings vertical, carrier in place, bottom housing securely bolted, NO gaskets in place, and top axle housing resting on carrier bearing, there should be a gap between the top axle housing and the banjo center. Rotate the top axle housing a little to verify the bearings are seated and centered. With a feeler gauge, measure the gap between the top axle housing and the banjo. Look at your gasket selection, and make a determination of how compressible you think the material is, and how much preload you are trying to set. You might measure .010 gap, guess at .003 compressibility, trade it for .003 preload, and assume your measurement is low by .002. So, for a first try, you might install a total of .012 of gaskets. On a good and lucky day, you could guess the preload correctly on the first try.

The steps of the preceding paragraph will only work if one of the axle housings is loose enough in the banjo to allow a little 'wiggle-room'. While doing this, note that the housings may be installed in ANY position, left-to-right, or top-to-bottom. Eliminate any burrs and dings on the locating lip, and look for a 'loose' position of at least one axle housing.

If you used a 'substitute' banjo center for this gasket pack determination, now measure the width of your ACTUAL banjo center, and the width of your 'substitute' banjo center. Compensate for the difference by changing your gasket-pack accordingly. For example, if your actual banjo width is 3.503, and your 'substitute' (set-up) banjo width is 3.508 inches wide, then you need to make up this difference (.005) when you assemble to your actual banjo center. In this case, add .005 more to the gasket-pack, for your actual assembly. (I have observed nominal banjo widths of 3.5 (early), and 3.8 inches.)

For the remainder of the assembly, follow the 'other' procedure. Install pinion, split the gaskets on the banjo, see where you are for backlash, then adjust accordingly. Obviously, this is accomplished by switching gaskets from side-to-side, keeping your total gasket-pack constant. With practice, you should often nail this on the first or second try. And, it's ok to use the other common 'tools', or methods, for setting up rear ends. If there is any doubt about the bearings or races being 'seated', it never hurts to 'pull' a little on the axle housing, with no gaskets, when you are at the appropriate step, mentioned three (and four) paragraphs back. I recommend patterning, and would adjust the pattern, no matter what. When all is 'right', the backlash should be 'on', too.

Other service manual data that might be useful: Use a .008-to-.010-inch gasket on the right side, for your first 'trial' assembly. Pinion bearing preload is adjusted for 20-25 pound-inch drag. Backlash should be .003-to-.008-inch. My experience has been that the right-side gasket often needs to be reduced to .004-.005 (while adjusting backlash).

Happy 'differentialling'. With a little care, you should have excellent results.

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