Rear Axle: Timken 51540

The visible 'chip' in the pinion gear occured when the Rear Pinion Bearing swarmed on my Dad in the late 1950's or early 1960's. He replaced the bearing at that time but the end of the pinion shaft was damaged so he did not realize that there was supposed to be a snap ring there to hold the bearing race in place. Amazingly, it ran with no problems from the time he replaced the bearing until I parked the truck in the late 1980's. The race was still in place when I disassembled the axle in 1999.

It took Fort Worth Gear & Axle a bit longer to complete the rebuild on the rear axle than it did on the front. The biggest problem was that the ring and pinion gear set needed replacing. The used sets that FWGA and I came up with were not worth using and the normal channels that I had checked with said new sets were unavailable.

FWGA found a guy in Canada who had three NOS sets - but no rivets to install the ring gear. After talking with me, they tried Rockwell to see if they could get the rivets (Rockwell bought out Timken). Rockwell had the rivets and shipped them to FWGA. They then called the guy back in Canada to order a gear set only to find out he had already sold all of them. He promised that he could find another set and did so.

The only part that FWGA did not find is the double-race for the two front pinion bearings (the Timken has a total of three pinion bearings.) They thought that my race was in good shape and were not concerned about not replacing it. All other bearings were replaced.

FWGA's recommendation on gear oil surprised me on both of the axles. They recommended 85W140, which is what I put in. They claim that 80W90 is much too thin for the summers in the southern part of the country.

The rear axle was painted with POR-15 before installing. While painting I discovered that one of the spring perches had the hole for the spring pin worn oversized. After thinking about it and seeking advice from members of WillysTech I decided to leave well enough alone and not try to 'fix' it. If I had noticed the problem before having the axle rebuilt I probably would have had a shop weld it up and re-drill the hole.

I was concerned about installing the axle because my normal Willys parts sources said they did not have the u-bolts to mount the Timken to the springs. I found a perfect match at the local O'Reilly Auto Parts Store in the Motomite Help! line. The Help! part number is 35624 and the dimensions as listed on the package are 1/2"x8"x3-1/16", Round.

January 5, 2001 Installed the rear brake backing plate assemblies today which required adjusting the rear axle bearings. The bearing on the Timken axle is adjusted by adding/removing shims between the axle housing and the retaining flange to obtain an endplay between .003" and .007". You will have to bend the Principle of Merl ("Never pound on the threaded end of anything.") slightly because the axle bearings need to be 'seated' to get an accurate reading using a dial indicator. I used a rubber mallet. You will need to tap the left shaft to seat the right bearing, and tap the right shaft to seat the left bearing. You can then take your measurement. If there is not enough endplay you need to add one or more shims; if too much you will need to remove shim(s). On the Timken, you can place all of the shims on one side instead of 'balancing' them between the two sides as in the Spicer 53. Some people will adjust the bearings 'tight' and then coat the shims with a sealant (copper-coat or something similar). The sealant will add a small amount of thickness and increase endplay slightly. I did not do this since I have not had problems with grease leaking past the shims in the few axles I have done.

NOTE: According to Carl Walck (Walck's 4WD) and Paul Barry (Willys America) shims are no longer available for the Timken (and Spicer 53) axle. You can, however, use the Dana 44 shims if you modify them since the 44 uses smaller axle bearings. Walck's suggestion was to remove the axle shaft, place a rag in the housing, install the shims, and use a die grinder to make the hole in the shim match the housing. Paul Barry's suggestion was to use a 'penny cutter' to cut the hole larger. I didn't want to remove the axle shaft so I used a pair of compound-action cutters - be warned, however, your hand will get a workout on the thicker shims this way. If you use the cutter method, double check that the hole is large enough to fit over the bearing race in the axle housing. If it's not, your endplay measurement will not be accurate.

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Copyright © 2000 David Hoelzeman
Last Updated: June 19, 2002