Rear Axle (Worm) Issues

[HKDude]

I’m experiencing a problem with my rear axle; it’s a 29 worm. I finally got my front end together and put tires on it to roll it into the driveway. Worked great (going forward) and I was very happy. However, when I tried to push it back into the garage, the rear wheels locked up and it wouldn’t roll. I was very unhappy.

Upon further review, it appears the worm shaft doesn’t line up when I install the roller & thrust ball bearing and the cap. The reason I say this is because without the cap or bearings installed, I can push on the worm with the palm of my hand and the truck will roll backwards. The problem appears to be the roller bearing… With just the thrust bearing it seems to work with the cap installed.

I have two questions. First, how much gap should there be between the axle housing and the thrust ball bearing? See attached picture because there seems to be a large gap there. My thinking is a smaller gap there would decrease the amount of side to side travel the worm has and eliminate my issue.

The second question is in regards to the thrust bearing nut and collar. What purpose do they have besides hold the thrust ball bearing on? As you can see from the next picture, the bearing rides on the shoulder and the collar butts up to it. It doesn’t matter how tight that nut is, it isn’t going to affect the play of that bearing. The reason for this question is that I don’t see how tightening that nut will affect the main issue I’m having when I try to roll the truck backwards.

Any advice or ideas? I’m really going to want to use reverse occasionally.

-mike

[tiredtruckrestorer]

Hello Mike,

Since no one else made any suggestions as what may be your problem, I thought maybe I could offer a few suggestions. In the May 1929 Service Bulletins they describe how to check the squareness of the rear face of the axle housing by installing a dial indicator to the worm shaft, jacking up one wheel, rotating the wheel forward, and checking that the runout is no more than .010". Position the dial indicator to ride on the housing between the bolt holes and the inner edge. Also lay the rear cover plate on a surface plate and check for squareness. If it rocks on the surface plate, replace the cover plate. Did you use a gasket on the rear cover? Installing cover without one may have put more pressure on thrust bearing. Check that the bearing didn't wear into the back cover plate. In May 1929 a new hardened cover plate was introduced to help solve this problem. Also at this time, Ford must have had a problem with the 10 ball thrust bearing supplied by Gurney. These were replaced with a 9 ball Gurney or a 10 ball Federal bearing. I did't have time to pull out any bearings, but often thrust bearings are marked as to which is the thrust side. If installed backwards, they may not function as intended. Hope this may help, Keith.

[1oldman57]

I don't know if you have solved your problem yet, but to take out the gap around the worm thrust bearing collar on my truck, a prior owner used shims. I am sending a picture of the shims that were in my December 28 AA. This method may not be stock but it isn't expensive.
Hope this helps you.
Tim
Mt. Pleasant, MI

[Shorthaul]

I'm going along with Tired TR on the gasket or flatness of the cap, bearing placed in backward if possible. That shoulder holds the outer race from moving, but the cap may be loading up pressure on the inner race and when the lash in the bevel gear is taken up in reverse it applies side load the bearing and it won't roll under pushing power. Probably would under 40 HP in reverse, that wouldn't be a good thing though.

[SHELBY MESSER]

Mike, You may or may not have a problem with bearings and adjustments. You have a rack and pinion rear axle assy. right? Almost impossible to push by hand. Here is what I would do! With engine in truck drive line attached. Pull all 4 spark plugs (if engine turns), put the transmission in reverse. With the hand crank or starter spin or turn the engine, do not mash the clutch. The hand crank would be best as you could tell how mush pressure are using to move the truck backward. This is what I think you should first! Hope this helps solve your problem. Seems I've heard others with this same issue! Shelby, Louisiana.