MTFCA Forum

I see many posts regarding tight rear wheels, but my rear wheel almost dropped off when I removed the nut. How tight should the hub fit on the axle, and when do I know if shims are needed?

That question aside, I think I may need a new axle anyway, as it has .055" up & down play and the outer bearing is only about .003 undersized.

Shims are not usually needed unless you have the extra drums for Rocky Mountain brakes which pushes the inner parking brake hub closer to the backing plate. I tighten the nuts to 100 ft lbs. Usually stop at about 98 ft lbs and then tighten just enough to install the cotter pin. However if the taper is worn on either or both the axle or the hub, it might need some replacement parts. Another thing to check is the slop for the key in the axle. If it has been running loose for a period of time sometimes the axle will crack and then also needs to be replaced.
Norm

Hows you key & keyway or pin?

The key seems OK at 1/4", but it is loose in the keyway (which has no obvious damage). I haven't checked the 1-1/16" measurement on the axle, but I can feel wear with my finger. I think most of the slop is in the axle.

mortier wrote: ↑

Fri Apr 19, 2024 8:48 pm

That question aside, I think I may need a new axle anyway, as it has .055" up & down play and the outer bearing is only about .003 undersized.

You need a new axle.

What is the condition of the bearing sleeve? It could also be adding significantly to your up & down play.

A shim is needed if the wheel, when tight on the axle, goes on far enough to cause interference with the brake shoes/springs/perch nut etc. If this is the case, fitting ONE shim will help space the wheel out away from the backing plate somewhat. If that does not work, ONE thicker shim may do the trick. Multiple shims should be avoided. However, if a new key is still loose in the axle or hub keyway, they too need replacing.

The beauty of safety hubs is wear in the bearings/axle are of no consequence. The worn sleeve is removed. The worn bearing is discarded. The worn axle stays there and now carries no load, so a worn bearing journal is of no consequence. A big plus is that the rear axle assembly doesn't have to be removed from the car or disassembled.

Hope this helps,
Allan from down under.

mortier wrote: ↑

Sat Apr 20, 2024 7:45 am

The key seems OK at 1/4", but it is loose in the keyway (which has no obvious damage). I haven't checked the 1-1/16" measurement on the axle, but I can feel wear with my finger. I think most of the slop is in the axle.

Did you check the keyway in the hub for fit or only in the axle?

Loose wheels are the most common cause of rear axle damage / failure. On cars I've worked on about 8 out of 10 have needed new axles. Cracked or wallowed-out keyways, deep scoring from the hyatt bearings, worn tapers, etc.

When inspecting a club member's car I frequently find the rear axle nut loose. It is important that you initially torque it to around 80-90 ft-lbs and then after 100 miles or so, check it again. You may be surprised to find you can get some movement out of the nut (like one castellation.) I check mine each spring before touring season.

I strongly recommend you consider installing floating safety hubs. They transfer much of the load from the axle to the axle tube, and replace the outer hyatt bearing and seals. They require no service and as an added bonus, won't let your wheel fall off in the unlikely event that your axle breaks. The new axles are about 1/16 inch longer which helps with clearances.

The attached photo was taken at the shop of a well-known Michigan antique car restorer. He tries to do a bunch of Model T rear ends at the same time (like an assembly line) and these are axles that needed replacement (and a few new ones). Two of my friends have axles in that pile. The gears are a particular PITA to remove and install. He modified a hydraulic press to make the job a little easier.

Thanks for the tips. The safety hubs seem like a good idea. The axle nuts were finger-tight only.
The last moron that worked on the rear axle put the oil seals in wrong. One side had the steel washer outside the axle housing cap, and no felt washers in either axle. I'm also thinking the inner oil seals are missing, as I can't feel them. How deep are they in the axle tubes?

Research answered my question. The outer axle seal rests against the rear of the axle sleeve, so it's located when the sleeve is installed. I'll use a little Permatex on it, as suggested. I didn't know where they were located because they were missing on my car. No wonder there was almost no oil in the differential. The car had no seals at all!

Missing seals wouldn't be the cause of no rear axle lube - it can migrate out towards along the axles out towards the wheels but doubt it would be the cause to empty it - most all them drip from the center !

Phillip - Finger tight? Oh my! I wonder how many reading this also have loose rear axle nuts..... I'm sure there's a few.

A new Model T owner friend of mine was driving a busy (six lane) city street last fall when one of his wheels fell off. We think the nut was tightened, at least somewhat, but the cotter key was overlooked.

Normally very little differential lube would migrate out the axle tubes. Sometimes engine oil makes it's way down the driveshaft, fills the differential and runs out the tubes. Oil on the wheel hubs is a sign this is happening. Modern neoprene axle seals work better but can still let some oil by.