Rear Axle Hub Torque '31 Series 60

[Pat_n_Pat]

Does anyone have the torque specs for the rear axle hub nut for a 1931 Series 60? I marked the nuts when I removed them. Taking them back to the same point gives me about 120 ft lbs. That seems a little low to me, but I definitely do not want to overtighten and crack a hub.

Pat:confused:

[Mark Shaw]

Pat,

My 31 Buick Specs and Adjustments booklet shows no torques for the axle nut. My Dykes only says to "tighten up well on the nut" and "lock it with a cotter pin".

I suggest you use a 12" wrench to tighten it to the nearest slot that will allow the cotter pin to lock it in place. Then wiggle the wheel to check for wobble. The rear wheels should have full contact with the axle taper and should not wobble.

My 2 cents...

[Pat_n_Pat]

Hi Mark:

My manual and Dykes say the same......no torque spec for the rear. 120 ft lbs seems OK on the rear after having checked with some old-school mechanics. I would rather err on the "not tight enough" side because these drums are just not available!

Pat

[Bob Engle]

I have seen 4 different instances where the rear axle and hub were damaged from a loose fit. Two occasions, the key was completely worn down and the drum spun on the axle. The keyways on the drum and axle were damaged. New keyways were cut on the drum and axle 90 degress from the damaged keyways and the tapers had to be cleaned up. The other two had key and keyway damage, but not worn through. Oversized keys were installed in these two applications. A worn taper shaft or drum will let the drum seat too far and cause seal and backing plate rubbing. Replacement or major weld and recut parts is required to correct this problem.

Bob

I use prussian blue to check the contact on the taper at a hand fit pressure. I check the key for a tight slip fit on the shaft and drum. Replace if the key is loose. I then assemble and torque to 80 90 ft-lb. The taper is slight and will generate a lot of force.

[Mark Shaw]

I can add one more thing to check...

Make sure the key fits the full length of the keyway slot. Mine broke because the key did not get installed correctly. Without the key all the way in the slot, the inside end of the slot became the weak point.

[Pat_n_Pat]

Thanks Bob and Mark:

Bob, I always use Prussian blue to check the fit on tapered shafts; and both rear hubs check out fine.

I agree that the taper compounds the force tying the axle to the hub. The key is only there for alignment and should really not take any of the torque transmitted to the wheels (If it was designed to take torque it would be a splined shaft). A worn or “wallowed” key/slot would indicate to me that the hub nut was not tight enough and the key was taking brunt of the force.

80-90 ft lbs sounds very low to me. My ’35 Cad (which has a 1” thread instead of the Buick’s 7/8”) calls for 285-315 ft lbs. My Ford Service Bulletin says Henry lowered the torque to a minimum of 220 ft lbs. All Chrysler products called for a minimum of 142 ft lbs. While I don’t have my Packard manual handy, I believe it calls for a minimum of 140 ft lbs.

By my calculations, a stock Buick Series 60 would put almost 2,700 ft lbs of torque on the axle/hub connection. In the Great Race we will put full torque to the rear axle about 100 times a day from a dead stop. That is why I am very concerned that I torque to the designed setting.

Was there ever a published torque setting, possibly in a service manual?

Pat

[buick32]

Does anyone have the torque specs for the rear axle hub nut for a 1931 Series 60? I marked the nuts when I removed them. Taking them back to the same point gives me about 120 ft lbs. That seems a little low to me, but I definitely do not want to overtighten and crack a hub.

Pat:confused:

Buick made no torque specs until sometime in the late 1930's They relied instead on the length of the wrench to apply the proper torque using the strength of the knowledgeable workman as the guide to proper torque. That being said, the outer bearing is not an issue. The drum is on the axle with a taper fit which you do not want too loose, as movement will wollow out the drum, I don't know anyone who is man enough to get it too tight with an ordinary wrench. As a result, the drums are a real bear to remove, even with a puller. Next, you should consider the differential side bearings. The original ones were ball bearings, but ball bearings are not good at handling axial loads, and they often seized and ruined the housing. In about 1934 they ceased to use ball bearings, replacing them with tapered roller bearings which do handle the load. A word to the wise? The nut is locked with a star washer to retain it with no lash once it is tight.

[Pat_n_Pat]

Buick 32:

Thanks for the info. So that is why we cannot find any torque specs. I am very used to pulling drums on tapered shafts. Not too bad if you have the right tools. Will the tapered rollers fit in the earlier axle? I have the tab washers to lock the nut. Do you know of a source for those tab washers? Bending the tabs tends to weaken them, and I would like to use new ones.

I think I will torque to 120, run it for a while (if it ever stops raining) and then re-torque. We have to get the car out to develop performance tables for the Great Race.

Pat