What torque? Rear brake nut 1 13/16"

[Tom Magdaleno]

I always try to be safe, I keep a fire extinguisher on the passenger floorboard and the battery shutoff is on the floorboard as well.  I have the ebrake adjusted properly etc, but yesterday I think I screwed up and could have wrecked my car.

I went to a car show up the coast in Carpenteria.  It was about a 40 minute drive and after I got off the freeway I heard a nut clanging around in my hubcap.  I parked and pulled off the hubcap to find the giant 1 13/16th nut had fallen off!  By a stroke of luck there was a guy there showing his tractor trailer repair rig, he had a wrench big enough for me to snug it up.  When I got home I torqued it to 178 ft lbs because it seemed to make sense for a nut that big.  I also put blue loc-tite on it.  I looked in the manual and could not find a name for this nut or a spec for the torque. 
My friend told me the rear wheel could have come off.  If thats true its a real bad design and I feel real stupid for not torquing the hell out of it last time I worked on the brakes.   Funny thing is I had a bad dream the night before that the front tie rod broke and I lost control of the car on the freeway.  So I checked it before I left.  It turns out it was the rear that was the problem.  Well, I made it home in one piece, and I'll use my day off tomorrow to give the car a safety inspection.  But what is the proper torque for that nut?  Should it have some kind of washer or lock washer? 

[The Tassie Devil(le)]

G'day Tom,

I will be leaving the Torque Setting specifications to the more learned in our community, but seeing as the hub is going onto a Tapered Shaft, it shouldn't be necessary to go so high with the wrench.

And, seeing as it is a tapered "Joint" there should be no necessity for a Lock Washer, Spring Washer, or even Loctite to retain the nut.   BUT, there should at least be a Split Pin to retain it.

If the Hub was hot when you tightened the nut up, then I can envisage you having a terrible time getting it apart in time to come.   You might need to heat it up to remove, as when pitting it on so tightly, when it cools down, boy, will it shrink to tightly grip the tapered axle.

Bruce.

[Bob Hoffmann CLC#96]

Tom,
There's a special washer that goes under the nut. It has tabs on it that you bend over the nut so it doesn't come off. I could not find a torque spec. but I agree that 178#'s is WAY too much. Check the  other side while you're at it. Good luck.
HTH, Bob

[Jeff Hansen]

Tom,

Definitely find a shop manual to get the proper torque spec for the axle shaft nuts.

FWIW, the axle shaft nuts on my '42 are supposed to be torqued to between 285 and 315 pounds.  Yes, 300 pounds!

Bob is right about the special washers, too.  McVey's appears to be selling them per there May catalog.  The part is called "Rear Axle/Nut Lock Washer".

HTH,
Jeff

[markl]

Tom,
I second Bob and Tom's recommendation on fitting the tabbed lock washer.  And 178 ft-lb is in the ball-park.  My 1948 Willys PU w/ a Timken rear axle (same taper shaft set-up) calls for 150 ft-lb Minimum.  Make sure every thing is clean and free of corrosion, and then I'd put a very light coating of anti-seize on the axle taper before assembling.

Mark Lowery CLC#25216

[Bob Schuman]

Tom,
And I second Mark's suggestion about lightly coating the axle taper with anti-sieze compound. This will make any future disassembly easy, but without it, removal can become a very difficult task. Don't use the anti-sieze on th threads, though.
Bob Schuman,CLC#254

[Terry Wenger]

Tom:

The '41 shop manual calls for an axle shaft hub nut torque of 285 to 315 Ft. Lbs.I would use that for the  '38-90 along with the special washers mentioned above. Shop manuals before 1941 did not give a torque spec. for that application, but all those rear axles are essentially the same.

Terry Wenger

[Tom Magdaleno]

Thanks for all the replies.  I'll order those washers and torque it to 285 with some anti seize on it.  The other side was loose too.  Could my wheel have fallen off?   

[Philippe M. Ruel]

I read in an old Chilton's that rear axle shaft nut on 1935-1946 V8s requires 285-315 lb.ft.

They say, too, that this nut is 1", quite small compared to the 1-13/16" nut Tom mentions on his 38 V16 - unless 1" is thread diameter.

[TJ Hopland]

So did the average auto shop have the tools to get a bolt that tight back then?   Or did you head over to the local rail road shop?

[Jim Stamper]

     On a 37-60 series the nut takes a 1 5/8" socket. I don't know what the torque should be but plenty tight probably is tight enough, but the flat keeper washer that slots onto a ridge on the drum on one side of the nut and is bent over onto a flat on the opposite side of the nut is an absolute necessity, if you desire any piece of mind.

     I once had the left rear wheel and hub come off on a 1940 Lincoln I had bought that was being delivered to me. Those use a cotter pin through the nut, and whoever had put it on last had neglected that little detail.The fender skirt kept the tire wheel and hub from coming completely off and the hubcap retained the nut, but it was not a good situation. Probably the last old car the delivery guy ever drove.

[Bob Schuman]

If you don't have a torque wrench, you tighten it the way an old time mechanic told me( about early Chrysler hemi head bolts), to tighten until just before your a--hole pops out!.
Bob Schuman, CLC#254

[Misfit]

Any good tractor-trailer tire shop will have the proper torque wrench. The lug nuts holding these rims on are torqued to 450 ft lbs.

The wrench is about 4 feet long and takes two people to correctly torque the wheel lugs.

Fins

[Tom Magdaleno]

The scary thing is that someone elses half-*ss work on this car in the past (throwing away the special washers), along with my ignorance of the workings of these old axles could have cost me my life.  Unfortunately the service manual does not show this part or mention its importance either.  Maybe it was common knowledge at the time, but I'm used to "modern" drum brakes like on my 65 Chevy.

[Steve Passmore]

There is no setting for this nut in the shop manual.  I have a 20 inch wrench that fits the nut and I beat on the end of that with a 4 lb hammer until it wont move any more then beat the washer over, anyway, those tapers really hold if their done up tight in the first place, just had reason to remove a rear drum that I coated in copper ease year before last and the car has not been driven yet, still took a 20 ton puller to move it. I remember a friends car that we couldn't get the taper free with all the pullers we tried, he loosened the nut and drove the car for two weeks thinking that would move it, it did not, and eventually had to use gas destroying all the seals in the process.

[Tom Magdaleno]

I got the washers and installed them.  Here is a picture for anyone else that is interested.  I found the easiest way to bend the metal was to heat it up and then use the back of a hammer to pry. 

[Otto Skorzeny]

Interesting. Crude but effective. 

I wonder why they didn't use a castellated nut with a pin through it like one finds on front wheels.

[The Tassie Devil(le)]

By looking at the picture, to run a castellated nut, the axle would have had to be made longer to allow for the deeper nut.

But, knowing Cadillac Engineers, and I wish I really did know them, there would have been a really good reason, seeing as no expense was spared in making vehicles back then.

Bruce.

[Steve Passmore]

The castellated nuts on the front are OK because you don't do these up tight,  I always" feel" the bearing then back off to the nearest split-pin hole. If your torquing up the axle shaft nut to the figures talked about here 2-300lbs, then you had to back off to find the nearest hole in the castellated nut I think you would be defeating the object, unless Cadillac had some other engineering reason for doing it?