Bus Rear Axle Nut Coming Loose

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hambone
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Bus Rear Axle Nut Coming Loose

Post by hambone » Mon Mar 27, 2017 4:46 pm

The big rear nut works its way loose enough to sound like a tire terribly out of vibration. I have already replaced the nut, it stays put for a month then comes loose again.
The threads on the stub shaft where the nut tightens appear to be worn loose and shiny, whereas the threads towards the end of the shaft are tight.
I'm afraid I'll have to replace the stub axle, is this true? Loctite doesn't seem like a longterm solution. What do you think? I've never encountered this before.
This is for a 1969 Bus that has been giving me a lot of trouble lately....
3 year part! 1968-70 gotta love it.

If the shaft is replaced, can I leave the bearings and seals alone? They were repacked just a couple of years ago.
Thank you thank you.
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Re: Bus Rear Axle Nut Coming Loose

Post by hambone » Mon Mar 27, 2017 4:49 pm

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Re: Bus Rear Axle Nut Coming Loose

Post by asiab3 » Mon Mar 27, 2017 9:16 pm

Bob, can you describe your tightening technique in vivid detail?

I ask, because many people snug the nut, then put the car on the ground for the final tighten. (I assume they do this is for safety.)

The best torque for your thrust surfaces is achieved with getting the nut as close to final torque as you can with NO load on the axle. This means you'll need to be wary of your jack stand placement, with a floor/bottle jack to balance out any unsafe movement of the chassis. Any load on the axle during tightening can cause radial forces to act on the alxe/nut and give you a false torque reading, or even a stack up of parts that isn't all that tight to begin with.

I have not yet seen an axle come loose on a stub axle tightened this way. The aforementioned "loose stack up of parts" is what I have seen to be the leading cause of axle-loosening. The 220-ish (sorry, I am without manuals at the moment) foot pounds + advance to the next cotter hole works well enough that I have never had to go over that like some people on That Site have been known to advise. I use a good helping of anti-seize or wheel bearing grease on the threads. This prevents rust but ALSO ensures that you're measuring actual tightening torque, instead of just friction in the thread. (Colin is doing the same thing on his cylinder head studs this week; be thankful that we have assembled and running engines right now :) )

If all else fails, I have two extra '69 axles. $20 plus shipping if you want one.
Robbie

--

This one made a hell of a racket until I learned the "torque of the ground trick:"
1969 bus, "Buddy"
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Re: Bus Rear Axle Nut Coming Loose

Post by hambone » Tue Mar 28, 2017 11:03 am

Hi, thank you for the writeup. Yep mine wiggles just like the video. I have been doing it with the wheels on the ground, had no inkling of the "jacked up" method. I stood about 2 feet out on a breaker bar holding onto the gutter. No problems until the big BFG tires.
I worry that since the threads have been loose for a while they have been damaged with back and forth movement of the nut.
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Re: Bus Rear Axle Nut Coming Loose

Post by hambone » Fri Mar 31, 2017 7:21 pm

Ok the nut has been tightened again with the wheel offa the ground. Fingers crossed, I have been doing that a lot lately!
Mountain driving really took a toll on the brakes, they were way out of adjustment and the front end needed serious greasing after only 4k miles.
Even forced out a tiny drop of water from the centerpin! O' Oregon.
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Re: Bus Rear Axle Nut Coming Loose

Post by Amskeptic » Fri Mar 31, 2017 9:53 pm

hambone wrote:
Fri Mar 31, 2017 7:21 pm
Ok the nut has been tightened again with the wheel offa the ground. Fingers crossed, I have been doing that a lot lately!
Mountain driving really took a toll on the brakes, they were way out of adjustment and the front end needed serious greasing after only 4k miles.
Even forced out a tiny drop of water from the centerpin! O' Oregon.
Be aware that rear axle nuts lose clamping force when the "sandwich" of bearing races, spacers and most especially, the drum itself, get shorter due to chafing or bearing wear. Do you have brazilian or German drums?
Colin
BobD - 1978 Bus . . . . . . . . . . .110,350 miles
Chloe - 1970 bus . . . . . . . . . . . 206,775 miles
Naranja - 1977 Westfalia . . . . 72,350 miles
Pluck - 1973 Squareback . . . . . 55,478 miles
Alexus - 1991 Lexus LS400 . . . 64,425 miles

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Re: Bus Rear Axle Nut Coming Loose

Post by hambone » Sun Apr 02, 2017 12:44 pm

One drum of each. Bearings are new, spacer didn't seem damaged at the time.
I will revisit this IF it comes loose in another 800 miles...
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Re: Bus Rear Axle Nut Coming Loose

Post by hambone » Thu Apr 20, 2017 11:55 am

Loose again. NOW what? Let's just say this is inopportune timing. Life has floored me and I can't deal with this properly.
Spacer? Drum? Axle? What the hell is goin on here Mama Bus....
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Re: Bus Rear Axle Nut Coming Loose

Post by hambone » Thu Apr 20, 2017 1:07 pm

I have another, used drum I can install. I just like to know what is causing the issue to begin with instead of replacing parts.
Well the drum is original, maybe it's just worn out.
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Re: Bus Rear Axle Nut Coming Loose

Post by hambone » Thu Apr 20, 2017 8:03 pm

Tightened down again, I'm giving it one more chance! Bah.
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Re: Bus Rear Axle Nut Coming Loose

Post by Amskeptic » Mon Apr 24, 2017 5:44 am

hambone wrote:
Thu Apr 20, 2017 8:03 pm
Tightened down again, I'm giving it one more chance! Bah.
Which drum is allowing this loosening? Brazilian or German? If the drum is mushing itself after just a few miles after torquing the nut, you have lousy metal collapsing under load. My Chloe Braxilian drum had a raised area to the outside of the spacer which just kept squishing the drum thrust surface.

Yeah, so which drum is on the Axle Nut Is Loosening side?
Colin
BobD - 1978 Bus . . . . . . . . . . .110,350 miles
Chloe - 1970 bus . . . . . . . . . . . 206,775 miles
Naranja - 1977 Westfalia . . . . 72,350 miles
Pluck - 1973 Squareback . . . . . 55,478 miles
Alexus - 1991 Lexus LS400 . . . 64,425 miles

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Re: Bus Rear Axle Nut Coming Loose

Post by hambone » Mon Apr 24, 2017 5:13 pm

It's the old German drum, pass side. Driver's side was German but the threads failed a couple of years ago. Thanks to Kirk who had a couple of Brazil drums lying around, replaced that side only. Still have the other. It sounds like something is a little out of balance back there now, wonder if the splines are worn or just a tire or my paranoia.
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Re: Bus Rear Axle Nut Coming Loose

Post by hambone » Fri Apr 28, 2017 11:53 am

I have a new wheel cylinder to install, plus some new shoes if needed. Also will replace that drum.
That's what I get. Well 20 years out of Brazil Varga wheel cylinders not bad. But that drum has me a bit disappointed - only lasted 48 years.
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Re: Bus Rear Axle Nut Coming Loose

Post by hambone » Mon May 01, 2017 12:39 pm

Drum has been replaced, along with a leaky wheel cylinder. The old one was indeed screwed up, splines banged up and the hubs with a worn groove.
The shaft was polished chrome shiny from all the slapping around. There is no slop or damage when things are tightened up, it seems that the drum took most of the damage, soft cast iron. I'm hoping this is it, but wouldn't be shocked if it isn't...
So much quieter without that out of balance wobble.
http://greencascadia.blogspot.com
http://pdxvolksfolks.blogspot.com
it balances on your head just like a mattress balances on a bottle of wine
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Re: Bus Rear Axle Nut Coming Loose

Post by Amskeptic » Fri May 05, 2017 7:48 am

hambone wrote:
Mon May 01, 2017 12:39 pm
Drum has been replaced, along with a leaky wheel cylinder. The old one was indeed screwed up, splines banged up and the hubs with a worn groove.
The shaft was polished chrome shiny from all the slapping around. There is no slop or damage when things are tightened up, it seems that the drum took most of the damage, soft cast iron. I'm hoping this is it, but wouldn't be shocked if it isn't...
So much quieter without that out of balance wobble.

My fingers are crossed. Vigilant to the care and feeding of these old horses.
Colin
BobD - 1978 Bus . . . . . . . . . . .110,350 miles
Chloe - 1970 bus . . . . . . . . . . . 206,775 miles
Naranja - 1977 Westfalia . . . . 72,350 miles
Pluck - 1973 Squareback . . . . . 55,478 miles
Alexus - 1991 Lexus LS400 . . . 64,425 miles

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