Axle bolts

>
>
> A little update. Three axle bolts do not pass the visual test and
> need replacement. I use a torque wrench on most installations.
> There is not enough room between the upper joint and the CV joint
> to use a torque wrench and socket. It would require a 3/4" offset
> wrench extension and calculation to determine the correct setting
> on the torque wrench. So I used the red-faced method.
>
> John Sharpe

John - I've never had any problem using my 1/2" drive torque wrench
to tighten all the bolts. I use a 3/8" drive socket, a 2" 3/8
extension and then a 3/8 to 1/2 adapter on the wrench. I do have to
revolve the axle to get to all the bolts but that has not been a
problem.

Emery Stora
77 Kingsley
Santa Fe, NM



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I wasn't going to way in on this one, but - I bought
my 77 Kingsley last Feb in the Seattle area, drove it
home to Texas (2500 miles), wasn't able to go anywhere
until fall because I was going through back problems,
fusion, recuperation, and all that goes with that.
This fall we went on a short trip to Glenrose, Texas
as a shakedown trial. Then we went to the Texas coast
for Thangsgiving (1000 miles). The only problem was
the exhaust got louder the further we went on the way
home. While I was repairing the left exhaust gasket
and donut I happened to look at the axle bolts.
Surprise, there were only three bolts remaining and I
could turn them with my fingers. I could hardly
beleive that I would not have heard some noise or felt
some vibration or would have had some indication that
the joint was coming apart. Lucky, I guess.
I began the task of finding some replacement bolts
without a lot of luck. Finally went to "Fastenal" and
they had bolts that looked like ours, but were 16
threads per inch. I was hunting a 12 point, 3/8" dia,
1.25" length, 24 threads with a shoulder. The only
thing we came up with was an allen head 3/8 - 24 X 2"
long. Had to buy the 2" to get a shoulder. The specs
said they were 182,000 # tensile. I replaced the three
missing bolts with these bolts after shortening them
to 1.25". Now after reading about all the items about
the axle bolts here, I'm a little concerned.


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Don, If there is anyone that puts on a big load on it, it is me. I run
Cad 540 With fuel Injection and twin turbos. I hav on this 2nd coach
over 350,000 miles on it.
I reuse the bolts and use lock tite. Occasionally I will replace the
lock washer.
In every case where the bolt was a problem was due to not torqueing enough.
I have removed those bolts to switch finaln drives for testing 4-5
times. It's always a good idea to check them when you grease the
coach. You need to inspect the bottom more than you like.

On 1/13/07

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Got mine from Jim Bounds. Allen head & came with washers.
Al Scott
75 PB
Dixon, CA
------------------------------------------------

> to 1.25". Now after reading about all the items about
> the axle bolts here, I'm a little concerned.
>
>
>
>
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John writes...

> IMHO the shoulders on the bolts are necessary since the bolts are
> the only mechanical device that prevents the axle from twisting on
> the output flange. Pulling 10-12K pounds puts such an incredible
> load on the connection that I feel that six 3/8" bolts torqued to
> 65'# needs some additional help.

I would respectfully disagree. The clamping force is all this joint
needs to prevent slipping, and if it did slip because the bolts were
too loose, the weak link on the bolts is right at the joint interface,
where the factory bolts are still threaded.

Bolts with unthreaded sections increase the shear strength, but only
when both sides of the joint bear on the unthreaded section. That
isn't the case here.

One reason the bolts are tightened so much is to prevent a loss of
clamping force. As Jim mentions, they do loosen, and I believe that
this is always because they were insufficiently tightened. Properly
tightened, however, the clamping force should be more than enough to
carry all the torque through the joint. Remember that the maximum
torque is that applied by the engine. Braking forces don't go through
this joint. Only a fraction of the weight of the coach is applied to
these bolts.

Rick "who would always use a torque wrench for tightening that close
to the yield strength of the bolt" Denney

'73 230 Ex-Glacier "Jaws"
Northern Virginia

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Don,
The allen head bolts are very suitable substitutes. The ones I used
to sell at rallys were always G10.

> I wasn't going to way in on this one, but - I bought
> my 77 Kingsley last Feb in the Seattle area, drove it
> home to Texas (2500 miles), wasn't able to go anywhere
> until fall because I was going through back problems,
> fusion, recuperation, and all that goes with that.
> This fall we went on a short trip to Glenrose, Texas
> as a shakedown trial. Then we went to the Texas coast
> for Thangsgiving (1000 miles). The only problem was
> the exhaust got louder the further we went on the way
> home. While I was repairing the left exhaust gasket
> and donut I happened to look at the axle bolts.
> Surprise, there were only three bolts remaining and I
> could turn them with my fingers. I could hardly
> beleive that I would not have heard some noise or felt
> some vibration or would have had some indication that
> the joint was coming apart. Lucky, I guess.
> I began the task of finding some replacement bolts
> without a lot of luck. Finally went to "Fastenal" and
> they had bolts that looked like ours, but were 16
> threads per inch. I was hunting a 12 point, 3/8" dia,
> 1.25" length, 24 threads with a shoulder. The only
> thing we came up with was an allen head 3/8 - 24 X 2"
> long. Had to buy the 2" to get a shoulder. The specs
> said they were 182,000 # tensile. I replaced the three
> missing bolts with these bolts after shortening them
> to 1.25". Now after reading about all the items about
> the axle bolts here, I'm a little concerned.
>
>
>
> > To unsubscribe or change your settings -
> > http://www.gmcnet.org/settings.htm
> > Donate to support GMCnet -
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> >
>
>
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>

--
Steve Ferguson
'76 EII
Sierra Vista, AZ
Urethane bushing source
www.bdub.net/ferguson/

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> While I was repairing the left exhaust gasket
> and donut I happened to look at the axle bolts.
> Surprise, there were only three bolts remaining and I
> could turn them with my fingers. I could hardly
> believe that I would not have heard some noise or felt
> some vibration or would have had some indication that
> the joint was coming apart. Lucky, I guess.

You are not the first one. I got a Black List call from a GMCer a couple of years ago. He had a coach load of people going to a football game in Chicago. All of a sudden without any warning the coach would not move any more. When I got there we found ALL of the bolts missing on the right side and two missing on the left. It was a Saturday and we had a time finding something suitable to use. We finally found some grade 8 bolts that he could use temporarily at TSC. When he got home he replaced all of them with the proper bolts.

When I had mine out of my coach, I reused the old bolts, torqued them to spec, and used Locktite.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana

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I wasn't going to weigh in on this one either but, several years ago I was
down in Portland, OR on a weekend trip and pulled over to the side of the
freeway to the accompaniment of a loud clunking sound. Investigation found
that the left inboard CV joint was held together with two loose and badly
damaged bolts. I removed three bolts from the right side and reattached the
left side and gently drove home (135 miles) without any farther problems. I
too converted to socket-head (allen) bolts and have not had any problems.
That might be because of the 6 spare bolts I carry with me. Never have
needed them but I have loaned then to others...........Terry
PS It is always the left side that comes loose.


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I'm convinced that that is a critical maintenance/inspection issue on
any motorhome with a 425 tranny. I had the same problem with a Cortez
just west of Indianapolis on a sunny morning in January a couple of
years ago. The local ACE hardware store had enough socket-head cap
screws (also known as Allen head) to fix me up and they are still in
place. The Cortez uses a slightly bigger output flange with 8 bolts
rather than 6 and I still had the left side come loose. It was a pretty
scary happening. I had just picked the unit up the night before and
driven from the east side across town in rush hour traffic with the
shaft wobbling back and forth, held in place by only 2 loose, bent
bolts.
I had a few other surprises to deal with but that one was almost fatal.

Big Jim

-----Original Message-----
From: Terry Skinner [mailto:gmcnut]=20
Sent: Sunday, January 14, 2007 8:02 AM
To: gmclist
Subject: Re: [gmclist] Axle bolts

I wasn't going to weigh in on this one either but, several years ago I
was=20
down in Portland, OR on a weekend trip and pulled over to the side of
the=20
freeway to the accompaniment of a loud clunking sound. Investigation
found=20
that the left inboard CV joint was held together with two loose and
badly=20
damaged bolts. I removed three bolts from the right side and reattached
the=20
left side and gently drove home (135 miles) without any farther
problems. I=20
too converted to socket-head (allen) bolts and have not had any
problems.=20
That might be because of the 6 spare bolts I carry with me. Never
have=20
needed them but I have loaned then to others...........Terry
PS It is always the left side that comes loose.=20

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