Axle bolts

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John

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Dec 23, 2006
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Getting ready to install rebuilt axles. Can I reuse the 6 axle bolts that attach the inner joint to the output shaft? If not what is the spec on the bolts? Is there enough room between the CV shaft and the upper ball joint to use a socket on the torque wrench?
--
John Sharpe
Humble,TX
78 Eleganza

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John, We examine each bolt, if ok we reuse it and use the Blue loc
tite to prevent it fr on backing off. The torque specs are on the high
side, about 60 ft. lbs.
Re. your question on clearance, I 'm not sure as to what you asking.
The top ball joint has considerable space and I don't know what you
would be doing in that area. We do enough work on these coaches to
where we seldom need to use a torque wrench other than to check work
done by new technician.

>
>
> Getting ready to install rebuilt axles. Can I reuse the 6 axle bolts that attach the inner joint to the output shaft? If not what is the spec on the bolts? Is there enough room between the CV shaft and the upper ball joint to use a socket on the torque wrench?
> --
> John Sharpe
> Humble,TX
> 78 Eleganza
>
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John,
The short answer is yes, by all means, reuse them. The long answer
is, clean them well in a product that leaves no oily film. Clean the
threaded holes the same way. Brake parts cleaner in an aerosol can
works great. It is difficult enough to go around in a tightening
sequence and you must do it at least 3 times. As Jim K. states, you
must use a threadlocking compound on the bolts. Use a torque wrench
or if you are a seasoned mechanic, "red face" the bolts with your
longest wrench. Takes two people as it's difficult to hold the
rotating assy while tightening.
Failure to do the above will lend support to the myth that these
bolts have to be replaced each time they are removed. (And leave you
stranded somewhere.)

>
>
> Getting ready to install rebuilt axles. Can I reuse the 6 axle bolts that attach the inner joint to the output shaft? If not what is the spec on the bolts? Is there enough room between the CV shaft and the upper ball joint to use a socket on the torque wrench?
> --
> John Sharpe
> Humble,TX
> 78 Eleganza
>
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--
Steve Ferguson
'76 EII
Sierra Vista, AZ
Urethane bushing source
www.bdub.net/ferguson/

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From: "Steven Ferguson"

> Takes two people as it's difficult to hold the rotating assy while
> tightening.

John,
The other method you can use is to have a helper operating a jack while you
lay under the coach and do the bolt torqueing. The helper jacks up the
wheel enough to allow you to rotate the assembly to get the wrench on the
bolts easily. Then lowers the wheel to the ground so you can torque them
without worrying about the wheel turning. Just keep going around until you
are satisified you have the bolts torqued to the correct spec.

Bob Sobrito
La Mesa, Ca
77 Kingsley 455
Rear twins

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John,
This post shows why I do all of my vehicle maintenance. It and several others on this subject are examples of the bad advice you can get on this forum.

The Maintenance Manual says to install new bolts and torque them to 75 ft lbs. Normal bolt torque is approximately 75% to 80% of yield strength. The recommended torque for 3/8-24 grade 8 bolts is 37 ft lb. While these bolts are probably higher strength than grade 8 bolts, 75 ft lbs is still very close to 100% of their yield strength. I am sure the GM engineers had a reason for specfying new bolts and I don't know enough to second guess them. Visual inspection of bolts will not detect internal cracks and the cost of a proper NDT inspection probably exceeds the cost of new bolts and I don't know of a NDT inspection that will tell if a bolt has been overstressed.

Replacement bolts can be purchased from a GM dealer, McMaster Carr, and most good bolt stores and are cheap insurance against a breakdown in my opinion.

I have been an auto mechanic for over 40 yrs and my arms are not calibrated well enough to accurately torque bolts. I use a torque wrench on ALL bolts that can be reached with a torque wrench. Even the 1/4 oil pan bolts. That is the only way to insure the bolts are correctly installed. I even carry a torque wrench in the GMC in case I have a flat tire.

Before starting to remove the axle bolts you should buy a new 12 point 7/16 socket that will fit your ratchet and torque wrench. This will minimize the chances of rounding off a bolt head. If a head rounds off, it can be cut off with a Dremel tool and the bolt removed with vise grips.

Jim Moore
75 PB (with new axle bolts torqued to 75 ft lb)
Battle Ground, WA

>John, We examine each bolt, if ok we reuse it and use the Blue loc
>tite to prevent it fr on backing off. The torque specs are on the high
>side, about 60 ft. lbs.
>Re. your question on clearance, I 'm not sure as to what you asking.
>The top ball joint has considerable space and I don't know what you
>would be doing in that area. We do enough work on these coaches to
>where we seldom need to use a torque wrench other than to check work
>done by new technician.

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Jim M. Your an exceptional mechanic. This is a sincere complement.
I'm sure that these bolts have been removed and re done few times so
I'm sure we will start replacing them from now on.
Re. the bolts; I'm having hard time locating the bolts with the
partial threads. Are the ones you aquired identical in thread length?

> John,
> This post shows why I do all of my vehicle maintenance. It and several others on this subject are examples of the bad advice you can get on this forum.
>
> The Maintenance Manual says to install new bolts and torque them to 75 ft lbs. Normal bolt torque is approximately 75% to 80% of yield strength. The recommended torque for 3/8-24 grade 8 bolts is 37 ft lb. While these bolts are probably higher strength than grade 8 bolts, 75 ft lbs is still very close to 100% of their yield strength. I am sure the GM engineers had a reason for specfying new bolts and I don't know enough to second guess them. Visual inspection of bolts will not detect internal cracks and the cost of a proper NDT inspection probably exceeds the cost of new bolts and I don't know of a NDT inspection that will tell if a bolt has been overstressed.
>
> Replacement bolts can be purchased from a GM dealer, McMaster Carr, and most good bolt stores and are cheap insurance against a breakdown in my opinion.
>
> I have been an auto mechanic for over 40 yrs and my arms are not calibrated well enough to accurately torque bolts. I use a torque wrench on ALL bolts that can be reached with a torque wrench. Even the 1/4 oil pan bolts. That is the only way to insure the bolts are correctly installed. I even carry a torque wrench in the GMC in case I have a flat tire.
>
> Before starting to remove the axle bolts you should buy a new 12 point 7/16 socket that will fit your ratchet and torque wrench. This will minimize the chances of rounding off a bolt head. If a head rounds off, it can be cut off with a Dremel tool and the bolt removed with vise grips.
>
> Jim Moore
> 75 PB (with new axle bolts torqued to 75 ft lb)
> Battle Ground, WA
>
> >John, We examine each bolt, if ok we reuse it and use the Blue loc
> >tite to prevent it fr on backing off. The torque specs are on the high
> >side, about 60 ft. lbs.
> >Re. your question on clearance, I 'm not sure as to what you asking.
> >The top ball joint has considerable space and I don't know what you
> >would be doing in that area. We do enough work on these coaches to
> >where we seldom need to use a torque wrench other than to check work
> >done by new technician.
>
>
>
> To unsubscribe or change your settings - http://www.gmcnet.org/settings.htm
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>

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Jim Kanomata writes...

> Jim M. Your an exceptional mechanic. This is a sincere complement.
> I'm sure that these bolts have been removed and re done few times so
> I'm sure we will start replacing them from now on.
> Re. the bolts; I'm having hard time locating the bolts with the
> partial threads. Are the ones you aquired identical in thread length?

I'm not sure I can think of a reason why they need to be partially
threaded. They are bolted so tight that friction carries all the load
of the joint. I'm assuming that the mounting fits together to provide
axial alignment, but I haven't had mine apart yet.

The bolts I have bought (but not yet used) are 91271A644, from
McMaster-Carr. They are 3/8-16x1-1/4", 12-point head. Their minimum
tensile strength is 170,000 psi, which exceeds Grade 8.

$8.43 for a box of 50.

Rick "who paid 30 cents less in May '04" Denney

'73 230 Ex-Glacier "Jaws"
Northern Virginia

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3/8-24

> Jim Kanomata writes...
>
> > Jim M. Your an exceptional mechanic. This is a sincere complement.
> > I'm sure that these bolts have been removed and re done few times so
> > I'm sure we will start replacing them from now on.
> > Re. the bolts; I'm having hard time locating the bolts with the
> > partial threads. Are the ones you aquired identical in thread length?
>
> I'm not sure I can think of a reason why they need to be partially
> threaded. They are bolted so tight that friction carries all the load
> of the joint. I'm assuming that the mounting fits together to provide
> axial alignment, but I haven't had mine apart yet.
>
> The bolts I have bought (but not yet used) are 91271A644, from
> McMaster-Carr. They are 3/8-16x1-1/4", 12-point head. Their minimum
> tensile strength is 170,000 psi, which exceeds Grade 8.
>
> $8.43 for a box of 50.
>
> Rick "who paid 30 cents less in May '04" Denney
>
> '73 230 Ex-Glacier "Jaws"
> Northern Virginia
>
>
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>

--
Carleton Douglas
73 custom, by myself
Prescott, AZ

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You gonna tell me again how that 40 years experience has taught you that a
12 point socket minimizes rounding?
jofarr, soddy tn

----- Original Message -----
From: "Jim Moore"

> I have been an auto mechanic for over 40 yrs and my arms are not
> calibrated well enough to accurately torque bolts. I use a torque wrench
> on ALL bolts that can be reached with a torque wrench. Even the 1/4 oil
> pan bolts. That is the only way to insure the bolts are correctly
> installed. I even carry a torque wrench in the GMC in case I have a flat
> tire.
>
> Before starting to remove the axle bolts you should buy a new 12 point
> 7/16 socket that will fit your ratchet and torque wrench. This will
> minimize the chances of rounding off a bolt head.

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> You gonna tell me again how that 40 years experience has taught you that a
> 12 point socket minimizes rounding?
> jofarr, soddy tn
>
> ----- Original Message -----
> From: "Jim Moore"
>
> > I have been an auto mechanic for over 40 yrs and my arms are not
> > calibrated well enough to accurately torque bolts. I use a torque wrench
> > on ALL bolts that can be reached with a torque wrench. Even the 1/4 oil
> > pan bolts. That is the only way to insure the bolts are correctly
> > installed. I even carry a torque wrench in the GMC in case I have a flat
> > tire.
> >
> > Before starting to remove the axle bolts you should buy a new 12 point
> > 7/16 socket that will fit your ratchet and torque wrench. This will
> > minimize the chances of rounding off a bolt head.

Not wanting to enter into the fray, but the bolts in question have a 12 point head.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana

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Come on boys, settle down. If we all think alike there ain't no thinkin'
done.

Thanks,

Gary Worobec
Anza, CA
1973 23' Glacier

----- Original Message -----
From: "Ken Burton"
To: "gmclist"
Sent: Friday, January 12, 2007 5:15 PM
Subject: Re: [gmclist] Axle bolts

>
>

>> You gonna tell me again how that 40 years experience has taught you that
>> a
>> 12 point socket minimizes rounding?
>> jofarr, soddy tn
>>
>> ----- Original Message -----
>> From: "Jim Moore"
>>
>> > I have been an auto mechanic for over 40 yrs and my arms are not
>> > calibrated well enough to accurately torque bolts. I use a torque
>> > wrench
>> > on ALL bolts that can be reached with a torque wrench. Even the 1/4
>> > oil
>> > pan bolts. That is the only way to insure the bolts are correctly
>> > installed. I even carry a torque wrench in the GMC in case I have a
>> > flat
>> > tire.
>> >
>> > Before starting to remove the axle bolts you should buy a new 12 point
>> > 7/16 socket that will fit your ratchet and torque wrench. This will
>> > minimize the chances of rounding off a bolt head.
>
> Not wanting to enter into the fray, but the bolts in question have a 12
> point head.
> --
> Ken Burton - N9KB
> 76 Palm Beach
> Hebron, Indiana
>
> To unsubscribe or change your settings -
> http://www.gmcnet.org/settings.htm
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Not intending a frey; that was what I thought he meant; but, the general
statement just did not appear quite right, It would fit only in the axle
situation. Of course, I have now re-read and the "all" bolts comment was in
the paragraph above and the one dealing with a 12 point was applied to the
axle bolts only. Be assured, I apologize for the tone of my question as it
does read more smart alecky than I intended.
jofarr, soddy tn, '74 canyonlands 26/3

----- Original Message -----
From: "Ken Burton"
> Not wanting to enter into the fray, but the bolts in question have a 12
> point head.
> --
> Ken Burton - N9KB
> 76 Palm Beach
> Hebron, Indiana
>
> To unsubscribe or change your settings -
> http://www.gmcnet.org/settings.htm
> Donate to support GMCnet - http://www.gmcnet.org/support.html
>

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Rick,
I agree with you the high torque is because the flanges depend on clamping force to carry the load and the shoulder isn't needed.

A few comments, the current price from McMaster is $9.21 for 25 which is really cheap insurance against breakdown and sitting on the side of the road.

The bolts I got from my local bolt supply house and the ones from McMaster have a 3/8" 12 pt heads so a new 3/8" 12 pt socket is needed to torque them.

The 1 1/4" bolts were about 1/8" too long on the passenger side and hit something. I ground about 1/8" off the bolts on that side.

At the risk of creating another war, I placed a floor jack under the lower "A" frame on the side I was working on and jacked that side up until the wheel cleared the ground by about 1/2". I placed a short piece of 2"X4" board against the tire to keep it from turning when I was loosening or tightening an axle bolt. I also left the transmission in park. It was easy to back up the wheel and remove the board when I needed to reposition the axle to reach other bolts.

The bolts should be tightened in about 3 steps in a pattern where the second bolt is 180 deg from the first, the third is 90 deg from the first, the fourth bolt 180 deg from the third, the fifth between the 1st and 4th, the 6th 180 deg from the fifth, the 7th between the 2nd and 4th, the 8th 180 deg from the 7th.
Jim Moore
75 PB
Battle Ground, WA

 
Jesse,
No problem. You post is not as smart alecky as my post.
Jim Moore

-----Original Message-----
>From: jesse farr
>Sent: Jan 12, 2007 5:55 PM
>To: gmclist
>Subject: Re: [gmclist] Axle bolts
>
>Not intending a frey; that was what I thought he meant; but, the general
>statement just did not appear quite right, It would fit only in the axle
>situation. Of course, I have now re-read and the "all" bolts comment was in
>the paragraph above and the one dealing with a 12 point was applied to the
>axle bolts only. Be assured, I apologize for the tone of my question as it
>does read more smart alecky than I intended.
>jofarr, soddy tn, '74 canyonlands 26/3
>
>----- Original Message -----
>From: "Ken Burton"
>> Not wanting to enter into the fray, but the bolts in question have a 12
>> point head.
>> --
>> Ken Burton - N9KB
>> 76 Palm Beach
>> Hebron, Indiana
>>
>> To unsubscribe or change your settings -
>> http://www.gmcnet.org/settings.htm
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>>
>
>
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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.

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.

The issue of using a new 12 point socket addresses the issue that the bolts have 12 point heads (not hex heads) and a new socket would have a closer fit than a worn 12 point socket.

Thanks for all the responses. I like to use original equipment parts or ones that truly exceed their quality, and follow factory maintenance & repair procedures. I have not noticed that there has been a failure issue with these inner axle bolts. So what ever is being done has not created a significant failure rate. So... what about replacing the stripped bolts with available bolts from a donor vehicle and replacing all bolts with identical new ones when they are available? Or am I creating an imminent disaster?
--
John Sharpe
Humble,TX
78 Eleganza

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John,
I was able to torque all the axle bolts by rotating the axle.

The weakest point in the bolts is the root diameter. The bolts with shoulders have root diameters at the flange joint and into the outer flange which is where the bolt will shear. This must be the case if the threads don't bottom out when tightening the bolts.

There have been cases reported on this forum of bolts backing out leaving the GMC stranded on the side of the road.

"High collar" lock washers (McMaster Cat. No. 90073A231) should be used with these bolts and socket head cap screws.

The GM part no for the bolts is 394777. The GM part no for the washers is 9439512. Both are still available from GM according to Denny Allen.
Jim Moore

-----Original Message-----
>From: John
>Sent: Jan 12, 2007 6:43 PM
>To: gmclist
>Subject: Re: [gmclist] 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.
>
>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.
>
>The issue of using a new 12 point socket addresses the issue that the bolts have 12 point heads (not hex heads) and a new socket would have a closer fit than a worn 12 point socket.
>
>Thanks for all the responses. I like to use original equipment parts or ones that truly exceed their quality, and follow factory maintenance & repair procedures. I have not noticed that there has been a failure issue with these inner axle bolts. So what ever is being done has not created a significant failure rate. So... what about replacing the stripped bolts with available bolts from a donor vehicle and replacing all bolts with identical new ones when they are available? Or am I creating an imminent disaster?
>--
>John Sharpe
>Humble,TX
>78 Eleganza
>
>To unsubscribe or change your settings - http://www.gmcnet.org/settings.htm
>Donate to support GMCnet - http://www.gmcnet.org/support.html

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