Home » Public Forums » GMCnet » Near disaster...lower control arm
| Near disaster...lower control arm [message #102801] |
Wed, 13 October 2010 12:39  |
Larry
Messages: 2875
Registered: January 2004
Location: Menomonie, WI
Karma: 10
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Senior Member |
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In early September, just before going to DeQuoin, I was doing some maintenance on the gas tanks. Just a year earlier, I had removed the upper and lower arms to replace the bushings, repair the shock mounts and do an alignment. If you have done a bushing replacement, you know that the nut that goes on the bolt holding the control arm to the frame is a grade 8 crimping style nut. I was shocked to find that the front bolt that holds the driver side lower control arm to the frame had lost it’s nut and backed its way out until only a couple of threads were holding it. The nut had lost it’s crimping tension, worked loose, dropped into the frame (where I found it laying) and the bolt then backed it’s way out. I was breathless thinking of what might have happened if it had come out while on the road. I checked the one on the passenger side to find that the nut was still on the bolt, but had loosened a couple of turns. I had to release the tension on the torsion bar, to move the arm into position so that I could get the front bolt back in where it belongs. The rear control arm bolts were tight. I then used Red Locktight on the nut to keep it in place. I have since found out from Dave Lenzi that the nut should be replaced at each use, or at a minimum use locktight with further application as the nut will loose it’s crimping tension.
I bring all of this to the groups attention, so that IF you have replaced the control arm bushings or for any reason have removed the lower control arms, you should probably check the bolt for tightness and remove the nut for locktight or replacement. I will be going to Fastenall today to see if I can get a new set of grade 8 nuts. PLEASE check your lower control arm bolts now.
Larry 
78 Royale w/500 Caddy
Menomonie, WI.
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| photos [message #102805 is a reply to message #102801] |
Wed, 13 October 2010 13:05  |
bukzin
Messages: 840
Registered: April 2004
Location: North California
Karma: 0
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Senior Member |
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Larry,
Would you post some photos?
Thanks!
Bukzin
1977 Palm Beach
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| Re: [GMCnet] Near disaster...lower control arm [message #102807 is a reply to message #102801] |
Wed, 13 October 2010 13:41 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Senior Member |
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Those nut are the locking type . I would stay away from the Red and
use the blue.
On Wed, Oct 13, 2010 at 10:39 AM, Larry <weidnerl@wwt.net> wrote:
>
>
> In early September, just before going to DeQuoin, I was doing some maintenance on the gas tanks. Just a year earlier, I had removed the upper and lower arms to replace the bushings, repair the shock mounts and do an alignment. If you have done a bushing replacement, you know that the nut that goes on the bolt holding the control arm to the frame is a grade 8 crimping style nut. Â Â I was shocked to find that the front bolt that holds the driver side lower control arm to the frame had lost it’s nut and backed its way out until only a couple of threads were holding it. The nut had lost it’s crimping tension, worked loose, dropped into the frame (where I found it laying) and the bolt then backed it’s way out. I was breathless thinking of what might have happened if it had come out while on the road. I checked the one on the passenger side to find that the nut was still on the bolt, but had loosened a couple of turns. Â I had to release the tension on the torsion
> Â bar, to move the arm into position so that I could get the front bolt back in where it belongs. The rear control arm bolts were tight. I then used Red Locktight on the nut to keep it in place. I have since found out from Dave Lenzi that the nut should be replaced at each use, or at a minimum use locktight with further application as the nut will loose it’s crimping tension.
>
> I bring all of this to the groups attention, so that IF you have replaced the control arm bushings or for any reason have removed the lower control arms, you should probably check the bolt for tightness and remove the nut for locktight or replacement. Â I will be going to Fastenall today to see if I can get a new set of grade 8 nuts. Â PLEASE check your lower control arm bolts now.
> --
> Larry  :)
> 78 Royale w/500 Caddy
> Menomonie, WI.
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
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--
Jim Kanomata
Applied/GMC, Fremont,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
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Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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| Re: Near disaster...lower control arm [message #102822 is a reply to message #102801] |
Wed, 13 October 2010 15:33 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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Senior Member |
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| Larry wrote on Wed, 13 October 2010 13:39 |
In early September, just before going to DeQuoin, I was doing some maintenance on the gas tanks. Just a year earlier, I had removed the upper and lower arms to replace the bushings, repair the shock mounts and do an alignment. If you have done a bushing replacement, you know that the nut that goes on the bolt holding the control arm to the frame is a grade 8 crimping style nut. I was shocked to find that the front bolt that holds the driver side lower control arm to the frame had lost it’s nut and backed its way out until only a couple of threads were holding it. The nut had lost it’s crimping tension, worked loose, dropped into the frame (where I found it laying) and the bolt then backed it’s way out. I was breathless thinking of what might have happened if it had come out while on the road. I checked the one on the passenger side to find that the nut was still on the bolt, but had loosened a couple of turns. I had to release the tension on the torsion bar, to move the arm into position so that I could get the front bolt back in where it belongs. The rear control arm bolts were tight. I then used Red Locktight on the nut to keep it in place. I have since found out from Dave Lenzi that the nut should be replaced at each use, or at a minimum use locktight with further application as the nut will loose it’s crimping tension.
I bring all of this to the groups attention, so that IF you have replaced the control arm bushings or for any reason have removed the lower control arms, you should probably check the bolt for tightness and remove the nut for locktight or replacement. I will be going to Fastenall today to see if I can get a new set of grade 8 nuts. PLEASE check your lower control arm bolts now.
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Larry,
That is very good information and caused me to remember that those nuts are actually called "prevailing torque" lock nut. Most of those produced in recent years (last 10~15) meet the IFI standard for no loss in residual torque (the locking factor) in 5 assemblies, but that is a recent standard and there is no reason to expect it of 35+yo hardware.
PT locknuts come it two main kinds, the kind that are just crushed across two flats so they are not round, and the kind that have three "hammered" areas on one end of the nut. If you disassembling something and there is no lockwasher, look at the nut carefully.
In Short, If you run into one of those kind nuts that might be original hardware, you have three options: (more or less in order)
1 - Get a new one
2 - Set it with a thread locking compound
3 - Assemble it with a lock washer (if there is enough thread and only if the fastener has a final tension).
If you run into PT nut and it is easy to run down - IT IS NO GOOD.
If you buy a replacement hardware anywhere and it does not feel right during assembly, be aware it may that it meet the label specifications. There are an awful lot of "Pacific Rim" fasteners coming into the country that are substandard and they even show up on the shelves of good suppliers.
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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| Re: [GMCnet] Near disaster...lower control arm [message #102826 is a reply to message #102822] |
Wed, 13 October 2010 15:42 |
k2gkk
Messages: 4452
Registered: November 2009
Karma: -8
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Senior Member |
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Additional option if bolt is long enough:
Use "regular" nut and seat a second nut
down on it and reef the two together!
Use Loc-Tite when you do!
Being "anal" or "o.c." is NOT all bad
when it comes to safety!
* * * * * * * * *
* Mac Macdonald *
* Hamcall K2GKK *
* USAF, Retired *
* Oklahoma City *
** "Money Pit" **
* '76 ex - P.B. *
* * * * * * * * *
----------------------------------------
> To: gmclist@temp.gmcnet.org
> From: mcolie@chartermi.net
> Date: Wed, 13 Oct 2010 15:33:44 -0500
> Subject: Re: [GMCnet] Near disaster...lower control arm
>
>
>
> Larry wrote on Wed, 13 October 2010 13:39
> > In early September, just before going to DeQuoin, I was doing some maintenance on the gas tanks. Just a year earlier, I had removed the upper and lower arms to replace the bushings, repair the shock mounts and do an alignment. If you have done a bushing replacement, you know that the nut that goes on the bolt holding the control arm to the frame is a grade 8 crimping style nut. I was shocked to find that the front bolt that holds the driver side lower control arm to the frame had lost it’s nut and backed its way out until only a couple of threads were holding it. The nut had lost it’s crimping tension, worked loose, dropped into the frame (where I found it laying) and the bolt then backed it’s way out. I was breathless thinking of what might have happened if it had come out while on the road. I checked the one on the passenger side to find that the nut was still on the bolt, but had loosened a couple of turns. I had to release the tension on the torsi
> on bar, to move the arm into position so that I could get the front bolt back in where it belongs. The rear control arm bolts were tight. I then used Red Locktight on the nut to keep it in place. I have since found out from Dave Lenzi that the nut should be replaced at each use, or at a minimum use locktight with further application as the nut will loose it’s crimping tension.
> >
> > I bring all of this to the groups attention, so that IF you have replaced the control arm bushings or for any reason have removed the lower control arms, you should probably check the bolt for tightness and remove the nut for locktight or replacement. I will be going to Fastenall today to see if I can get a new set of grade 8 nuts. PLEASE check your lower control arm bolts now.
>
> Larry,
>
> That is very good information and caused me to remember that those nuts are actually called "prevailing torque" lock nut. Most of those produced in recent years (last 10~15) meet the IFI standard for no loss in residual torque (the locking factor) in 5 assemblies, but that is a recent standard and there is no reason to expect it of 35+yo hardware.
>
> PT locknuts come it two main kinds, the kind that are just crushed across two flats so they are not round, and the kind that have three "hammered" areas on one end of the nut. If you disassembling something and there is no lockwasher, look at the nut carefully.
>
> In Short, If you run into one of those kind nuts that might be original hardware, you have three options: (more or less in order)
> 1 - Get a new one
> 2 - Set it with a thread locking compound
> 3 - Assemble it with a lock washer (if there is enough thread and only if the fastener has a final tension).
>
> If you run into PT nut and it is easy to run down - IT IS NO GOOD.
>
> If you buy a replacement hardware anywhere and it does not feel right during assembly, be aware it may that it meet the label specifications. There are an awful lot of "Pacific Rim" fasteners coming into the country that are substandard and they even show up on the shelves of good suppliers.
>
> Matt
> --
> Matt & Mary Colie
> '73 Glacier 23 Chaumiere (say show-me-air)
> SE Michigan - DTW 3.2/4R
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
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| Re: [GMCnet] Near disaster...lower control arm [message #102865 is a reply to message #102801] |
Wed, 13 October 2010 19:30 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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Larry,
Glad you did not suffer a disaster!
I reinforced the lower A-Frames in The Blue Streak following Steve
Ferguson's method. I also installed his urethane bushings.
When I removed the old rubber bushings I noted that the steel inner sleeve
had cut marks on the ID from the bolt threads. I then examined the standard
bolt and noted that there was a short (3/8" long?) section under the head
that was 1/2" in diameter then the bolt tapered down and back out to 1/2" at
the threads. The fact that the there were cut marks in the ID of the inner
steel bushing made me think that the bushing was shifting on the bolt.
Wasn't much but being the anally retentive perfectionist that I am it was
unacceptable! ;-)
I bought some 6" long grade 8 bolts which had an unthreaded section of 5
inches. That was long enough to have an unthreaded section through both of
the flanges welded to the frame. In fact it was a bit too long. When I put
the A-Frames back in I found that the 1/2" bolts I bought would not fit
through the steel liner of the urethane bushings so I honed them out with a
Harley brake master cylinder hone I have. Once I got them to slide through
easily I cleaned everything up, put a washer under the head of the bolt,
lubricated the bolt and sleeve with oil and slid it through the forward
frame tab and into the sleeve. I noted that I had a very short section of
unthreaded bolt out the rear frame tab. I put a flat washer over the exposed
end of the bolt followed by a lock washer. This covered the unthreaded part
of the bolt. I then repeated these operations on the rear bolt. Both bolts
were installed aircraft style - head facing direction of travel. When it
came time to torque them down I used an all steel self locking nut. I can't
remember if I used Locktite or not.
At any rate I would be very surprised if those nuts came off!
Regards,
Rob M.
USAussie
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org
[mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Larry
Sent: Wednesday, October 13, 2010 12:39 PM
To: gmclist@temp.gmcnet.org
Subject: [GMCnet] Near disaster...lower control arm
In early September, just before going to DeQuoin, I was doing some
maintenance on the gas tanks. Just a year earlier, I had removed the upper
and lower arms to replace the bushings, repair the shock mounts and do an
alignment. If you have done a bushing replacement, you know that the nut
that goes on the bolt holding the control arm to the frame is a grade 8
crimping style nut. I was shocked to find that the front bolt that holds
the driver side lower control arm to the frame had lost it’s nut and
backed its way out until only a couple of threads were holding it. The nut
had lost it’s crimping tension, worked loose, dropped into the frame
(where I found it laying) and the bolt then backed it’s way out. I was
breathless thinking of what might have happened if it had come out while on
the road. I checked the one on the passenger side to find that the nut was
still on the bolt, but had loosened a couple of turns. I had to release
the tension on the torsion
bar, to move the arm into position so that I could get the front bolt back
in where it belongs. The rear control arm bolts were tight. I then used Red
Locktight on the nut to keep it in place. I have since found out from Dave
Lenzi that the nut should be replaced at each use, or at a minimum use
locktight with further application as the nut will loose it’s crimping
tension.
I bring all of this to the groups attention, so that IF you have replaced
the control arm bushings or for any reason have removed the lower control
arms, you should probably check the bolt for tightness and remove the nut
for locktight or replacement. I will be going to Fastenall today to see if
I can get a new set of grade 8 nuts. PLEASE check your lower control arm
bolts now.
--
Larry :)
78 Royale w/500 Caddy
Menomonie, WI.
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: [GMCnet] Near disaster...lower control arm [message #102877 is a reply to message #102865] |
Wed, 13 October 2010 20:36 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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Senior Member |
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| Robert Mueller wrote on Wed, 13 October 2010 20:30 |
<snip - read it>
|
Rob,
That sounds like a real good approach.
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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