Home » Public Forums » GMCnet » Torsion bar failure
| Torsion bar failure [message #158431] |
Sun, 29 January 2012 13:29  |
voodoolng
Messages: 40
Registered: February 2004
Location: Colo
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I have been junkyarding and found something interesting. When I pull the rear torsion bar cross memebers Iam finding 50% are cracked. In the area where the prokchop rest in the upper area of the cross member its cracked and breaking through. I had one member where it was cracked at both end. I have posted pictures of this area and the piece of support that has started to break through. Please check this area in your support for fatigue. Tim(voodoolng album)
73 Glacier Voodoo lounge
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| Re: Torsion bar failure [message #158433 is a reply to message #158431] |
Sun, 29 January 2012 14:04  |
midlf
Messages: 2212
Registered: July 2007
Location: SE Wisc. (Palmyra)
Karma: 1
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| voodoolng wrote on Sun, 29 January 2012 13:29 |
I have been junkyarding and found something interesting. When I pull the rear torsion bar cross memebers Iam finding 50% are cracked. In the area where the prokchop rest in the upper area of the cross member its cracked and breaking through. I had one member where it was cracked at both end. I have posted pictures of this area and the piece of support that has started to break through. Please check this area in your support for fatigue. Tim(voodoolng album)
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Link:
http://www.gmcmhphotos.com/photos/showphoto.php?photo=42548&title=cracked-rear-torsion-bar-housings-004&cat=5980
Steve Southworth
1974 Glacier TZE064V100150 (for workin on)
1975 Transmode TZE365V100394 (parts & spares)
Palmyra WI
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| Re: [GMCnet] Torsion bar failure [message #158435 is a reply to message #158433] |
Sun, 29 January 2012 14:18 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Tim, what I believe that you are seeing with the cracks in the crossmember
is the result of some idiot with an air impact wrench and a torsion bar
tool overrotating the porkchop with the tool, bottoming ( or topping out)
the porkchop with the tool and then by continued application of torque,
fracturing of the crossmember. Just an educated guess on my part, but I
have seen evidence of the pork chops touching the inside of the crossmember
also. That can only be caused by the pork chop overrotating. In normal
operation, the porkchop does not come that close to the crossmember.
Jim Hupy
Salem, OR
78 GMC Royale 403
On Sun, Jan 29, 2012 at 12:04 PM, Steve Southworth <midlf@centurytel.net>wrote:
>
>
> voodoolng wrote on Sun, 29 January 2012 13:29
> > I have been junkyarding and found something interesting. When I pull the
> rear torsion bar cross memebers Iam finding 50% are cracked. In the area
> where the prokchop rest in the upper area of the cross member its cracked
> and breaking through. I had one member where it was cracked at both end. I
> have posted pictures of this area and the piece of support that has started
> to break through. Please check this area in your support for fatigue.
> Tim(voodoolng album)
>
>
> Link:
>
>
> http://www.gmcmhphotos.com/photos/showphoto.php?photo=42548&title=cracked-rear-torsion-bar-housings-004&cat=5980
>
>
>
> --
> Steve Southworth
> 1974 Glacier TZE064V100150 (for workin on)
> 1975 Transmode TZE365V100394 (parts & spares)
> Palmyra WI
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
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| Re: [GMCnet] Torsion bar failure [message #158443 is a reply to message #158435] |
Sun, 29 January 2012 15:15 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Tim,
I sure wish you'd gone junkyarding 2 weeks ago! I'd have checked my
crossmember in that area while I had it out -- I didn't. But perhaps I'd
have noticed damage because I did thoroughly degrease and paint it before I
put it back in.
IIRC, I recently posted a note cautioning those trying to use the
adjustable porkchops that they should NOT grind away that area of the
crossmember. Your information reinforces that contention.
Jim, I disagree with your analysis of the problem. If over-tightening of
the adjusting bolt was responsible for the damage, it should be on the
other side of the hump in the crossmember -- toward the small end of the
pork chop. The damage in the pictures is exactly where I'd expect to see
it -- where the vertical force on the small end from the adjusting bolt is
reacted by the cross member on the other end of the pork chop. Since every
ripple in the road will cause a variation in the load in that area, it's
surprising we haven't seen/heard of more problems there.
I don't understand your statement, "the porkchop does not come that close
to the crossmember". Seems to me the pork chop MUST contact the cross
member in that area to provide the equal and opposite force to the
adjusting screws. What there should not be there is much evidence of
movement.
This would be an easy area to reinforce before the damage progresses -- but
the cross member's going to have to come out. Torque bar tool
manufacturers & seller, gear up! :-)
Ken H.
Americus, GA
'76 X-Birchaven w/Cad500/Howell EFI+ & EBL
www.gmcwipersetc.com
On Sun, Jan 29, 2012 at 3:18 PM, James Hupy wrote:
> Tim, what I believe that you are seeing with the cracks in the crossmember
> is the result of some idiot with an air impact wrench and a torsion bar
> tool overrotating the porkchop with the tool, bottoming ( or topping out)
> the porkchop with the tool and then by continued application of torque,
> fracturing of the crossmember. Just an educated guess on my part, but I
> have seen evidence of the pork chops touching the inside of the crossmember
> also. That can only be caused by the pork chop overrotating. In normal
> operation, the porkchop does not come that close to the crossmember.
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: [GMCnet] Torsion bar failure [message #158447 is a reply to message #158446] |
Sun, 29 January 2012 16:30 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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Bob,
I, too, wondered about the source, especially with the dearth of GMCMH's in
junk yards. :-)
But the forces there, and the concerns, should be similar, IMHO. Have you
ever seen any damage on a MH?
Ken H.
On Sun, Jan 29, 2012 at 5:25 PM, Bob Drewes wrote:
>
>
> midlf wrote on Sun, 29 January 2012 14:04
> > voodoolng wrote on Sun, 29 January 2012 13:29
> > > I have been junkyarding and found something interesting. When I pull
> the rear torsion bar cross memebers Iam finding 50% are cracked. In the
> area where the prokchop rest in the upper area of the cross member its
> cracked and breaking through. I had one member where it was cracked at both
> end. I have posted pictures of this area and the piece of support that has
> started to break through. Please check this area in your support for
> fatigue. Tim(voodoolng album)
> >
> >
> > Link:
> >
> >
> http://www.gmcmhphotos.com/photos/showphoto.php?photo=42548&title=cracked-rear-torsion-bar-housings-004&cat=5980
>
>
> I don't think the pic listed above is an OEM GMC MH cross member, it looks
> like from a K2500/K3500 pkup truck.
>
>
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: [GMCnet] Torsion bar failure [message #158455 is a reply to message #158447] |
Sun, 29 January 2012 17:28 |
Surbo
Messages: 213
Registered: February 2004
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| Ken Henderson wrote on Sun, 29 January 2012 16:30 |
Bob,
I, too, wondered about the source, especially with the dearth of GMCMH's in
junk yards. 
But the forces there, and the concerns, should be similar, IMHO. Have you
ever seen any damage on a MH?
Ken H.
On Sun, Jan 29, 2012 at 5:25 PM, Bob Drewes wrote:
>
>
> midlf wrote on Sun, 29 January 2012 14:04
> > voodoolng wrote on Sun, 29 January 2012 13:29
> > > I have been junkyarding and found something interesting. When I pull
> the rear torsion bar cross memebers Iam finding 50% are cracked. In the
> area where the prokchop rest in the upper area of the cross member its
> cracked and breaking through. I had one member where it was cracked at both
> end. I have posted pictures of this area and the piece of support that has
> started to break through. Please check this area in your support for
> fatigue. Tim(voodoolng album)
> >
> >
> > Link:
> >
> >
> http://www.gmcmhphotos.com/photos/showphoto.php?photo=42548&title=cracked-rear-torsion-bar-housings-004&cat=5980
>
>
> I don't think the pic listed above is an OEM GMC MH cross member, it looks
> like from a K2500/K3500 pkup truck.
>
>
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Ken;
I have never seen that damage on a GMCMH cross member. I have heard of that sort of damage to the K2500/K3500 cross members when they have the heavy duty TB and put a snow plow blade, or a V blade, which is heavier in weight, on the front. The ranchers can also do the damage with the front mounted cow/calf catch pens, especially going across the prairie hitting all the prairie dog mounds! I seem to think there was an upgrade on some of the GM models for this.
The engineers need to go for a ride with one of these guys some day!
If there are three cowboys riding in a pkup, who is the smartest?? (the middle guy, he doesn't have to open gates, and he can run the radio and the heater/AC)
Bob D
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| Re: [GMCnet] Torsion bar failure [message #158456 is a reply to message #158446] |
Sun, 29 January 2012 17:26 |
Mr ERFisher
Messages: 7117
Registered: August 2005
Karma: 2
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Senior Member |
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Yes
I think we need to be careful, with titles like this
we really do not have a big problem with the gmc torsion bars.
an intellectual discussion, but not a large problem to gmc owners.
most of us never looked at ride height, until, JerryW did the diy alignment.
now we all look ;>)
gene
On Sun, Jan 29, 2012 at 2:25 PM, Bob Drewes <bmdrewes@iw.net> wrote:
>
>
> midlf wrote on Sun, 29 January 2012 14:04
> > voodoolng wrote on Sun, 29 January 2012 13:29
> > > I have been junkyarding and found something interesting. When I pull
> the rear torsion bar cross memebers Iam finding 50% are cracked. In the
> area where the prokchop rest in the upper area of the cross member its
> cracked and breaking through. I had one member where it was cracked at both
> end. I have posted pictures of this area and the piece of support that has
> started to break through. Please check this area in your support for
> fatigue. Tim(voodoolng album)
> >
> >
> > Link:
> >
> >
> http://www.gmcmhphotos.com/photos/showphoto.php?photo=42548&title=cracked-rear-torsion-bar-housings-004&cat=5980
>
>
> I don't think the pic listed above is an OEM GMC MH cross member, it looks
> like from a K2500/K3500 pkup truck.
>
> Bob Drewes in SESD w/1-ton installed
>
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--
Gene Fisher -- 74-23,77PB/ore/ca
“Give a man a fish; you have fed him for today --- give him a URL and
-------
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| Re: [GMCnet] Torsion bar failure [message #158554 is a reply to message #158455] |
Mon, 30 January 2012 09:21 |
Bob de Kruyff
Messages: 4260
Registered: January 2004
Location: Chandler, AZ
Karma: 1
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Senior Member |
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""I seem to think there was an upgrade on some of the GM models for this.
The engineers need to go for a ride with one of these guys some day!
""
Good idea. We have full time fleets of various trucks in test/service at farms, plowing services, mines, military use as well as support at Baja functions.
Bob de Kruyff
78 Eleganza
Chandler, AZ
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| Re: [GMCnet] Torsion bar failure [message #158728 is a reply to message #158455] |
Tue, 31 January 2012 12:05 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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This just in from SuspensionMaxx:
" The rear crossmember on the GM HD 2500 and 3500 trucks have a
reinforcement on top of the torsion bar cam its a welded in strap.
1500s do not .
The GMC MH may develop these cracks over time, I dont think an
inspection should be overlooked during dis-assembly. Problem is if a
plate is added it would lower the TB bar and make it tougher to install the
MAXXCAM since we are tight as is. On top would be best and allow for
welding outside the crossmember channel."
IF I have occasion to remove my #4 crossmember again, I WILL weld a strap
across the top of the hump where the porkchop rests. Very likely not
needed, but with the increased load from the 1-Ton front end, there's no
use taking a chance.
The new adjustable pork chops modified for the GMC should be available
soon; JimK will have them as soon as they've been tested.
Ken H.
Americus, GA
'76 X-Birchaven w/Cad500/Howell EFI+ & EBL
www.gmcwipersetc.com
On Sun, Jan 29, 2012 at 6:28 PM, Bob Drewes wrote:
>
> I have never seen that damage on a GMCMH cross member. I have heard of
> that sort of damage to the K2500/K3500 cross members when they have the
> heavy duty TB and put a snow plow blade, or a V blade, which is heavier in
> weight, on the front. The ranchers can also do the damage with the front
> mounted cow/calf catch pens, especially going across the prairie hitting
> all the prairie dog mounds! I seem to think there was an upgrade on some of
> the GM models for this.
...
>
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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