Home » Public Forums » GMCnet » [GMCnet] 1 ton added load on theTorsion Bars, A frames, and pork chops
| [GMCnet] 1 ton added load on theTorsion Bars, A frames, and pork chops [message #285512] |
Fri, 21 August 2015 00:18  |
BobDunahugh
Messages: 2465
Registered: October 2010
Location: Cedar Rapids, IA
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A friend that put the 1 ton unit in his GMC. Had one of his torsion bars break. So I gave him one of the extra bars that I had. That got me thinking again. I didn't measure the distance. But that unit, and the wheel spacers have to increase the load on the bar, pork chop, and A frame. And I've had a pork chop break with my stock front end. Seems to me that the load would have to be in the 15% range at the most. Anyone checked that out?B ob Dunahugh78 Royale
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| Re: [GMCnet] 1 ton added load on theTorsion Bars, A frames, and pork chops [message #285563 is a reply to message #285512] |
Fri, 21 August 2015 22:01  |
habbyguy
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It occurs to me that the amount of lift (at the coach) generated by running over a given object will also be proportionally less with a wider wheel track, offsetting the leverage "advantage" pretty much entirely.
It might help to think in terms of running over a 2x4 with a "normal" GMC, and one with axles 10 feet long... the second one would hardly affect the coach (and therefore, torsion bar) at all.
It's true that slamming into something that maxes out the suspension will be worse with the longer axles, but... c'mon... how often is THAT gonna happen?
Mark Hickey
Mesa, AZ
1978 Royale Center Kitchen
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| Re: [GMCnet] 1 ton added load on theTorsion Bars, A frames, and pork chops [message #285578 is a reply to message #285577] |
Sat, 22 August 2015 07:59 |
Joe Weir
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Location: Columbia, SC
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I am not an engineer, so bear with me.
The suspension arms have limits of travel, so while the end of the "lever" may be 2-3" longer with spacers, the torsion bar twists the same distance either way, no? If anything, the torsion bar twists less for the same amount of vertical travel at the end of the lever.
Edit - Nevermind. I get it now. Thats what I get for posting before coffee.
76 Birchaven - "Wicked Mistress" - New engine, trans, alum radiator, brakes, Sully airbags, fuel lines, seats, adult beverage center... those Coachmen guys were really thinking about us second hand owners by including that beverage center...
Columbia, SC.
[Updated on: Sat, 22 August 2015 08:07] Report message to a moderator |
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| Re: [GMCnet] 1 ton added load on theTorsion Bars, A frames, and pork chops [message #285579 is a reply to message #285563] |
Sat, 22 August 2015 08:07 |
GMC.LES
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Registered: April 2014
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Here is my simple thinking on the subject.
On a set of scales, would the individual front wheels apply less vehicle weight to the road surface with a 1 ton setup over a stock setup? No. The weights would be the same.
So if the vehicle weights are the same, but applied over a longer lever(wider wheel track), the forces applied at the torsion bar will be higher. If the lever is 10% longer, the forces at the torsion bar should also be ~10% higher.
How does all this affect ride quality and suspension performance? I'll leave that part of the discussion for the rest of you to banter about :)
Les Burt
Montreal
'75 Eleganza 26'
The EWIP (Eternal Work In Progress)
> On Aug 21, 2015, at 11:01 PM, Mark wrote:
>
> It occurs to me that the amount of lift (at the coach) generated by running over a given object will also be proportionally less with a wider wheel
> track, offsetting the leverage "advantage" pretty much entirely.
>
> It might help to think in terms of running over a 2x4 with a "normal" GMC, and one with axles 10 feet long... the second one would hardly affect the
> coach (and therefore, torsion bar) at all.
>
> It's true that slamming into something that maxes out the suspension will be worse with the longer axles, but... c'mon... how often is THAT gonna
> happen?
> --
> Mark Hickey
> Mesa, AZ
> 1978 Royale Center Kitchen
>
> _______________________________________________
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| Re: [GMCnet] 1 ton added load on theTorsion Bars, A frames, and pork chops [message #285583 is a reply to message #285579] |
Sat, 22 August 2015 09:56 |
habbyguy
Messages: 896
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Les Burt[1 wrote on Sat, 22 August 2015 06:07]So if the vehicle weights are the same, but applied over a longer lever(wider wheel track), the forces applied at the torsion bar will be higher. If the lever is 10% longer, the forces at the torsion bar should also be ~10% higher.
The missing piece of this puzzle is that if your lever is 10% longer, then applying a given amount of lift (inches, not pounds) at one end will result in a smaller angular deflection of the axle than the shorter lever. Lift one end of a pencil 1", and then lift one end of a broomstick 1" to visualize the difference.
Yes, the lever arm is longer and - at a given ANGLE of deflection - applies more torque to the torsion bar. But unless the bumps you hit with your one ton front end are 10% bigger than they used to be with the stock front end, the torsion bar won't know the difference between your stock coach or one with the one ton front end, at least in relation to bumps. I'm thinking the static loading on the torsion bars would by that 10% though... but I was more concerned about the dynamic loading (which dramatically increases the forces at the torsion bars).
Mark Hickey
Mesa, AZ
1978 Royale Center Kitchen
[Updated on: Sat, 22 August 2015 10:16] Report message to a moderator |
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| Re: [GMCnet] 1 ton added load on theTorsion Bars, A frames, and pork chops [message #285591 is a reply to message #285583] |
Sat, 22 August 2015 11:20 |
GMC.LES
Messages: 505
Registered: April 2014
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My understanding is this:
1) Assuming that the suspension moves the exact same amount with both setups. When the suspension encounters road obstacles, the forces applied to the torsion bar should be the same EXCEPT that in the one ton, the bar must perform it's duties in a smaller angular arc. This would require a stiffer bar to equal the performance of the oem setup.
2) In reality, if the bar was the same in both setups, the 1ton should experience slightly more suspension travel for a given road oscillation due to the longer lever. I believe this has been reported by several who have upgraded.
3) The above is based on the effects of spring rate, which also applies to torsion bars. Increasing spring rate delivers the same resistance in a shorter travel, or a higher resistance for the same travel. Travel for a torsion bar would be in degrees of angular deflection.
Since I do not have a running coach with 1 ton or HD bars, Nor do I have any degree of any kind, I have no specific experience with this other than what I have gathered through my working career.
Les Burt
Montreal
'75 Eleganza 26'
The EWIP (Eternal Work In Progress)
>
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| Re: [GMCnet] 1 ton added load on theTorsion Bars, A frames, and pork chops [message #285595 is a reply to message #285591] |
Sat, 22 August 2015 12:25 |
emerystora
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1. why would the suspension move the exact same amount with both setups? If you go over a bump or pothole I would think that with a longer lever the angular twist would be less so the suspension would move less that it would with a shorter arm.
If this is correct then the other assumptions you have made are incorrect.
If I am wrong in 1 above then please help me to understand.
Emery Stora
77 Kingsley
Frederick, CO
> On Aug 22, 2015, at 10:20 AM, Les Burt wrote:
>
> My understanding is this:
>
> 1) Assuming that the suspension moves the exact same amount with both setups. When the suspension encounters road obstacles, the forces applied to the torsion bar should be the same EXCEPT that in the one ton, the bar must perform it's duties in a smaller angular arc. This would require a stiffer bar to equal the performance of the oem setup.
>
> 2) In reality, if the bar was the same in both setups, the 1ton should experience slightly more suspension travel for a given road oscillation due to the longer lever. I believe this has been reported by several who have upgraded.
>
> 3) The above is based on the effects of spring rate, which also applies to torsion bars. Increasing spring rate delivers the same resistance in a shorter travel, or a higher resistance for the same travel. Travel for a torsion bar would be in degrees of angular deflection.
>
> Since I do not have a running coach with 1 ton or HD bars, Nor do I have any degree of any kind, I have no specific experience with this other than what I have gathered through my working career.
>
>
>
> Les Burt
> Montreal
> '75 Eleganza 26'
> The EWIP (Eternal Work In Progress)
>>
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| Re: [GMCnet] 1 ton added load on theTorsion Bars, A frames, and pork chops [message #285643 is a reply to message #285583] |
Sun, 23 August 2015 01:33 |
James Hupy
Messages: 6806
Registered: May 2010
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Wear points on the stock front end include, but are not limited to, brake
pads and rotors, lower control arm ball joints, upper and lower control arm
bushings, wheel bearings, hubs and knuckles, tie rod ends and the list
goes on. The 1 ton erases the hub and knuckle problem, upgrades the brake
and ease of replacing the rotors and gives you a 100 thousand mile no
maintenance wheel bearing. Unless you just love getting greasy repacking
and servicing your front wheel bearings every 25 thousand miles or so, it
is a no brainer. To say nothing of cost. 1 ton is cheaper by quite a bit
than replacing the same parts in a stock front end. But, as Jim Bounds is
fond of saying, "Hey, this is America, and it's your money. Spend it how
you want to".
Jim Hupy
Salem, Or ( presently on a Rhine river cruise with a bunch of GMCers)
On Aug 22, 2015 4:57 PM, "Mark" wrote:
> Les Burt[1
>> wrote on Sat, 22 August 2015 06:07]So if the vehicle weights are the
> same, but applied over a longer lever(wider wheel track), the forces applied
>> at the torsion bar will be higher. If the lever is 10% longer, the
> forces at the torsion bar should also be ~10% higher.
>
> The missing piece of this puzzle is that if your lever is 10% longer, then
> applying a given amount of lift (inches, not pounds) at one end will result
> in a smaller angular deflection of the axle than the shorter lever. Lift
> one end of a pencil 1", and then lift one end of a broomstick 1" to
> visualize the difference.
>
> Yes, the lever arm is longer and - at a given ANGLE of deflection -
> applies more torque to the torsion bar. But unless the bumps you hit with
> your
> one ton front end are 10% bigger than they used to be with the stock front
> end, the torsion bar won't know the difference between your stock coach or
> one with the one ton front end.
>
> --
> Mark Hickey
> Mesa, AZ
> 1978 Royale Center Kitchen
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
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| Re: [GMCnet] 1 ton added load on theTorsion Bars, A frames, and pork chops [message #285656 is a reply to message #285652] |
Sun, 23 August 2015 11:42 |
Joe Weir
Messages: 769
Registered: February 2013
Location: Columbia, SC
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Yes.
The one ton itself is not the issue, it is that it requires the use of the spacers for the stock style wheels, thereby moving the wheel outboard by 2-something inches and increasing the length of the "lever" on the torsion bar.
Using spacers on the stock suspension does the same thing.
76 Birchaven - "Wicked Mistress" - New engine, trans, alum radiator, brakes, Sully airbags, fuel lines, seats, adult beverage center... those Coachmen guys were really thinking about us second hand owners by including that beverage center...
Columbia, SC.
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| Re: [GMCnet] 1 ton added load on theTorsion Bars, A frames, and pork chops [message #285675 is a reply to message #285512] |
Sun, 23 August 2015 18:14 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
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Old rule of thumb - never buy a Beetle which has reversed rims - they would eat axle bearings. The Super Beetle didn't seem to suffer that way. Nor dune buggies, probably due to the much reduced weight.
--johnny
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: [GMCnet] 1 ton added load on theTorsion Bars, A frames, and pork chops [message #285707 is a reply to message #285656] |
Mon, 24 August 2015 03:28 |
James Hupy
Messages: 6806
Registered: May 2010
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Not correct. The aluminum spacers used on the 1 ton are a replacement for
the cast iron 40 lb. spacers that GM used when their trucks and big vans
are fitted with 16's.
Jim Hupy
On Aug 23, 2015 6:42 PM, "Joe Weir" wrote:
> Yes.
>
> The one ton itself is not the issue, it is that it requires the use of the
> spacers for the stock style wheels, thereby moving the wheel outboard by
> 2-something inches and increasing the length of the "lever" on the
> torsion bar.
>
> Using spacers on the stock suspension does the same thing.
> --
> 76 Birchaven - "Wicked Mistress" - New engine, trans, alum radiator,
> brakes, Sully airbags, fuel lines, seats, adult beverage center... those
> Coachmen
> guys were really thinking about us second hand owners by including that
> beverage center...
> Columbia, SC.
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
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| Re: [GMCnet] 1 ton added load on theTorsion Bars, A frames, and pork chops [message #285720 is a reply to message #285707] |
Mon, 24 August 2015 09:03 |
Mr ERFisher
Messages: 7117
Registered: August 2005
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Read here
http://gmcmotorhome.info/front.html
On Monday, August 24, 2015, James Hupy wrote:
> Not correct. The aluminum spacers used on the 1 ton are a replacement for
> the cast iron 40 lb. spacers that GM used when their trucks and big vans
> are fitted with 16's.
> Jim Hupy
> On Aug 23, 2015 6:42 PM, "Joe Weir"
> wrote:
>
>> Yes.
>>
>> The one ton itself is not the issue, it is that it requires the use of
> the
>> spacers for the stock style wheels, thereby moving the wheel outboard by
>> 2-something inches and increasing the length of the "lever" on the
>> torsion bar.
>>
>> Using spacers on the stock suspension does the same thing.
>> --
>> 76 Birchaven - "Wicked Mistress" - New engine, trans, alum radiator,
>> brakes, Sully airbags, fuel lines, seats, adult beverage center... those
>> Coachmen
>> guys were really thinking about us second hand owners by including that
>> beverage center...
>> Columbia, SC.
>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>>
> _______________________________________________
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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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