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| Introduction and Question on Torsion Bars [message #285454] |
Thu, 20 August 2015 11:56  |
TR 1
Messages: 348
Registered: August 2015
Location: DFW
Karma: -7
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Senior Member |
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Hello, all. My name is Mark and our family just purchased a 73 Painted Desert. I've been reading this site and others before we purchased our coach, so I am somewhat familiar with the general workings, quirks, etc. of our coaches, but am still mostly new to GMCs and motorhomes in general. Ours is a mostly restored coach, but on the 1200 mile ride home, we did notice some issues. Some are now solved, (had a heck of a time with vapor lock on the Onan in the Texas heat (ended up doing a pusher pump on the fuel feed) and I had to rewire the dash HVAC fan circuit to run it on high) but this last one I am less familiar with and was hoping for some help/advice.
I've noticed the right front side of the coach in particular riding lower since the trip. (Rear appears to be normal) The other day, I jacked up the coach to inspect and maybe adjust the torsion bars, and while the left torsion bar adjuster is kind of in the middle, (where I assume it should be) the right side is completely maxed out. I'm not too familiar with t-bar suspension setups, but it seems to me like my right bar is failing, and I assume the previous owner compensated for this by maxing out the adjuster. There also appears to be a fairly pronounced curve in the right bar, whereas the left bar is mostly straight.
Am I right in thinking I have a failing torsion bar? I read that there is an option out there for an upgraded replacement bar (Huber bar?) but I am not sure they are available now, and with just buying the coach, I don't know that they would be within our budget right now, anyway. Other than used, are there any other replacement t-bar options available? If not going with new bars (which I would assume you would always want to replace in pairs), is replacing just the right side t-bar with a used one an option? Or should used bars be replaced in pairs as well? Also, I don't know that it matters, but our coach is running the Manny 1 ton front end.
Thanks in advance
Mark
Mark S. '73 Painted Desert,
Manny 1 Ton Front End,
Howell Injection,
Leigh Harrison 4bag and Rear Brakes,
Fort Worth, TX
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| Re: Introduction and Question on Torsion Bars [message #285455 is a reply to message #285454] |
Thu, 20 August 2015 12:18  |
A Hamilto
Messages: 4508
Registered: April 2011
Karma: 39
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Senior Member |
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TR 1 wrote on Thu, 20 August 2015 11:56Hello, all. My name is Mark and our family just purchased a 73 Painted Desert. I've been reading this site and others before we purchased our coach, so I am somewhat familiar with the general workings, quirks, etc. of our coaches, but am still mostly new to GMCs and motorhomes in general. Ours is a mostly restored coach, but on the 1200 mile ride home, we did notice some issues. Some are now solved, (had a heck of a time with vapor lock on the Onan in the Texas heat (ended up doing a pusher pump on the fuel feed) and I had to rewire the dash HVAC fan circuit to run it on high) but this last one I am less familiar with and was hoping for some help/advice.
I've noticed the right front side of the coach in particular riding lower since the trip. (Rear appears to be normal) The other day, I jacked up the coach to inspect and maybe adjust the torsion bars, and while the left torsion bar adjuster is kind of in the middle, (where I assume it should be) the right side is completely maxed out. I'm not too familiar with t-bar suspension setups, but it seems to me like my right bar is failing, and I assume the previous owner compensated for this by maxing out the adjuster. There also appears to be a fairly pronounced curve in the right bar, whereas the left bar is mostly straight.
Am I right in thinking I have a failing torsion bar? I read that there is an option out there for an upgraded replacement bar (Huber bar?) but I am not sure they are available now, and with just buying the coach, I don't know that they would be within our budget right now, anyway. Other than used, are there any other replacement t-bar options available? If not going with new bars (which I would assume you would always want to replace in pairs), is replacing just the right side t-bar with a used one an option? Or should used bars be replaced in pairs as well? Also, I don't know that it matters, but our coach is running the Manny 1 ton front end.
Thanks in advance
Mark Call Jim K. He can tell you what you need, and sell you the same. 1-800-752-7502 http://www.appliedgmc.com/
The Huber bars were a limited batch run and are gone.
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| Re: Introduction and Question on Torsion Bars [message #285457 is a reply to message #285454] |
Thu, 20 August 2015 12:48 |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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Senior Member |
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Just an opinion here, but I wouldn't see why the torsion bars would need to be replaced in pairs unless you were going with a completely different spring rate, such as in the Huber bars. They are independent of one another and are adjusted independently. I would guess there are a number of used torsion bare available in good condition as take-offs from people who replaced theirs with the new ones from Peter Huber. The 1-ton front end tends to increase the load on the factory bars by increasing the leverage on the arm due to the wheel spacers. Others have had issues with getting their coaches to proper ride height without changing the 'pork chops' to ones with different angles after installing the system. That is another option (different pork chops) but if the bar has a bend in it, I would think about replacing it with a good used one.
Another issue may be an imbalance on the rear ride height. If one of the air bags has too much pressure on it, it will increase the load on the opposite side front torsion bar. The overloaded torsion bar may also be trying to support more than it's share of the front end weight. The best way to measure this is to have each corner of the coach weighed. There should not be much of a difference from side to side, in the front or rear. My guess is that your right front wheel and your left rear wheels are going to weigh in at a substantial amount that the opposite corners.
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
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| Re: Introduction and Question on Torsion Bars [message #285469 is a reply to message #285464] |
Thu, 20 August 2015 16:03 |
TR 1
Messages: 348
Registered: August 2015
Location: DFW
Karma: -7
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Senior Member |
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Bullitthead wrote on Thu, 20 August 2015 14:41My right bar was curved and the coach was always low on the right, and the chop adjuster was already maxed out, so I replaced it with a used one. Thanks Chuck!  After I put the new one in(adjusted to the same pork chop position as the left one), it maintained the same front height as the old one but it was not curved. The right front still wanted to be low after settling. So before I unbalanced the adjustment to compensate, I decided to put the Onan and a humongous battery back in the left rear compartment (Onan was removed and replaced with batteries by the P.O.). Now the right front is at the same height as the left and it drives a little better, too.
Bullitthead: Only thing is I don't see how it could be a weight balance issue, as nothing has changed on the coach and it appears to be getting worse... The coach has fiberglass flares in the front, and I've noticed they seem to be rubbing on the tire more and more on sharp turns... FWIW, Onan is in place as well as the 2 coach bats in the rear compartment...
Carl S, I'll try to go through the rear suspension balancing procedures... And try to figure a place to get a 12,000 pound 6 wheel vehicle corner weighed, which I am guessing will not be easy...
A Hamilto: Yes, I'm planning to give applied a call on some other parts as well, so I will for sure ask about my torsion bar issue....
Mark S. '73 Painted Desert,
Manny 1 Ton Front End,
Howell Injection,
Leigh Harrison 4bag and Rear Brakes,
Fort Worth, TX
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| Re: Introduction and Question on Torsion Bars [message #285470 is a reply to message #285454] |
Thu, 20 August 2015 16:13 |
KB
Messages: 1262
Registered: September 2009
Karma: 0
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Senior Member |
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I know this sounds counter-intuitive, but before blaming the torsion bar, try setting the bolts
to the same number of turns. (you will need an unloader tool to adjust the porkchop bolts; you have to
take the load off the bolt or you risk stripping it out).
The problem is the rear suspension actively compensates so you end up with the front and rear
suspensions 'fighting' each other and the weight distribution gets thrown way off. This can get far
enough off to overload tires and affect handling. I'd wager that you'll find you need higher air pressure
in the bag on the opposite rear corner to compensate for the porkchop bolt that is maxed out (cranked all the way up),
and that if you weighed the front end, you'd find much higher weight on one side.
Eg, if your front right porkchop bolt is cranked all the way up, your left rear airbag will
need higher pressure to maintain correct ride height, and your right front tire will be overloaded.
When I got our coach, one side had the bolt cranked all the way up. When I installed the one-ton kit,
I dutifully re-installed that bolt the way I'd found it. I then spent the next year or two fighting
to try and get the ride height correct, and even resorted to a longer bolt at one point. Always had
to put way more air pressure in the opposite rear corner, and it seemed like the more I tried to get
the ride height correct, the worse the handling got.
Then one day I read a lengthy exchange here on the forum on the topic, and decided to try setting the
porkchop bolts to exactly the same number of turns. Amazingly, after I did that, the front height was equal,
the rear airbags required about the same pressure, and best of all, the handling improved dramatically.
May not work in your case, but cheap to try.
Karen
1975 26'
[Updated on: Thu, 20 August 2015 16:15] Report message to a moderator |
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| Re: Introduction and Question on Torsion Bars [message #285475 is a reply to message #285454] |
Thu, 20 August 2015 17:39 |
Rick Williams
Messages: 256
Registered: July 2004
Karma: 0
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Senior Member |
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Hi Mark
Welcome to the GMCnet and congratulations on finding your coach. My coach was severely out of balance when I purchased it. One adjuster was in most of the way and the other was out. The air bags had 10 or 15 lbs difference and the passenger front wheel weight was 700 lbs more than the driver side.
You need to start at the beginning and set the ride heights. There must be several written procedures on here as well as in manual. I think there are at least as many methods as there are Kens on this site. Someone will probably point you to one. If your air bags do not have schrader valves, do that first. It is a convenient way to add air and check pressure. You will need to eventually weigh each front wheel separately. State Police Motor Carrier officers have portable scales. It is interesting to know the weight of each wheel before you start. It is even better if you have scales available during the procedure but not absolutely necessary. When you are finished, if the ride heights are on, the air bags are close in pressure and the adjusters are nearly the same, the weight on each front wheel should be close. But do get it weighed. It is valuable information. As mentioned earlier, you need an unloader for the adjusters. Do not attempt it without one. If you can not get the ride heights close then you may need to look at the pork chop or the torsion bar. Ask as many questions as you like.
Rick
Rick Williams
Bliss, Michigan
1978 Eleganza II
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| Re: Introduction and Question on Torsion Bars [message #285481 is a reply to message #285454] |
Thu, 20 August 2015 18:24 |
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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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Mark,
Welcome to the group, family, cult, asylum....
If you do not have the whole set of manuals, they can be downloaded at Bdub's page.
You sound like you have most of the issues well in hand.
Did you know that the cab fan is only supposed to run on high with the engine running? That is to keep it from killing the battery.
Do us that might like to assist you a favor. Go to the control panel/account settings and fill in a more complete sigfile. It should have your real name (so when we meet we know who you are), a short line about the coach, year and serious mods can make a difference, and a geographic reference so a person that might like to help will know if you are in striking range. Most of that is in this post if one chooses to hunt it up, but this will probably not be your last post.
Speaking of... Your coach is a 73, if it still has points in the distributor and you don't feel like buying an HEI and hammering the air filter housing, get the Pertronix kit. Put it in, time it and forget it. I made this and another suggestion to a new owner of a 73 - Buy a grease gun and a tube of Valvoline SynPower (8$) and try your best to over grease the bogies. 73&4 have smaller pins and a less than best practice lube arrangement. Greasing every 1K is not over doing.
GMC motorhomes have a huge presence on Facebook, this is both good and bad. It is a great social network, but many of those offering advice do not have as much experience as some that are here. Before you do or buy anything, as here first.
Lastly, but not least by any means, you are now a part of a virtual community like few others. These people will offer help just because they can. I am a waterman, and this reminds me so much of that world, that I have chosen to welcome new members much as a new vessel or owner would be welcomed there. So,
May the Good Lord bless this coach and all those that set forth within her.
Welcome Mark,
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] Introduction and Question on Torsion Bars [message #285527 is a reply to message #285469] |
Fri, 21 August 2015 08:22 |
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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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Mark,
You can weigh a GMC at a CAT scale and get the weights on the front right, front left, rear right and rear left.
Cat scales have three pads:
1) The front pad weighs the prime mover
2) The second pad weighs the first trailer
3) The third pad weighs the second trailer
Find a CAT scale that is not too busy and go in and speak to the operator. Tell them that you have a motorhome and you want to weigh
it a number of times. You will be using the second and third pads because you need the weights for the left and right sides and to
do that you'll have to pull one set of wheels off the scales to the right or left depending on which side you want to weigh. That
means they will not be able to communicate with you through the normal speaker / mike located adjacent to the front pad. Ask them
for a cell phone number you can call them on. They will charge you for multiple weights but IIRC the whole job is less than $20.
Once you have made the arrangements go out and pull your GMC on the scales so that the front wheels are sitting on the second pad
and the rear wheels are sitting on the third pad. Call the scale operator and ask them to weigh the GMC. This will give you the
total weight on the front and rear axles of the GMC.
Back off the scales and pull back on with the driver side wheels on the concrete off the scale and the wheels on the second and
third pads are as close to center of the pads as possible. Call the scale operator and ask them to weigh the GMC. This will give you
the weight on the front and rear passenger side wheels.
Back off the scales and pull back on with the passenger side wheels on the concrete off the scale and the wheels on the second and
third pads are as close to center of the pads as possible. Call the scale operator and ask them to weigh the GMC. This will give you
the weight on the front and rear driver side wheels.
I have done this a number of times at different CAT scales. CAT scales are extremely accurate and when you add up the different
weights that the scale operator will give you they WILL make 100% sense.
If what I have described above is not clear I'll be happy to explain further.
Regards,
Rob M.
The Pedantic Mechanic
-----Original Message-----
From: Mark Sawyer
Bullitthead: Only thing is I don't see how it could be a weight balance issue, as nothing has changed on the coach and it appears
to be getting worse... The coach has fiberglass flares in the front, and I've noticed they seem to be rubbing on the tire more and
more on sharp turns... FWIW, Onan is in place as well as the 2 coach bats in the rear compartment...
Carl S, I'll try to go through the rear suspension balancing procedures... And try to figure a place to get a 12,000 pound 6 wheel
vehicle corner weighed, which I am guessing will not be easy...
A Hamilto: Yes, I'm planning to give applied a call on some other parts as well, so I will for sure ask about my torsion bar
issue....
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GMCnet mailing list
Unsubscribe or Change List Options:
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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] Introduction and Question on Torsion Bars [message #285535 is a reply to message #285527] |
Fri, 21 August 2015 09:39 |
Mr ERFisher
Messages: 7117
Registered: August 2005
Karma: 2
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Senior Member |
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On Friday, August 21, 2015, Robert Mueller wrote:
> Mark,
>
> You can weigh a GMC at a CAT scale and get the weights on the front right,
> front left, rear right and rear left.
>
>
They are free in organ, when the truck scale is closed on a highway
Erf
> Cat scales have three pads:
>
> 1) The front pad weighs the prime mover
> 2) The second pad weighs the first trailer
> 3) The third pad weighs the second trailer
>
> Find a CAT scale that is not too busy and go in and speak to the operator.
> Tell them that you have a motorhome and you want to weigh
> it a number of times. You will be using the second and third pads because
> you need the weights for the left and right sides and to
> do that you'll have to pull one set of wheels off the scales to the right
> or left depending on which side you want to weigh. That
> means they will not be able to communicate with you through the normal
> speaker / mike located adjacent to the front pad. Ask them
> for a cell phone number you can call them on. They will charge you for
> multiple weights but IIRC the whole job is less than $20.
>
> Once you have made the arrangements go out and pull your GMC on the scales
> so that the front wheels are sitting on the second pad
> and the rear wheels are sitting on the third pad. Call the scale operator
> and ask them to weigh the GMC. This will give you the
> total weight on the front and rear axles of the GMC.
>
> Back off the scales and pull back on with the driver side wheels on the
> concrete off the scale and the wheels on the second and
> third pads are as close to center of the pads as possible. Call the scale
> operator and ask them to weigh the GMC. This will give you
> the weight on the front and rear passenger side wheels.
>
> Back off the scales and pull back on with the passenger side wheels on the
> concrete off the scale and the wheels on the second and
> third pads are as close to center of the pads as possible. Call the scale
> operator and ask them to weigh the GMC. This will give you
> the weight on the front and rear driver side wheels.
>
> I have done this a number of times at different CAT scales. CAT scales are
> extremely accurate and when you add up the different
> weights that the scale operator will give you they WILL make 100% sense.
>
> If what I have described above is not clear I'll be happy to explain
> further.
>
> Regards,
> Rob M.
> The Pedantic Mechanic
>
>
> -----Original Message-----
> From: Mark Sawyer
>
> Bullitthead: Only thing is I don't see how it could be a weight balance
> issue, as nothing has changed on the coach and it appears
> to be getting worse... The coach has fiberglass flares in the front, and
> I've noticed they seem to be rubbing on the tire more and
> more on sharp turns... FWIW, Onan is in place as well as the 2 coach bats
> in the rear compartment...
>
> Carl S, I'll try to go through the rear suspension balancing
> procedures... And try to figure a place to get a 12,000 pound 6 wheel
> vehicle corner weighed, which I am guessing will not be easy...
>
> A Hamilto: Yes, I'm planning to give applied a call on some other parts as
> well, so I will for sure ask about my torsion bar
> issue....
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
--
Gene Fisher -- 74-23,77PB/ore/ca
“Give a man a fish; you have fed him for today --- give him a URL and
-------
http://gmcmotorhome.info/
Alternator Protection Cable
http://gmcmotorhome.info/APC.html
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| Re: Introduction and Question on Torsion Bars [message #285738 is a reply to message #285454] |
Mon, 24 August 2015 11:27 |
TR 1
Messages: 348
Registered: August 2015
Location: DFW
Karma: -7
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Senior Member |
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Thanks to everyone for the warm welcome and all the advice. I think my next course of action is:
1. Verify ride-height is set correctly using one of the established procedures
2. Corner weight the rig
3. Re-evaluate torsion bar and go from there.
Thank you all again!
Mark S. '73 Painted Desert,
Manny 1 Ton Front End,
Howell Injection,
Leigh Harrison 4bag and Rear Brakes,
Fort Worth, TX
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