Home » Public Forums » GMCnet » weight effect on steering
| weight effect on steering [message #195457] |
Sun, 13 January 2013 15:45  |
skip2
Messages: 544
Registered: September 2011
Location: Winter Haven,FL (center o...
Karma: 3
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Been tightening up my steering and thought I had it pretty well worked out with some items and ideals from Mr. Lenzi and I noticed when my fuel got below half it would go back to it's old habits of trying to wander and wheel had to be to the right a little to go straight. It drove very well with full fuel tank to just above half. Left the campground with about 3/4 black tank because cable guy was blocking dump site, but that weight to the rear didn't make any difference. Couldn't fill up fuel completely, nonethanol pump didn't work today, so put in only 10 gallons, 60lbs, and that little bit made the steering clean up and wheel was back to dead center when straight ahead. Had this with previous SOB but it got better when fuel got below 1/2 tank. It's tank was behind the axle.
I've got the air bag valves on travel and it seems to be counteracting weight changes, you can put my 200+ on one side or the other and you can hear the air flowing through the valves and the gauges on the dash show the pressure change.
Honest, I'm not hallucinating.
Any ideals, no matter how far out, would be appreciated.
Also learned today with the mark/sully airbag setup(I built my own brackets, did not get from sully)You can collapse a bag so far that it will collapse into itself and block the inlet so you have to jack up the bogie to uncover inlet and let the air in.
Skip Hartline
74 Canyon Lands, FiTech,
3.7 FD LSD, Manny Tranny,
Springfield Distributor,
2001 Chevy Tracker Ragtop Towd
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| Re: [GMCnet] weight effect on steering [message #195485 is a reply to message #195457] |
Mon, 14 January 2013 06:42  |
jayrabe
Messages: 509
Registered: June 2009
Location: Portland, OR
Karma: 0
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From recent experience with a new quad-bag install that left me with rear ride height up too high, I can confirm that handling in that situation is very poor. Try manually lowering the rear ride height when you're below 1/2 tank of fuel.
Jay Rabe 76 PB Portland, OR
> To: gmclist@temp.gmcnet.org
> From: skiphartline@aol.com
> Date: Sun, 13 Jan 2013 15:45:40 -0600
> Subject: [GMCnet] weight effect on steering
>
>
>
> Been tightening up my steering and thought I had it pretty well worked out with some items and ideals from Mr. Lenzi and I noticed when my fuel got below half it would go back to it's old habits of trying to wander and wheel had to be to the right a little to go straight. It drove very well with full fuel tank to just above half. Left the campground with about 3/4 black tank because cable guy was blocking dump site, but that weight to the rear didn't make any difference. Couldn't fill up fuel completely, nonethanol pump didn't work today, so put in only 10 gallons, 60lbs, and that little bit made the steering clean up and wheel was back to dead center when straight ahead. Had this with previous SOB but it got better when fuel got below 1/2 tank. It's tank was behind the axle.
> I've got the air bag valves on travel and it seems to be counteracting weight changes, you can put my 200+ on one side or the other and you can hear the air flowing through the valves and the gauges on the dash show the pressure change.
> Honest, I'm not hallucinating.
> Any ideals, no matter how far out, would be appreciated.
> Also learned today with the mark/sully airbag setup(I built my own brackets, did not get from sully)You can collapse a bag so far that it will collapse into itself and block the inlet so you have to jack up the bogie to uncover inlet and let the air in.
> Skip Hartline
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| Re: weight effect on steering [message #195497 is a reply to message #195457] |
Mon, 14 January 2013 09:34 |
habbyguy
Messages: 896
Registered: May 2012
Location: Mesa, AZ
Karma: 3
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Rob's point is a good one. If your auto-level system is working correctly, the rear of the coach will be at the right height all the time.
Of course, it is possible to fine-tune the level of your coach on the road using manual adjustment. I know the ride height on the rear of my coach is a little high, which I suspect was done by the PO to compensate for the rear chassis rollers he installed (which stick down quite a bit under the rear frame rails, and would drag a whole lot at the normal "low" ride height). My solution is simply to set the coach at "auto" around town, or when I'm getting ready to gas up, so I don't drag the rollers. At low non-interstate speeds, the ride and handling is perfectly fine this way. Then when I get on the open road again, I put the leveling system in manual and lower the rear manually (I've calculated about how long it takes for the bags to air down appropriately). I could always set the "auto" for the lower "correct" ride height, and manually raise the pressure when I need it, but it's so much quicker to air the system down than it is up that I prefer it the way I do it.
It's also kind of fun to be able to "adjust my headlights" by manipulating the air bag pressure. Give a car geek extra switches to play with, and you see what happens... 
Mark Hickey
Mesa, AZ
1978 Royale Center Kitchen
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| Re: [GMCnet] weight effect on steering [message #195499 is a reply to message #195497] |
Mon, 14 January 2013 09:55 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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If you guys insist on constantly adjusting your ride height, it tells me
that you must be unsatisfied with the way your coach is handling. Please
go to the trouble of either adjusting the height control valves on the rear
suspension, or have someone who knows what they are doing perform this
task. Then, and only then, check the front torsion bar adjustments. Use
the slotted holes in the frame, and get it within + or- 1/4". Then drive
your coach and see what you have. If you don't follow this procedure you
will not have a foundation to measure from. Based on personal experience
with many coaches over years of practice, I find that it takes longer to
get the ride height correct, than it does to align a coach. When these
coaches are right, they really do drive well. But they still weigh over
10,000 pounds. They are not a sports car. Nimble for a motorhome, but not
for a late model Corvette.
Jim Hupy
Salem,Or
78 Gmc Royale 403
On Jan 14, 2013 7:35 AM, "Mark" <mark@habcycles.com> wrote:
>
>
> Rob's point is a good one. If your auto-level system is working
> correctly, the rear of the coach will be at the right height all the time.
>
> Of course, it is possible to fine-tune the level of your coach on the road
> using manual adjustment. I know the ride height on the rear of my coach is
> a little high, which I suspect was done by the PO to compensate for the
> rear chassis rollers he installed (which stick down quite a bit under the
> rear frame rails, and would drag a whole lot at the normal "low" ride
> height). My solution is simply to set the coach at "auto" around town, or
> when I'm getting ready to gas up, so I don't drag the rollers. At low
> non-interstate speeds, the ride and handling is perfectly fine this way.
> Then when I get on the open road again, I put the leveling system in
> manual and lower the rear manually (I've calculated about how long it takes
> for the bags to air down appropriately). I could always set the "auto" for
> the lower "correct" ride height, and manually raise the pressure when I
> need it, but it's so much quicker to air the system down than it is up that
> I prefer it the way I do it.
>
> It's also kind of fun to be able to "adjust my headlights" by manipulating
> the air bag pressure. Give a car geek extra switches to play with, and you
> see what happens... :lol:
> --
> Mark Hickey
> Mesa, AZ
> 1978 Royale Center Kitchen
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
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| Re: [GMCnet] weight effect on steering [message #195504 is a reply to message #195488] |
Mon, 14 January 2013 10:16 |
jayrabe
Messages: 509
Registered: June 2009
Location: Portland, OR
Karma: 0
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You're exactly right. But if he runs in auto, and handling changes when his gas tank is 1/2 empty, it suggests to me that his auto ride height system is NOT working correctly, and he could test/check that by manually adjusting rear height to see if things improved. Just data collection, not a proposal for long-term fix. Jay Rabe 76 PB Portland, OR
> From: robmueller@iinet.net.au
> To: gmclist@temp.gmcnet.org
> Date: Tue, 15 Jan 2013 00:30:41 +1100
> Subject: Re: [GMCnet] weight effect on steering
>
> Skip / Jay,
>
> I'm confused! If you set the front and rear ride height re the MM and the rear ride height system is working properly why would you
> have to set it manually?
>
> Regards,
> Rob M.
> USAussie - Downunder
> AUS '75 Avion - The Blue Streak TZE365V100428
> USA '75 Avion - Double Trouble TZE365V100426
>
>
>
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| Re: [GMCnet] weight effect on steering [message #195505 is a reply to message #195504] |
Mon, 14 January 2013 10:26 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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Jay, it seem to me that I read that he has Sullybags with his own end plate
adapters. I have not seen his set up, but I have seen Todd's setup. His
(Todd's) bags only carry 35-40 psi on the coach I am familiar with to be at
correct ride height in the rear. A full tank of gasoline, depending on the
alcohol blend weighs around 400 pounds, more or less. Is that enough to
affect steering and ride with those bags? I don't have enough information
to say for sure, so at best this is a SWAG. If his system functions
correctly in auto, it SHOULD respond to changes is load of this magnitude,
but ??? Perhaps the Jury is still out on this one.
Jim Hupy
Salem, OR
78 GMC Royale 403
On Mon, Jan 14, 2013 at 8:16 AM, Jay Rabe <jayrabe@hotmail.com> wrote:
>
> You're exactly right. But if he runs in auto, and handling changes when
> his gas tank is 1/2 empty, it suggests to me that his auto ride height
> system is NOT working correctly, and he could test/check that by manually
> adjusting rear height to see if things improved. Just data collection, not
> a proposal for long-term fix. Jay Rabe 76 PB Portland, OR
> > From: robmueller@iinet.net.au
> > To: gmclist@temp.gmcnet.org
> > Date: Tue, 15 Jan 2013 00:30:41 +1100
> > Subject: Re: [GMCnet] weight effect on steering
> >
> > Skip / Jay,
> >
> > I'm confused! If you set the front and rear ride height re the MM and
> the rear ride height system is working properly why would you
> > have to set it manually?
> >
> > Regards,
> > Rob M.
> > USAussie - Downunder
> > AUS '75 Avion - The Blue Streak TZE365V100428
> > USA '75 Avion - Double Trouble TZE365V100426
> >
> >
> >
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> > http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
> _______________________________________________
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| Re: [GMCnet] weight effect on steering [message #195525 is a reply to message #195505] |
Mon, 14 January 2013 14:04 |
skip2
Messages: 544
Registered: September 2011
Location: Winter Haven,FL (center o...
Karma: 3
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Senior Member |
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Yes, I have the sully bag setup, I built the plates from the original specs when they were on the forum. I run around 40 psi in normal situations. Another quick question, isn't there a formula for how much one thread on the torsion bar bolt is worth on heigth?
Thanks for all the comments and suggestions
Could be the auto level is off because most of this started when I started using the travel mode instead of closing the valves and locking the bags down.
Skip Hartline
74 Canyon Lands, FiTech,
3.7 FD LSD, Manny Tranny,
Springfield Distributor,
2001 Chevy Tracker Ragtop Towd
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| Re: weight effect on steering [message #195536 is a reply to message #195457] |
Mon, 14 January 2013 15:48 |
bwevers
Messages: 597
Registered: October 2010
Location: San Jose
Karma: 5
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Senior Member |
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Just a thought, the spring rate is much lower with the
big airbags, only 40PSI pressure. There's less roll stiffness in
the rear than on the stock suspension.
Regards,
Bill
Bill Wevers GMC49ers, GMC Western States
1975 Glenbrook - Manny Powerdrive, OneTon
455 F Block, G heads
San Jose
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| Re: [GMCnet] weight effect on steering [message #195574 is a reply to message #195536] |
Tue, 15 January 2013 00:21 |
sgltrac
Messages: 2797
Registered: April 2011
Karma: 1
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Senior Member |
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Actually Bill if when you say roll you mean body roll as in transition of weight and therefore lean of the body in response to a turn input it has been observed by myself and reported by others that body roll is actually decreased with the Sullybilt rear suspension in comparison to the oem set up.
Sully
77 royale
Seattle.
Sent from my iPhone
On Jan 14, 2013, at 1:48 PM, Bill Wevers <gmc1975@att.net> wrote:
>
>
> Just a thought, the spring rate is much lower with the
> big airbags, only 40PSI pressure. There's less roll stiffness in
> the rear than on the stock suspension.
>
> Regards,
> Bill
> _______________________________________________
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Sully
77 Royale basket case.
Future motorhome land speed record holder(bucket list)
Seattle, Wa.
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