Home » Public Forums » GMCnet » Alignment-Height Setting (And alignment math)
| Alignment-Height Setting [message #78669] |
Wed, 31 March 2010 06:14  |
g.winger
Messages: 792
Registered: February 2008
Location: Warrenton,Missouri
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Ok, I have the same problem that was posted a month or two ago,,,, about to run out of adjustment on the left side but plenty of threads left on the rite. Had trouble getting it to respond to changes though, would jack it up, set 2 stands, istall tool,,make adjustment,,,reverse. Spent 1/2 a day sunday with very poor results. Had the rear set to the proper height and on blocks so it would be safe. Problem was,,,,, the front tires would stick and it would stay very high. So I put two pieces of tough 1/8 inch plastic w/grease between them under each wheel. WOW,,,what a diffrence that made. Totally changes things. With the left a little low I got it adj. to 1/4 degree of camber on each side and 4 d. caster on the rite,,,2 3/4 left. Am going to get a little more on the left and then drive it a couple miles and check it again. Confused on the adj. screws though???? Any thoughts,,,,{double checked,,,bars in corectly,,left and right,,,letters to the rear. thinking of reversing the left} Thanks,,,,PL
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| Re: [GMCnet] Alignment-Height Setting [message #78671 is a reply to message #78669] |
Wed, 31 March 2010 06:39  |
Steven Ferguson
Messages: 3447
Registered: May 2006
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Paul,
By reversing the bars I take it you mean front to back vice side to
side? The RH and LH bars cannot be interchanged.
That's a good tip about using a "live" surface under the front tires
while adjusting the ride height.
You can get a longer adjusting bolt (G8) and radius the head. It is
done often.
On Wed, Mar 31, 2010 at 4:14 AM, Paul Leavitt <leavittpaul@yahoo.com> wrote:
Ok, I have the same problem that was posted a month or two ago,,,,
about to run out of adjustment on the left side but plenty of threads
left on the rite.
--
Steve Ferguson
'76 EII
Sierra Vista, AZ
Urethane bushing source
www.bdub.net/ferguson/
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| Re: [GMCnet] Alignment-Height Setting [message #78685 is a reply to message #78669] |
Wed, 31 March 2010 07:25 |
GMCWiperMan
Messages: 1248
Registered: December 2007
Karma: 1
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Paul,
If I'm reading correctly, you blocked the rear at ride height. Now you've
established the same condition for the front end that we discussed here
recently for the front: The "locked down" rear is going to prevent free
movement of the front, due to the stiffness of the body+frame. When you
adjust one side in front, the other front side will move almost the same
amount -- you'll drive yourself batty trying to achieve the correct level.
And then when you un-block the rear, it will change again.
After you've established the correct rear ride height (and only then), you
should adjust the front ride height with the rear actively maintaining level
with Auto control. That will allow some independence between the front end
adjustments and the final result will be your road-ready condition.
As for the too-short bolt, if there's still clearance above the pork chop to
the crossmember, you can replace the OEM bolt with a longer Gr 8 bolt,
rounded on the end to fit the socket in the pork chop. If there's no
clearance, you'll have to get a differently clocked pork chop or a different
torsion bar. Jim K has them. I've heard it said that you can rotate the
pork chop one position; I've never seen a bar permanently twisted enough to
allow that; I'd be afraid to use it if I did.
Ken H.
On Wed, Mar 31, 2010 at 7:14 AM, Paul Leavitt <leavittpaul@yahoo.com> wrote:
>
>
> Ok, I have the same problem that was posted a month or two ago,,,, about to
> run out of adjustment on the left side but plenty of threads left on the
> rite. Had trouble getting it to respond to changes though, would jack it up,
> set 2 stands, istall tool,,make adjustment,,,reverse. Spent 1/2 a day sunday
> with very poor results. Had the rear set to the proper height and on blocks
> so it would be safe. Problem was,,,,, the front tires would stick and it
> would stay very high. So I put two pieces of tough 1/8 inch plastic w/grease
> between them under each wheel. WOW,,,what a diffrence that made. Totally
> changes things. With the left a little low I got it adj. to 1/4 degree of
> camber on each side and 4 d. caster on the rite,,,2 3/4 left. Am going to
> get a little more on the left and then drive it a couple miles and check it
> again. Confused on the adj. screws though???? Any thoughts,,,,{double
> checked,,,bars in corectly,,left and right,,,letters to the rear. thinking
> of reversing the le
> ft} Thanks,,,,PL
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
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| Re: Alignment-Height Setting [message #78708 is a reply to message #78669] |
Wed, 31 March 2010 09:53 |
g.winger
Messages: 792
Registered: February 2008
Location: Warrenton,Missouri
Karma: 0
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Steve and Ken, thankyou, that makes sense, that the frame stiffness is messing me up. Idealy you would need to support the REAR in one spot. IF you could support it centerd under the trailer hitch it would help setting front height. BUT that won't work. Everything would bend AND it would put to much weaght on the front. So we need a struchure to span betwwen the 4 rear wheels, support 8k lbs. and allow it to pivot on the roll axis. Steve, yes, swap end for end not L,R. But, if the flats or hex are 2-3 degrees off end to end if you swap the bar front to rear you won,t gain anything,,,is this correct??? I don't like to jack it up in the middle. I use 2 floor jacks, one of those light craftsman 2t. and a snap-on 2 1/2. If I get one ahead of the other it will lift the frame off the low one!!! Ouch, hard to believe the frame is that stiff. Now if I could only find a cheap set of electronic scales. Thanks again,,,PL
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| Re: [GMCnet] Alignment-Height Setting [message #78713 is a reply to message #78708] |
Wed, 31 March 2010 10:03 |
Steven Ferguson
Messages: 3447
Registered: May 2006
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That is correct Paul.
On Wed, Mar 31, 2010 at 7:53 AM, Paul Leavitt <leavittpaul@yahoo.com> wrote:
Steve, yes, swap end for end not L,R. But, if the flats or hex are
2-3 degrees off end to end if you swap the bar front to rear you won,t
gain anything,,,is this correct??? I don't like to jack it up in the
middle. I use 2 floor jacks, one of those light craftsman 2t. and a
snap-on 2 1/2. If I get one ahead of the other it will lift the frame
off the low one!!! Ouch, hard to believe the frame is that stiff. Now
if I could only find a cheap set of electronic scales. Thanks
again,,,PL
> _______________________________________________
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--
Steve Ferguson
'76 EII
Sierra Vista, AZ
Urethane bushing source
www.bdub.net/ferguson/
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| Re: [GMCnet] Alignment-Height Setting [message #78722 is a reply to message #78708] |
Wed, 31 March 2010 11:10 |
GMCWiperMan
Messages: 1248
Registered: December 2007
Karma: 1
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Paul,
I thought about lifting the coach under the center rear for front alignment,
as you suggest. Then someone reminded me that doing that would allow any
rear weight imbalance to bias the front ride heights. By setting the rear
ride height first and then keeping it in Auto during the front alignment,
the rear suspension compensates for any weight imbalance, leaving the front
free to compensate only for front imbalances not cancelled out through the
body stiffness.
Ken H.
Americus, GA
'76 X-Birchaven
www.gmcwipersetc.com
On Wed, Mar 31, 2010 at 10:53 AM, Paul Leavitt <leavittpaul@yahoo.com>wrote:
>
>
> Steve and Ken, thankyou, that makes sense, that the frame stiffness is
> messing me up. Idealy you would need to support the REAR in one spot. IF you
> could support it centerd under the trailer hitch it would help setting front
> height. BUT that won't work. Everything would bend AND it would put to much
> weaght on the front. So we need a struchure to span betwwen the 4 rear
> wheels, support 8k lbs. and allow it to pivot on the roll axis. Steve, yes,
> swap end for end not L,R. But, if the flats or hex are 2-3 degrees off end
> to end if you swap the bar front to rear you won,t gain anything,,,is this
> correct??? I don't like to jack it up in the middle. I use 2 floor jacks,
> one of those light craftsman 2t. and a snap-on 2 1/2. If I get one ahead of
> the other it will lift the frame off the low one!!! Ouch, hard to believe
> the frame is that stiff. Now if I could only find a cheap set of electronic
> scales. Thanks again,,,PL
> _______________________________________________
>
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| Re: [GMCnet] Alignment-Height Setting [message #78767 is a reply to message #78722] |
Wed, 31 March 2010 16:22 |
jayrabe
Messages: 509
Registered: June 2009
Location: Portland, OR
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OK, thoroughly confused now. Been researching ride-height adjustment procedure recommendations for some time before this thread started, and I'd thought the accepted best way was:
http://users.sfo.com/~eagle/rear.html#height
to pull the front wheels, block front to correct ride height, then do rear adjustment, then do front adjustment.
J "struggling with too many ways to skin a cat" Rabe
76 Palm Beach
Portland, OR
> Date: Wed, 31 Mar 2010 12:10:44 -0400
> From: ken0henderson@gmail.com
> To: gmclist@temp.gmcnet.org
> Subject: Re: [GMCnet] Alignment-Height Setting
>
> Paul,
>
> I thought about lifting the coach under the center rear for front alignment,
> as you suggest. Then someone reminded me that doing that would allow any
> rear weight imbalance to bias the front ride heights. By setting the rear
> ride height first and then keeping it in Auto during the front alignment,
> the rear suspension compensates for any weight imbalance, leaving the front
> free to compensate only for front imbalances not cancelled out through the
> body stiffness.
>
> Ken H.
> Americus, GA
> '76 X-Birchaven
> www.gmcwipersetc.com
>
>
> On Wed, Mar 31, 2010 at 10:53 AM, Paul Leavitt <leavittpaul@yahoo.com>wrote:
>
> >
> >
> > Steve and Ken, thankyou, that makes sense, that the frame stiffness is
> > messing me up. Idealy you would need to support the REAR in one spot. IF you
> > could support it centerd under the trailer hitch it would help setting front
> > height. BUT that won't work. Everything would bend AND it would put to much
> > weaght on the front. So we need a struchure to span betwwen the 4 rear
> > wheels, support 8k lbs. and allow it to pivot on the roll axis. Steve, yes,
> > swap end for end not L,R. But, if the flats or hex are 2-3 degrees off end
> > to end if you swap the bar front to rear you won,t gain anything,,,is this
> > correct??? I don't like to jack it up in the middle. I use 2 floor jacks,
> > one of those light craftsman 2t. and a snap-on 2 1/2. If I get one ahead of
> > the other it will lift the frame off the low one!!! Ouch, hard to believe
> > the frame is that stiff. Now if I could only find a cheap set of electronic
> > scales. Thanks again,,,PL
> > _______________________________________________
> >
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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| Re: [GMCnet] Alignment-Height Setting [message #78844 is a reply to message #78767] |
Thu, 01 April 2010 06:31 |
Steven Ferguson
Messages: 3447
Registered: May 2006
Karma: 0
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Senior Member |
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Jay,
The method you reference is the one I prefer.
http://users.sfo.com/~eagle/rear.html#height
When it is all over and the coach returns (within tolerance) to the
correct ride height setting whether it is from full raise or from the
lowest (bags deflated) setting, you have it as close as it can be
adjusted.
I feel that a lot of the problems encountered are the results of old
age and many fingers in the pot over the years.Worn components, tired
torsion bars, years of poor loading procedures etc., all compounded by
different owners making corrections not following recommended,
established procedures. Starting from scratch, then following the
above procedure is the best it can be done.
Sometimes we have a tendency to "overthink" a simple process.
On Wed, Mar 31, 2010 at 2:22 PM, Jay Rabe <jayrabe@hotmail.com> wrote:
OK, thoroughly confused now. Been researching ride-height adjustment
procedure recommendations for some time before this thread started,
and I'd thought the accepted best way was:
--
Steve Ferguson
'76 EII
Sierra Vista, AZ
Urethane bushing source
www.bdub.net/ferguson/
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
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