Home » Public Forums » GMCnet » Ride height
| Ride height [message #141920] |
Wed, 31 August 2011 21:59  |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
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I measured my frame at the slot in the front and rear. the rear is close but the front is 2" low. It is still at the factory setting as far as I know. I found an old 1930's Axel tool that should suffice to unload the adjuster. It has a 1" shaft so it should be plenty strong enough. It looks like some adjust the screw with the front wheels on the ground and some with the wheels suspended. I also read 1 turn is approximately 1"??. So if the rear is set correctly and I tighten the 2 screws 12 turns each I should be in the ball park? Jacking with the wheels off the ground will be easier on the screws??
Roy
Roy Keen
Minden,NV
76 X Glenbrook
[Updated on: Wed, 31 August 2011 22:02] Report message to a moderator |
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| Re: [GMCnet] Ride height [message #141921 is a reply to message #141920] |
Wed, 31 August 2011 22:16  |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
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Roy,
A few points:
If the Axle Tool has a large cross-bar, as old tools are prone to do, it may
not work well on the GMC. Even with a modern tool, it's important to
tighten the support nuts so that the crossbar is near or against the
crossmember. Otherwise, the unloader will tend to lean against the
adjusting screw, making it impossible to turn. A wide crossbar will
probably always interfere with the adjusting screw. Just a caution -- if it
works, Great.
Having the weight off of the front wheel definitely reduces the load on the
unloader tool; should have no effect on the adjusting screw since it's
unloaded.
6 turns of the adjusting screw should yield about one inch change in ride
height.
Before you start, it would be a REAL good idea to read the ride height
adjusting section of the wheel alignment instructions Jerry Work posted last
week.
Ken H.
On Wed, Aug 31, 2011 at 10:59 PM, <roy@gmcnet.org> wrote:
>
>
> I measured my frame at the slot in the front and rear. the rear is close
> but the front is 2" low. It is still at the factory setting as far as I
> know. I found an old 1930's Axel tool that should suffice to unload the
> adjuster. It has a 1" shaft so it should be plenty strong enough. It looks
> like some adjust the screw with the front wheels on the ground and some with
> the wheels suspended. I also read 1 turn is approximately 1". So if the rear
> is set correctly and I tighten the 2 screws 12 turns each I should be in the
> ball park? Jacking with the wheels off the ground will be easier on the
> screws??
> Roy
>
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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: Ride height [message #141984 is a reply to message #141964] |
Thu, 01 September 2011 10:52 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
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The front wheels are currently on 3 1/2" blocks. the tool I have is like none I have seen before. the body opens to 4" which is just wide enough ,the depth is just right. I had to fabricate a steel bar with a centering bolt to secure it at the top. the adjusting screw is 1" thick fine thread and the adjusting nut is 15/16" this has to be as strong as the factory type unloader. It is probably a special tool for a Reo or something I'll never know. I'll take some of the load off the front wheels before I unload the bar. Thanks guys
Roy
Roy Keen
Minden,NV
76 X Glenbrook
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| Re: Ride height [message #142159 is a reply to message #141984] |
Fri, 02 September 2011 18:40 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
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Well the antique tool did the job of unloading the torsion bars.
I set the front from the level garage floor to the top of the slot as the spec calls out (12 turns = 2")to 13 1/8". That was way high according to the drive axel. I wound up setting it at
12 5/8" to the top of the slot after driving around a few miles. At this setting the axel is level. I set the rear to 8 1/2"(under the frame) 11 1/2 at the slot to have it slightly down in back. I don't know why it didn't like the 13 1/8" setting as I'm running 225 75 16 tires but they are new and have agressive thread. I'll check it again after the next trip. From what I have read level axel's are the goal.
Roy
Roy Keen
Minden,NV
76 X Glenbrook
[Updated on: Fri, 02 September 2011 20:26] Report message to a moderator |
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| Re: Ride height [message #142168 is a reply to message #142165] |
Fri, 02 September 2011 19:24 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
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Bruce thanks for your input. One thing I did notice with the amount I raised the front it seems to ride a little stiffer IE
there are more pots rattling.
Roy
Roy Keen
Minden,NV
76 X Glenbrook
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| Re: [GMCnet] Ride height [message #142185 is a reply to message #142182] |
Fri, 02 September 2011 21:14 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
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I suppose that could cause some it of they are defiantly due for
replacement but not this year. I need to get some use out of the coach. The fiasco I had with the body pads earlier ate up too much of my time. Paula has been on me about living under the coach and putting off needed chores. But you made a good point I have been putting off changing the bushings and they are obviously worn.
Roy
Roy Keen
Minden,NV
76 X Glenbrook
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| Re: [GMCnet] Ride height [message #142206 is a reply to message #142182] |
Sat, 03 September 2011 00:41 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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| Robert Mueller wrote on Fri, 02 September 2011 20:54 |
Roy,
This is interesting. I got to thinking about how you could have level axles at a lower ride height and as far as I can figure the OD
of the tires is one reason (which you've noted) and the second is the condition of the lower bushings.
If they are like the ones on the right in SteveF's picture:
http://www.gmcmhphotos.com/photos/showphoto.php?photo=17313
That would cause some of it but not half an inch.
Anybody else have any ideas?
Regards,
Rob M.
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I saw a set last year at Blaine's work rally where the steel center bushing was wearing on the steel outer sleeve. The rubber was completely gone in that area. The owner replaced them with Urethane bushings.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] Ride height [message #142326 is a reply to message #142182] |
Sat, 03 September 2011 22:50 |
GMCNUSA
Messages: 283
Registered: August 2006
Location: Indianapolis, IN
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| Robert Mueller wrote on Fri, 02 September 2011 21:54 |
Roy,
This is interesting. I got to thinking about how you could have level axles at a lower ride height and as far as I can figure the OD
of the tires is one reason (which you've noted) and the second is the condition of the lower bushings.
If they are like the ones on the right in SteveF's picture:
http://www.gmcmhphotos.com/photos/showphoto.php?photo=17313
That would cause some of it but not half an inch.
Anybody else have any ideas?
Regards,
Rob M.
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Does it say anywhere in the manuals that the axels should be level? When I set up the suspension and drive train of a hotrod I strive for 2 to 3 degrees of offset angle at the u-joints to prevent vibration. I do not know if CV joints need offset. A real mechanic will probably know the answer.
Larry Dilk
Indianapolis, IN
76 Eleganza II
Patterson 455,Turbo City TBI,
Just LOVE It!
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| Re: [GMCnet] Ride height [message #142331 is a reply to message #142326] |
Sat, 03 September 2011 23:20 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Larry,
I have never found any statements regarding the axles being level in the MM.
I agree with you that drive shafts with universal joints should be setup with a slight angle.
I'm GUESSTIMATING here: the axles in the GMC are about 1 1/4" OD, about 18" long, solid metal with splines machined at both ends.
A drive shaft is usually a hollow tube about 3-4 inches in diameter; two times as long, with u-joint "flanges" welded on both ends,
and they are balanced.
I reckon it is remote that you would get any vibration from the front axles unless an inner or outer CV joint were seriously messed
up!
I first heard about setting the axles level from Ken Frey of Frey's Automotive in Quakertown, PA:
http://www.kenlfreyautorepair.com/home
If you note he has 40 years experience as a mechanic so I reckon he'd qualify as a "real mechanic." ;-)
He told me two things about setting the ride height in a GMC:
1) the front ride height should be set to make the axles level
2) the rear ride height should be set so that you can draw a line from the center of the middle wheel axle / stub shaft to the rear
axle / stub shaft and that line should intersect the middle of the bogie pivot points.
As I noted in a number of other threads, The Blue Streak is up on jack stands with the rear air suspension inop so I can't verify
any of this stuff. I ga-ron-tee as soon as I get it back on the ground I WILL verify all this information.
Regards,
Rob M.
-----Original Message-----
From: Larry and Cheryl Dilk
Does it say anywhere in the manuals that the axels should be level? When I set up the suspension and drive train of a hotrod I
strive for 2 to 3 degrees of offset angle at the u-joints to prevent vibration. I do not know if CV joints need offset. A real
mechanic will probably know the answer.
--
Larry
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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] Ride height [message #142332 is a reply to message #142331] |
Sat, 03 September 2011 23:28 |
GMCNUSA
Messages: 283
Registered: August 2006
Location: Indianapolis, IN
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| Robert Mueller wrote on Sun, 04 September 2011 00:20 |
Larry,
I have never found any statements regarding the axles being level in the MM.
I agree with you that drive shafts with universal joints should be setup with a slight angle.
I'm GUESSTIMATING here: the axles in the GMC are about 1 1/4" OD, about 18" long, solid metal with splines machined at both ends.
A drive shaft is usually a hollow tube about 3-4 inches in diameter; two times as long, with u-joint "flanges" welded on both ends,
and they are balanced.
I reckon it is remote that you would get any vibration from the front axles unless an inner or outer CV joint were seriously messed
up!
I first heard about setting the axles level from Ken Frey of Frey's Automotive in Quakertown, PA:
http://www.kenlfreyautorepair.com/home
If you note he has 40 years experience as a mechanic so I reckon he'd qualify as a "real mechanic." 
He told me two things about setting the ride height in a GMC:
1) the front ride height should be set to make the axles level
2) the rear ride height should be set so that you can draw a line from the center of the middle wheel axle / stub shaft to the rear
axle / stub shaft and that line should intersect the middle of the bogie pivot points.
As I noted in a number of other threads, The Blue Streak is up on jack stands with the rear air suspension inop so I can't verify
any of this stuff. I ga-ron-tee as soon as I get it back on the ground I WILL verify all this information.
Regards,
Rob M.
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Well my axels are not level and my front ride height is within specs for ride height. So I'm wondering what should be changed or do nothing. I have ignored this topic always thinking some of the old timers would document the level axel criteria.
Larry Dilk
Indianapolis, IN
76 Eleganza II
Patterson 455,Turbo City TBI,
Just LOVE It!
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| Re: [GMCnet] Ride height [message #142336 is a reply to message #142332] |
Sun, 04 September 2011 00:24 |
Keith V
Messages: 2337
Registered: March 2008
Location: Mounds View,MN
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I would think you want some movement so you don't have all the wear in one little spot on the bearing.
Move it around a little, spread the wear out
Keith Vasilakes
Mounds View. MN
75 ex Royale GMC
ask me about MicroLevel
Cell, 763-732-3419
My427v8@hotmail.com
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| Re: [GMCnet] Ride height [message #142357 is a reply to message #142326] |
Sun, 04 September 2011 09:53 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Larry, It is common to have cross and yoke universal joints slightly out of
plane by 1 or 2 degrees. That is supposed to minimize vibrations and ensure
that the needles circulate instead of remain in a stationary position, The
purpose is to extend the service life. The Ruzeppa type joint like our GMCs
use on the outboard end, have large diameter balls with mating housings that
will tolerate considerably more misalignment than the cross and yoke design.
The inboard joints on our GMCs are ball and trunion design with three needle
filled large diameter balls that run in a machined track and are located by
hardened trunion pins. The purpose of this type of joint is to allow the
shaft to extend and retract with suspension movement and also to transmit
power to the wheel. A tip that I learned about whether the joints are failed
or not is to point the wheels straight ahead, and moving the coach slowly
forward on a very smooth surface, lightly hold the steering wheel between
the thumb and forefinger, see if there is any oscillation felt through the
light touch of the wheel. If you feel three oscillations per revolution of
wheel travel, the inboard joints are at fault. If you feel a lot more
oscillations, then it is likely that the outboard joints are the problem.
Not scientific, just seat of the pants stuff, but it tells you where to
start looking if problems are suspected. The horiziontal plane of the entire
shaft when the coach is at correct ride height is slightly lower on the
outboard end. If your bushings are worn out in the lower control arms, then
it could be quite different. Some coaches with everything in the front
suspension quite worn drive fairly well on smooth roads when there is slight
winds. When driving conditions are poor and everything is worn, the same
coach can be a handful to control.
Jim Hupy
Salem, OR
78 GMC Royale 403
On Sat, Sep 3, 2011 at 8:50 PM, Larry and Cheryl Dilk <lwd222@msn.com>wrote:
>
>
> Robert Mueller wrote on Fri, 02 September 2011 21:54
> > Roy,
> >
> > This is interesting. I got to thinking about how you could have level
> axles at a lower ride height and as far as I can figure the OD
> > of the tires is one reason (which you've noted) and the second is the
> condition of the lower bushings.
> >
> > If they are like the ones on the right in SteveF's picture:
> >
> > http://www.gmcmhphotos.com/photos/showphoto.php?photo=17313
> >
> > That would cause some of it but not half an inch.
> >
> > Anybody else have any ideas?
> >
> > Regards,
> > Rob M.
>
>
>
> Does it say anywhere in the manuals that the axels should be level? When I
> set up the suspension and drive train of a hotrod I strive for 2 to 3
> degrees of offset angle at the u-joints to prevent vibration. I do not know
> if CV joints need offset. A real mechanic will probably know the answer.
> --
> Larry Dilk
> Indianapolis, IN
> 76 Eleganza II
> Patterson 455,Turbo City TBI,
> Just LOVE It!
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
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