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| Re: [GMCnet] ride height adjustment [message #30544 is a reply to message #30543] |
Tue, 16 December 2008 08:13   |
Mr ERFisher
Messages: 7117
Registered: August 2005
Karma: 2
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axles ? or bogie arms ?
axles would be set by torson bars?
hummmmm
have not seen this
gene
On Tue, Dec 16, 2008 at 6:03 AM, Rob Mueller <robmueller@iinet.net.au>wrote:
> G'day,
>
> Ken Frey sets the front ride height by setting the front wheels straight
> ahead and putting a level on top of the right and left axles. He adjusts
> the
> torsion bars until the bubble is centered.
>
> He noted this method compensates for different size tires.
>
> Comments?
>
> Regards,
> Rob Mueller
> At the Coop
>
> -----Original Message-----
> From: gmclist-bounces@temp.gmcnet.org
> [mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Mr.erf ERFisher
> Sent: Tuesday, December 16, 2008 8:44 AM
> To: gmclist@temp.gmcnet.org
> Subject: [GMCnet] ride height adjustment
>
> did you look here?
> http://gmcmotorhome.info/rear.html#height
>
> The proper height is measured at the slot on the frame at the rear. I
> don't recall the number but it is in the manual.
>
>
> gene
>
> --
> 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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> _______________________________________________
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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
-------
http://gmcmotorhome.info/
Alternator Protection Cable
http://gmcmotorhome.info/APC.html
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| Re: [GMCnet] ride height adjustment [message #30548 is a reply to message #30543] |
Tue, 16 December 2008 09:20 |
Bob de Kruyff
Messages: 4260
Registered: January 2004
Location: Chandler, AZ
Karma: 1
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""G'day,
Ken Frey sets the front ride height by setting the front wheels straight
ahead and putting a level on top of the right and left axles. He adjusts the
torsion bars until the bubble is centered.
He noted this method compensates for different size tires.
Comments?""
I can see how that would work. What I don't know is whether the axle shafts are completely horizontal in the design position (original tire size and specified trim heights). If so, then this is OK. The axle shaft angles should be a good indication of
front suspension geometry without worrying about tire size.
Bob de Kruyff
78 Eleganza
Chandler, AZ
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| Re: [GMCnet] ride height adjustment [message #30560 is a reply to message #30557] |
Tue, 16 December 2008 10:59 |
Keith V
Messages: 2337
Registered: March 2008
Location: Mounds View,MN
Karma: 0
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So what is the procedure for adjusting the torsion bars?
I've read there is an unloader involved?
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 adjustment [message #30571 is a reply to message #30543] |
Tue, 16 December 2008 11:33 |
Rick Denney
Messages: 430
Registered: January 2004
Karma: 0
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Senior Member |
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Rob Mueller writes...
> G'day,
> Ken Frey sets the front ride height by setting the front wheels straight
> ahead and putting a level on top of the right and left axles. He adjusts the
> torsion bars until the bubble is centered.
> He noted this method compensates for different size tires.
> Comments?
Personally, I think one needs to isolate front and rear to set the
torsion bars. The air bags will adjust for side-to-side mismatches in
the torsion bars, leading to diagonal imbalances.
Ken Burton dials out this imbalance by using wheel scales and
adjusting the torsion bars and air bags systematically to achieve the
correct ride height while maintaining equal side-to-side weights.
For those of us who don't have scales, there is probably an easier
way, though it is still a bit time-consuming.
First, I would jack up the coach in the front from the exact center of
the front cross member. That way, the coach is free (up to a point) to
rock back and forth with changes in the air bags. Then, I would adjust
the rear air bags to provide approximately correct ride height and a
level coach on the front. That sets the rear such that it won't be
attempting to correct for a front imbalance. Then, I would lower the
front and adjust the torsion bars to achieve proper front ride height,
without touching the bags. That should prevent an imbalance in the
front caused by an opposite bias in the rear.
Once the torsion bars were set, I would then adjust the bag leveling
valves to achieve proper ride height on the rear when in Travel mode.
My coach was correct as received so I have not ever gone through this.
But I think getting rid of those diagonal biases is one key to getting
a coach to handle properly--my coach has been pretty good despite a
range of issues that are frequently seen on the list of causes of poor
handling.
Rick "who would NEVER have different tire sizes side-to-side on the
coach--ESPECIALLY on the front" Denney
'73 230 Ex-Glacier "Jaws"
Northern Virginia
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'73 Glacier 230 "Jaws"
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| Re: [GMCnet] ride height adjustment [message #30591 is a reply to message #30571] |
Tue, 16 December 2008 15:21 |
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mike miller
Messages: 3576
Registered: February 2004
Location: Hillsboro, Oregon
Karma: 0
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| Rick Denney wrote on Tue, 16 December 2008 09:33 |
> Ken Frey sets the front ride height by setting the front wheels straight
> ahead and putting a level on top of the right and left axles. He adjusts the
> torsion bars until the bubble is centered.
> He noted this method compensates for different size tires.
....
Rick "who would NEVER have different tire sizes side-to-side on the coach--ESPECIALLY on the front" Denney
|
Rick,
I suspect he was not talking about different sizes on the same axle. I believe he was talking about having taller (or shorter) tires having an effect on the height of the frame off the ground. (The method in the manual.)
If you have tall tires and followed the "measuring at the frame" method, the front suspension would be set too low. Changing angles of the axles and other suspension geometry.
His use of the levels on the axles are to get them at the "correct angle" regardless of the tire size... rather than setting the frame at a set height from the ground.
The only question I have is, "Is the correct angle of the axle level with the ground?"
Mike Miller -- Hillsboro, OR -- on the Black list
(#2)`78 23' Birchaven Rear Bath -- (#3)`77 23' Birchaven Side Bath
More Sidekicks than GMC's and a late model Malibu called 'Boo'
http://m000035.blogspot.com
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| Re: [GMCnet] ride height adjustment [message #30612 is a reply to message #30609] |
Tue, 16 December 2008 18:34 |
Mr ERFisher
Messages: 7117
Registered: August 2005
Karma: 2
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Senior Member |
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looks like this
http://gmcwsproducts.blogspot.com/2007/08/gmc-tools-from-tony.html
gene
On Tue, Dec 16, 2008 at 4:14 PM, Ken Henderson <ken0henderson@gmail.com>wrote:
> Keith,
>
> A torsion bar unloader is definitely a mandatory tool for adjusting
> them. It's basically a big grade 8+ U-bolt with a positioning nipple in
> the base of the U. That nipple fits into a hole on the top of the
> crossmember supporting the rear end of the torsion bar. A hefty
> crossbar across the free ends of the U carries a 5/8"-3/4" grade 8
> forcing screw. The rounded end of that forcing screw fits into a dimple
> in the "pork chop" which anchors the rear end of the torsion bar.
> Tightening the forcing screw releases the load on the 9/16" cap screw
> which determines the angular position of the pork chop. Turning that
> adjusting screw without releasing the load on it is a sure way to strip it.
>
> The full procedure for adjusting the torsion bars is adequately covered
> in the manual, though the explanation in Claude Brousson's paper is more
> complete and readable, IMHO.
>
> Ken Henderson
> Americus, GA
> www.gmcwipersetc.com
> '76 X-Birchaven
>
>
>
>
> Keith V wrote:
> > So what is the procedure for adjusting the torsion bars?
> > I've read there is an unloader involved?
> >
> >
> HO.<br>
> <br>
> <pre class="moz-signature" cols="72">Ken Henderson
> Americus, GA
> www.gmcwipersetc.com
> '76 X-Birchaven
>
> </pre>
> <br>
> <br>
> Keith V wrote:
> <blockquote cite="mid:7760.4947de70@gmc.mybirdfeeder.net<mid%3A7760.4947de70@gmc.mybirdfeeder.net>"
> type="cite">
> <pre wrap="">
> So what is the procedure for adjusting the torsion bars?
> I've read there is an unloader involved?
>
> </pre>
> </blockquote>
> </body>
> </html>
> _______________________________________________
> GMCnet mailing list
> Gmclist@temp.gmcnet.org
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
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: [GMCnet] ride height adjustment [message #30622 is a reply to message #30614] |
Tue, 16 December 2008 19:22 |
GMCWiperMan
Messages: 1248
Registered: December 2007
Karma: 1
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Senior Member |
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Using a level on the front axles makes all kinds of sense if you
remember that any CV or U-joint is wasting energy in any position except
"straight through" (input and output shafts aligned). So for maximum
efficiency, minimum wear, least torque steer, and minimum noise, the
axles should be level. When moving, the CV joint will continually
change, so the best way we can hope to achieve the minimum average
misalignment is to set them level at rest. I suspect that's how the OEM
spec ride height was set.
If the tire size has been changed from OEM, the ride height needs to be
changed to compensate. Claude Brousson has a table of the adjustments
in the paper I linked to earlier. If one uses the "level axles"
procedure, front tire size is eliminated from the equation; the torsion
bars must not be used to adjust the ride height away from "level
axles". That leaves only the rear ride height to be changed to
compensate for the tire change. Bob Drewes' straight edge across the
spindles and Zerk fittings is the quickest, easiest way to set that --
and it doesn't require a calculator. :-)
Now if you've got itsy bitsy tires on the front and Tonka Toy tires on
the rear, or vice-versa, start calculating. Either way, it will
probably drive like a soap box derby car.
Ken Henderson
Americus, GA
www.gmcwipersetc.com
'76 X-Birchaven
mills wrote:
> If the Level method results in the measured front height different than
> the "measure the slot in the frame" height do you compensate on the rear
> height or put it at factory height and enjoy the extra caster (assuming
> the front was higher).
>
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| Re: [GMCnet] ride height adjustment [message #30632 is a reply to message #30609] |
Tue, 16 December 2008 19:59 |
Keith V
Messages: 2337
Registered: March 2008
Location: Mounds View,MN
Karma: 0
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Senior Member |
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It looks like I need to get a copy of the repair manual.
I keep hearing about it..
| GMCWiperMan wrote on Tue, 16 December 2008 18:14 |
Keith,
A torsion bar unloader is definitely a mandatory tool for adjusting
them. It's basically a big grade 8+ U-bolt with a positioning nipple in
the base of the U. That nipple fits into a hole on the top of the
crossmember supporting the rear end of the torsion bar. A hefty
crossbar across the free ends of the U carries a 5/8"-3/4" grade 8
forcing screw. The rounded end of that forcing screw fits into a dimple
in the "pork chop" which anchors the rear end of the torsion bar.
Tightening the forcing screw releases the load on the 9/16" cap screw
which determines the angular position of the pork chop. Turning that
adjusting screw without releasing the load on it is a sure way to strip it.
The full procedure for adjusting the torsion bars is adequately covered
in the manual, though the explanation in Claude Brousson's paper is more
complete and readable, IMHO.
Ken Henderson
Americus, GA
www.gmcwipersetc.com
'76 X-Birchaven
|
Keith Vasilakes
Mounds View. MN
75 ex Royale GMC
ask me about MicroLevel
Cell, 763-732-3419
My427v8@hotmail.com
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