| Urethane vs rubber suspension bushings [message #64026] |
Thu, 12 November 2009 13:39  |
seven
Messages: 322
Registered: July 2008
Location: Calgary Canada
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I have one of my coach's up on blocks to redo the front end new bushings, brakes, shocks and bearings. Is there a complete Urethane bushing Kit
Jay Fox
Calgary AB
73 Painted Desert (Turtle)
78 Transmode (Trailer Donor)
[Updated on: Thu, 12 November 2009 13:39] Report message to a moderator |
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| Re: [GMCnet] Urethane vs rubber suspension bushings [message #64034 is a reply to message #64026] |
Thu, 12 November 2009 14:08  |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
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Jay,
Yes, you can get them from:
Applied GMC - Jim K
http://www.appliedgmc.com/
The COOP - Jim B
http://www.gmccoop.com/
However, the general consensus is to use offset bushings in the upper
control arms to get more caster.
The weight of the GMC is carried by the lowers.
Regards,
Rob Mueller
Sydney, Australia
AUS '75 Avion-The Blue Streak TZE365V100428
USA '75 Avion-Double Trouble TZE365V100426
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org
[mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Jay Fox
Sent: Friday, 13 November 2009 6:40 AM
To: gmclist@temp.gmcnet.org
Subject: [GMCnet] Urethane vs rubber suspension bushings
I have one of my coach's up on blocks to redo the front end new bushings
brakes shocks and bearings. Is there a complete Urethane bushing Kit
--
Jay Fox
Calgary AB Canada
73 Painted Desert (Turtle)
Wifes 75 Transmode (Unutter1)
78 Transmode (Donor)
Official Club Haulers
http://www.amra.ca
http://www.amra.ca/Club%20Hauler.htm
http://www.amra.ca/Pictures/Club%20Haulers%202/
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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] Urethane vs rubber suspension bushings [message #64160 is a reply to message #64113] |
Fri, 13 November 2009 14:06 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Jay,
Here's a message I sent in last month:
G'day,
There are a number of good write-ups on the internet on how to install
offset bushings in the upper control arms of a GMC. The general consensus of
opinion seems to be that a GMC will handle best with as much positive caster
as you can get with as close to zero camber as possible and zero toe in or
slight toe out. Furthermore it appears that it is difficult to get much
caster in 1973 and 1974 coaches whereas later coaches 1975 thru 1978 seem to
be able to get more. Offset bushings enable one to get more caster by moving
the upper ball joint towards the REAR of the GMC.
The write-ups refer to the arrows on Moog offset bushings to assist with the
installation. John Sharpe and I recently replaced the bushings in his upper
control arms which he got from NAPA that did not have arrows on them and it
got confusing; as a matter of fact we installed the first pair incorrectly!
Fortunately we realized it when we started on the second set and corrected
our mistake.
Jim K shipped me offset bushings for The Blue Streak that did not have
arrows on them also and the fact I screwed up helping John got me wondering
whether or not I installed them correctly or not. I checked some photos of
the control arms and found that the bushings were installed correctly. The
fact that I had done it correctly on The Blue Streak yet screwed it up when
helping John made us decide to publish how to install offset bushings
whether they had arrows or not.
The upper control arms are stamped with an "L" or an "R". When you remove
them check and make sure they have been installed correctly. Yes, they can
be interchanged! We discovered this while looking at another coach! We do
not really know if it affects driveability or not but the coach had been
driven 1000's of miles with the control arms installed that way. We wondered
if swapping them could / would get you more caster so we compared them and
made some measurements. Unfortunately they were the same.
Place the Right upper control arm on your workbench with the ball joint
facing you (taper pointing down) and the bushing holes away from you; the
arm on your right is the front arm of the control arm, the arm on the left
is the rear arm.
Install the offset bushing in the front arm of the control arm so that the
hole for the adjusting bolt is as far from the ball joint as possible.
Install the offset bushing in the rear arm of the control arm so that the
hole for the adjusting bolt is as close to the ball joint as possible.
This will move the Right upper control arm ball joint rearward and enable
you to get more caster.
Place the Left upper control arm on your workbench with the ball joint
facing you (taper pointing down) and the bushing holes away from you; the
arm on your left is the front arm of the control arm, the arm on the right
is the rear arm.
Install the offset bushing in the front arm of the control arm so that the
hole for the adjusting bolt is as far from the ball joint as possible.
Install the offset bushing in the rear arm of the control arm so that the
hole for the adjusting bolt is as close to the ball joint as possible.
This will move the Left upper control arm ball joint rearward and enable you
to get more caster.
When you install the upper control arms set the control arm rear adjuster on
both sides so that the bolt is as close to the GMC frame as possible. The
cam on the adjuster eccentric will be with the high side facing out. Use the
front adjuster to set the camber to "0" degrees or as close as possible, be
advised you may not be able to get "0" degrees camber. Adjusting the camber
to the minimum will result in the maximum caster you can get on your coach.
On Double Trouble Tom Hampton was only able to get 1.9 degrees positive
caster at zero degrees camber and zero toe in/out. John got 2.0 degrees
positive caster at zero degrees camber and zero toe in/out. It would have
been possible to get more caster on the left side.
A word to the wise; when installing RUBBER control arm bushings (upper
and/or lower) a "best practice" is not to tighten the bolts that retain the
bushings in the frame brackets to the specified torque until the GMC is on
the ground with full weight on the wheels. Leave the bolts loose enough so
that the steel sleeves in the bushings can rotate on the bolts. This will
allow the steel sleeves in the bushings to rotate around the bolts and place
them in the "middle" of their operating / twisting range when tightened.
Good Luck,
Rob Mueller / John Sharpe
Sydney, Australia / Humble, Texas
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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] Urethane vs rubber suspension bushings [message #74554 is a reply to message #64160] |
Sun, 21 February 2010 13:18 |
MikeT
Messages: 225
Registered: November 2009
Location: Marine City, Michigan
Karma: 0
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Rob,
Great write up on Bushing replacement. Based on you comments, I think the best way to go is urethane on the lowers and offset on the uppers. Your write up suggests offset on both uppers and I see other recommend only on the upper fronts and OEM on the upper rears.
Your write up states taper pointing down. "Place the Left upper control arm on your workbench with the ball joint
facing you (taper pointing down) and the bushing holes away from you; the
arm on your left is the front arm of the control arm, the arm on the right
is the rear arm." What is the taper?
I assume I have the ball joint closest to me and ball joint nut pointing down on the bench all right side up. Or is the arm upside down that you are discussing? Ball joint nut facing up to the ceiling?
If I am reading this correctly. The front leg of the upper control arm has the cam bolt hole closest to the frame and the rear leg has the cam bolt hole closest to the ball joint.
Also, do you recommend replacing the cam bolts or just cleaning up the old ones?
Thanks
Mike Thomas
Marine City, MI
77 ex Palm Beach
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| Re: [GMCnet] Urethane vs rubber suspension bushings [message #74586 is a reply to message #74554] |
Sun, 21 February 2010 17:30 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Mike,
Thanks for the compliment.
I will respond to your comments and questions below in CAPS.
Regards,
Rob Mueller
Sydney, Australia
AUS '75 Avion-The Blue Streak TZE365V100428
USA '75 Avion-Double Trouble TZE365V100426
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org
[mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Thomas Mike
Sent: Monday, 22 February 2010 6:18 AM
To: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] Urethane vs rubber suspension bushings
Rob,
Great write up on Bushing replacement. Based on you comments, I think the
best way to go is urethane on the lowers and offset on the uppers.
THAT IS WHAT I'VE DONE ON TWO COACHES. THE LOWERS CARRY THE WEIGHT.
Your write up suggests offset on both uppers and I see other recommend only
on the upper fronts and OEM on the upper rears.
IMHO THE GURU ON FRONT SUSPENSION / ALIGNMENT IS DAVE LENZI. I SPOKE WITH
HIM AT LENGTH AND HE NOTED THAT INSTALLING OFFSET BUSHINGS IN BOTH THE FRONT
AND REAR ARMS MIGHT HELP GET A BIT MORE CASTER AND IT WOULDN'T HURT. IF YOU
ARE GOING TO INSTALL ONLY ONE OFFSET IT IS BETTER TO PUT IT IN THE REAR.
HAVING SAID THAT YOU HAVE A 1977 COACH AND AS I UNDERSTAND IT YOU CAN GET
MORE CASTER ON '76 - '78 COACHES.
Your write up states taper pointing down. "Place the Left upper control arm
on your workbench with the ball joint facing you (taper pointing down) and
the bushing holes away from you; the arm on your left is the front arm of
the control arm, the arm on the right is the rear arm." What is the taper?
THE TAPER IS THE PART WITH THE THREAD ON THE END THAT GOES INTO THE KNUCKLE.
I assume I have the ball joint closest to me and ball joint nut pointing
down on the bench all right side up. Or is the arm upside down that you are
discussing? Ball joint nut facing up to the ceiling?
YES, THAT IS CORRECT, THE BALL JOINT NUT POINTING DOWN.
If I am reading this correctly. The front leg of the upper control arm has
the cam bolt hole closest to the frame and the rear leg has the cam bolt
hole closest to the ball joint.
YES, THAT IS CORRECT. THE OBJECT OF THE OFFSET BUSHINGS IS TO MOVE THE BALL
JOINT TOWARDS THE REAR OF THE COACH TO GET MORE CASTER.
Also, do you recommend replacing the cam bolts or just cleaning up the old
ones?
ON BOTH MY COACHES I JUST CLEANED THEM UP WITH A WIRE BRUSH. ALSO CLEAN THE
SURFACES THE ADJUSTING PLATES COME IN CONTACT WITH. USE A BIT OF GREASE ON
THE BOLTS AND PLATES WHEN YOU PUT EVERYTHING BACK TOGETHER AS IT WILL MAKE
THEM TURN EASIER WHEN YOU DO THE ALIGNMENT.
Thanks
--
Mike T
Troy, MI
77 Eleganza II
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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] Urethane vs rubber suspension bushings [message #74649 is a reply to message #74554] |
Mon, 22 February 2010 04:41 |
Steven Ferguson
Messages: 3447
Registered: May 2006
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Mike,
Here you go:
http://www.gmcws.org/Tech/Getting_Your_GMC_Under_Control.pdf
Here's the whole enchilada for control arms:
http://www.gmcws.org/tech.htm
On Sun, Feb 21, 2010 at 12:18 PM, Thomas Mike <mthomas@wideopenwest.com> wrote:
>
>
> Rob,
>
> Great write up on Bushing replacement. Based on you comments, I think the best way to go is urethane on the lowers and offset on the uppers. Your write up suggests offset on both uppers and I see other recommend only on the upper fronts and OEM on the upper rears.
>
> Your write up states taper pointing down. "Place the Left upper control arm on your workbench with the ball joint
> facing you (taper pointing down) and the bushing holes away from you; the
> arm on your left is the front arm of the control arm, the arm on the right
> is the rear arm." What is the taper?
>
> I assume I have the ball joint closest to me and ball joint nut pointing down on the bench all right side up. Or is the arm upside down that you are discussing? Ball joint nut facing up to the ceiling?
>
> If I am reading this correctly. The front leg of the upper control arm has the cam bolt hole closest to the frame and the rear leg has the cam bolt hole closest to the ball joint.
>
> Also, do you recommend replacing the cam bolts or just cleaning up the old ones?
>
> Thanks
>
>
> --
> Mike T
> Troy, MI
> 77 Eleganza II
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
Steve Ferguson
'76 EII
Sierra Vista, AZ
Urethane bushing source
www.bdub.net/ferguson/
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| Re: [GMCnet] Urethane vs rubber suspension bushings [message #74665 is a reply to message #74649] |
Mon, 22 February 2010 08:31 |
MikeT
Messages: 225
Registered: November 2009
Location: Marine City, Michigan
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WOW!!
Thanks Steve. Surprised with all my surfing over the last 4 months I haven't found that.
Great presentation.
I have the uppers off but need a torsion bar unloader for the lowers. The lowers are currently supported by bottle jacks. I hope the lowers are in as good a shape as the uppers. Some of your pictures scared me.
Still trying to find a torsion bar unloader. I hate paying $125 for a tool I will only use once. But, if I gotta, I gotta. I'd rather use the $125 for more new parts for the coach.
Thanks
Mike Thomas
Marine City, MI
77 ex Palm Beach
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| Re: [GMCnet] Urethane vs rubber suspension bushings [message #74672 is a reply to message #74665] |
Mon, 22 February 2010 09:36 |
C Boyd
Messages: 2629
Registered: April 2006
Karma: 18
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Senior Member |
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| MikeT wrote on Mon, 22 February 2010 09:31 |
WOW!!
Thanks Steve. Surprised with all my surfing over the last 4 months I haven't found that.
Great presentation.
I have the uppers off but need a torsion bar unloader for the lowers. The lowers are currently supported by bottle jacks. I hope the lowers are in as good a shape as the uppers. Some of your pictures scared me.
Still trying to find a torsion bar unloader. I hate paying $125 for a tool I will only use once. But, if I gotta, I gotta. I'd rather use the $125 for more new parts for the coach.
Thanks
|
Sir: you don`t have to have an unloader tool to remove the lower A-arm. Block the frame up, put a floor jack under the lower arm, remove the shock, lower ball joint, and sway bar bolt then let the jack down slowly. It should be loose about 5 oclock. make sure and tie up the hub if you are not removing it.
with the pressure off you can remove the bolts and remove, just mark the clocking as to put it back from whence it came. If you remove the tensioner bolt, count the # of turns and wright it down. It isn`t hard, just a little agrivating the first time. be careful..
C. Boyd
76 Crestmont
East Tennessee
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| Re: [GMCnet] Urethane vs rubber suspension bushings [message #74679 is a reply to message #74672] |
Mon, 22 February 2010 10:16 |
MikeT
Messages: 225
Registered: November 2009
Location: Marine City, Michigan
Karma: 0
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Mr. Boyd, That's great advice.
I tried that with a floor jack. Got the floor jack to the lowest position and the lower control arm bottomed out on a cross member that runs across at a 45 degree angle. It was resting on that crossmember with still allot of torque. That was about the 5 o'clock position
That's why I thought I still needed the torsion bar unloader tool to release the rest of the tension. Maybe now I can just turn the torsion bar bolt and unload the rest.
Thanks
Mike Thomas
Marine City, MI
77 ex Palm Beach
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| Re: [GMCnet] Urethane vs rubber suspension bushings [message #74682 is a reply to message #74679] |
Mon, 22 February 2010 10:26 |
C Boyd
Messages: 2629
Registered: April 2006
Karma: 18
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Senior Member |
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| MikeT wrote on Mon, 22 February 2010 11:16 |
Mr. Boyd, That's great advice.
I tried that with a floor jack. Got the floor jack to the lowest position and the lower control arm bottomed out on a cross member that runs across at a 45 degree angle. It was resting on that crossmember with still allot of torque. That was about the 5 o'clock position
That's why I thought I still needed the torsion bar unloader tool to release the rest of the tension. Maybe now I can just turn the torsion bar bolt and unload the rest.
Thanks
|
It has been a while since I did mine, but now I do remember removing the brace. If you do remove the bolt, clean & lube it.
C. Boyd
76 Crestmont
East Tennessee
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