Home » Public Forums » GMCnet » Rear Suspension System Inspection and Overhaul
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| Re: [GMCnet] Rear Suspension System Inspection and Overhaul [message #199537 is a reply to message #199512] |
Sat, 23 February 2013 20:44   |
John Wright
Messages: 118
Registered: September 2008
Karma: 0
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Senior Member |
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Joe,
Unless the rear bushing are worn there is no reason to disassemble the rear suspension. Just change the rear bearing and seals and then redo the brakes and replace the shocks with KYB's. Anything more is too much.
J.R. Wright
GMC GreatLaker
GMC Eastern States
GMCMI
78 Buskirk 30' Stretch
1975 Avion (Under Reconstruction)
Michigan
On Feb 23, 2013, at 7:50 PM, Joe Crutchfield <joe.crutchfield@hotmail.com> wrote:
>
>
> I am planning to begin disassembling the rear suspension on my GMC and would appreciate your feedback on items that I should inspect and repair/replace. I have no maintenance records on the unit so I do not know what has been done, nor when. From what I have been able to determine, everything looks fairly much OEM. I plan to stay with OEM unless the cost of upgrades would not be much more expensive than OEM, or, in cases where OEM parts are no longer available.
>
> I try to read all the previous posts relating to a topic before asking questions, but I am sure I will need your help as I work through each of the processes. I have the hundreds of pages of maintenance manuals, and I will refer to them for the how-to detail.
>
> At this point I wanted to get your thinking about what I should do while I have the suspension disassembled. I know many of you could write a book about this topic but I am just trying to get a check list right now.
>
> Thanks
>
>
> --
> Joe Crutchfield,
> Watertown, TN,
> 77 Royale by Coachman, Rear Bath, 455, 3.07,
>
> "Strangers are just friends I haven't met yet" - Will Rogers.
> _______________________________________________
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| Re: [GMCnet] Rear Suspension System Inspection and Overhaul [message #199539 is a reply to message #199537] |
Sat, 23 February 2013 21:11 |
Dennis S
Messages: 3046
Registered: November 2005
Karma: 2
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Senior Member |
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| John Wright wrote on Sat, 23 February 2013 20:44 |
Joe,
Unless the rear bushing are worn there is no reason to disassemble the rear suspension. Just change the rear bearing and seals and then redo the brakes and replace the shocks with KYB's. Anything more is too much.
J.R. Wright
GMC GreatLaker
GMC Eastern States
GMCMI
78 Buskirk 30' Stretch
1975 Avion (Under Reconstruction)
Michigan
On Feb 23, 2013, at 7:50 PM, Joe Crutchfield <joe.crutchfield@hotmail.com> wrote:
>
>
> I am planning to begin disassembling the rear suspension on my GMC and would appreciate your feedback on items that I should inspect and repair/replace. I have no maintenance records on the unit so I do not know what has been done, nor when. From what I have been able to determine, everything looks fairly much OEM. I plan to stay with OEM unless the cost of upgrades would not be much more expensive than OEM, or, in cases where OEM parts are no longer available.
>
> I try to read all the previous posts relating to a topic before asking questions, but I am sure I will need your help as I work through each of the processes. I have the hundreds of pages of maintenance manuals, and I will refer to them for the how-to detail.
>
> At this point I wanted to get your thinking about what I should do while I have the suspension disassembled. I know many of you could write a book about this topic but I am just trying to get a check list right now.
>
> Thanks
>
> Joe Crutchfield,
> Watertown, TN,
> 77 Royale by Coachman, Rear Bath, 455, 3.07,
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In addition -- you might review the rear suspension section on Gene's site...
http://gmcmotorhome.info/
http://gmcmotorhome.info/list.html see suspension
I am not sure where I got the big red straws I use to remove the old grease from the pins -- McAlisters deli I think -- but pick up samples at most of the fast food places and test for best fit.
and for rear suspension photos and how-to go to
http://www.gmcmhphotos.com/photos/
use the search function here -- bogie is a good term -- that is what we generally call the rear suspension.
Dennis
Dennis S
73 Painted Desert 230
Memphis TN Metro
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| Re: Rear Suspension System Inspection and Overhaul [message #199541 is a reply to message #199512] |
Sat, 23 February 2013 21:17 |
Dennis S
Messages: 3046
Registered: November 2005
Karma: 2
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Senior Member |
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| JoeC wrote on Sat, 23 February 2013 18:50 |
I am planning to begin disassembling the rear suspension on my GMC and would appreciate your feedback on items that I should inspect and repair/replace. I have no maintenance records on the unit so I do not know what has been done, nor when. From what I have been able to determine, everything looks fairly much OEM. I plan to stay with OEM unless the cost of upgrades would not be much more expensive than OEM, or, in cases where OEM parts are no longer available.
I try to read all the previous posts relating to a topic before asking questions, but I am sure I will need your help as I work through each of the processes. I have the hundreds of pages of maintenance manuals, and I will refer to them for the how-to detail.
At this point I wanted to get your thinking about what I should do while I have the suspension disassembled. I know many of you could write a book about this topic but I am just trying to get a check list right now.
Thanks
|
Joe,
Here is a photo sample that shows in detail the breakdown of the rear suspension and some significant re-engineering by the owner.
http://www.cathy-ron.com/GMC%20Rear%20Hub%20%26%20Suspension.html
Dennis
Dennis S
73 Painted Desert 230
Memphis TN Metro
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| Re: [GMCnet] Rear Suspension System Inspection and Overhaul [message #199550 is a reply to message #199541] |
Sat, 23 February 2013 21:53 |
sgltrac
Messages: 2797
Registered: April 2011
Karma: 1
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Senior Member |
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Joe, I second the don't rip it all down if its not needed advice you've already been given. Support the rear of the coach with the bags deflated and shocks off. If there is no significant play in the arms about the pivot pin, remove what you can scavenge from behind the grease nipple and buy a greaser kit from Jim k. If the arm slides toward you or away from you straight on the pin it can usually be adjusted by torquing the pivot nut.
Don't rip it apart just because. It's a sucky job.
IMHO
Sully
77 royale
Seattle
Sent from my iPhone
On Feb 23, 2013, at 7:17 PM, Dennis Sexton <dennisfsexton@aol.com> wrote:
>
>
> JoeC wrote on Sat, 23 February 2013 18:50
>> I am planning to begin disassembling the rear suspension on my GMC and would appreciate your feedback on items that I should inspect and repair/replace. I have no maintenance records on the unit so I do not know what has been done, nor when. From what I have been able to determine, everything looks fairly much OEM. I plan to stay with OEM unless the cost of upgrades would not be much more expensive than OEM, or, in cases where OEM parts are no longer available.
>>
>> I try to read all the previous posts relating to a topic before asking questions, but I am sure I will need your help as I work through each of the processes. I have the hundreds of pages of maintenance manuals, and I will refer to them for the how-to detail.
>>
>> At this point I wanted to get your thinking about what I should do while I have the suspension disassembled. I know many of you could write a book about this topic but I am just trying to get a check list right now.
>>
>> Thanks
>
>
> Joe,
>
> Here is a photo sample that shows in detail the breakdown of the rear suspension and some significant re-engineering by the owner.
>
> http://www.cathy-ron.com/GMC%20Rear%20Hub%20%26%20Suspension.html
>
> Dennis
> --
> Dennis S
> 73 Painted Desert 230
> Germantown, TN
> _______________________________________________
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Sully
77 Royale basket case.
Future motorhome land speed record holder(bucket list)
Seattle, Wa.
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| Re: [GMCnet] Rear Suspension System Inspection and Overhaul [message #199562 is a reply to message #199537] |
Sat, 23 February 2013 23:16 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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JR,
Your message below got me to wondering just how much play was allowed at the end of the bogie arms.
I checked MM X-7525 - NADA. I checked X-7625 - Nada.
I FINALLY found the spec for acceptable limits of bogie pin wear. It's in X-7725 Section 4A, Page 4A-22, Worn Control Arm Bushing.
It states:
Worn Control Arm Bushing
1. Raise vehicle.
2. Remove wheel bearing dust caps, and wipe grease from end of spindle.
3. Place dial indicator at end of spindle. Mount dial indicator on a suitable stand.
4. Check wheel and control arm assembly. Total indicated reading on dial indicator should not exceed .050". If lateral movement is
greater than this, bushings and/or mounting pins should be replaced.
Man fifty thou sure don't sound like much to me!
Regards,
Rob M.
-----Original Message-----
From: John Wright
Joe,
Unless the rear bushing are worn there is no reason to disassemble the rear suspension. Just change the rear bearing and seals and
then redo the brakes and replace the shocks with KYB's. Anything more is too much.
J.R.
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Unsubscribe or Change List Options:
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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] Rear Suspension System Inspection and Overhaul [message #199613 is a reply to message #199555] |
Sun, 24 February 2013 09:52 |
sgltrac
Messages: 2797
Registered: April 2011
Karma: 1
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Senior Member |
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I've got a few hubcaps. 3-4 with maybe one as high as a B grade if you are interested
Sully
77 royale
Seattle
Sent from my iPhone
On Feb 23, 2013, at 8:16 PM, Joe Crutchfield <joe.crutchfield@hotmail.com> wrote:
>
>
> Thanks Sully, and to the others who have responded. I understand and agree. I try to do my homework before starting anything like this and know that I can get good advice from the members of the forum. It only makes sense to redo the bearings, brakes and shocks - but I wanted to at least inspect any other areas that might be a concern while I have it torn down.
>
> The PO put new tires on the rusty 16.5 inch wheels about two years ago and he lost three of the hub caps. I plan to keep the 16.5 wheels until I need new tires, but plan to get them powder coated and run them without hub caps until I do need new tires. I will then change them to the 16 inch alum wheels.
>
> JR mentioned bushings but I do not know what condition they are in.
>
> Dennis, thanks for the links you gave me also. I had seen some of them but I bookmarked all of them so I can read them closer.
>
> Please continue to provide me any information if you think of something else. I am sure I will get some more responses on this subject too.
> --
> Joe Crutchfield,
> Watertown, TN,
> 77 Royale by Coachman, Rear Bath, 455, 3.07,
>
> "Strangers are just friends I haven't met yet" - Will Rogers.
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
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Sully
77 Royale basket case.
Future motorhome land speed record holder(bucket list)
Seattle, Wa.
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| Re: Rear Suspension System Inspection and Overhaul [message #199617 is a reply to message #199512] |
Sun, 24 February 2013 10:26 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Senior Member |
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You don't need to take apart pins and bushings to "see". Feel test is how you see. If you don't ream the new ones right you'll have more than.050 anyway. Just grease them every trip with Valvoline Synpower. (Think of it like how you would treat a Cat earthmover where daily grease is cheap compared to mechanical repairs)
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: [GMCnet] Rear Suspension System Inspection and Overhaul [message #199621 is a reply to message #199562] |
Sun, 24 February 2013 10:59 |
Dennis S
Messages: 3046
Registered: November 2005
Karma: 2
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Senior Member |
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Rob,
For spindle in/out movement -- I have been referring to Denny Allen's comment quoted on Gene's site.
quote
Another variable from coach to coach is the wear on the rear pins. I have a coach here that had a mind of its own according to the owner. The rear pins were very loose so the coach was riding on four casters back there. The easiest/best way to check and get a repeatable measurement is: Support the coach under the rear suspension mounting bracket at approximatly the correct ride height. Loosen all lug nuts on both wheels. Release all air from the air bag. Jack up the suspension arm only--just enough to get the wheel off.
With a piece of wood, standing on end, support the end of the control arm at the spindle end. Move the spindle end of the arm towards and away from the frame and measure the total movement with a tape measure. GM Service Bulletin #75-TM-4 states 1/8" is maximum.
end quote
I wonder which was the latest -- the service bulletin or the X-7725?
Dennis
| Robert Mueller wrote on Sat, 23 February 2013 23:16 |
JR,
Your message below got me to wondering just how much play was allowed at the end of the bogie arms.
I checked MM X-7525 - NADA. I checked X-7625 - Nada.
I FINALLY found the spec for acceptable limits of bogie pin wear. It's in X-7725 Section 4A, Page 4A-22, Worn Control Arm Bushing.
It states:
Worn Control Arm Bushing
1. Raise vehicle.
2. Remove wheel bearing dust caps, and wipe grease from end of spindle.
3. Place dial indicator at end of spindle. Mount dial indicator on a suitable stand.
4. Check wheel and control arm assembly. Total indicated reading on dial indicator should not exceed .050". If lateral movement is
greater than this, bushings and/or mounting pins should be replaced.
Man fifty thou sure don't sound like much to me!
Regards,
Rob M.
|
Dennis S
73 Painted Desert 230
Memphis TN Metro
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| Re: [GMCnet] Rear Suspension System Inspection and Overhaul [message #199680 is a reply to message #199621] |
Sun, 24 February 2013 18:20 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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Dennis,
Thanks for this reference, 0.125 makes more sense than 0.050.
I would think that the MM as it had to be published after 1975. However, the 0.050 seems a bit "overzealous".
It would be interesting to replace the bushings and see what you wind up with.
If I remember I'll check Double Troubles bogie arms and see what I get.
Regards,
Rob M.
-----Original Message-----
From: Dennis Sexton
Rob,
For spindle in/out movement -- I have been referring to Denny Allen's comment quoted on Gene's site.
quote
Another variable from coach to coach is the wear on the rear pins. I have a coach here that had a mind of its own according to the
owner. The rear pins were very loose so the coach was riding on four casters back there. The easiest/best way to check and get a
repeatable measurement is: Support the coach under the rear suspension mounting bracket at approximatly the correct ride height.
Loosen all lug nuts on both wheels. Release all air from the air bag. Jack up the suspension arm only--just enough to get the wheel
off.
With a piece of wood, standing on end, support the end of the control arm at the spindle end. Move the spindle end of the arm
towards and away from the frame and measure the total movement with a tape measure. GM Service Bulletin #75-TM-4 states 1/8" is
maximum.
end quote
I wonder which was the latest -- the service bulletin or the X-7725?
Dennis
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GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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: Rear Suspension System Inspection and Overhaul [message #199684 is a reply to message #199618] |
Sun, 24 February 2013 18:34 |
gbarrow2
Messages: 765
Registered: February 2004
Location: Lake Almanor, Ca./ Red Bl...
Karma: 3
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Senior Member |
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And when replacing the flexible brake hoses be especially careful not to crossthread the center fitting- or you will be dropping the black tank just access the up stream hard line connection in order to replace the damaged fitting.
A LOT of extra work because of a simple preventable mistake.
Gene Barrow
Lake Almanor, Ca.
1976 Palm Beach
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| Re: [GMCnet] Rear Suspension System Inspection and Overhaul [message #199721 is a reply to message #199680] |
Sun, 24 February 2013 21:12 |
Dennis S
Messages: 3046
Registered: November 2005
Karma: 2
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Senior Member |
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Rob,
Just discussion and some observations from my 73.
When I tried to adjust the top hats -- of course, they would not move -- so I have been regularly applying penetrating lube (Boeshield) in hopes they may free up. If I tightened the swing arm locking nut to 80 ft lbs torque -- there must be enough spring in the bogie case -- the arm would be tight and there was no lateral movement. But when I then backed off and re-torqued to the factory 15-20 ft lbs the slack returned. This led me to conclude that a very small clearance between the top hat and the thrust washer would allow almost the full 1/8 inch in lateral movement of the swing arm.
Also, the center to center from the pins to the spindle is 18 inches and the diameter of the tire is about 28 inches -- so 1/8 inch lateral movement of the swing arm is just under 1/4 inch measured at the leading edge of the front rear tire.
When you measure your swing arms I will be very interested to know the results.
Dennis
| Robert Mueller wrote on Sun, 24 February 2013 18:20 |
Dennis,
Thanks for this reference, 0.125 makes more sense than 0.050.
I would think that the MM as it had to be published after 1975. However, the 0.050 seems a bit "overzealous".
It would be interesting to replace the bushings and see what you wind up with.
If I remember I'll check Double Troubles bogie arms and see what I get.
Regards,
Rob M.
-----Original Message-----
From: Dennis Sexton
Rob,
For spindle in/out movement -- I have been referring to Denny Allen's comment quoted on Gene's site.
quote
Another variable from coach to coach is the wear on the rear pins. I have a coach here that had a mind of its own according to the
owner. The rear pins were very loose so the coach was riding on four casters back there. The easiest/best way to check and get a
repeatable measurement is: Support the coach under the rear suspension mounting bracket at approximatly the correct ride height.
Loosen all lug nuts on both wheels. Release all air from the air bag. Jack up the suspension arm only--just enough to get the wheel
off.
With a piece of wood, standing on end, support the end of the control arm at the spindle end. Move the spindle end of the arm
towards and away from the frame and measure the total movement with a tape measure. GM Service Bulletin #75-TM-4 states 1/8" is
maximum.
end quote
I wonder which was the latest -- the service bulletin or the X-7725?
Dennis
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Dennis S
73 Painted Desert 230
Memphis TN Metro
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| Re: [GMCnet] Rear Suspension System Inspection and Overhaul [message #199770 is a reply to message #199721] |
Mon, 25 February 2013 07:40 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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Dennis,
Quite frankly I have never worked on a bogie to date. My only exposure was when I was at the Coop and Jason checked the ones on
Double Trouble. The rear wheels were off and the bags were depressurized. He pulled the ends of the bogie arms in / out and noted
that they were OK, noting that the passenger side was a "bit loose." Since it trucks down the road on the straight and narrow I
haven't done anything about that. I do have a set of Tru-Tracks from Tom Hampton that I will be fitting. Also the middle and rear
tires wear true so that's another indication that everything is OK.
I will have to do some homework and study the MM, Parts Book, and GMCnet messages before I feel confident to comment on your email
below.
Regards,
Rob M.
-----Original Message-----
From: Dennis Sexton
Rob,
Just discussion and some observations from my 73.
When I tried to adjust the top hats -- of course, they would not move -- so I have been regularly applying penetrating lube
(Boeshield) in hopes they may free up. If I tightened the swing arm locking nut to 80 ft lbs torque -- there must be enough spring
in the bogie case -- the arm would be tight and there was no lateral movement. But when I then backed off and re-torqued to the
factory 15-20 ft lbs the slack returned. This led me to conclude that a very small clearance between the top hat and the thrust
washer would allow almost the full 1/8 inch in lateral movement of the swing arm.
Also, the center to center from the pins to the spindle is 18 inches and the diameter of the tire is about 28 inches -- so 1/8 inch
lateral movement of the swing arm is just under 1/4 inch measured at the leading edge of the front rear tire.
When you measure your swing arms I will be very interested to know the results.
Dennis
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GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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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