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[GMCnet] Why put in thicker body pads then GM engineeringcalled for.? [message #342443]

Thu, 11 April 2019 00:16

BobDunahugh

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Registered: October 2010
Location: Cedar Rapids, IA

Karma: 11

Senior Member

I saw some photos here a few days ago. That was showing thicker pads then GM engineering called for. I believe that the originals were at .5 inch, or just under. I have some that I can check. thick Bob Dunahugh
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Re: [GMCnet] Why put in thicker body pads then GM engineeringcalled for.? [message #342445 is a reply to message #342443]

Thu, 11 April 2019 10:44

Harry

Messages: 1888
Registered: October 2007
Location: Victoria, BC CANADA

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How much thicker were the ones you saw being installed?

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Re: [GMCnet] Why put in thicker body pads then GM engineeringcalled for.? [message #342448 is a reply to message #342443]

Thu, 11 April 2019 12:23

BobDunahugh

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Registered: October 2010
Location: Cedar Rapids, IA

Karma: 11

Senior Member

I just measured an old compressed pad. 5/16th. May have been 3/8th new. But that's more then enough clearance for the 1/4th inch air lines. Bob Dunahugh 78 Royale

________________________________
From: Bob Dunahugh
Sent: Thursday, April 11, 2019 12:16 AM
To: gmclist@list.gmcnet.org
Subject: Why put in thicker body pads then GM engineeringcalled for.?

I saw some photos here a few days ago. That was showing thicker pads then GM engineering called for. I believe that the originals were at .5 inch, or just under. I have some that I can check. thick Bob Dunahugh
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Re: [GMCnet] Why put in thicker body pads then GM engineeringcalled for.? [message #342449 is a reply to message #342443]

Thu, 11 April 2019 13:15

RF_Burns

Messages: 2277
Registered: June 2008
Location: S. Ontario, Canada

Karma: 3

Senior Member

From my Googling around it appears that early coaches had thick pads about 1/2". Here is a photo from Bert & Faye Curtis's sit showing old pads versus their replacement thick pad (which is the set I used):

http://www.gmcmhphotos.com/photos/body-pads/p25791-body-pads.html

It then appears GM went to a long strip thinner pad, then to short thin pads. I speculate these changes were most likely driven more by cost saving in assembly and materials than best function.

Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.
1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that

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Re: [GMCnet] Why put in thicker body pads then GM engineeringcalled for.? [message #342460 is a reply to message #342449]

Thu, 11 April 2019 19:17

Burt and Faye curtis

Messages: 256
Registered: June 2012

Karma: 4

Senior Member

The thicker pads were of a "softer" rubber than the thinner ones used in
the later coaches. By durometer (?) readings from original pads. Probably
when the coach weight was on either, they each gave close to the same
clearance.

Fay Curtis
'76 Glenbrook
Kneeland, CA

On Thu, Apr 11, 2019, 11:23 AM Bruce Hislop via Gmclist <
gmclist@list.gmcnet.org> wrote:

> From my Googling around it appears that early coaches had thick pads about
> 1/2". Here is a photo from Bert & Faye Curtis's sit showing old pads versus
> their replacement thick pad (which is the set I used):
>
> http://www.gmcmhphotos.com/photos/body-pads/p25791-body-pads.html
>
> It then appears GM went to a long strip thinner pad, then to short thin
> pads. I speculate these changes were most likely driven more by cost saving
> in assembly and materials than best function.
>
>
>
> --
> Bruce Hislop
> ON Canada
> 77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.1 ton front end
> http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
> My Staff says I never listen to them, or something like that
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
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Re: [GMCnet] Why put in thicker body pads then GM engineeringcalled for.? [message #342462 is a reply to message #342448]

Thu, 11 April 2019 23:27

BobDunahugh

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Registered: October 2010
Location: Cedar Rapids, IA

Karma: 11

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David. I've seen pads from 3/4 to 1 inch. I'm not saying don't do it. I just haven't seen a reason to do it. Doing it would give you more engine air cleaner. Bob Dunahugh

________________________________
From: Bob Dunahugh
Sent: Thursday, April 11, 2019 12:23 PM
To: gmclist@list.gmcnet.org
Subject: RE: Why put in thicker body pads then GM engineeringcalled for.?

I just measured an old compressed pad. 5/16th. May have been 3/8th new. But that's more then enough clearance for the 1/4th inch air lines. Bob Dunahugh 78 Royale

________________________________
From: Bob Dunahugh
Sent: Thursday, April 11, 2019 12:16 AM
To: gmclist@list.gmcnet.org
Subject: Why put in thicker body pads then GM engineeringcalled for.?

I saw some photos here a few days ago. That was showing thicker pads then GM engineering called for. I believe that the originals were at .5 inch, or just under. I have some that I can check. thick Bob Dunahugh
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Re: [GMCnet] Why put in thicker body pads then GM engineeringcalled for.? [message #342468 is a reply to message #342462]

Fri, 12 April 2019 06:42

Jp Benson

Messages: 649
Registered: October 2011
Location: Fla

Karma: 2

Senior Member

BobDunahugh wrote on Thu, 11 April 2019 23:27

David. I've seen pads from 3/4 to 1 inch. I'm not saying don't do it. I just haven't seen a reason to do it. Doing it would give you more engine air cleaner. Bob Dunahugh

Using 1" pads gave enough clearance to move the fuel fill to the center of the coach. It was nice to get rid of that long tube inside of the frame rail and all the rubber parts attached to it. I was also able to increase my DIY gray tank capacity by about 5 gallons. That estra clearance is noticeable when working under the coach and is handy for stringing wires etc. It's nice having finger room on top of frame rails and cross members. Custom fuel tanks could also be made larger. I see that JimB is doing and interesting custom single tank mod that solves the EFI return line problem. With an extra 1/2" of clearance he could install a 60 gallon tank.

JP

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Re: [GMCnet] Why put in thicker body pads then GM engineeringcalled for.? [message #342476 is a reply to message #342468]

Fri, 12 April 2019 08:42

Justin Brady

Messages: 769
Registered: April 2015
Location: Bell Buckle, TN

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Mine are 3/4" because that's the rubber that was locally available. They work fine and you gain a little clearance for running air lines and the like without fear of them pinching.
I don't see one being better or worse than the other honestly, just what I had on hand.

Justin Brady http://www.thegmcrv.com/ 1976 Palm Beach 455

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Re: [GMCnet] Why put in thicker body pads then GM engineeringcalled for.? [message #342486 is a reply to message #342476]

Fri, 12 April 2019 21:55

Jp Benson

Messages: 649
Registered: October 2011
Location: Fla

Karma: 2

Senior Member

So Bob's question got me to thinking about the frequent debates on this forum about horse mat v rubber sheet v hockey pucks etc. It appears mostly to be one of those rhetorical debates like taste great vs less filling. Or so I've concluded after reading this website on load bearing polyurethane pads:

https://gallaghercorp.com/design-guide/polyurethane-load-bearing-capacity/

For a GMC motorhome, given the load on the surface area of the pads the compression of the pads would be a few hundredths of an inch no matter what the durometer (Shore rating) of the rubber material used. It's more important that the pads be bonded only on one side.

It could help to lubricate the unbonded side of the pad. This is where hockey pucks might have an advantage over horse mat simply because they have such a smooth surface (i.e. less friction) and horse mat is much rougher.

To answer Bob's question, pad compression is linear with pad thickness so a 1" pad would have twice the give of a 1/2" pad.

If you desire a more comfortable ride consider the suspension system or the seat cushions.

JP

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Re: [GMCnet] Why put in thicker body pads then GM engineeringcalled for.? [message #342494 is a reply to message #342443]

Sat, 13 April 2019 09:48

tgeiger

Messages: 518
Registered: February 2006
Location: kansas city

Karma: -1

Senior Member

This is good info guys. Did not know about the glueing of one side and lubeing the other for vehicle movement slippage but makes absolute sense. I assume the glue is on the top of the pads and the lube is on the bottom at the rail bearing point? Make sense to me since we're running the Tek screws up into the aluminum bands. Any other tips on this? Starting that pad insert this afternoon.

Thanks,
Tom
76 Eleganza 2
KCMO

Tom Geiger 76 Eleganza II KCMO

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Re: [GMCnet] Why put in thicker body pads then GM engineeringcalled for.? [message #342510 is a reply to message #342494]

Sun, 14 April 2019 12:07

jimk

Messages: 6734
Registered: July 2006
Location: Belmont, CA

Karma: 9

Senior Member

Gluing is tricky as you need to let it tack up so it does not get squesed
out.
We use screws to hold the pads along with the glue.

On Sat, Apr 13, 2019 at 7:49 AM tom geiger via Gmclist <
gmclist@list.gmcnet.org> wrote:

> This is good info guys. Did not know about the glueing of one side and
> lubeing the other for vehicle movement slippage but makes absolute sense. I
> assume the glue is on the top of the pads and the lube is on the bottom at
> the rail bearing point? Make sense to me since we're running the Tek screws
> up into the aluminum bands. Any other tips on this? Starting that pad
> insert this afternoon.
>
> Thanks,
> Tom
> 76 Eleganza 2
> KCMO
>
> _______________________________________________
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--
Jim Kanomata
Applied/GMC, Newark,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
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Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502

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