GMCforum: GMCnet » rear frame member odd shape

Home » Public Forums » GMCnet » rear frame member odd shape (rear frame member curved indentation)

Show: Today's Messages :: Polls :: Message Navigator

rear frame member odd shape [message #250773]

Tue, 27 May 2014 18:24

Messages: 1262
Registered: September 2009

Karma: 0

Senior Member

I've been looking at our coach with the thought of adding a tow hitch, and noticed an odd
difference between the 73 and 75 coach frames. The rearmost frame member on the 73
is just a straight piece of U-channel. On the 75 (and I see pics of other later coaches) there's
a weird curved shape formed into the bottom center of the channel. You can see a good picture
of one here:
http://www.gmcmhphotos.com/photos/installing-a-blaine-merrill-tow-hitch/p13806.html

So the question then is, how come? What was that curve for?
Did GM originally provide some kind of hitch that fit in the curve somehow, or ???

thanks,
Karen
1975 26'

Report message to a moderator

Re: [GMCnet] rear frame member odd shape [message #250779 is a reply to message #250773]

Tue, 27 May 2014 19:03

USAussie

Messages: 15912
Registered: July 2007
Location: Sydney, Australia

Karma: 6

Senior Member

Karen,

Interesting! I just checked Parts Book 78Z / Section 11 - Frame / Page 11-2 / Figure 11.002 / Key 10 - Extension Assy- rear frame
(SOA) (repl. 691904)

Maybe it was added to allow the 3" dump fit closer to the frame and further from the road?

Regards,
Rob M.
Sydney, Australia

-----Original Message-----
From: KB

I've been looking at our coach with the thought of adding a tow hitch, and noticed an odd
difference between the 73 and 75 coach frames. The rearmost frame member on the 73
is just a straight piece of U-channel. On the 75 (and I see pics of other later coaches) there's
a weird curved shape formed into the bottom center of the channel. You can see a good picture
of one here:
http://www.gmcmhphotos.com/photos/installing-a-blaine-merrill-tow-hitch/p13806.html

So the question then is, how come? What was that curve for?
Did GM originally provide some kind of hitch that fit in the curve somehow, or ???

thanks,
Karen

_______________________________________________
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

Report message to a moderator

Re: [GMCnet] rear frame member odd shape [message #250784 is a reply to message #250779]

Tue, 27 May 2014 20:16

James Hupy

Messages: 6806
Registered: May 2010

Karma: -62

Senior Member

Karen, it gives clearance for the center 3" dump.
Jim Hupy
Salem, Or.
78 GMC Royale

On Tue, May 27, 2014 at 5:03 PM, Robert Mueller wrote:

> Karen,
>
> Interesting! I just checked Parts Book 78Z / Section 11 - Frame / Page
> 11-2 / Figure 11.002 / Key 10 - Extension Assy- rear frame
> (SOA) (repl. 691904)
>
> Maybe it was added to allow the 3" dump fit closer to the frame and
> further from the road?
>
> Regards,
> Rob M.
> Sydney, Australia
>
> -----Original Message-----
> From: KB
>
> I've been looking at our coach with the thought of adding a tow hitch, and
> noticed an odd
> difference between the 73 and 75 coach frames. The rearmost frame member
> on the 73
> is just a straight piece of U-channel. On the 75 (and I see pics of other
> later coaches) there's
> a weird curved shape formed into the bottom center of the channel. You
> can see a good picture
> of one here:
>
> http://www.gmcmhphotos.com/photos/installing-a-blaine-merrill-tow-hitch/p13806.html
>
> So the question then is, how come? What was that curve for?
> Did GM originally provide some kind of hitch that fit in the curve
> somehow, or ???
>
> thanks,
> Karen
>
> _______________________________________________
> 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:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist

Report message to a moderator

Re: [GMCnet] rear frame member odd shape [message #250903 is a reply to message #250784]

Thu, 29 May 2014 12:40

Messages: 1262
Registered: September 2009

Karma: 0

Senior Member

thanks, I can't tell if our 75 has original plumbing or not, but it does
have a central dump tube that might have originally tucked into that curve.

So does this mean that if you install a rear hitch (eg, the through-the-bumper version with the support
bar between the frame members) that you have to modify the plumbing??

thanks
Karen
1975 26'

Report message to a moderator

Re: [GMCnet] rear frame member odd shape [message #250913 is a reply to message #250903]

Thu, 29 May 2014 15:18

Carl S.

Messages: 4186
Registered: January 2009
Location: Tucson, AZ.

Karma: 13

Senior Member

KB wrote on Thu, 29 May 2014 10:40

thanks, I can't tell if our 75 has original plumbing or not, but it does
have a central dump tube that might have originally tucked into that curve.

So does this mean that if you install a rear hitch (eg, the through-the-bumper version with the support
bar between the frame members) that you have to modify the plumbing??

thanks
Karen
1975 26'

I just cut mine off shorter and replaced the cap on the end. I have a macerator and have never used the 3" dump, but it's still there (albeit in a less convenient place) if I need it.

Carl Stouffer '75 ex Palm Beach Tucson, AZ. Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member

Report message to a moderator

Re: [GMCnet] rear frame member odd shape [message #250916 is a reply to message #250913]

Thu, 29 May 2014 16:04

James Hupy

Messages: 6806
Registered: May 2010

Karma: -62

Senior Member

Karen, fairly easy fix if you have a valterra 3" dump valve upstream from
the spot where your new hitch starts under the coach. Just close the valve,
then using a sawzall or a hacksaw or similar and leave a short straight
section of pipe protruding rearward to glue a coupling onto. then using
space available, a 90 degree 3" PVC elbow and new 3" pipe, make the new
dump pipe exit on the side of the coach that you prefer at the very back of
the coach. If you have a lever that controls the valve, I usually choose
that side as the termination point for the 3" drain fitting. If yours has a
short straight section on it just ahead of the cap fitting and is in good
shape, cut it off straight and use a coupling there as well. Not rocket
science, but well within your capabilities. Be sure to use hangers to
support the drain system every 12- 18 inches or so.
Jim Hupy
Salem, OR
78 GMC Royale 403

On Thu, May 29, 2014 at 1:18 PM, Carl Stouffer wrote:

> KB wrote on Thu, 29 May 2014 10:40
>> thanks, I can't tell if our 75 has original plumbing or not, but it does
>> have a central dump tube that might have originally tucked into that
> curve.
>>
>> So does this mean that if you install a rear hitch (eg, the
> through-the-bumper version with the support
>> bar between the frame members) that you have to modify the plumbing??
>>
>> thanks
>> Karen
>> 1975 26'
>
>
> I just cut mine off shorter and replaced the cap on the end. I have a
> macerator and have never used the 3" dump, but it's still there (albeit in a
> less convenient place) if I need it.
>
> --
> Carl Stouffer
> '75 ex Palm Beach
> Tucson, AZ.
> _______________________________________________
> 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:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist

Report message to a moderator

Previous Topic:	Facebook
Next Topic:	UPS lost my final drive!

Goto Forum:

-=] Back to Top [=-

Current Time: Fri Oct 04 12:24:19 CDT 2024

Total time taken to generate the page: 0.00748 seconds