Home » GMC » GMCnet » Differences between a 73/74 and 76+ models
| Re: Differences between a 73/74 and 76+ models [message #170357 is a reply to message #170325 ] |
Sun, 20 May 2012 22:25   |
 Bob de Kruyff
Messages: 2344
Registered: January 2004
Location: Chandler, AZ |
Senior Member |
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| JohnL455 wrote on Sun, 20 May 2012 16:55 |
I have not driven a 403, but my 455 with stock gears at 3.07 seems fine. At highway cruse I like to do 65 so I wouldn't want more than like a 3.42, though on paper I'm below the torque curve. Others would say Higher numbers would be better. I'd love a 3.55 in the city and stop and go traffic so the torque converter wasn't doing what the gears should, but with 3 forward gears, so it is. From what I know the 403 is fine with a 3.55 or better and that makes sense to me. If it's spark and carb are setup right I don't think there is much difference or disadvantage. Maybe pulling a toad on a grade it would matter but....
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John--I have driven many back to back and i doubt you will ever be able to do a blind test.. Given all that I think the 403 is more durable and not suspect to the numerous intake problems..
Bob de Kruyff
78 Eleganza
Chandler, AZ
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| Re: [GMCnet] Differences between a 73/74 and 76+ models [message #170369 is a reply to message #170352 ] |
Mon, 21 May 2012 01:21 |
Robert Mueller
Messages: 9201
Registered: July 2007
Location: Sydney, Australia |
Senior Member |
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Adrien,
I'm confused!
I am looking at Parts Book 78Z page 23-24 FLOOR SUPPORT AND WHEELHOUSE where I see Key's 27, 29, 33, 34, 36, and 37 all of which are
referred to as SUPPORT - floor effective (prior to 1975) .
Regards,
Rob M.
-----Original Message-----
From: Adrien Genesoto
Bob & the rest on the forum,
I read this thread and so far no one has mention about the difference in floor structure between '73-74 and '75 and later.
I think that the alum floor joist structure is bound to add some rigidity to the walls since the frame in inboard of the walls,
along with the floor insulation and alum cover.
Non of which the early model have. And if GM didn't find it necessary, I'm sure they wouldn't have added the extra cost.
JMO
Adrien
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Rob Mueller
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: [GMCnet] Differences between a 73/74 and 76+ models [message #170371 is a reply to message #170342 ] |
Mon, 21 May 2012 02:23 |
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Mike Miller
Messages: 3352
Registered: February 2004
Location: Hillsboro, Oregon |
Senior Member |
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| ljdavick wrote on Sun, 20 May 2012 18:08 |
Keep going Mike. It's interesting!
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OK
Most of this is off the top of my head. Please fill in the blanks or provide corrections.
| Quote: |
~ Fist 100 coaches Many small running changes made to correct deficiencies in the early designs.
first few years rivets “as needed” at seams got fewer rivets as confidence /skill with adhesive improved
1973 door latch change later design was more reliable early design looked better
1973 rain gutters added
1973 rear spindle recall
1975 Stopped offering non- transmode 23 foot coaches
1975 Transmodes available
1975 floor structure
1975 thiner floor with isolation & aluminum
1975 larger boogie pins with redesigned arms
1975 Redesigned fiberglass wheel wells
1975 frame changes
1975 interior up fitting was brought in house
1975 metal cockpit seat pedestals (center pivot)
1975 Plastic fresh water plumbing (from copper)
1975 Interior modules by Grand Rapids Furniture Co. dovetail joints replaced glue and staples.
1975 flex steel seating w/automotive type woven fabrics
1975 house battery to rear and delete gen set battery
1975.25 Windows – late style
1975.5 Imron paint
1976 twin bed/dry bath introduced Edgemont “low price” coach Return of wood/foam seating
1976.5 electro level
1977 dash redesign (w/level controls to side panel)
1977 85mph speedometer
1977.5 403 engine w/radiator ducting
1978 added fan delay
1978 mirror mount changed to bolts
1978.5 electro level 2
1978.5 paint change??
1973 Body isolation pads – full frame
1975 Body isolation pads – smaller
???? Body isolation pads – Thicker
1973 Air conditioning type 1
???? Air conditioning type 2
1977 Air conditioning type 3
???? Dash air “OFF” removed
???? Non-grounded speaker wires
???? Steering link change (to non-adjustable)
???? steering wheel change (GM coach)
???? steering wheel change (Transmode)
???? metal cockpit seat pedestals (offset pivot)
???? Front suspension geometry
???? radial wheels
???? Bunk-bed attachment change
1973 Canyon Lands, Glacier, Painted Desert and Sequoia White, Camel, Pineapple Yellow, Bittersweet, Sky Blue, Parrot Green
1974 Canyon Lands, Glacier, Painted Desert and Sequoia White, Camel, Pineapple Yellow, Bittersweet, Sky Blue
1974.5 Eleganza SE
1975 Eleganza II, Palm Beach + Transmodes
1976 Eleganza II, Palm Beach, Glenbrook, Edgemont + Transmodes
1977 Eleganza II, Palm Beach, Kingsley, Coca Cola/GadAbout + Transmodes + twin bed/dry bath floor plan Eleganza II
1978 Eleganza II, Palm Beach, Kingsley, Coca Cola/GadAbout + Transmodes
Notes:
76 or newer you are subject to smog-checks
Coachmen Industries (Jimmy Motors) producing the Royale (26-foot) and Birchaven (23-foot).
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Mike Miller -- Hillsboro, OR -- on the Black list
(#1)'73 26' exPainted D. -- (#2)`78 23' Birchaven Rear Bath -- (#3)`77 23' Birchaven Side Bath
http://m000035.blogspot.com
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| Re: [GMCnet] Differences between a 73/74 and 76+ models [message #170487 is a reply to message #170369 ] |
Tue, 22 May 2012 00:46 |
Adrien G.
Messages: 208
Registered: May 2008
Location: Yuba City, Ca. |
Senior Member |
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Rob M.,
Quote >>>>I am looking at Parts Book 78Z page 23-24 FLOOR SUPPORT AND WHEELHOUSE where I see Key's 27, 29, 33, 34, 36, and 37 all of which are
referred to as SUPPORT - floor effective (prior to 1975) .<<<<
In answer to
-----Original Message-----
From: Adrien Genesoto
Bob & the rest on the forum,
I read this thread and so far no one has mention about the difference in floor structure between '73-74 and '75 and later.
I think that the alum floor joist structure is bound to add some rigidity to the walls since the frame in inboard of the walls,
along with the floor insulation and alum cover.
Non of which the early model have. And if GM didn't find it necessary, I'm sure they wouldn't have added the extra cost.
JMO
Rob,
I don't have a book on the early models. I can say about my experience that I had with one '73, which up until then I thought that frame and body structure where all the same.
I had found a '73 that I could purchase the rear section to stretch my '75. I finished striping the walls (things where the same), the floor didn't look the same.
The '73 floor ply was directly 0n top of the isolation strip with small alum angles between the plywood panels.
The '75 floor plywood is on top of an alum joist frame (made of enclosed wall channel inside face down, the floor ply mounted on top like the outside skin is mounted to the wall channels) allowing for insulation and an alum skin cover inside each grid section.
So, I had to give up on the idea to use the '73, it would have meant a lot of extra work trying adapt it.
Just my experience on the learning process of these machines.
”When we avoid the mistakes we might have made, we sometimes make the mistakes that we might have avoided.”
Adrien & Jenny
75 Glenbrook
Yuba City,Ca.
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