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| Final drive capacity [message #235056] |
Sat, 04 January 2014 12:03  |
Hal StClair
Messages: 971
Registered: March 2013
Location: Rio Rancho NM
Karma: -12
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Senior Member |
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I'm trying to figure out the torque capacity of the original ring and pinion used in our coaches.
The AAM/GM independent fronts had a 4643 ft lb ratting and the Dana 70's were rated 8000 ft lb's. These are max short duration ratings, the continuous rating for the Dana 70 is 2000 ft lb's but the IFS isn't rated as continuous. Does anyone know if there is a designation, ie Dana, Rockwell, Spicer used so I might find the information?
On another note, would anyone have an idea how much a differential would be de-rated buy running it backward, pulling vs pushing?
I'd much rather use something readily available in my swap so it can be more easily duplicated if desired. But the final product must be robust enough for the application.
Thanks for any advice,
Hal
"I enjoy talking to you. Your mind appeals to me. It resembles my own mind, except you happen to be insane."
1977 Royale 101348,
1977 Royale 101586, Diesel powered,
1974 Eagle Bus 45',w/slideout,
Rio Rancho, NM
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| Re: [GMCnet] Final drive capacity [message #235064 is a reply to message #235056] |
Sat, 04 January 2014 12:36  |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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Hal,
I have no idea where you'd find your answers -- I'm surprised you learned
what you state, for that matter.
But I'm curious about the differential question: The only way I can see
you'd change from "pushing" to "pulling" is by swapping ends with the
housing; that is, put the R. end on the Left and the L end on the Right. I
can't imagine why you'd do that unless it's to get the pinon from the front
to the rear or vice-versa. If that's the purpose, would it not be
practical to rotate the differential about its axles? Hmmm...I guess that
might put the pinion too high, huh? Maybe the differential housing is
symmetrical -- I've heard that Beetle housings are such that the ring gear
can be moved from one side of the pinion to the other -- never done it
myself though.
Ken H.
On Sat, Jan 4, 2014 at 1:03 PM, Hal StClair wrote:
>
> I'm trying to figure out the torque capacity of the original ring and
> pinion used in our coaches.
> The AAM/GM independent fronts had a 4643 ft lb ratting and the Dana 70's
> were rated 8000 ft lb's. These are max short duration ratings, the
> continuous rating for the Dana 70 is 2000 ft lb's but the IFS isn't rated
> as continuous. Does anyone know if there is a designation, ie Dana,
> Rockwell, Spicer used so I might find the information?
>
> On another note, would anyone have an idea how much a differential would
> be de-rated buy running it backward, pulling vs pushing?
>
> I'd much rather use something readily available in my swap so it can be
> more easily duplicated if desired. But the final product must be robust
> enough for the application.
> ...
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: [GMCnet] Final drive capacity [message #235067 is a reply to message #235064] |
Sat, 04 January 2014 13:00 |
Hal StClair
Messages: 971
Registered: March 2013
Location: Rio Rancho NM
Karma: -12
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Senior Member |
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I guess they normally reverse cut gears for front ends but they never did that for the Dana 70. The way Revcon did it was run the gearset in a 'pull' configuration as I understand it. If it were in the reversed or 'high pinion' configuration it would require the engine to be mounted higher. I understand it caused some long term issues for durability so would assume the capacity would be reduced. I'd rather use the GM IFS front but am not sure if it will live long term. It is much easier to source and reproduce if someone so desired.
Thanks,Hal
"I enjoy talking to you. Your mind appeals to me. It resembles my own mind, except you happen to be insane."
1977 Royale 101348,
1977 Royale 101586, Diesel powered,
1974 Eagle Bus 45',w/slideout,
Rio Rancho, NM
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| Re: Final drive capacity [message #235117 is a reply to message #235056] |
Sat, 04 January 2014 21:35 |
Craig Lechowicz
Messages: 541
Registered: October 2006
Location: Waterford, MI
Karma: 0
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Senior Member |
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Hal, I don't have any real data for you, but maybe a couple of thought starters. Back in the day, a number of Corvair's ended up with small block Chevy's in them, and I believe those ran the ring and pinion "backwards". It's a much lighter car than a GMC, but a big torque increase for a small block vs. a Corvair. I know there is some advantage to having the teeth curved the right way, but I don't think it's a huge difference.
At the end of the day, wheel spin serves as a pretty good safety valve on driveline torque, so if you have hard enough tires, (as most GMC's do) it may not be a big issue. AAM (American Axle Manufacturing) is a company, just like Dana, Rockwell or Spicer, so American Axle is the designation you are looking for. If you are lucky, you might be able to call them and actually get an answer. I believe their headquarters is still in Hamtramck, MI, and if you get a cooperative sales engineer, they may be able to help out. They used to be Chevrolet Gear and Axle (part of GM) and were sold off back in the '80's I think, and set up as a separate public company.
Craig Lechowicz
'77 Kingsley, Waterford, MI
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