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-   -   8 3/4 Chrysler pro gears? (https://classracer.com/classforum/showthread.php?t=66715)

Jeff Teuton 07-02-2017 09:43 AM
Re: 8 3/4 Chrysler pro gears?
 
I also have a complete Moser Dana 60 w/5.13 pro gear axle to axle. Call for more info.

Coleydog 07-02-2017 11:26 AM
Re: 8 3/4 Chrysler pro gears?
 
All this bad vibe has made me change direction, going with Dana instead. Always heard the 8-3/4 was more efficient.

Myron Piatek 07-03-2017 12:21 PM
Re: 8 3/4 Chrysler pro gears?
 
Quote:
Originally Posted by Coleydog (Post 538663)
All this bad vibe has made me change direction, going with Dana instead. Always heard the 8-3/4 was more efficient.
I read a dedicated article comparing rear end efficiency in one of the old car magazines a long time ago. Of the rears that I remember they tested, this was the order of efficiency:

1) GM 12 bolt
2) Dana 60
3) Chrysler 8 3/4
4) Ford 9"

I believe it said that the biggest factor is the placement of the pinion in relationship to the ring gear. The higher the pinion (closer to center), the more efficient it is. The 9" has the additional disadvantage of an extra pinion bearing.

I don't recall what others were tested.

Somebody makes/made a 12 bolt style center section for 9" housings. Was it Jim Kinnett that had a 12 bolt or a Chrysler 9 1/4 rear in his SS/AA Cuda?

Jim Wahl 07-03-2017 12:25 PM
Re: 8 3/4 Chrysler pro gears?
 
Quote:
Originally Posted by Myron Piatek (Post 538714)
I read a dedicated article comparing rear end efficiency in one of the old car magazines a long time ago. Of the rears that I remember they tested, this was the order of efficiency:

1) GM 12 bolt
2) Dana 60
3) Chrysler 8 3/4
4) Ford 9"

I believe it said that the biggest factor is the placement of the pinion in relationship to the ring gear. The higher the pinion (closer to center), the more efficient it is. The 9" has the additional disadvantage of an extra pinion bearing.

I don't recall what others were tested.

Somebody makes/made a 12 bolt style center section for 9" housings. Was it Jim Kinnett that had a 12 bolt or a Chrysler 9 1/4 rear in his SS/AA Cuda?
Kinnett ran a 12 bolt GM rear in both the Hemi SS car and the Pro Stocker. I have seen them both personally. Jim

.

Bob Mulry 07-03-2017 12:44 PM
Re: 8 3/4 Chrysler pro gears?
 
Quote:
Originally Posted by Myron Piatek (Post 538714)
I read a dedicated article comparing rear end efficiency in one of the old car magazines a long time ago. Of the rears that I remember they tested, this was the order of efficiency:

1) GM 12 bolt
2) Dana 60
3) Chrysler 8 3/4
4) Ford 9"

I believe it said that the biggest factor is the placement of the pinion in relationship to the ring gear. The higher the pinion (closer to center), the more efficient it is. The 9" has the additional disadvantage of an extra pinion bearing.

I don't recall what others were tested.

Somebody makes/made a 12 bolt style center section for 9" housings. Was it Jim Kinnett that had a 12 bolt or a Chrysler 9 1/4 rear in his SS/AA Cuda?
Hi,

Strange still manufactures an aluminum 12 bolt drop out center section that fits into a 9" Ford housing........

I wonder if that will pass tech (HA HA) for a GM Stock Eliminator car?????

Just sayin'

Dwight Southerland 07-03-2017 01:07 PM
Re: 8 3/4 Chrysler pro gears?
 
Quote:
Originally Posted by Myron Piatek (Post 538714)
I read a dedicated article comparing rear end efficiency in one of the old car magazines a long time ago. Of the rears that I remember they tested, this was the order of efficiency:

1) GM 12 bolt
2) Dana 60
3) Chrysler 8 3/4
4) Ford 9"

I believe it said that the biggest factor is the placement of the pinion in relationship to the ring gear. The higher the pinion (closer to center), the more efficient it is. The 9" has the additional disadvantage of an extra pinion bearing.
It's called hypoid distance. Dana 60 is 1.125". MoPar 8 3/4, GM 12 bolt and 10 bolt, AMC Model 20 are 1.50". Ford 9" is 2.25". The farther the pinion is from the centerline of the ring gear, the greater the angle of the drive teeth to the ring gear teeth and more friction. Bearing size is a factor for efficiency as well as rotating mass.
I remember that same article, but have since learned from other sources who have done serious experimentation that the Dana 60 is more efficient than the 12 bolt.

SSDiv6 07-03-2017 04:27 PM
Re: 8 3/4 Chrysler pro gears?
 
Quote:
Originally Posted by Dwight Southerland (Post 538719)
It's called hypoid distance. Dana 60 is 1.125". MoPar 8 3/4, GM 12 bolt and 10 bolt, AMC Model 20 are 1.50". Ford 9" is 2.25". The farther the pinion is from the centerline of the ring gear, the greater the angle of the drive teeth to the ring gear teeth and more friction. Bearing size is a factor for efficiency as well as rotating mass.
I remember that same article, but have since learned from other sources who have done serious experimentation that the Dana 60 is more efficient than the 12 bolt.
Dwight is correct; after much analysis, the final result is the Dana 60 is the most efficient of the bunch.

SSDiv6 07-03-2017 04:30 PM
Re: 8 3/4 Chrysler pro gears?
 
Quote:
Originally Posted by Bob Mulry (Post 538716)
Hi,

Strange still manufactures an aluminum 12 bolt drop out center section that fits into a 9" Ford housing........

I wonder if that will pass tech (HA HA) for a GM Stock Eliminator car?????

Just sayin'
Bob,

The Strange 12-Bolt, 9" drop out has weight limitations on its use.
It's designed for very lightweight cars, dragsters and roadsters.

Coleydog 07-03-2017 06:26 PM
Re: 8 3/4 Chrysler pro gears?
 
Quote:
Originally Posted by SSDiv6 (Post 538731)
Dwight is correct; after much analysis, the final result is the Dana 60 is the most efficient of the bunch.
Maybe someone will make more ratios again. Picked up another Dana housing yesterday, free

Todd Boyer 07-05-2017 09:48 PM
Re: 8 3/4 Chrysler pro gears?
 
Quote:
Originally Posted by Myron Piatek (Post 538714)
I read a dedicated article comparing rear end efficiency in one of the old car magazines a long time ago. Of the rears that I remember they tested, this was the order of efficiency:

1) GM 12 bolt
2) Dana 60
3) Chrysler 8 3/4
4) Ford 9"

I believe it said that the biggest factor is the placement of the pinion in relationship to the ring gear. The higher the pinion (closer to center), the more efficient it is. The 9" has the additional disadvantage of an extra pinion bearing.

I don't recall what others were tested.

Somebody makes/made a 12 bolt style center section for 9" housings. Was it Jim Kinnett that had a 12 bolt or a Chrysler 9 1/4 rear in his SS/AA Cuda?
I remember reading that Rick Johnson ran a 9 1/4 Mopar rear in his SS/AA Barracuda at one time. He may still.


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