Multi rearend comparo
10-10-2002, 01:50 PM
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Multi rearend comparo
On the issue of rearend strength, efficiency and overall suitability for a particular application you come across arguements, like this:
GM 12 bolt vs. Ford 9 inch
Generalities:
the 12 bolt is more efficient with the 12 bolt pinion axis separated from the ring gear axis or axle centerline by 1.5" where the 9 inch is separated by 2.25" and has more of a sliding motion more similar to a worm gear than the average ring and pinion.
the 9 inch is stronger as a unit pound for pound as a unit (realizing there are many variations) and has the convenience of being able to quickly swap the gear by pulling the center section and replacing. This is especially easy with a full floater as the rear wheels can stay on the car. Less efficiency = more heat and less power to the ground, it has been said maybe 2-3% less than other rears.
What about other rearends like the 8.75 Mopar? It is known for high ring and pinion efficiency. Does anyone know the pinion to ring gear axis separation on this rear?
Dana 60. It has a pinion to ring gear axis separation of 1.125" and so is also more efficient than the 9 inch with it's 2.25" figure. It's also strong with a larger ring gear of 9.54" on at least one version, and is widely used in trucks. Short comings? Heavy. It's pinion is not straddle mounted like a 9 inch.
57-64 Olds/Pontiac. From what I have heard it is fairly efficient and I believe the ring gear is larger than 9". Not a big aftermarket for it though.
What about similar data for the 8.5 GM 10 bolt, the 7.5-7.625 10 bolt?
If chicane67 is reading this, particularly because of your land speed experience and apparent R@D in this area, but looking to hear ideas from anyone, how about the BW 9 bolt? What do you think of it's viability for land speed? Any idea what the specs are related to ring and pinion efficiency? What is it strong enough for in it's stock form for land speed or street/strip? It has the advantage for racing, of already using bearing retainers like a 9 inch instead of c clips which are frowned upon and usually disallowed by many racing bodies. What about modifying it to with Ford housing ends and associated larger bearings? 28 spline enough for the dif end? Other than ratio limitations it seems to have good potential for limited racing value, even in it's stock form.
GM 12 bolt vs. Ford 9 inch
Generalities:
the 12 bolt is more efficient with the 12 bolt pinion axis separated from the ring gear axis or axle centerline by 1.5" where the 9 inch is separated by 2.25" and has more of a sliding motion more similar to a worm gear than the average ring and pinion.
the 9 inch is stronger as a unit pound for pound as a unit (realizing there are many variations) and has the convenience of being able to quickly swap the gear by pulling the center section and replacing. This is especially easy with a full floater as the rear wheels can stay on the car. Less efficiency = more heat and less power to the ground, it has been said maybe 2-3% less than other rears.
What about other rearends like the 8.75 Mopar? It is known for high ring and pinion efficiency. Does anyone know the pinion to ring gear axis separation on this rear?
Dana 60. It has a pinion to ring gear axis separation of 1.125" and so is also more efficient than the 9 inch with it's 2.25" figure. It's also strong with a larger ring gear of 9.54" on at least one version, and is widely used in trucks. Short comings? Heavy. It's pinion is not straddle mounted like a 9 inch.
57-64 Olds/Pontiac. From what I have heard it is fairly efficient and I believe the ring gear is larger than 9". Not a big aftermarket for it though.
What about similar data for the 8.5 GM 10 bolt, the 7.5-7.625 10 bolt?
If chicane67 is reading this, particularly because of your land speed experience and apparent R@D in this area, but looking to hear ideas from anyone, how about the BW 9 bolt? What do you think of it's viability for land speed? Any idea what the specs are related to ring and pinion efficiency? What is it strong enough for in it's stock form for land speed or street/strip? It has the advantage for racing, of already using bearing retainers like a 9 inch instead of c clips which are frowned upon and usually disallowed by many racing bodies. What about modifying it to with Ford housing ends and associated larger bearings? 28 spline enough for the dif end? Other than ratio limitations it seems to have good potential for limited racing value, even in it's stock form.
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