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Old 10-05-2007, 07:17 PM   #1
RocketBlock
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Default Re: replacement 12 bolt rear

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Originally Posted by Alan Roehrich View Post
Most all of the companies that sell rear ends use the KTRE housing for their heavy duty 12 bolt stuff. The KTRE housing is great, because it is thick, and stiff, and you can get it with a 3.250 carrier bearing bore, so you can use an aluminum spool and 35 spline axles.
Then this is the aftermarket block of rear ends? Looking at the rulebook it says "same type from the automobile manufacturer"
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Old 10-06-2007, 08:44 AM   #2
Dwight Southerland
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Default Re: replacement 12 bolt rear

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Then this is the aftermarket block of rear ends?
Yes. Some have'm; some don't. Same deal. The rich get richer and the poor still have to struggle.
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Old 10-06-2007, 02:08 PM   #3
Alan Roehrich
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Default Re: replacement 12 bolt rear

Seeing as how one of the services I provide at the shop is rear ends, I looked at the prices for building them, and I also looked around to see how hard it is to find cores. Considering that around here a USED, 35-40 year old 12 bolt housing, with no guarantee that it is suitable to build a good rearend from, is about $400 to $600, and you'll spend another $500 or so
prepping the housing with caps, studs, and other parts/labor, at a minimum, the aftermarket unit is cheaper.
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Old 10-06-2007, 02:36 PM   #4
Dwight Southerland
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Default Re: replacement 12 bolt rear

Alan - I agree with you 100%. If you are wanting to build a top quality rear end, and I think it is a good investment, the aftermarket pieces are definitely the way to go. Looking at the stocker population, the majority of the cars are serviced by aftermarket housings - 12 bolt GM, 9" Ford, Chrysler 8 3/4 & Dana 60. Maybe there should be an accepted "definition" that says any GM product can use a 12-bolt, any Ford product can use a 9" and any Chrysler (and I guess AMC) can use an 8 3/4 or Dana 60. It's almost like that now; in fact, most would argue that it is. It would just simplify matters to make it a ruling and put it in writing.
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Old 10-10-2007, 04:38 AM   #5
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Default Re: replacement 12 bolt rear

Suppose you already have a couple stock GM 12-bolts, but you don't have piles of cash lying around. What would you do? Beef up the better of the two stockers, or sell one (or both) and get an aftermarket unit?
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Old 10-10-2007, 08:39 AM   #6
Dwight Southerland
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Default Re: replacement 12 bolt rear

Beef it up. Nothing wrong with the old stuff if done well. Just if you are starting from scratch with nothing (no housing) the new stuff is a good consideration. I know top A, B, and C stick cars running old housings and have for 20+ years.
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Old 10-10-2007, 10:44 AM   #7
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Default Re: replacement 12 bolt rear

Tom's Differentials sells a carrier cap kit for about $70, it upgrades the driver side cap, and comes with 1/2" cap screws for the driver side, 7/16" upgrade cap screws for the passenger side.

On a side note, when the new housings were introduced, Tom refused to sell them because in his opinion, the cases were not within usable tolerances for his standards. That was the last word I had from him on the subject 3-4 years ago.

I have 2700+ passes on my old A-Body 12-bolt with the Tom's cap kit, no troubles, and have a car out there that is 3200# + driver running 8.60's with the old M/W cap kit, he kills a Pro gear about every 300+ passes, but no housing troubles.
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Old 10-11-2007, 11:41 AM   #8
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Default Re: replacement 12 bolt rear

Quote:
Originally Posted by Alan Roehrich View Post
Seeing as how one of the services I provide at the shop is rear ends, I looked at the prices for building them, and I also looked around to see how hard it is to find cores. Considering that around here a USED, 35-40 year old 12 bolt housing, with no guarantee that it is suitable to build a good rearend from, is about $400 to $600, and you'll spend another $500 or so
prepping the housing with caps, studs, and other parts/labor, at a minimum, the aftermarket unit is cheaper.
Alan Is it possible to run the "Gun Drilled" 35 spline MW axles in the "factory GM 12-bolt housing?
I've already replaced the tubes w/ DOM tubes, and added MW caps?
Is it safe to run the smaller bearings?
The Moser housings for the A & G bodies do not incorporate the "bumper tab" for Weibe Suspensions?
Greg
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Old 10-11-2007, 02:06 PM   #9
Dwight Southerland
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Default Re: replacement 12 bolt rear

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Is it possible to run the "Gun Drilled" 35 spline MW axles in the "factory GM 12-bolt housing?
I've already replaced the tubes w/ DOM tubes, and added MW caps?
Greg
Yes, you can. You will have to use MW housing ends for large axle bearings. Call MW and tell them what you are doing.
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Old 10-11-2007, 03:02 PM   #10
Todd Geisler
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Default Re: replacement 12 bolt rear

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Originally Posted by Dwight Southerland View Post
Yes, you can. You will have to use MW housing ends for large axle bearings. Call MW and tell them what you are doing.

Agreed. I have Mark Williams 35 spline axles (no drilled) in a 12 bolt which has been in service since the mid 90's. All the internal parts are holding up extremely well and have not replaced anything other than gear sets for tweaking of ratios with combination changes.

The MW captured bearing housing ends are really nice as well.

11/16" drive studs, billet caps and a girdle cover should be on the parts order list as well.

Last edited by Todd Geisler; 10-11-2007 at 03:09 PM.
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