replacement 12 bolt rear

RocketBlock · 10-05-2007, 07:17 PM

Quote:

Originally Posted by Alan Roehrich

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"

Dwight Southerland · 10-06-2007, 08:44 AM

Quote:

Originally Posted by RocketBlock

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.

Alan Roehrich · 10-06-2007, 02:08 PM

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.

Dwight Southerland · 10-06-2007, 02:36 PM

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.

NovaMan · 10-10-2007, 04:38 AM

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?

Dwight Southerland · 10-10-2007, 08:39 AM

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.

Dave Goob Cook · 10-10-2007, 10:44 AM

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.

Greg Barsamian · 10-11-2007, 11:41 AM

Quote:

Originally Posted by Alan Roehrich

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

Dwight Southerland · 10-11-2007, 02:06 PM

Quote:

Originally Posted by Greg Barsamian

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.

Todd Geisler · 10-11-2007, 03:02 PM

Quote:

Originally Posted by Dwight Southerland

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.

10-06-2007, 02:08 PM	#3
Alan Roehrich Veteran Member Join Date: May 2006 Location: Murfreesboro TN Posts: 5,105 Likes: 1,564 Liked 1,789 Times in 408 Posts	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. __________________ Alan Roehrich 212A G/S

10-06-2007, 02:36 PM	#4
Dwight Southerland VIP Member Join Date: Dec 2001 Location: Arkansas - In the middle of everything. Posts: 1,999 Likes: 64 Liked 773 Times in 192 Posts	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.

10-10-2007, 04:38 AM	#5
NovaMan Member Join Date: Sep 2004 Location: Kalamazoo, MI Posts: 117 Likes: 0 Liked 0 Times in 0 Posts	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? __________________ ~Pete 1970 Nova

10-10-2007, 08:39 AM	#6
Dwight Southerland VIP Member Join Date: Dec 2001 Location: Arkansas - In the middle of everything. Posts: 1,999 Likes: 64 Liked 773 Times in 192 Posts	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.

10-10-2007, 10:44 AM	#7
Dave Goob Cook Member Join Date: Dec 2006 Location: Indy Posts: 422 Likes: 0 Liked 0 Times in 0 Posts	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.