replacement 12 bolt rear

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.

NovaMan · 10-14-2007, 04:53 AM

I thought you could only fit 35-spline axles in a housing with a 3.250" bore, or is that only if you want to run an aluminum spool? Or is that just completely incorrect?

How much better is a billet driver side cap than a support cover with factory caps? What about two billet caps compared to one?

Dwight Southerland · 10-14-2007, 08:35 AM

Quote:

Originally Posted by NovaMan

I thought you could only fit 35-spline axles in a housing with a 3.250" bore, or is that only if you want to run an aluminum spool?

Only if you want to use an aluminum spool.

Quote:

Originally Posted by NovaMan

How much better is a billet driver side cap than a support cover with factory caps?

Two different approaches. The support cover will support the bearing cap to keep it from breaking and give support to the whole housing to keep it from deflecting. The steel bearing cap will not break and adds some strength to the housing because of the bigger bolts and larger footprint.

Quote:

Originally Posted by NovaMan

What about two billet caps compared to one?

Just adds more rigidity to the housing and will not break.

Greg Barsamian · 10-14-2007, 09:51 PM

Can a "stock" GM 12-bolt be machined to accept the 3.250 bearing to use an Aluminum Spool?

NovaMan · 10-17-2007, 04:52 AM

From a machining standpoint, I have to believe it's possible - it was done once when the housing was built. But from a strength standpoint, I suspect it would weaken the housing too much: your billet caps would probably take it, but there isn't much meat to spare ahead of them in the case, and it also wouldn't leave much metal between the bore and the bolts.

How do you remove the stock axle tubes, and where do you find DOM axle tubing?

10-14-2007, 04:53 AM	#4
NovaMan Member Join Date: Sep 2004 Location: Kalamazoo, MI Posts: 117 Likes: 0 Liked 0 Times in 0 Posts	Re: replacement 12 bolt rear I thought you could only fit 35-spline axles in a housing with a 3.250" bore, or is that only if you want to run an aluminum spool? Or is that just completely incorrect? How much better is a billet driver side cap than a support cover with factory caps? What about two billet caps compared to one? __________________ ~Pete 1970 Nova

10-14-2007, 09:51 PM	#6
Greg Barsamian VIP Member Join Date: Jan 2002 Location: Central Massachusetts Posts: 1,402 Likes: 732 Liked 427 Times in 97 Posts	Re: replacement 12 bolt rear Can a "stock" GM 12-bolt be machined to accept the 3.250 bearing to use an Aluminum Spool?

10-17-2007, 04:52 AM	#7
NovaMan Member Join Date: Sep 2004 Location: Kalamazoo, MI Posts: 117 Likes: 0 Liked 0 Times in 0 Posts	Re: replacement 12 bolt rear From a machining standpoint, I have to believe it's possible - it was done once when the housing was built. But from a strength standpoint, I suspect it would weaken the housing too much: your billet caps would probably take it, but there isn't much meat to spare ahead of them in the case, and it also wouldn't leave much metal between the bore and the bolts. How do you remove the stock axle tubes, and where do you find DOM axle tubing? __________________ ~Pete 1970 Nova