replacement 12 bolt rear

[Todd Geisler]

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]

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]

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.

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.

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]

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

[NovaMan]

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?

[Alan Roehrich]

According to Mark Williams, yes, a stock housing can be machined to take the 3.250 bearing. They charge $550 or so. We have a stock housing in the car that takes the 3.250 bearing. But I think it was originally in a Kingwood Estate wagon, not a Camaro. If you want 3.250 bearings for an aluminum spool, buy the KTRE housing. It's not money well spent on a stock housing.

To remove the tubes, you cut them off flush with the housing, drill out the plug welds, and take a torch or a grinder and cut slots in the section of tube left in the housing. I did the 12 bolt in my Cutlass that way. I took the stock tubes, turned them down in a lathe, heated the housing, and drove them back in, plug weld them and then weld them all the way around. My housing is narrowed but the tubes are not cut and welded. WAY more work than most want to do. I'd say several of the steel supply companies can get you the tubing.