89 Iroc Z

How hard would it be to modify a 12 bolt to work in our cars. I have a welder. I know I need to weld on mounts for the springs, LCA’s, and torque arm.

Here are my Questions:
1) What all has to be done to a 12 bolt to able to bolt it up to a thirdgen?
2) Can I use my same driveshaft?
3) Was any 12 bolt the same length as the 10 bolts we have in our cars? Then I wouldn’t have to shorten or lengthen the axel tubes.
4) I know the 12 bolts that came off some chevelle, monte carlo, and elcomino’s had spring mounts (as shown in the picture below), does anyone have a clue if they are the same distance apart as my car?

LT1guy

iTrader: (1)

1) You need mounts for the coil springs (probably not in the right place on any production 12 bolt), panhard bar, LCAs (again, doubtful they're even close...the only ones that had them would be GM A-body (Chevelle, etc) and the housing is too wide), and hardest of all a torque arm. Because the center section is cast iron, it would be very difficult to properly weld a torque arm bracket (would have to be fabricated) to it. The shock brackets may need to be relocated, and your factory brakes likely won't bolt up.
2) Yes, with a u-joint change.

3) Nope. The narrower ones, as used in some 66-67 Novas and 67-69 Camaros, may be close but for what they go for you could buy a Moser housing (my recommendation)

4) Doubt it, but they're the least of your worries.

If you're stuck on a 12 bolt, buy a Moser...it will be worth it in the long run. A 9" would be a little easier to do yourself, since the torque arm bracket (fabricated, or Currie or Moser might sell you theirs) could be bolted up to threaded tubes welded to the housing (steel).

ede

you'd have to relocate all the brackets and hangers and weld on something for a torque arm mount. not sure about finding one the correct width, but it's a good guess you'll need to change the width. if you have some basic fabrication skills i don't think it'd be hard to do

89 Iroc Z

Where is the cheapest place to buy just the modified 12 bolt housing? Can anyone give me links to the company websites?

AlkyIROC

LT1guy got it all right.

http://www.moserengineering.com/catalog/housings.htm
http://www.currieenterprises.com/

Expect to pay around $2000 for a complete diff either a 12 bolt or 9".

89 Iroc Z

Okay I went to both sites but was confused on the actual price of just the housing because they listed many different costs for housings. Can anyone clarify this for me? Also the housing these sites sell I could use a stock torque arm with right?

AlkyIROC

If you want "just" a 9" housing (comes with axles) go to www.spohn.net

A 9" housing with axles is around $900. Pick up a center section with carrier and gears locally to save a few bucks but make sure you have it before you order the housing with axles since you'll need to know the spline count.

The "bolt-in" 12 bolt and 9" housings are just that, Bolt-in. They include all the brackets and mounts to install all the factory style suspension parts.

cy Z28

How do you plan on mouting the torque arm fellas??

The moser unit is a quality peice. It's all new and bolts in w/ little hassle. Were you gonna weld the torque arm mounts to the casting? I dont' think so.

89 Iroc Z

I want the modified 12-bolt hosing, not the ford 9 inch

on http://www.moserengineering.com/cata...ring%20Package it says "Dana 60 & 12 Bolt Chevy housing (when available) 265 each " Is this correct, I think this is a pretty good deal.

I need a new rear, I don’t have a working one now so I want to purchase modified 12-bolt housing put a stock 12 bolt GM carrier and gears in and get some stock axels cut and Resplined. Then I can slowly upgrade it to take more power as I modify my car. But I want a strong base to start with.

cy Z28

exactly how much power do you put down right now?
how much power do you expect to have, and how soon?
and what rear is in the car now... 9/10 bolt?

89 Iroc Z

Don't these aftermarket modified 12 bolt housing come with the torque arm mount already?

cy Z28

Yes, i was referrring to the other housing.

here's what you do... call up summit, order a 3.73 gearset, a Ratech install kit and the solid pinion spacer... Call SLP, get a "take-out" torsen diff. for 50 bucks. You're in for around 300 now. 400 if you get the diff girdle.

Next go to the local GM dealer, go to one of the service writers and ask for a 'Heavy line technician" somebody that does gears for a living. Ask that man to do your car on the side for cash. (unless you know somebody that does gears you can trust)

Then when he's done... you get your welder out and run a bead around the axle tubes where they meet the center casting.

You just got a rearend that will hold about 450 rwhp for 500-600 bucks.

ede

the center section of most if not all rears i believe is cast steel. very weldable without a lot of extra preperation. use low hydrogen electrodes and you shouldn't have a problem. i've welded on a lot, maybe 100s no leaks and no cracks.

LT1guy

iTrader: (1)

I bent an axle tube on a similarly prepped 10 bolt in a car with 330 rwhp...with a 6 speed. An auto car might live, but when a budget 9" could be put together for $1100 or so ($795 for Moser housing/axle package + swap meet rebuilt chunk), I wouldn't bother.

89 Iroc Z

I want to make a 12 bolt. Does anyone know where the cheapest place I could buy a modified housing would be? Moser’s website was very unclear on the 12 bolt housing cost. There price list says $459 for the 9 inch housing but I want to build a 12 bolt.