looking to purchase a moser 12 bolt or 9 inch. would like to hear a little from people who have either to help me with my desision. wanting to convert from drum to disk and will be swapping my t-5 to a t-56. any suggestions?

 

If you have less than 600 HP then the 12 bolt would probably be better. The 12 bolt is lighter, cheaper and takes less power to turn. The Moser 12 bolt is very strong. The 9 inch can be shipped by UPS because it is shipped in 3 packages and you can have more than one chunk built with different gear ratios if you want to change them often. Moser sells complete Wilwood disc brake kits and also has some economy disc brake kits.

 

DO NOT GET A 12-BOLT!

...the torque arm setup in a 3rd or 4th gen puts too much stress on the pinion, and IT WILL WHINE behind a standard transmission with any sort of spirited driving.

https://www.brutespeed.com/rear_end_information.htm

spend any time on LS1tech and its common knowledge that you skip the 12 bolt if you have a manual.

...Honestly, I'm looking at getting an S60 myself.

 

from moser the 9 inch is cheaper. i thought. and i was taking the tourqe arm off the trans anyways. will i still have problems.

 

Moser 12 bolt with Eaton Posi and 30 spline c clip axles starts around $2165 plus shipping. The 9 inch housing and axle package is around $900 and a complete chunk with a limited slip differential is around $1500, so the 9 inch is around $250 to $300 more than the 12 bolt.

 

s60 is about 2300 shipped with a posi...


s60 needs a shorter d/s but any rear should get an upgrade

 

is the problem with the 12 bolt fixable? thats what im leaning towards.

 

its how its cast... not much you can do with it..

 

I have a moser 9" and it whines and I do know lot of people have the same problem with it but I think it has more to do with moser gears or setup then the design of the rear. With that said I still say get a 9" rear since it's supost to be stronger then the 12 bolt and after multiple 5-6k clutch dumps I couldn't be happier. One thing though they are friggin heavy once assembled compared to the stocker.

 

If you torque the torque arm mount bolts to the specified torque, they won't distort the pinion housing. Same problem occurs with the 10 bolt. Tighten the bolts too much and the pinion bearings can fail. Over the years, GM changed the casting to help reduce this distortion.

There's nothing wrong with using a S60, 12 bolt or 9". It comes down to a personal preference. With the 9", you always have room for upgrading in the future. Start off with 2.73 gears on a posi and finally decide for 4.56 or deeper gears later. There's no series change with a 9". All the gear sets fit the same carrier.

You can also make the 9" lighter by upgrading to an aluminum center section and go with a big Dayton pinion support bearing for even more strength.

The amount of power loss between the S60, 12 bolt and 9" probably won't be noticed in a street car. The S60 is the biggest and heaviest but also eats up the most power.