what rearend should i purchase

**Semperfiws6** · 02-01-2007, 01:07 PM

im looking into either a moser 12 bolt or a 9in rear end. i already blew the rear end and my car is pretty much stock. i want it to handle anything i do to it in the future. it probably wont be on the track much, but i drive pretty hard. any suggestions?

**1SSWFO** · 02-01-2007, 03:12 PM

I am in the same boat. I called Moser and told them what I was looking for and the guy there said not to do the 12 bolt he said go with the 9" it would hold anything that I could throw at it. He told me that the 12 bolt was fine on a auto but for a six speed I would have trouble running the juice off the line with slicks. I even checked the Strange but you have to change too much shit, send them your brakes and shit? The 9" is the way for me in about 2 months.

**1SSWFO** · 02-01-2007, 05:23 PM

don't you love it how a post just dies off????

**Semperfiws6** · 02-02-2007, 07:32 AM

Originally Posted by 1SSWFO

don't you love it how a post just dies off????

i was defenitely leaning toward the 9in. its good to know im not alone on this. our wait will be well worth it.

Ratdaddy07 · 02-02-2007, 08:36 AM

You said you wont be at the track much, I have 420 at the wheels and run drag radials at the track and I will be surprised if I ever break the 12 bolt and I do have an M6. Nothing ever wrong with overkill I guess but I think you will lose a little more power to turn the 9". Something to think about.

**INMY01TA** · 02-04-2007, 03:44 PM

M6 or A4? For an M6 if were gonna see alot of track time I'd go 9 inch but for little track time I'd go 12 bolt. My cars an M6 and I go to the track maybe twice a year. 5,500 rpm dumps on slicks w/no problems yet. For an A4 I'd go 12 bolt no matter what.

**Semperfiws6** · 02-04-2007, 06:15 PM

Originally Posted by Ratdaddy07

You said you wont be at the track much, I have 420 at the wheels and run drag radials at the track and I will be surprised if I ever break the 12 bolt and I do have an M6. Nothing ever wrong with overkill I guess but I think you will lose a little more power to turn the 9". Something to think about.

how much power do you think i will lose? will it really be that noticeable?

Ratdaddy07 · 02-07-2007, 05:35 AM

I don't know how much because I put the car on the dyno after the new rear-end, did 420. I could tell by the seat of the pants though and by the fact that at 75 I could drop it in 4th hammer it and break the tires loose with the factory rear ( of course that is also why I had to get a new one) and it wouldn't after the new rear-end and tune. I think some also had to do with before the tune even though it burped and died and was a bitch to drive in town I think it actually had more power than after the tune.

**Firebirdjones** · 02-08-2007, 09:46 AM

I have had bad experiences with Moser over various things on more than one occasion. If you are going to an aftermarket rearend, I would head straight for Strange. I have had both Moser and Strange housings in front of me and the Strange unit is by far the better piece to start with.
They at least use factory GM brackets, Or I should say the last one I had here did,,,,and have the clips on the axle tubes to hold the brake lines.
Moser units make their own bracketry out of sheetmetal and it's kinda ugly in my opinion, although it works, it doesn't look factory,,,there are no clips for the brake lines, so we had to make our own and weld them on.
There are other things I could get into that would take forever to post here but you get the general idea.
The 12 bolt will hold a ton of power, just depends on how you build it. You can go with a standard type 30 spline posi with stock 30 spline axles and it would take a decent amount of abuse. If you want more I would suggest a 33 spline Eaton posi unit with 33 spline c clip eliminator axles. A stock 9 inch will come with 31 spline and then you have to upgrade from there.
I have seen 12 bolts built like this behind 10 second Fbodies and 6 speed transmissions and work just fine. It's my personal rearend of choice for a GM car,,,but I like to keep it all GM.
A 9 inch has a couple of advantages, it is slightly stronger, due to the relationship the pinion has with the ring gear, but this robs a little horsepower to turn it. It also has the advantage of simple gear swaps, that is if you plan on changing the gears around alot, a favorite among the dirt track roundy round racers. If you plan on sticking with one gear then you really are not gaining anything here.
A 9 inch will be heavier than the 12 bolt, take more power to turn as well.
Both have advantages and disadvantages,,,depends on what you want. Larry.

**Jon7I2** · 02-08-2007, 10:14 AM

What about Strange's S-60.? I heard that is suppose to be the best.

**Firebirdjones** · 02-08-2007, 10:22 AM

The dana 60 is a huge piece, has been pretty rare too until Strange came out recently with a remake, so I don't have alot of assembly experience with them. It's very heavy and very strong, and probably overkill, but would be a cool conversation piece under an f-body at the local cruise in. LOL.
Buddy of mine ran one in a 55 chevy back in the early 70's, can't remember how fast the car was but it was a wheel stander. Only thing I remember every going wrong with the rearend is the axle tubes were bent forward from years of racing, so we had to straighten the housing on a jig,,,but it never broke. Pretty cool that strange has brought an oldie back to life. Larry.

**Jon7I2** · 02-08-2007, 10:53 AM

yea definitely. Cuz wen i get a rear end i only want to do it once. I don't ever want it to break, and i want to be able to beat the hell outt of it w/ confidence.

**1BADDLS1** · 02-09-2007, 07:22 AM

Strange NOT MOSER
12 bolt was assembled improperly & blew 3 days after install then 2nd blew after 6 months in veh @ 1st trip to the track... & we had to pay all the shipping
then they admitted they installed a crush sleeve instead of solid spacer which contributed to the failures but wouldnt send the part, we had to buy it
had it rebuild by a local pro & hasnt had any issues not & NO howling... from MOSER is Howled LIKE CRAZY

auto go 12 bolt M6 go S60 STRANGE only... save yourself the head aches

**Jon7I2** · 02-09-2007, 08:11 AM

Originally Posted by 1BADDLS1

Strange NOT MOSER

auto go 12 bolt M6 go S60 STRANGE only... save yourself the head aches

Thats what i had thought.

**Firebirdjones** · 02-09-2007, 09:37 AM

Wow can I tell stories about Moser and there howling rearends, but I will save the space.
But as far as 12 bolts breaking due to a crush sleeve,,,that is a new one on me. In no way have I ever found the solid spacers to add any strength to the rearend.
The purpose of the solid spacer is to take the hassle of getting the stock cruch sleeve to start crushing without going to far,,,and also for repeat gear changes so it can be reused over and over,,,but I find that rather silly since stock crush sleeves are so cheap to by,,,why bother, plus who does repeat gear changes in 12 bolt rearends,,,thats where a 9 inch comes in handy.
Another issue I have had with solid spacers, it it's rather hard and more time consuming to get the proper preload on the bearings,,,without that the pinion bearings won't live. So I have found the solid spacers rather useless and have never had a 12 bolt failure due to that, even behind 6-700 hp engines.
I would attribute your 12 bolt failure to poor assembly techinique by moser,,,especially since you mentioned it howled from the get go,,,something was not setup correctly right out of the box, from there it's just a matter of time. Larry.

**1BADDLS1** · 02-09-2007, 11:01 AM

Originally Posted by Firebirdjones

I would attribute your 12 bolt failure to poor assembly techinique by moser,,,especially since you mentioned it howled from the get go,,,something was not setup correctly right out of the box, from there it's just a matter of time. Larry.

thats what we said, but they insisted that M6 cars NEEDED the solid spacer of they doomed... then made us buy it even though they assembled it incorrectly...

it finally doesnt have issues... cant wait to rip it out of his car and throw it in mine when he ups to the S60

**z28misfit** · 02-09-2007, 11:58 AM

I ended up going with the S60 for my car. Now I talked to Moser already about a 9".It is definately stronger than a 12bolt, but if you are going to run a posi and not a spool they told me to go with the 12bolt. The case being that the 12bolt has a 33spline posi and the 9" only a 30 or 31 spline unit(not for sure which one of those it is), but if you want a spool, then go with the 9''. Now the S60 is way overkill for my car,even once heads go on. It is heavy and will take more power to turn the larger ring and pinion , but you should never have rear problems again. It has a 35spline posi unit in it and if you really want to lighten things up a little, then put a spool in it. Now I hear the S60 is more efficient than the 9" due to pinion angle but the 9" I would imagine makes up for it in it's weight being less. The 12bolts are strong, but I've been told they are kind of marginal around the 600-800hp range. Will use less power up,probably plenty good for your current setup, but if you want the best bang for the buck, then go with the 60.

**99RedRagtop** · 02-21-2007, 07:37 PM

+1...
you simply can't beat the deal on the S60. they are by far the best bang for the buck. the 9" has torque arm clearance issues, as well as driveshaft angularity problems.
the S60 will come with 35 spline axles, the 12 bolt is 30 or 33, depending on which diff you use. the 9" will come with 31 spline, unless you upgrade.
the strange rears will come with 3 or 4 channel abs/tcs standard, as where the 9" only has 4 ch available as an option for more $.
the S60 will be a few lbs heavier than the 12 bolt and the 9" but the efficency of the bigger gears will offset this.
and to top it all off, the S60 is cheaper than all of them.

**99RedRagtop** · 02-21-2007, 07:47 PM

But as far as 12 bolts breaking due to a crush sleeve,,,that is a new one on me. In no way have I ever found the solid spacers to add any strength to the rearend.
Larry.[/QUOTE]

the solid spacer won't necessarily add strength, but it will not collapse under severe load like a crush sleeve will. yes it takes more time to set up, but it is by far superior to any crush sleeve. if a crush sleeve collapses, even one-thousandth of a inch(.001), it is enough to release pinion bearing preload and sooner or later cause gear failure. Strange assembles all their rearends with a solid spacer.

**Firebirdjones** · 02-22-2007, 02:42 AM

Hmmmm, never had a crush sleeve collapse on any of mine I have assembled. Unless they give me a reason to switch I will stick with them for now. I wasn't aware of strange assembling all of theirs with solid spacers,,I have only bought bare housings from them to assemble the rear myself. Thanks for the heads up...Larry.