9" why

**2000dreambird** · 06-27-2009, 09:25 PM

ok maybe its just me i'm GM all the way why!!!!!i ask again why a ford 9" rear end i see people do it to there birds an ss's all the time around here is it just a MA thing don't you need to hack up the car to install it ?

**Mr. Luos** · 06-27-2009, 09:30 PM

No hacking.

I have one. I NEVER have to worry about it.

**2000dreambird** · 06-27-2009, 09:43 PM

why don't you have to worrie about it i'm all for a good swap if i can justify it

**Mr. Luos** · 06-27-2009, 09:44 PM

Basicly as strong as they come.

I have a Moser 9", no hacking, it is a bolt in piece.

**JoshieDoom** · 06-27-2009, 09:48 PM

Bolt in replacement, strong as piss. Hacking is for PCs.

Go Dana 60 if you dont like the 9 inch. Or 12 bolt.

**2000dreambird** · 06-27-2009, 09:50 PM

i hear alot about the 9 whining hows the dana an the 12 b do

**JoshieDoom** · 06-27-2009, 09:52 PM

Originally Posted by 2000dreambird

i hear alot about the 9 whining hows the dana an the 12 b do

All can be equally strong is set up well. The s60 by strange and the m9 by moser are the two best you can get for our f-bodies.

All are bolt in replacement.

If setup, broke in, and use correctly the rear shouldnt whine.

**2000dreambird** · 06-27-2009, 10:01 PM

i think i got 3:23 's in it now (stock) what do you think is best for street use as far as smoking most the normals around.....thanx for the info

**ntimid8r** · 06-27-2009, 10:08 PM

I suggest you do your own research but here's my .02 for ya.

Basically the 9" is a stronger unit than the 12 bolt. For one, the ring gear being 9 inches versus the 8.875 inch in the 12 bolt. Also the 9" has a rear pinion support that helps lessen the gear deflection under high torque launches. Another plus for the 9" is the lower pinion location which provides better tooth contact. If you want to change gears with a 9", just swap the gear pumpkin. A 12 bolt has to remove the ring gears and be dialed back in which is a tedious job.

The 12 bolt is not a shabby unit by any means but the 9" is more durable. There's a few aftermarket companies that make 9" kits that are a direct replacement for 4th gen f-bodies, so just follow the directions then remove and replace. No hacking required. In my opinion the Midwest Chassis & Performance is the best 9" unit on the market today.

A 9" will cost a little more than a 12 bolt but as always, it all depends on what you can afford. A 12 bolt will do great for most all 4th gen f-bodies. If you want bullet-proof, then go 9".

**2000dreambird** · 06-27-2009, 10:14 PM

your the man that helped alot awsome detail thanx

**Mr. Luos** · 06-27-2009, 10:15 PM

I don't like how the torque arm mounts to the Dana or the 12 bolt. Break it, and the entire housing is trashed.
Break the mount on the 9"...and it is only gonna cost the bracket.

**ntimid8r** · 06-27-2009, 10:21 PM

Originally Posted by Mr. Luos

I don't like how the torque arm mounts to the Dana or the 12 bolt. Break it, and the entire housing is trashed.
Break the mount on the 9"...and it is only gonna cost the bracket.

How many torque arm mounts have you broke on the Dana or 12 bolt?

**Hi-Po** · 06-27-2009, 10:37 PM

Originally Posted by ntimid8r

How many torque arm mounts have you broke on the Dana or 12 bolt?

Bob at EPP will tell you the same thing. Sure, its not common to break TQ arm mounts. What IS common is launching on a 12 bolt housing in a f-body setup and getting gear whine right after. Thats why, specifically, a 9" IS the better setup. For both reasons, and they go hand in hand with each other. The TQ Arm mount is in a location to where it not only has a less chance of breaking, but more importantly... wont create gear noise when subjects to a track.

**Hi-Po** · 06-27-2009, 10:50 PM

BTW. My 9" has almost zero noise. 1100 miles on it.

**ntimid8r** · 06-27-2009, 11:00 PM

Originally Posted by Hi-Po

Sure, its not common to break TQ arm mounts.

So if it's not common, they why paint the picture of a 12 bolt being a useless rearend?

I have a 12 bolt and have made many launches and hmm there's no whine noise going on? How about posting your own experiences and not hear say.

**Hi-Po** · 06-27-2009, 11:09 PM

Originally Posted by ntimid8r

So if it's not common, they why paint the picture of a 12 bolt being a useless rearend?

I have a 12 bolt and have made many launches and hmm there's no whine noise going on? How about posting your own experiences and not hear say.

Ok, I will post my own experiences. Lets start Rich. Moser 12 bolt. You wanna start there? I guess we will.

It whined, after 1/4 wacks and som sticky MT time on the street. Yea I had one of those also.

9". No whine. Granted no 1/4 trips yet as I just got it re-re-tuned. Ill be sure to let you know

And no where, did I say a 12 bolt was a bad rear. Hell, mine should have lasted forever. The fact is, that it whined, on both.... decel and accel.

Experiences.

**ntimid8r** · 06-28-2009, 07:25 AM

Originally Posted by Hi-Po

Ok, I will post my own experiences. Lets start Rich. Moser 12 bolt. You wanna start there? I guess we will.

It whined, after 1/4 wacks and som sticky MT time on the street. Yea I had one of those also.

9". No whine. Granted no 1/4 trips yet as I just got it re-re-tuned. Ill be sure to let you know

And no where, did I say a 12 bolt was a bad rear. Hell, mine should have lasted forever. The fact is, that it whined, on both.... decel and accel.

Experiences.

You're the one posting about how common it is that the tq arm mounts break on a 12 bolt like you run a shop and see it all day long. But in reality you had one Moser brand and it whined on ya. Did you contact Moser to resolve the problem? Obviously they didn't set the back lash correctly. But I still don't see you posting your experience of the tq arm mount breaking when you previously posted of how common that is.

Thanks for sharing your expert analysis though.

**Firebirdjones** · 06-28-2009, 08:33 AM

I've built quite a few for people, 12 bolts and 9 inchers that is.
I've found (through alot of headache) to stay away from the moser cast 12 bolt housings. However,,from that point on, I've used Strange 12 bolt housings and had nothing but great experiences with them.

I'm a 12 bolt fan, never had gear whine issues, (once I switched housings) and never had any issues with torque arms, some high HP applications as well. I just don't see that huge casting ever being an issue. The 9 inch is a good piece as well.

As mentioned the 9 inch has a lower mounted pinion in relation to the centerline of the ring gear. That alone is what gives the 9 inch a strength advantage,,,but it also has a downfall. That is also why the 9 inch takes more power to turn it.
I'm not a big fan of the pinion supports, and that is a real weak spot in the 9 inch. It's not until you get into the high end aftermarket supports where they become worthy in my opinion. I can't tell you how many 9 inch housings I've set up and found a cracked pinion supports or inner bearing supports. In severe cases you can blow the pinion right out of the case with the driveshaft still attatched to it,,,,don't ask

I've never found or seen torque arm issues with the 12 bolt or 9 inch. The 12 bolt if built properly can withstand just as much abuse.
As far as setting up gears between the 2 it's not really an issue unless you are class racing in NHRA or roundy round racing where gear swaps every weekend are the norm.
As far as that goes the 9 inch has an advantage,,,that is if you can afford to have extra third members laying around at about $1,000-$1,500 a piece ready to go.

The reality is though, you still have to setup those third members too, just as you would any other rearend. So don't let that be a deciding factor by any means.

So really it just comes down to what you would like to have.

**Hi-Po** · 06-28-2009, 08:48 AM

Originally Posted by ntimid8r

You're the one posting about how common it is that the tq arm mounts break on a 12 bolt like you run a shop and see it all day long. But in reality you had one Moser brand and it whined on ya. Did you contact Moser to resolve the problem? Obviously they didn't set the back lash correctly. But I still don't see you posting your experience of the tq arm mount breaking when you previously posted of how common that is.

Thanks for sharing your expert analysis though.

Ok, thats cool.

To the orginal poster, there is minimal, almost zero "hacking" as you say to fit a Non GM rear end under your Fbody. If you want to keep ABS, it will be extra if you have a 3 channel rear. Some people have had to make alittle more room in certain areas for the TQ arm. Also, the bracket for the Tq arm sometimes has to be notched slightly. I didnt see any of those issues, but some have. Ill never look back from my 9". Love it.

**ntimid8r** · 06-28-2009, 08:51 AM

Originally Posted by Firebirdjones

I've built quite a few for people, 12 bolts and 9 inchers that is.
I've found (through alot of headache) to stay away from the moser cast 12 bolt housings. However,,from that point on, I've used Strange 12 bolt housings and had nothing but great experiences with them.

I'm a 12 bolt fan, never had gear whine issues, (once I switched housings) and never had any issues with torque arms, some high HP applications as well. I just don't see that huge casting ever being an issue. The 9 inch is a good piece as well.

As mentioned the 9 inch has a lower mounted pinion in relation to the centerline of the ring gear. That alone is what gives the 9 inch a strength advantage,,,but it also has a downfall. That is also why the 9 inch takes more power to turn it.
I'm not a big fan of the pinion supports, and that is a real weak spot in the 9 inch. It's not until you get into the high end aftermarket supports where they become worthy in my opinion. I can't tell you how many 9 inch housings I've set up and found a cracked pinion supports or inner bearing supports. In severe cases you can blow the pinion right out of the case with the driveshaft still attatched to it,,,,don't ask

I've never found or seen torque arm issues with the 12 bolt or 9 inch. The 12 bolt if built properly can withstand just as much abuse.
As far as setting up gears between the 2 it's not really an issue unless you are class racing in NHRA or roundy round racing where gear swaps every weekend are the norm.
As far as that goes the 9 inch has an advantage,,,that is if you can afford to have extra third members laying around at about $1,000-$1,500 a piece ready to go.

The reality is though, you still have to setup those third members too, just as you would any other rearend. So don't let that be a deciding factor by any means.

So really it just comes down to what you would like to have.

Good and accurate info, thanks for your post.

I have a Strange 12 bolt as well. I didn't want to post any negative speculations that I've heard about Moser brand. But from my research, I didn't want to go with Moser. My 12 bolt has been flawless and I pump 540 rwhp through it and no issues.