aight guys, time for a real rear end...which one?

[raroZ28]

Ford 9"
or Moser 12 bolt?

Are they the same rear end??

What's the difference? Which gear ratio for a street driven car? I'm thinking 3.70's or 3.89's.

This is where I'm putting my next chunk of change. No use in running 12's or 11's if I'm going to be afraid of blowing the rear end every time I floor it, right?

[Injuneer]

No they are not the same.

Moser and Strange make a "12-bolt" GM rear. That has a fixed center section, and the gears are changed by removing the rear cover and ripping the guts out. The 12-bolt is a good choice up to 800HP.

Moser makes a "9-inch" Ford rear. It has a removable center section so you can swap out gears simply by swapping out the center section. The 9-inch is a good choice over 800HP. It is heavier, and has some dimensional issues, with regard to the pinion center line height, offset of the overall size. Also loses 3% more power.

The general view seems to be "the 9-inch is stronger".... but in my opinion, the "base" configurations are very similar. The 9-inch does have many more options that allow it to handle 1,500HP or more.

Gear selection will be determined by engine redline, tire diameter, trap speed, transmission type, etc. Fill in the blanks and you can choose a gear ratio. The 12-bolt comes in 3.42, 3.73, 4.11, 4.56. The 9-inch has some different ratios, including the (I think) 3.89 and 4.30.

[Z Ya Later]

Dude, you're not gonna blow the rear end when you floor it. The problem with the stock rear is the initial torque transfer. Flooring it while rolling isn't the problem, its dumping the clutch with a tached-out motor is where the stock rear will give out. But, when do you need to do that? A good launch only requires the motor to be at ~1500-2000 rpm.

With that said, if you're gonna replace the rear, go with the 12-bolt. Not sure about the Strange unit, but with the Moser you can retain all your factory equipment like the ABS, TCS if you have it, sway bar and get a conversion yoke for your stock driveshaft. The 12-bolt will be plenty for your setup. As for gears, if you're gonna make it a track-ready, street-driven car, I'd go with 3.42s or 3.73s. You'll get better mileage outta the 3.42s and they are plenty torqy for a good launch (the GN has 3.42s stock). 3.73s will get you out of the hole faster, but mileage will suffer.

On a side note, please tell me you've done or will be doing the driveshaft. I wouldn't put much faith in the stock unit.

***EDIT***

Yeah, what Fred said on the rears lol

[Injuneer]

OK... now the differnces between the Moser 12-bolt and the Strange 12-bolt:

Strange:

-Uses stock dimension brackets and axle tubes. All stock 4th Gen parts bolt on

-Uses stock DS length

-Comes fully assembled, lubed and run-in on a dyno at the factory.

-Stock style "through-bolt" TA attachment

-Stock TA location

-Includes 1350 pinion yoke, crossover u-joint, 33-spline axles, C-clip eliminators, aluminum rear cover with pre-load bolts.

-Extra cost availability of ABS or TCS. On TCS, you need to send them your old backing plates with sensors. The Strange ABS sensor SUCKS.

-Typically one month or more delivery, particularly if you get the "super strength" Posi (probably a good idea over 500HP).

Moser:

-Uses 3" axle tubes and oddball LCA brackets. Requires larger mounts for sway bar and needs "special" LCA relo brackets.

-In some cases (50%) requires a slightly shorter DS.

-Comes "in pieces". You assemble, including some end cap shims that Moser often forgets to include, need to swap backing plates, buy your own lube.

-Uses individual bolts on top and bottom of TA mount, that are near impossible to keep tight. Will damage the TA.

-TA is offset slightly to drivers side. Requires your TA have an extra set of mounting holes.

-1350 pinion yoke, crossover u-joint, 33-spline axles, C-clip eliminators, aluminum rear cover with pre-load bolts are "extra cost" options.

-Extra cost availability of ABS or TCS.

-2-day delivery

Neither comes painted.

[MN6WS6]

So in other words, if you want to put your rearend together and have basically nothing work with it but need it fast, get the Moser. If you want everything to bolt up out of the box, but can wait, get the Strange. I know of a 1,000 HP 4th gen that went through 9" like they were squeeze butter. After about the fourth or fifth one, it finally worked. Those problems, the 3% extra loss, and the fact that it's a Ford rearend would make me never put it in my car. Of course I'm not out there running 8's all day either, so it would be overkill in my car.

I honestly would go with the Strange. It comes ready to run, which is why it takes longer to get it. You unbolt your rearend and bolt this one in, simple as that. Everything bolts to it because it uses 4th gen axle tubes. A friend of mine got his in just under 3 weeks, and he absolutely loves it. Another friend has one in his low 10 second street car with AC, PW, PDL, PS, we're talking a true daily driver, and he does drive it to work everyday. The guys here with the Mosers ended up having issues (gear whine, leaking axle seals). Moser will tell you to use muffler clamps to hold on your swaybar. I'm sorry, but that screams "redneck engineering" to me. And if you're gonna pay close to 2g's anyway, the least they could do is put the thing together for you.

[raroZ28]

It's a 6 speed car. It will be something like MN6WS6's friends car. I drive my camaro a lot. Not to work or school, but when summer hits I always have it out. And whenever I go somewhere with friends, they want to take my car.

I plan on making about 500 HP with my car. Nothing crazy. I just want it to last, and take a ton of hits at the track without breaking or even springing a leak.

Where can I get this strange rear end? My rear end is acting up on me now. I'm thinking about borrowing a little outta my 401K to help pay for the rear end.

[Injuneer]

Check T. Byrne Motorsports, or any of the popular F-Body performance parts shops. Tom just posted on another board that the Strange prices are about to go up.

[wolfdogs]

Joe's?......... oh.....sorry.......

[raroZ28]

Joe's?......... oh.....sorry.......

LMAO! I expected nothing less when I saw that you were the last to reply lol.

Fred, doesn't get more out of the box than that, damn. I don't even go to tbryne's site anymore though... It's always more overpriced than anywhere else. I'll check it out though, thanks.

[Injuneer]

I got mine through T. Byrne in a "group purchase". Look around for one.

[fastTa]

Try checking out the "For Sale" sections on ls1tech.com, cz28.com, and racingjunk.com

There are always good used and new 12 bolts for sale.

[N20LT4Bird]

Or.....bang your head against the wall for a month while engineering and welding up your own like I did.