Can anybody tell me the difference between the two ? Which is stronger , least amount of noise , etc. What gear ratio is the best for the street vs strip ? Last , but not least,how weak is my 2002 camaro ss auburn rear end ? Thanks for the replies




ROB

 

I've recently bought a Moser 9" and I did quite a bit of research before buying.The 9" is said to be stronger but comes with a few draw backs.For one the 9" is a little heavier than the 12 bolt,not sure how much though.One thing that turned me away from the 12 bolt was that the limited slip posi will have to be rebuilt eventually with new clutches.I have'nt heard many people with 12bolts complain about this but Moser said that it could come as quick as a year depending on how much you will be going to the strip and how hard you would be launching.For me thats every weekend with slicks and launching as hard as I can.The 12bolt is supposedly more comfortable.
I went with the bullet proof Detroit Locker and i've read a few people dislike the ratcheting of the locker but I was very surprised and inpressed.To me it's not bad at all,hardly noticable.The biggest thing I notice is when I turn off one street onto another it feels like a lttle slack gets in the rear for just a very quick second,hardly noticable to me.Another thing with the 9" is if you have 4ch ABS you will have to delete it as I did in my case.Very simple and seeing it done I probably would do it again regardless of which rear I had.Depends on what your plans are for the car.If you plan on mild mods I would go with the 12bolt.If you wanna turn some good engine numbers and alot of hard launches at the strip i'd suggest the 9".
These are just some of the things that i've learned when I was trying to decide.Glad I went with the 9" though.
Good luck on you decision and if you have any more questions feel free to ask and i'll be glad to help if I can.
JE

 

I'm pretty sure you can get lockers for 12 bolts.. or torque sensing types like Detroit TrueTrac (worm gears, no clutches) for 12 bolts too.


actually, you should be able to get 4 channel ABS working, since the sensors are at the end of hte axles.. 3 channel can't work htough since there's no room in the pumpkin for the ABS ring.

 

Yeah sorry about the ABS,I had it backwards.I can't remember the reason but Moser said I could'nt get the locker in their rear.Eaton and Auburn I believe it was,was the only options if i'm not mistaken.Seems like it had something to do with the axles.I can't remember though so it might be worth checking into.
JE

 

So what is it ? ABS or not on the 9 inch ? If I couldnt have that I would stick with the 12 bolt . Actual driving with the car would be fun with out ABS , alot better without it in certain situations . I want to have it in my car though . I want to keep it as clean and as stock as a I can . Thanks for the reply

Rob

 

If thats what you wanna do. i Would just go with a MOSER 12 bolt w/ 4:10's...how often will the car see the track?

 

Sounds like basically a stock car. Why are you even considering a 12-bolt, let alone a 9"? A 9" is WAY overkill for 99+% of even the modded 4th gen's out there. A 9" is very strong, very heavy, and has a lot of parasitic loss. I'd say that it should be reserved for big hp cars that see lots of track time (prepped surface, sticky tires). Otherwise, it's not worth the disadvantages.

Rich

 

Ah intresting.. looking thru TracTech's application guide, there is no Detroit Locker for Gm 8 7/8" 12 bolts for gear ratio's 4.10 and up.. You can get them for 3.90's and down though.

 

My Moser 12-bolt has gone two racing seasons wothout a problem. The only thing I had to do was an axle bearing 3 weeks ago, and I went and replaced both sides for insurance.
-Goose

 

Point taken . See its like this, keep it with low miles and pretty much stock or spend some cash and have fun with it . I was thinking for now a full exhaust , and then down the road not sure how far , heads and cam. I figure between 400 and 500 hp when im done . Thanks for the replys .


Rob

 

I have blown up 12 bolts from 2 different manufacturers more times than Carter has liver pills. I'm probably on Ring & Pinion number 10 or more now. Slicks and a healthy clutch = Kaboom even with 390 RWHP.

I have no experience with a 9" but sure would like to try. I'd be a great test case for the 9" vs 12 bolt strength debate. My good street 12 bolt is up for trade for a 9" right now. Anybody interested? My race 12 bolt is going back in this weekend with the spool and Richmond Pro gears. We'll see how the Pro gears hold up.

Steve

 

Mines over 800rwhp and I have had a 12-bolt in it for four years. First two years with a manual tranny/Street Twin. That's with 10" slicks and a race weight ~4,000lbs. The initial Eaton posi had bad heat treatment on the spider gears and failed very early, the replacement has been fine.

Rich

 

Now were getting somewhere

 

Ditto.... 800HP, used to be a T56, Street Twin, 5K dumps and the Strange 12-bolt with the heavy duty posi is intact after more than 5 years. Buddy of mine pushed his super heavyweight 30th SS convertible to almost 1,000HP with the same Strange setup I have. Only when he pushed it up to 1,325HP did he opt for the 9-inch.

 

There's a huge difference between an ocasional weekend at the track, and bracket racing an M6 car 10 or more passes every weekend. Fatigue plays a roll in most of my 12 bolt R&P failures. Although, I have indeed exploded a fresh set of gears on the 1st launch . I've said it before and I'll say it again. It ain't always the horsepower level that kills them. It is the amount of rotating mass or more specificaly the polar moment of inertia, the launch RPM (dynamic energy) ,The amount of clutch friction and the rate of clutch application, Tire traction, Torque arm stiffness, and car mass. A 12 bolt on an auto car will probably last forever because the torque converter is a huge impact dampener. An auto with a transbrake is probably worse than footbreaking, but still probably not a violent as a stick car launching hard.

I always figured my problems were a bad setup. So I got professionals to do itfor a while. Art Houser (Rearman) pretty good setup guy on the east coast- Blew his up. Strange Engineering - Blew that up, Drivetrain Specialist in Detroit- Blew that one up too. I've blown them up so often I finally bought the correct Mark Williams depth checker ( the $450 one) to do my own setups now. I can get pinion depth good to within .001" and backlash perfect at .008", beautiful textbook pattern, and sooner or later I'll blow it up.


Oh yea - I just blew up my strange 3 weeks ago. this gear set only had about 10 passes. Broke in correctly, heat cycled multiple times with probably 1000 street miles.

Sooo, the 12 bolt is a good rear but it's far from indestuctable, unless your footbraking an automatic