Predator

I've been trying for over a month to decide which way to go with a rear end replacement. In the very beginning it was the Strange 12-bolt with a posi, but then I decided that I didn't really want a posi, so I dropped the Strange from consideration. Then I decided that I'd go with a 9" with a Detroit True Trac, but I always felt it was overkill for my application. I believed that a 12-bolt with a True Trac would be the perfect solution but didn't think it was possible because I never considered a Moser 12-bolt to be in the running. Then I found out that Moser does offer a True Trac in their 12-bolts but I was still hesitant because of stuff I've read about Moser, gear setup problems, and the bolt-on TA situation, etc. I've been assured that this stuff can be worked out so I'm currently leaning toward a Moser 12-bolt with True Trac, but I haven't discounted a 9" with a True Trac.

I'm probably currently making about 360-370 hp but plan on adding an underdrive pulley and some aftermarket rocker arms, so I don't think I'll ever be over 400 rwhp. In fact, after the rear end upgrade I want to maybe add a new clutch and some more suspension upgrades like sway bars.

I apologize for being so longwinded, but I want some help making a decision between these two rear ends for my application. I can't seem to decide for myself so I'll go for whatever seems to be the majority choice. I know there's a lot of knowledge and experience floating around here, and I respect that.

So what should I go with, a 9" with a True Trac, or a Moser 12-bolt with a True Trac?

Thanks!

camaross305

iTrader: (9)

if your an m6 go with a 9''

Predator

Okay, is it really that simple, M6=9"? That's makes this decision easier than I thought.

EPP

iTrader: (22)

We use and install Moser 12 bolts with True Tracs in many, many F Body's. They will handle 600 rwhp, and we have had very few problems.

Moser 12 bolt with true trac, your choice of gear ratio.
Moser 33 spline axles, 10 year warranty
Moser ABS or ABS/TCS
Moser (TA) Performance aluminum cover with drain plug

Total $2,350, plus freight collect shipping of $65.00 to $150.00, depending on location away from Indiana. Bob

Predator

That's a very fair price Bob, especially considering that you throw in the TA cover too. Do you sell new backing plates, and if so could you deliver a rear end completely assembled, with the axle bearings pressed on?

Thanks.

pontiac

iTrader: (4)

MOSER 9" and never look back!!!!!!!!!!!!

Scalpel

iTrader: (4)

I'd go with Billingsley 9".

Predator

Fellas, thanks for being straight up!

That's been my ace-in-the-hole all along (Billingsley 9").

Jimmyz

iTrader: (3)

What are you going to do with the car? Drag race it every week, month, a few times per year? I just put a used Moser in my car with the moser gears from a drag car. Needless to say I'll be replacing the ring & pinion as it howls like a wolf on decell and tip in. If its just a daily driver you take to the track once and a while I'd NEVER buy a Ford 9".

If you drag race it weekly and dont mind losing 24rwhp due to the 9" get one as you'll more than likely never break it.

I hear people break 12 bolts but I've never seen it around here FWIW.

Predator

Are you trying to rain on my parade Jimmy?

Seriously, this has been my dilemma, and the reason for hesitating and not being able to make a decision. My car is a street car, but I may eventually go to the track just to get a timeslip, on street tires. Is it true that you lose about 24 hp with a 9"? How much do you lose with a 12-bolt? I don't mind some noise coming from the rearend, but I just never thought of it in terms of horsepower, that's a lot! Damn.

In all honesty, the reason I'm even thinking about replacing the rear is because I want 4.10 or 4.11 gears, and I didn't want to have to worry about breaking my 10-bolt, and I have an M6. In the beginning of my research I wasn't even considering a 9 inch, but so many people have recommended it.

Your post has been like a splash of cold water in my face. I'll probably get a 12-bolt afterall. Thanks for the help.

Predator

That's right! I can't make up my mind.

Jimmyz

iTrader: (3)

Predator - I know MANY people who have gone to the track with their 10 bolt for years with an M6 and have not broken it. If youre going to the track with street tires keep your 10 bolt and just have someone put the gear you want in it. My pig is the same year as yours and it's a street car with a 383 stroker in it. 460 rwtq. My 10 bolt was working fine and i've taken it to the track several times on street tires too. Unless your planning on launching @ 4-5K and dropping the clutch your 10 bolt should be fine for a long time. Yes people break them all the tiime but my guess is theyre using sticky tires to do so.

If you want to be safe with over kill, get a Moser 12 bolt and have someone check the gear setup B4 you install it in the car. If you buy a new one, have them ship it dry so you can get the gears set up properly to not make noise.

Jim

Predator

Jim, I appreciate your input! I always suspected that what you're saying was true, but it's easy to become swayed by the racers. I'm going to take your advice and settle on a 12-bolt.

BTW, do you think a True Trac is overkill for me too? I was originally thinking a 33 spline Eaton posi with the 800 lb. springs should suffice for a 99.9% street car with once-in-a-while street burnouts . Ya gotta have some fun!

Thanks again!

Jimmyz

iTrader: (3)

Is the True-Trac more $$$? The Eaton is more than enough if it is. BTW, thats the setup I have, Eaton posi 33 spline 800 lb springs.

Jim

Predator

A couple hundred more I think. It's a clutchless limited slip/soft locker.

Last question Jim, if you don't mind, do you ever have trouble with one-wheel traction with the Eaton? That's one thing I hate about my Torsen 10-bolt, one-tire burnouts.

Thanks!

BADSS

iTrader: (7)

I think you are confused about the Tru-trac (however you spell it). The True trac is a gear-driven limited slip differential (posi), it is NOT a locker. It is made by the same company that makes the Detroit Locker, but it is not a locking differential. The difference between the True trac and the Eaton is that the True trac uses worm gears (like the stock Torsen, only stronger) and the Eaton uses clutch packs with springs. Gear-type differentials are considered superior for road-racing and Autocross, but as far as which is stronger and superior for drag-racing is a matter of opinion. Hope this helps.

FWIW, I went through the same dilemma as you. I ended up going with a Strange 12 bolt with 4.10 gears and the Eaton posi. I went with the Strange because of all the horror stories I had heard about Moser. However, I have had more than my fair share of problems with the Strange. If I had it to do over again, I would either go with a Moser 12 bolt or a 9 inch. You do not want a locking differential for street use- although the hard-core drag racers will tell you it's not that bad. You may or may not break a 12 bolt at the strip, but the consensus seems to be that the gears WILL get noisy after some hard launches at the track even if the rear starts off silent. So if a noisy rearend is going to irritate you, I would recommend a 9 inch with your choice of a posi.

Jimmyz

iTrader: (3)

BADSS is right on the True-Trac. I again will go back to the begining...if this is a street car 99.9% of the time you dont NOT need a phucking 9" Ford IMHO. That being said, I know TONS of guys who would NEVER put that big hunk of metal in an F-Body...EVER! If you break a Moser 12-bolt R&P on street tires or Drag Radials it will be the first I've heard of.

Here's what you need: 12 Bolt Housing, M/E Custom Alloy Axles, Wheel Bearings, standard size Wheel Studs, Brake Retainer Plates, 3.73 Gears, 1350 series Pinion Yoke, Setup kit, and Assembly.

33 spline Eaton Posi-Unit

Performance Rearend Cover

3 Channel ABS setup or (4 channel if you have TCS)

Jim

NumberOneSled

iTrader: (1)

I was at the PRI show in Orlando this weekend and when I talked to one of the guys at the Moser booth he told me you couldn't put the True-trac in a 9". He seemed like a pretty knowledgeable guy, is this true?

Predator

BADSS, I did say the true trac was a "clutchless limited slip" as in gear driven, but this is not important. The other stuff you said was more important, and I appreciate the help!

Thanks Jim, I took notes, but I still want want 4.10s in place of the 3.73s. I have an M6.

I appreciate the great help. I think I'm all set. Thanks fellas!

Predator

A guy recently posted a thread about his 9" and True Trac. I think the thread was titled "9" is definitely the way to go." You can't put a True Trac in a Strange 12-bolt because of the angle that the splines are cut.