12 bolt. yes or no?

[Cookie]

Heres my situation. I just did a cam swap and I know my 10 bolt is on borrowed time. I found a used Moser 12 bolt 4 channel, 33 spline axles, detroit locker, 4:30 gears, and comes with OEM brakes 500 miles on it. Guy wants 1800 for it.


First question: I hear all these horror stories about us M6 guys destroying 12 bolts (and ever worse things about the mosers)... Ive got 390rwhp and 364rwtq. I might have it at the track 2 or 3 times a year and im not planning on doing any 6000rpm clutch dumps... 3500 MAYBE once in a while when im at the track. Is this thing gonna die on me? Should I wait on a 9"?

Second question: Am I going to hate the 4:30 gears for DD'ing? I was planning on 4.10's and 4.30's really arent that much worse... are they?

Third question: Is $1800 a good deal for a 12 bolt like this? $1800 is what he is asking... So I could probably get it for cheaper. Ive seen 4.10 2 channel 31 spline true trac ones go for 1500 so thats why im wondering.

PS: Ive already got UMI LCA's and im planning on getting a UMI tunnel mount torque arm/w the drive shaft loop, and SFC's.


Thanks for the advice

[INMY01TA]

I wasn't aware you could get a Detroit Locker in a 12 bolt w/33 spline axles. I don't htink you can but if so then yes $1,800 is a good deal. Weak point in a 12 bolt is the posi. I know some fast 6 speed/12 bolt guys that run spools in em with no issues. Maybe he means Detroit Tru Trac. Jury is still out on those.

[JwMonE99]

1800 is sadly a good deal for it.
No I dont think it would brake.
4.30s are probably a little too much for DD but its not bad.
If you are going to go with an aftermarket rear get this one, no need to spend the extra cash on a 9 inch. BTW your going to love the Detroit locker.

[Cookie]

ok cool thanks for the advice. I was thinkin about switchin to a true trac but ive been finding some very mixed reviews about them so i think ill stick with the locker and see how it goes. Might find some 4.10's for it though. Used a calculator and i think the 4.10's are definately going to be nicer for the street which is the main purpose for the car.

shouldnt be worried bout the torque arm mount on the rear? Ive read some bad things about 'em bein cheesy nd the bolts backing out. Double nut it maybe? w/locktite?

[rajiv1998]

ok cool thanks for the advice. I was thinkin about switchin to a true trac but ive been finding some very mixed reviews about them so i think ill stick with the locker and see how it goes. Might find some 4.10's for it though. Used a calculator and i think the 4.10's are definately going to be nicer for the street which is the main purpose for the car.

shouldnt be worried bout the torque arm mount on the rear? Ive read some bad things about 'em bein cheesy nd the bolts backing out. Double nut it maybe? w/locktite?

4.30's WILL be way to much gear for DD, and u will be shifting like a mad man when your driving. You better have something like a big T-rex or MS4 to make use of those gears. You will end up in 5th gear by the end of the 1/4. Why not buy some used 4.10's and put them in before the swap? The rear is gonna be out anyway so all you have to do is take them out and put them in.

[dklowrider]

you guys really run detroit lockers in a street car?

[Zboner]

ok cool thanks for the advice. I was thinkin about switchin to a true trac but ive been finding some very mixed reviews about them so i think ill stick with the locker and see how it goes. Might find some 4.10's for it though. Used a calculator and i think the 4.10's are definately going to be nicer for the street which is the main purpose for the car.

shouldnt be worried bout the torque arm mount on the rear? Ive read some bad things about 'em bein cheesy nd the bolts backing out. Double nut it maybe? w/locktite?

correct that is the weak point on the 12 bolts, but its a deal i wouldnt think you have anything to worry about man unless your making some SERIOUS power it should be fine.

I have seen some take a ton of abuse and they keep on truckin

[Cookie]

4.30's WILL be way to much gear for DD, and u will be shifting like a mad man when your driving. You better have something like a big T-rex or MS4 to make use of those gears. You will end up in 5th gear by the end of the 1/4. Why not buy some used 4.10's and put them in before the swap? The rear is gonna be out anyway so all you have to do is take them out and put them in.

im running an MS3

[Cookie]

i may see if i can find a true trac since its not like im puttin 500 ft/lbs thru it. A lot of my friends are tellin me that im going to hate a locker on the street, or im going to be coming around a wet on ramp and its gonna lock up on me and put the ass end in front and me in a guard rail.

ill prolly look for some 4.10 gears too... even though its only worth 2.5 mph at 2000rpm.

Im guessin too judging from reading in the randys ring and pinion book that these 12 bolts are the "car" 12 bolts and not the truck 12 bolts... reason i ask is because on JEGS site they only make 33 spline true tracs for the car style ones and not the truck style ones.

[Jays00ss]

I run 4.30's, and a Detroit locker as a daily driver in my Camaro during the nice months (April-October). Absolutely love the combo and in no way are 4.30's "Too much gear" I think they are about perfect. At 75 MPH in 6th I am at 1950 RPM.

at the track with a 410 rwhp car with 26.5" tall tires I am at 6500 rpm in 4th. right in the sweet spot of my cam range.

Detroit locker takes a little getting used to but I don't even notice it anymore and for an occasional pop, bang boom, Is the best "posi" you can buy, Because it's all mechanical no clutches to wear out, and practically bulletproof. Why do you think all the 4X4 owners use them.

I haven't had any issues at all with wet road driving. Just be a little cautious and you will never even notice you have the locker.

$1800 Is a smoking deal, set up will be just fine I wouldn't hesitate for 1 millisecond.

[Cookie]

I run 4.30's, and a Detroit locker as a daily driver in my Camaro during the nice months (April-October). Absolutely love the combo and in no way are 4.30's "Too much gear" I think they are about perfect. At 75 MPH in 6th I am at 1950 RPM.

at the track with a 410 rwhp car with 26.5" tall tires I am at 6500 rpm in 4th. right in the sweet spot of my cam range.

Detroit locker takes a little getting used to but I don't even notice it anymore and for an occasional pop, bang boom, Is the best "posi" you can buy, Because it's all mechanical no clutches to wear out, and practically bulletproof. Why do you think all the 4X4 owners use them.

I haven't had any issues at all with wet road driving. Just be a little cautious and you will never even notice you have the locker.

$1800 Is a smoking deal, set up will be just fine I wouldn't hesitate for 1 millisecond.

well i'd say that about settles it then... ill run the locker and the 4.30's and see how it goes.

Just out of curiosity... since you and I have almost the exact same power and it sounds like our cams are similar, what were you running in the 1/4? I was hopin I'd be low 12's with some drag radials.

[Jays00ss]

well i'd say that about settles it then... ill run the locker and the 4.30's and see how it goes.

Just out of curiosity... since you and I have almost the exact same power and it sounds like our cams are similar, what were you running in the 1/4? I was hopin I'd be low 12's with some drag radials.

I live in Colorado, we are at 5800 ft above sea level therefore we are about 1 to 1.4 seconds slower than those of you at sea level. I ran a 12.75 at 111 mph last year. I will be going to the track a whole lot more this year and should dramatically improve my times with more practice and tweaking of the car (tire pressures, launch rpm, more confidence (its been a few years since I have been serious at the track))

[Cookie]

wow. so that could mean my setup has high 11 potential. since the 2 tracks i run at are 563 feet and 440 feet. Didnt imagine it'd be that fast, Cool! Well good luck at the track this year and thanks again for the info!

[dklowrider]

I run 4.30's, and a Detroit locker as a daily driver in my Camaro during the nice months (April-October). Absolutely love the combo and in no way are 4.30's "Too much gear" I think they are about perfect. At 75 MPH in 6th I am at 1950 RPM.

at the track with a 410 rwhp car with 26.5" tall tires I am at 6500 rpm in 4th. right in the sweet spot of my cam range.

Detroit locker takes a little getting used to but I don't even notice it anymore and for an occasional pop, bang boom, Is the best "posi" you can buy, Because it's all mechanical no clutches to wear out, and practically bulletproof. Why do you think all the 4X4 owners use them.

I haven't had any issues at all with wet road driving. Just be a little cautious and you will never even notice you have the locker.

$1800 Is a smoking deal, set up will be just fine I wouldn't hesitate for 1 millisecond.

i must be missing something here. is the output ratio of an m6 in high gear that much higher than an a4? the rpm you give at 75 is what im turning at 70 w/2.73s and 26" tires. how is that?

[shady milkman]

good deal but pay attention..moser 12 bolts are notorious for having the torque arms back out...locktite and all..it doesnt matter...umi knows this and if you read their blurp about the torque arms they warn you....for that reason i would never consider a moser 12 bolt

[Firebirdjones]

good deal but pay attention..moser 12 bolts are notorious for having the torque arms back out...locktite and all..it doesnt matter...umi knows this and if you read their blurp about the torque arms they warn you....for that reason i would never consider a moser 12 bolt

I don't buy the torque arm problem. I've run and built plenty of 12 bolts for people and never once ran into a torque arm problem.

The only issue I have had (with Moser) is the damn housing not being square. Had my run in's with moser as well as my father. Don't care to deal with them anymore.
I have since switched to Strange and had "0" issues.

I personally don't care for the lockers on a street car. To each their own I guess. But if you ever get on a wet road with a drag radial you'll know why.
Eaton makes one of the best clutch style posi units out there. And they can be bought with 33 spline now. They have lived for me in the rears I have built with pretty stout 10 second street cars.
I have ran a Moroso Brute strength clutch style posi unit in my chevelle since 1988,,,,running 11.40's at 118 in a 4,108 lbs. car and at least 40,000 street miles. It hasn't once been out of the car for anything in 20 years. Still works just fine.

For the original poster,,,thats a good deal on a complete setup. It's probably going to make noise though. I'd stick it in,,,see how it goes. If you can live with the locker and rearend doesn't sound like a school bus then you're set to go. 4.30's aren't squat,,,leave em' and have some fun. You can always decide later if you want to change things around.

[Y2KPewterSS]

Read this thread Larry:

http://ls1.com/forums/showthread.php...ighlight=moser

There is a torque arm issue involving the Moser 12s. Its not a frequent problem that I am aware of, but it exists.

I don't buy the torque arm problem. I've run and built plenty of 12 bolts for people and never once ran into a torque arm problem.

The only issue I have had (with Moser) is the damn housing not being square. Had my run in's with moser as well as my father. Don't care to deal with them anymore.
I have since switched to Strange and had "0" issues.

I personally don't care for the lockers on a street car. To each their own I guess. But if you ever get on a wet road with a drag radial you'll know why.
Eaton makes one of the best clutch style posi units out there. And they can be bought with 33 spline now. They have lived for me in the rears I have built with pretty stout 10 second street cars.
I have ran a Moroso Brute strength clutch style posi unit in my chevelle since 1988,,,,running 11.40's at 118 in a 4,108 lbs. car and at least 40,000 street miles. It hasn't once been out of the car for anything in 20 years. Still works just fine.

For the original poster,,,thats a good deal on a complete setup. It's probably going to make noise though. I'd stick it in,,,see how it goes. If you can live with the locker and rearend doesn't sound like a school bus then you're set to go. 4.30's aren't squat,,,leave em' and have some fun. You can always decide later if you want to change things around.

[Firebirdjones]

Read this thread Larry:

http://ls1.com/forums/showthread.php...ighlight=moser

There is a torque arm issue involving the Moser 12s. Its not a frequent problem that I am aware of, but it exists.

Thanks for the link. It appears that the original problem was the torque arm breaking in half. He doesn't really mention if it was due to bolt retention from what I am gathering here.
But in any event, whether it's a real issue or not is questionable. I've never seen it. Although I stopped using Moser housings a few years ago and went with Strange.

Honestly though, when aftermarket suspension parts are used, whether it be control arms, panhard bars, and especially aftermarket torque arms,,,,going through all the bolts and retorquing should be a regular maintainance procedure, since most of this stuff is mounted so solid with either poly bushings or heim joints, vibration becomes a real issue. Things get loose as a result, it's just the nature of this stuff. I'd recommend it every time the car is up for an oil change. Only takes a few extra minutes.

[shady milkman]

I don't buy the torque arm problem. I've run and built plenty of 12 bolts for people and never once ran into a torque arm problem.

its only with the moser 12s..its about how moser doesnt go with through bolts..so instead of one..its two...or something along those lines..and other little problems ..but i dont even want to run that risk ya know..if im going to drop that money..why not get a even stronger unit that doesnt have that issue

[jgang]

Newbie here....I would like to know the rules about selling a new Moser 12 bolt rearend on here?