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moser 12 strength

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Old 05-21-2010, 09:56 AM
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Default moser 12 strength

how much power should a moser 12 take behind a 6 speed? has an eaton diff and 30 spline axles with 4.10s the softest tire i will run will probably be a mt et street radial.
Old 05-21-2010, 10:11 AM
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I would stay away from that 12 bolt... especially in a M6 car and sticky tires. rule of thumb is M6 street/strip car go right to a 9". if you are foot braking a A4 trans then maybe a 12 bolt.
Old 05-21-2010, 10:37 AM
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i know but iv already got it andi got a good deal on it when i bought it. im just curious for now. ill probably try stepping up to a moser fab 9 when i break this one. but for now i need to know its limits
Old 05-21-2010, 03:52 PM
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Moser has an easy axle formula to tell if the axles can handle the power...
Torque x first gear ratio x rear gear ratio x .90(90 % effeciency) = Max torque.
EX. 600 ft lbs x 1.86 first gear x 4.88 rear gear x .90 effeciency = 4901 MAX TORQUE, always error to the side of safety.

You need an axle with a 200% safety factor so you'll make sure 1 axle can handle that torque #.. Makes it almost impossible to break an axle.
30 spline axles = 6200 ft lbs per axle
31 spline axles = 7000 ft lbs per axle
33 spline axles = 8200 ft lbs per axle
35 spline axles = 9600 ft lbs per axle
40 spline axles = 12000 ft lbs per axle

There are a few things you can do to beef up a 12 bolt to handle power. Brace it and girdle it. I've seen plenty of 12 bolts handle good power.

Just adding, I would presume a 4.10 rear 6speed(2.97 first) that rear could handle 550ft+ lbs no prob with a 30 spline axle. I would imagine the eaton rear could handle that too, not sure how fast you'll kill the clutches.
Old 05-21-2010, 10:57 PM
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I think if you have problems it will be the diff if anything later upgrade the axles and go to a spool. I have seen a few M6s go fast on 12 bolts.
Old 05-22-2010, 05:29 AM
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Make sure you either Loc-tite the four torque arm bolts at the rear, or get drilled bolts and lockwire the bolts so they can't loosen up. Expect to hear gear noise with the 12 bolt after you've been to the dragstrip. Bob
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Old 05-22-2010, 09:08 AM
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it has a girdle on it now. im just curious at what point will it start to become an issue?

yea it does start whinning after i beat on it hard but it usually goes away in a couple min

do u think it could handle 450rwhp plus a 150 shot on et street radials?
Old 05-22-2010, 09:41 AM
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The 12 bolt in my car lived its first life in my friends 1180rwhp pro charged for a abusive 4-5K miles and never broke.
I have never tore it apart other then to change the oil out of it so I have never count how many spline they are but considering who it came from Im sure they are 35s.
Old 05-23-2010, 05:56 AM
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I put a 12 bolt (33 spline axles, eaton diff, support cover) in my GTA back in 2002 and still going strong after around 700 passes and 30K street miles in a 3650lbs car that goes 10.50 off a t-brake. I just change the oil once and a while

Good luck with it
Old 05-23-2010, 07:36 PM
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I would stay away from the street radials in a 6spd car even with a aftermarket rear. Go for the bias ply et streets they will do alot better.
Old 05-23-2010, 10:47 PM
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you should be more than good with that power on a 12 with an m6 with radials, like previously stated, make sure you use loc tite on the torque arm bolts and that no fluid found its way into them before installing the bolts
Old 05-24-2010, 08:59 AM
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you'll be fine, just make sure those torque arm bolts dont go anywhere- i have a moser 12 with 33 spline axles eaton hd and 4.11s and it whines but ill NEVER break that thing

however- with only bolt ons i did back out 2 bolts and bent the **** out of the torque arm mounting bracket- retorque them every oil change so it doesnt happen to you!




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