Mosier 12 bolt howling

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Aug 20, 2012 | 07:42 PM

Centerfold_Firehawk

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From: Amsterdam NY

Mosier 12 bolt howling

I have a 2000 firehawk with 375 rwhp and a Mosier 12 bolt with 3:73 gears and the car is a 6 speed too I drag raced it last year with 28" slicks and launched at 5500 rpms now the rear howls on deceleration I've been told that this will happen with hard launches on slicks with a 6 speed car by my brother but the rear end was in the car when I bought it otherwise I wod have put a 9" or s60 in it I am just wondering if I can just get a new gearset and set up the gears and get rid of the howling or did I deflect the housing beyond that thanks kevin

Aug 22, 2012 | 07:44 AM

Bob@BruteSpeed

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Kevin, most likely it will happen again. You can have a 12 bolt in an early Chevelle, Nova, Camaro, etc, and beat the snot out of it and not hurt anything. Put a 12 bolt into a late model f body that uses a torque arm, make a couple 4000 to 5000 rpm launches at the dragstrip, and I can just about guarantee you'll have a lot more gear noise on the way home. The torque arm seems to distort the housing on the 12 bolts, and it seems to happen to all the brands of 12 bolt rears. This does not happen to the 9 inch rears, and there is no price difference between the 12 bolt and nine inch rears. As the horsepower in our engines keep escalating, most people these days go straight to the nine inch rear. The 9-inch has an internal rear-pinion support that also supports the gear end of the pinion to limit gear deflection under high torque loads. This seems to be the major reason why the 9 inch doesn't start whining after high rpm clutch dumps, when the 12 bolt will pick up noise. The 9-inch locates its pinion gear lower on the ring gear to improve tooth contact, better the 12 bolt does. The 9-inch also has a 0.125-inch larger ring-gear diameter and internal pinion support than the 12 bolt.

http://shop.brutespeed.com/Brute-Spe...nformation.htm Bob

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Aug 22, 2012 | 09:06 AM

Centerfold_Firehawk

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From: Amsterdam NY

Thanks for the info bob

Aug 26, 2012 | 09:29 PM

prokilllsx

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Do you think this same thing could happen to a 9 bolt rear end with a Spohn crossmember mounted torque arm. She hooked good and is now whining loudly.

Aug 27, 2012 | 06:22 AM

Bob@BruteSpeed

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Quote:

Originally Posted by Centerfold_Firehawk

Thanks for the info bob

You're welcome! Bob

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Aug 27, 2012 | 06:28 AM

Bob@BruteSpeed

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Quote:

Originally Posted by prokilllsx

Do you think this same thing could happen to a 9 bolt rear end with a Spohn crossmember mounted torque arm. She hooked good and is now whining loudly.

http://www.thirdgen.org/techboard/fa...now-about.html

Check out the 2nd post in the above thread. Bob

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Aug 27, 2012 | 02:14 PM

prokilllsx

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From: ohio

Thanks Bob. Good link.

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