Brute Speed 10 Bolt, 12 Bolt and 9 inch Information

 The factory 10 bolt that came in these cars has a very small 7.5" gear.  A variation of this rear was used back in the '70's in the Chevy Monza, then in the Chevy S-10.  GM had to of known they would have warranty claims when they decided to use this rear in the 3rd and 4th gen f body's, apparently the cost of creating a stronger rear was higher than what they thought the warranty cost would be.  This has been a real plus for the aftermarket, as a bone stock LS1 F Body with a manual transmission can break one of these 10 bolt rears!  Many people have tried to beef these 10 bolt rears, spending a lot of money in the process.  What they normally end up with is a rear that still breaks, as everything on these rears is too small.
The 12 bolt rears that are available for these cars is a step in the right direction.  The 12 bolts are well known for being a stout rear that was a factory option back in the day in many performance cars.  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. The 9-inch rear end, originally offered in 1957-1987 Ford cars and light trucks, has been a mainstay in drag racing for over 50 years. Its beefy 9-inch ring gear proved to be an effective alternative to the 8-3/4 Mopar and GM 12-bolt (8.875-inch diameter ring gear) housings of the era. The Ford’s removable carrier design made it easy to swap gear sets, and the aftermarket responded by offering over two dozen ratios between 3.00 and 6.50:1.


3 channel / 4 channel

Our cars came with either ABS (automatic braking system) or with ABS and the optional TCS (traction control system) ABS is called 3 channel, ABS/TCS is called 4 channel. ABS has the connection routed into the top of the center section.  ABS/TCS has the connection outboard toward the ends of the rear end.

You can order the new rear without the ABS or the ABS/TCS.  Without ABS the ABS won't work on the front brakes either.  This will put the car back to what I call "old school" brakes, meaning, if you push down hard on the brake pedal the tires will lock up.  I have always preferred non ABS brakes myself.  You will end up with the ABS light being on in the dash if you elect not to use the rear with ABS.  This light cannot be tuned out.  You can remove the bulb, paint it black, put tape over it or simply ignore it.


 The 10 bolt rear in the above picture has the 3 channel option, which has an ABS plug on top of the housing.


 The 10 bolt in the above picture is equipped with the 4 channel option, which has a plug that goes into the backing plate.

The 3 channel can only be ordered with the nodular iron center section.

Moser began offering a three channel option for their nine inch rears back around 2008.  The three channel option is only offered with the nodular iron center section, so if you want an aluminum center section you'll have to decide whether to delete the ABS, or go with the 14 pound heavier nodular iron center.
The 4 channel can be ordered with either the standard nodular iron center section or with the aluminum center section, as the reluctor rings are outboard by the brakes.  4 Channel ABS/TCS users will need to press on their own exciter rings or add the option to have Moser supply exciter rings already installed on the axles.


Gear Noise

Occasionally I'll see threads on LS1tech regarding gear noise with a new rear end.  Sometimes these threads go into bashing a vendor or manufacturer because of the noise.  Naturally you don't want to shell out thousands of dollars for a new rear, only to have so much gear noise that you can't drown it out with the radio.  A little gear noise should be expected, as aftermarket gear sets are performance oriented and will sometimes produce a slight amount of gear whine.  The torque arms on the F Body cars don't help matters either, as they tend to act as a stethoscope, amplifying the gear noise right up to the drivers seat.  One problem that can happen is that the gears can be set up perfectly, but they produce an unacceptable amount of gear noise.  We have found that you can have two apparently identical gearsets, both installed the same, and yet one set will be quiet and the other set will end up being loud.  Fortuantely this does not happen very often, but when it does, the only solution is to remove the center section and send it back in to have another set of gears installed.


Gear Oil

The limited slip differential design has been extensively tested with high quality NON-Synthetic 80W90  hypoid oils ( regular mineral based oil ) treated with GM or Ford friction additives ( 3 oz. of additive will treat 1 quart of oil ).  To avoid differential clutch chatter ( noise ) and for optimum performance, use the oil and additive described above.  Use of other additive and oil types may cause differential clutch chatter.

Ford Friction Additive # C8A219B546A

GM Friction Additive # 1052358


Oil Fill Location

The oil fill is located on the left side of the housing on the Moser 9 inch rear end.  It is relatively close to the torque arm bracket.  Fill the rear up until the fluid starts to seep back out of the fill hole.  It should only take three quarts of gear lube. 



  For optimum traction with the 3rd and 4th gen Camaro and Firebirds, the lower control arms basically need to be parallel with the ground.  The lower control arm brackets need to extend further towards the ground for this to be accomplished.  BMR and other companies have offered lower control arm relocation brackets for many years, which have to be bolted or welded on to the lower control arm brackets.  Moser came out with the lower control arm relocation bracket option back in 2008.  Moser uses these longer brackets in place of the standard brackets, when this option is picked.  What this means is they do not look like an add on, or an after thought.   Moser's lca (lower control arm relocation brackets have three positions for placement of the lower control arms.  We have found the lowest position seems to work best for optimum traction. 



There are quite a few differentials that are available for the nine inch rears.  Choosing which one to order can be quite confusing. 

1. Auburn Pro Series

2. Trac-Loc Limited Slip

3. Detroit Truetrac

3. Detroit Locker

4. Wavetrac


1. The Auburn Pro Series is available from Moser for their 28 and 31 spline axles.  It is not a very popular differential with the LS crowd, and is not rebuildable.  Out of the over 1.4 million in Moser sales that I have done over the years, I have never sold a rear with an Auburn.


2. The Trac-Loc Limited Slip shown below was originally used by Ford in many of their vehicles.  It is available from Moser for their 28 and 31 spline axles.  It is a very good differential to up to 500 RWHP, and is rebuildable.  The Trac-Loc Limited Slip Differential is designed as a direct replacement for the hard to find expensive OEM unit, or for those enthusiasts desiring to convert to a limited slip.  Available for 9 Ford rear ends, this nodular steel casting is totally rebuildable, includes nickel steel side gears and pinion gears, and multiple plate 360-degree steel clutches.  This extremely tough and durable differential houses 400-ft/lb static springs, and is capable of 150 lb. braking torque.  Available in 28 or 31 spline.  Made in the U.S.A.


3. The Detroit Truetrac shown below is the first gear type limited slip differential in the industry.  It's patented design of parallel axis planetary helical gears provide a quiet, automatic splitting of torque.  Power transfer goes literally unnoticed by the driver – even in front wheel drive axles.  The Detroit Truetrac performs like an open differential under normal driving conditions and automatically transfers torque to the wheel with better traction when ground conditions warrant.  The limited slip responds instantly to torque feedback, anytime, at any speed. Available for 12 Bolt Chevy cars, Ford 8.8 rear ends, and Ford 9 applications, the Detroit Truetrac’s proven design, low cost and effective performance make it the choice of off-road, street, and strip enthusiasts everywhere.

The Truetrac is now availble in a 35 spline!

4. The Detroit Locker shown below is a very strong differential that can handle a lot of power.  It is available from Moser for their 28, 31 and 35 spline axles.  It can be a bear to get use to, as it doesn't always unlock each axle at the same time when you let off the gas.  This can cause the back of the car to wiggle around, and many people can't stand it. The locker will give the driveshaft more play that what most differentials will, which is inherit with the locker.  This play can cause those with manual transmissions to encounter problems shifting at part throttle.  At full throttle it is not a problem.  Something else I should mention, as it happened to us at the starting line at last years LSX Shootout, you have to make sure the locker is engaged at the starting line.  A short dry hop after the water burnout will engage the locker.  If you don't do the dry hop, the car may break on the starting line and never move an inch.  This happened to us...  I have had several people who had manual transmissions that had trouble shifting at part throttle speeds after they installed a rear with a locker. Basically with a locker the driveshaft will have more play in it which can cause the problem. At wide open throttle the problem goes away. Many people have lockers and manual transmissions without having shifting problems, so it is an intermittent problem. Moser Engineering carries a full line of Detroit Lockers to fit most popular rear ends used on the street, off-road, or on the racetrack.  Detroit Lockers are fully automatic locking traction differentials, manufactured by Tractech, a well-known manufacturer of heavy-duty traction differentials for OEM and replacement applications.  A Detroit Locker maximizes the available traction by delivering 100% of the torque and power to both drive wheels.  It is engineered to keep both wheels in a constant drive mode, yet has the ability to unlock, to permit the wheel to turn at different speeds if necessary.


 5. The Wavetrac comes with a limited lifetime warranty and is very driver friendly, you won't even know it is back there.  It is only offered by Moser for their 35 spline 9 inch and 12 bolt rears.

The Wavetrac® differential uses a patent pending design to improve grip in low traction conditions.  Precisely engineered, converging / diverging wave profiles are placed on one side gear and its mating preload hub.  As the two side gears rotate relative to each other, each wave surface climbs the other, causing them to move apart.  This imparts an increased normal force through the side gears, increasing the bias ratio as a function of load.  This increase occurs automatically only when conditions find it necessary, and it 'reverts' back to its nominal bias ratio quickly and seamlessly, maintaining optimal drivability and performance at all times.  It's like having two differentials in one: you get the benefit of a higher bias ratio when needed without detriment to the car's handling.  Interchangeable Friction Plates Provide Controlled Bias.


The Moser steel spool locks both axles together.  It is lighter than a differential, cost less, and with a spool you always know both rear tires are going to turn.  A spool is generally recommended for only dragstrip cars, although we have put spools in a lot of street cars without any problems.  If your car spends most of it's time on highways or rural country roads, then you might want to consider a spool.  The only time I normally notice when I am driving a car with a spool is when I make left or right turns in intersections.  The inner tire will scrub, which does accelerate tire wear. If your car spends a lot of time in an inner city environment, then I would stay away from a spool.  Parallel parking with a spool is not impossible, but it does require a lot more finesse to get the job done.  I know, as I tried it several years ago to see if it could be done.  If you try to do a u-turn with a car with a spool, you'll find you cannot turn nearly as tight.  The car will want to continue to plow forward instead of turning, which is called understeering.



Sway Bar Brackets

The Moser sway bar brackets give you more clearance for the sway bar to clear the third member. When these Moser sway bar brackets are ordered with the new rear end, the brackets come already welded to the rear.



 Axle Lengths For 93-02 F Body

Moser 9" Axles In Various Spline Sizes for 93-02 F Body

Axle lengths:

31 spline Truetrac:  33.4375 passenger side
                             30.375  driver side

31 spline Trac-Loc:  32.875 passenger side
                              30.375 driver side

31 spline Wavetrac: 32.875 passenger side
                              30.375 driver side

31 spline locker: 32.875 passenger side
                         30.375 driver side

35 spline locker: 33.00  passenger side
                         30.50  driver side

35 spline Truetrac: 33.875 passenger side
                              30.375 driver side

35 spline Wavetrac: 32.875 passenger side
                              30.375 driver side

Spool:  33.00  passenger side
           30.50  driver side

Moser M9" (fabricated 9 inch) Axles In Various Spline Sizes for 93-02 F Body

Axle lengths:

31 spline Truetrac:  33.875 passenger side
                             29.9375 driver side

31 spline Trac-Loc:  33.3125 passenger side
                             29.9375 driver side

31 spline locker: 33.3125 passenger side
                         29.9375 driver side

35 spline locker: 33.4375  passenger side
                         30.0625  driver side

35 spline Truetrac: 34.3125 passenger side
                            29.0625 driver side

35 spline Wavetrac: 33.3125 passenger side
                              29.9375 driver side

Spool:  33.4375  passenger side
           30.0625  driver side


Replacement Part Numbers and Notes

- Napa Replacement part numbers for nine inch wheel bearings and seals.
Bearing: 88128-R
Inside Seal: 15142

- Napa Replacement part numbers for 12 bolt wheel bearings

Bearing: 9508b


Note: Extreme Axles (gun drilled and star flanged are not recommended for street use)

Note: Universal Joint U-bolt Torque

1310 series and 1330 series should be tightened to 17 ft/lbs and 1350 series to 20 ft/lbs. You should never tighten the nuts on any u-bolt excessively. This will cause the cap to distort and the u-joint will fail prematurely.

Note: Heavier Duty Pinion Seal

CR-547785 uses Viton instead of natural rubber ($8.50 each). The fit is the same although the seal design is a little more robust. They ship these seals for multiple end uses including NASCAR. This seal should eliminate any pinion seal leaks.

Note: Timken Wheel Bearings

If you have ordered a Moser rear with Timken wheel bearings, do not use the inner wheel seals. The Timken wheel bearings need to be lubricated and the inner seals prevent the bearings from getting the necessary lubricant.

10 Bolt, 12 Bolt and 9 inch Information
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  • Item #: Brute Speed Rear Information
  • Manufacturer: Brute Speed
  • Condition: New
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Price $9,999.99
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