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.


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 a little over 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.

New for 2014! 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 shown below has been out on the market for a relatively short time.  It comes with a limited lifetime warranty and looks to be the "differential to do everything" that anyone is going to throw at it.  Moser (and the rest of the world) is very hopeful that this new differential will be able to handle the average 1000 hp build that everyone seems to be doing these days.  I can tell you that it 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.

Here's something else you won't find in any other design:
The Wavetrac® diff's behavior can be altered in the field to suit your needs.  It comes standard with carbon-fiber bias plates for the best all around performance.  Interchangeable plates using materials with different friction coefficients to fine-tune the bias ratio are sold separately.
These friction plates provide a mechanism to tune the response of the differential as a function of applied torque load.  The applied torque load manifests itself as an axial load from the differential pinions into the housing.  This axial force is then considered a normal force into the friction plate, and as a function of the effective coefficient of friction, will provide a resistive torque to the rotational motion of the differential pinions.  The resistive torque will add to the resistance of relative rotation of all components within the differential.  The resistive force, however, is non-uniform since it is a function of the axial load from the differential pinions.  The unbalance of the resistive torque will manifest as non-uniform energy absorption within the differential causing a bias ratio.

Each Wavetrac® Differential is crafted from the highest quality materials available.  The internal gears are made from high strength 9310 alloy steel.  The diff bodies are machined from case hardened steel billet.  To complete the package, every Wavetrac® differential is built exclusively using high quality, high strength fasteners from ARP®, the world leader in fastener technology.

• Innovative:
Patent pending Wavetrac® design automatically improves grip in low traction conditions.  This feature is truly innovative and unlike any other torque biasing diff design.
• Superior Materials:
9310 steel gears run in case-hardened billet steel bodies.  ARP® fasteners used throughout.
• Maintenance Free:
As supplied new, the Wavetrac® differential will perform a lifetime of service without maintenance or rebuilds.
• Customizable:
If desired, you can alter the diff’s behavior to suit your needs using optional components.
• Limited LIFETIME Warranty:
All Wavetrac® differentials include a transferable, Limited Lifetime Warranty.

To best understand how the Wavetrac® is truly different from the other gear differentials on the market, you first have to understand the primary problem that the Wavetrac® solves.
The problem: Loss of drive during zero or near-zero axle-load conditions.
Zero axle-load is a condition that occurs during normal driving, but creates the most noticeable problems when driving in extreme conditions.  Zero or near-zero axle-load is the condition that exists when there is ‘no-load’ applied through the drivetrain, when one drive wheel is nearly or completely lifted (often in aggressive cornering).  It also occurs during the transition from engine driving a vehicle to engine braking and back, even with both drive wheels firmly on the ground.

Here’s how that loss of drive hurts you:
1) If you lift a wheel, all gear diffs except Wavetrac®, will NOT power the other wheel.
2) During the transition from accel to decel, all gear diffs except Wavetrac®, do nothing.

Why does this happen?
All gear LSDs (including Torsen®, Truetrac®, Quaife®, Peloquin, OBX, etc.) work in basically the same manner: they divide the drive torque between the two axles, applying drive to each side, up to the available grip of each tire.  The amount of drive torque one wheel can get over the other is described as the bias ratio, a measure of the torque split across the axle.
Standard, open differentials have a bias ratio of 1:1.  They can only apply as much drive torque as there is available traction at one wheel.  When one wheel loses grip, the total available drive is lost as well (at a 1:1 ratio). All your power goes out the slipping wheel - along the path of least resistance.
Torque biasing differentials offer increased bias ratios over open differentials.  For example, if a diff has a bias ratio of 2.5:1, then it can apply drive torque to the wheel with the most traction (gripping wheel) at 2.5 times the traction limit of the wheel with the least traction (slipping wheel).  This is a significant improvement over an open diff… most of the time.
The problem is that when one tire has LITTLE or NO grip (zero axle-load), the other wheel gets ZERO DRIVE, because (basic math here): 2.5 x 0 = 0.
Lift a wheel (or substantially unload a wheel) and you get zero axle-load on that side - that means that during the time the wheel is unloaded, the typical diff will NOT power the wheel that’s still on the ground.  No matter how high the bias ratio, you get no power to the ground.
During the transition from accel to decel, where you have near zero torque on the axle, even if the wheels are on the ground, the typical diff is unable to begin applying drive torque until AFTER the zero torque condition is over.   While this condition is generally short-lived, the fact that most diffs can do nothing during that time means that there will be a delay once the zero torque condition stops - creating a reaction time in the driveline.

The Wavetrac®, however, is different:
The innovative, patent-pending, Wavetrac® device in the center of the diff responds during these exact conditions when zero or near-zero axle-load occurs. At or near zero axle-load, the axles (and therefore each side gear in the diff) start to turn at different speeds.
This speed differential causes the Wavetrac® device to step into action:
Precisely engineered 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.
Very quickly, this creates enough internal load within the Wavetrac® to STOP the zero axle-load condition.
The zero axle-load condition is halted, and the drive torque is applied to the wheel on the ground (the gripping wheel)… keeping the power down.
Some gear differentials rely solely on preload springs to combat loss of drive.  The drawback is that you can’t add enough preload to prevent loss of drive without creating tremendous handling and wear problems at the same time.  So, to avoid these problems, the preload from ordinary spring packs must be reduced to a level that renders them ineffective at preventing loss of drive.  The Wavetrac® is the only differential that can automatically add more load internally when it’s required.
In the case where both wheels are on the ground during zero axle load, such as during a transition to deceleration, the Wavetrac® device is able to prepare the drivetrain for when the zero torque condition stops, eliminating the delay seen with ordinary gear diffs.
What this means for you as a driver is that power is delivered to the gripping wheels for more time and in a more constant manner – making you faster and improving stability.
The Wavetrac® truly is different - and its innovative features can make a real difference in your car’s performance.




The Moser steel spool shown below, 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

Two three inch exhaust clamps will be needed to bolt the rear sway bar back up the the rear.  Exhaust clamps can be purchased in practically any auto parts section of any store. Slip the U part of the clamp over the axle tubes, and reuse the factory lower sway bar clamp parts.  Oblonging the holes in the lower clamps will be necessary, using a .25 drill bit.  It is quite common to have to rotate the sway bar with a pry bar towards the front of the car, while tightening the swar bar, to get the sway bar to clear the rear end.  You can also order the rear with the optional sway bar brackets already installed from Moser, so that all you have to do is to bolt your say bar back up.  The Moser sway bar brackets (pictured below) 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:

Truetrac:  33 7/16 passenger side
                30 3/8  driver side

Trac-Loc:  32.875 passenger side
               30 3/8 driver side

31 spline locker: 32.875 passenger side
                         30 3/8 driver side

35 spline locker: 33.00  passenger side
                         30.50  driver side

35 spline Wavetrac: 32.875 passenger side
                              30 3/8 driver side

Spool:  33.00  passenger side
          30.50  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 LLC
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Price $9,999.99

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