Welcome to Alloy USA - 10 Year Axle Warranty - 5 Year Ring & Pinion Warranty



 

Alloy USA Blog

Brake Rotors

When looking to buy new rotors you’ll notice there are different options. You have factory style rotors, slotted rotors, drilled rotors, vented rotors, and a hybrid of a slotted and drilled rotor. The differences between the rotors give you benefits that include better heat dissipation and providing a better brake pad bite.


A drilled and vented rotor will allow brake dust particles to flow from the brake pad into the drilled holes and out of the vents in the rotor, keeping the rotor free of brake dust. As you are driving the vented rotor is constantly venting hot gaseous air through the vents. This hot gaseous air builds between factory style rotors and pads, under heavy braking it can cause brake fade or a spongy brake pedal feel. For added performance, slotted rotors keep a fresh brake pad ready to bite.


A slotted rotor will keep a continuously clean surface on the brake pad. The grooves in the slotted rotor shave a small layer of brake pad off and help keep brake dust off of the pad. The slots also disrupt how the hot gaseous air builds. The use of a slotted rotor gives you the benefit of constantly having a fresh pad surface that performs like a new pad and increases the initial bite. Making a hybrid of a slotted and drilled rotor gives the best performance a rotor can have.




Axle ID

Dana 25/27 The Dana 25 and Dana 27 look identical; The Civilian Dana 25 and Dana 27 utilizes a thin cover that will accept taller gears and the Military Dana 25 uses a thicker cast steel cover. Both have closed knuckles and drum brakes. Both versions were used under the MB, GPW, M38, M38A1, M170, CJ-2A, CJ-3A, CJ-3B, early CJ-5, CJ-6, Willys Wagon, and Willys Pickup.


Dana 30 The Dana Model 30 has an 8 3/4 inch ring gear diameter and was found under the front of the 72-86 CJ-5, CJ-6, CJ-7, CJ-8, Commando and Cherokee. This Dana model featured open knuckles with disc or drum brakes and a 5x5 bolt pattern.


Dana 30 The Dana 30 continued its usage in the 87-95 Wrangler YJ, 84-01 Cherokee/Comanche, 97-06 Wrangler TJ/LJ, and 93-04 Grand Cherokee ZJ/WJ. This Dana model featured open knuckles with disc brakes and a 5x4.5 bolt pattern – it was also available in a high pinion.


There is also an independent front suspension Dana 30 that is used in the 02-14 Jeep Liberty.


General Specs
  • Ring Gear Diameter: 8 ¾ inches
  • Pinion Shaft Diameter: 1.750 inches
  • Ring Gear Bolts: 12
  • Right Hand Threads: 3/8x24 inch
  • Pinion Splines: 10
  • Cover Bolts: 10

AMC 20 The AMC 20 has an 8 3/4 inch ring gear diameter and from the factory has a 2 piece axle design. The available 1 pieces axle conversion adds strength. It was found in the rear of the 76-86 CJ-7, CJ-8 Wagoneer and J10/20 Trucks.


General Specs:
  • Ring Gear Diameter: 8 7/8 inches
  • Pinion Shaft Diameter: 1.625 inches
  • Ring Gear Bolts: 8
  • Right Hand Threads: 7/16 inch
  • Pinion Splines: 28
  • Cover Bolts: 12

Dana 35 – The Dana 35 has a 7 9/16 ring gear diameter with c-clip axles and was used in the rear of the 84-01 Cherokee/Comanche’s, 87-95 YJ, 97-06 TJ, 87-04 Grand Cherokee ZJ/WJ and 07 JK (limited number).


General Specs:
  • Ring Gear Diameter: 7 9/16 inches
  • Pinion Shaft Diameter: 1.406 inches
  • Ring Gear Bolts: 8
  • Right Hand Threads: 3/8x24 inch
  • Pinion Splines: 26
  • Cover Bolts: 10

Dana 44 The Dana 44 has been used by every major Domestic vehicle manufacturer. It can be found in the front or rear. It has an 8 1/2 inch ring gear diameter and could have closed or open knuckles with drum or disc brakes.


The early Dana 44 axles had lower spline counts (10 or 19) and may have had the 2 piece axle design (flanged) making them weaker than the later Dana 44. In most cases these had the closed knuckle and drum brakes. These came in the 54-71 CJ-5, CJ-6, DJ, Gladiator, Wagoneer, FC, Jeepster, and Willys Wagon and Truck.


The later Dana 44 axles had higher spline count (30) and a 1 piece axle making them stronger than their predecessor. These came in the 72-83 CJ-5, 72-75 CJ-6, 76-86 CJ-7, Wagoneers, J 10/20, 81-86 CJ-8, 72-01 Cherokee SJ/XJ/MJ, and 97-06 TJ.


The Grand Cherokee ZJ/WJ had an optional aluminum housing Dana 44, known as the Dana 44A which is weaker than the later Dana 44 mentioned above.


General Specs
  • Ring Gear Diameter: 8 1/2 inches
  • Pinion Shaft Diameter: 1.375 inches
  • Ring Gear Bolts: 10
  • Right Hand Threads: 3/8x24 inch
  • Pinion Splines: 26
  • Cover Bolts: 10

Dana 60 The Dana 60 in appearance looks like the Dana 44 but larger making it stronger. These have a 9 3/4 inch ring gear diameter with closed knuckles and drum brakes. These came in the 67-69 M715, M725 and M726, a version with full floating axles and smaller axle tubes was used in the 63-86 J10/20 and Gladiator.


General Specs:
  • Ring Gear Diameter: 9 3/4 inches
  • Pinion Shaft Diameter: 1.625 inches
  • Ring Gear Bolts: 12
  • Right Hand Threads: 1/2x20 inch
  • Pinion Splines: 29
  • Cover Bolts: 10

Dana 70 The Dana 70 is almost identical in appearance to the Dana 60. It has a 10 1/2 inch ring gear diameter with closed knuckles and drum brakes. These came in the 59-70 M715, M725, M726, FC and Gladiator.


General Specs:
  • Ring Gear Diameter: 10 1/2 inches
  • Pinion Shaft Diameter: 1.75 inches
  • Ring Gear Bolts: 12
  • Right Hand Threads: 1/2x20 inch
  • Pinion Splines: 29
  • Cover Bolts: 10

Chrysler 9 1/4 The Chrysler 9 1/4 has a 9 1/4 inch ring gear diameter and can have drum or disc brakes. After 97 the Chrysler 9 1/4 came with 29 spline axles not the 27 spline axles that the early 9 1/4 had. It was used in the 91-01 Cherokee XJ/MJ.


General Specs:
  • Ring Gear Diameter: 9 1/4 inches
  • Pinion Shaft Diameter: 1.875 inches
  • Ring Gear Bolts: 12
  • Right Hand Threads: 7/16x20 inch
  • Pinion Splines: 29
  • Cover Bolts: 12



Chromoly

Stock axle shafts are typically made from 1040 and 1541 steel and are perfectly adequate for stock applications. For performance axle shafts, we use 1541H steel, 4140 and 4340 Chromoly steel, which has been hardened to maximize the strength and ductility of the axle shafts.


1541 is a plain high carbon steel similar to 1040 but with added manganese for better hardenability, but there is not enough alloying elements in it to be classified as an “alloy” steel. 1040 and 1541 are used by manufacturers as a cheap alternative in meeting requirements for stock axles; they heat treat 1040 and 1541 by induction hardening, which is a production form of case hardening. It is fast, cheap and works very well. 1541 is able to be hardened to a greater depth (better hardenability) than 1040/1050 and is therefore stronger.


4140 and 4340 are true alloy steels. 4140 is alloyed with chromium, molybdenum and 4340 with chromium, molybdenum and nickel. 300M is also called 4340 modified, as it is basically 4340 with silicon added. The strength of steel is generally directly related to the hardness. The harder you can get the steel, the stronger it is (tensile strength), but you generally loose toughness. These alloys give the steel increased hardenability and reliable toughness at higher hardness/strength levels. They can be induction hardened but their purpose and advantage is that they can be thru hardened, due of their better hardenability. 4340 has better hardenability than 4140 so it can be heat treaded harder, and thus stronger, than 4140. The 4140 and 4340 material is available in commercial and aircraft quality. Aircraft quality is achieved by vacuum melting to minimize impurities and is a more costly endeavor. Most 4140 and 4340 axles are made of commercial quality steel.




How to Choose Ring and Pinion Gears

Torque is the main goal when re-gearing 4WD vehicles. More torque is needed to compensate for those big tires you added. And, more torque will get you up the steep hills.


The Gear Ratio Calculator below will help you select the best gears for your needs.

ring and pinion

If you mainly drive to work and on the highway, you may want lower ratios. This will give you better gas mileage, but not as much torque. Acceleration will be adequate, but won’t roll your eyes back in your head.


If you trailer your 4WD to the trails and are spinning big mud tires in a mud bog, you’ll want higher ratios. This is great, but your top speed will be limited. Think fast and furious.


When in doubt, go one ratio higher. We tend to add weight to our trucks over time…requiring more torque. And, some of us later decide to increase the tire size just one size…


It’s helpful to know what ring and pinion is in your truck now, you may find a tag or some numbers stamped near the differential. Knowing your current ratio will determine whether you need to change the differential carrier to fit the new ring gear or not.


It’s important to know what axles you have under your rig. The factory often sold several different axle choices. For example the ring gear in the Jeep Rubicon Dana 44 axle is thicker than non-Rubicon models.


Knowing what year the axle was built can be helpful. Keep in mind that if you bought your truck used, someone may have changed the axles before you bought it.


One thing to remember is that when you buy your ring and pinion gears, you will also need a master installation kit for each set. The master installation kit includes all the bearings, pinion seals, pinion shims, crush sleeve, pinion nut, ring gear bolts, and marking compound for the install.


Your sales rep will be able to help you find the gear ratios and components you need, but you can also narrow down your choice using the Gear Ratio Calculator.