Brake Drums - St. Louis Truck Driveshafts, Suspensions, Brakes 314-516-9466

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Brake Drums for Heavy Duty Trucks

At Plaza we love to talk about brakes. We work with Gunite, Meritor, Dayton Parts, and other suppliers to help you keep the cost of your brake materials down but also operate safely. We also hear a lot about the desire to reduce the weight of trucks in order to achieve better mileage and lower operating costs.

We have carried a few brake drums in our day and know very well how heavy they are. For some trucks and trailers reducing the weight of the brake drums might make sense. But this is not for everybody.

In order to know whether you should try to lighten up your brake drums we first need to know what business is your truck in.

 
What Business is Your Truck In?

Vocational Trucks. For example, consider a straight truck used for refuse hauling. It may have three axles and six brake drums to help it stop (and it hopefully is stopping A LOT). Other trucks in this same category would be dumps, concrete mixers, and tank trucks. 

OTR Tractors and Trailers. A tractor-trailer used for over-the-road hauling will most often have five axles and ten brake drums to help it stop (and it hopefully is NOT stopping a lot).  Do you realize that this tractor-trailer will have 67% more brake drums (and braking power) than the refuse hauler?

 
Four Characteristics of a Good Brake Drum

With a total of only six brake drums it is a lot more important for the operator of a refuse truck to insist on getting  “good brake drums”. So what is the difference between a “good brake drum” and a mediocre or inferior one?  Meritor lists these 4 attributes of a good brake drum as found in the Meritor Catalog of Drums, Hubs, and Rotors.
  1. Relatively Heavy
  2. Temperature and Wear Resistant High Tensile Iron
  3. Precisely Machined
  4. Balanced by Machining (rather than adding weights)

 
When Heavier is Better - Brake Drum Physics

Note that the very first item on Meritor’s list is that a brake drum must be relatively heavy.  What this means for operators of vocational trucks is that a good brake drum and low weight may not be compatible. To better understand why, look closely at the physics of braking.

Meritor starts with the fact that any braking system converts forward forces (speed and weight) into friction that immediately produces heat. This heat is dissipated but only slowly into other parts of the wheel and brake system and also only slowly into the surrounding air during the actual period when the brakes are applied. Sure your brakes cool off, but not while you are trying to stop. Thus, nearly all of the energy from the vehicle’s forward motion must be STORED by the brake drum in the form of heat (to be released only after the brakes are released).

A brake drum is really a “heat sink”.  A heavier drum can store more energy than a light one.  Therefore a heavier drum is more fade resistant or stronger. You might remember that two of the defects most commonly found with brake drum surfaces are “heat checking” and “martensite spotting” which clearly demonstrate that even cast iron has its limits when dealing with high heat conditions.
Meritor offers a full explanation of why a heavier drum can be better in some cases on these three pages from their catalog. (You should keep in mind that Meritor has been one of the first to promote lighter weight steel drums and they are still honest to admit the advantages of heavier weight.)
Meritor's Light Weight Drum
Meritor Steel Lite X-30 Brake Drum

 
Moral of the Story

Do not be confused by the increasing promotion of lower weight drums that also cost less. It is not necessarily a technological breakthrough when something that weighs less also costs less. Less molten metal goes into the product and the cost to transport the product to you is also less.

At Plaza we can say from experience: when vocational vehicles are hauling heavy loads with the minimum number of axles and brake drums, you should not be thinking about reducing weight or saving a few dollars with light weight brake drums.

 
How to determine the specs for the brake drum you are replacing

Below you will find a list of the brake drums currently in stock at Plaza, but it is often difficult to find a part number on the brake drum that needs replacing. If you can find a part number that is visible on the drum or you know the model number of the axle, you may have enough information to determine the correct replacement drum. In any case it helps to have additional info to confirm that a new drum will be an exact fit. It is sometimes best to collect the information at the right and verify the size of the drum you are replacing. The specialists at Plaza are also always available to help.

 
Helpful info for sizing brake drums

  • Number of bolt holes
  • Size of bolt holes
  • "Bolt circle" diameter
  • Pilot hole diameter
  • Brake Size
Picture
Count and measure bolt holes
Picture
Measure Bolt Circle Diameter
Picture
Measure diameter of pilot hole

 
Brake Drums Currently in Stock

The more frequently used “DISC” wheels are shown immediately below. Our selection of drums for "SPOKE" wheels will be found on this attached page.
 
DRUMreport

Disc Wheels


Brakesize
Bolt
Hole Pilot
Bolt circle

Aftermkt Part#
Holes
Size dia.
dia.
Mount

16.5 x 8.62

3807A iron 10
1 8.78
11.25

Trailer axles

3168 iron 10
.81 6.5
11.25 Inboard

16.5 x 8

3782X iron 10
1 8.78
11.25

Rear axles International, Mack, Trailers

16.5 x 7

3410X iron 10
1.25 9.44
11.25

3401 iron 10
1 8.78
11.25

Rear axle Mack

3576 iron 10
1 8.78
11.25

3600A iron 10
1 8.78
11.25

Vehicles: Freightliner, International, Volvo, Kenworth, Peterbilt, Mack

Ford, Fruehauf and other trailers

Single axle rating: 17-19,000#; 20-23,000#; 26,000#

Rear axles - Dana/Spicer, Eaton, Meritor

3600AX iron 10
1 8.78
11.25

same features as 3600A

3853A iron 10
1 8.78
11.25

53123537002 steel 10
.94 8.78
11.25

3441 iron 10
.87 9
11.25

2705 iron 10
.84 9.44
11.25 Inboard

Trailer axles

3120 iron 10
.84 9.44
11.25

Trailer axles

3141 iron 10
.81 9
11.25

Rear axles Freightliner, Ford, GM, Kenworth, Volvo, Peterbilt, Oskosh

3166 iron 10
.81 8.53
11.25

Freightliner Tag axles

3166A iron 10
.81 8.53
11.25

3490 iron 10
.81 8.65
11.25

3618 iron 10
.81 9.37
11.25 Inboard

3699 iron 10
.81 8.53
11.25

3853C iron 10
.81 8.53
11.25

53123564002 steel 10
.81 8.53
11.25

3141B iron 8
1 9
11.25

53123566002 steel 8
.92 9
275m

8656 iron 6
.65 11
12.75

Rear axle Mack

16.5 x 6

3513 iron 10
1.25 9
11.25

3687X iron 10
1.25 8.78
11.25

Vehicles: Freightliner, International, Volvo, Kenworth, Peterbilt

Vehicles: Mack, Western Star Axles: FRONT

3772X iron 10
1 8.78
11.25

16.5 x 5

3710X iron 10
1.25 8.78
11.25

FRONT axles, Freightliner, Ford, International, Kenworth, Mack, Peterbilt

Western Star, Thomas Buses

3758X iron 10
1.25 8.78
11.25

3595AX iron 10
1 8.78
11.25

FRONT axle, Mack

3595X iron 10
1 8.78
11.25

FRONT axle, Mack

15 x 8.62

3750B iron 10
1 8.78
11.25

3750BX iron 10
1 8.78
11.25

International rear axles

53123601002 steel 10
.94 8.78
11.25

15 x 7

3219AX iron 10
1 8.78
11.25

15 x 5

3597 iron 10
1.25 8.78
11.25

3597B iron 10
1 8.78
11.25

3169A iron 6
.81 6.44
8.75 Inboard

15 x 4

3158X iron 10
1.25 9
11.25

3674AX iron 10
1.25 8.78
11.25

3721AX iron 10
1.25 8.78
11.25

Vehicles: Freightliner, International, Volvo, Kenworth, Peterbilt

Front axles Mack, Ford

3800X iron 10
1.25 8.78
11.25

Front axles: Freightliner, Volvo, Western Star

53123542002 steel 10
1.25 8.78
11.25

3771X iron 10
1 8.78
11.25

3610X iron 10
.78 9.44
11.25 Inboard

3721B iron 8
1 9
10.82

15 x 3

3508 iron 10
.81 9.5
11.25 Inboard

14.5 x 10

3854X iron 10
1.25 9.44
11.25

12.25 x 7.5

3557 iron 10
.81 7.12
8.75 Inboard

3557A iron 6
.81 7.12
8.75 Inboard

3467B iron 6
.65/.5 7
8.25 Inboard