Raybestos Brake Pad Compounds

Published: December 8, 2016

I am a big fan of Raybestos brake pads. They are inexpensive, have great durability, and when properly matched to the vehicle offer good bite and modulation. A neat fact about Raybestos pads is that Porterfield can make any shape pad with any compound - if a particular compound is not listed for a particular vehicle, they can make a custom pad with the combination, and they don't charge extra for it unlike other vendors. Obviously it's great when the first pad is the perfect fit for the car, but when this does not happen, Raybestos pads offer quite a bit of tweakability without breaking the bank.

The pads can be ordered from Porterfield directly, although Top Brakes and Best Brakes provide free shipping with potentially lower prices. The only downside is that it takes a while to receive the pads as both Top Brakes and Best Brakes end up ordering them from Porterfield for you. I typically get the pads delivered in about 2-3 weeks from placing the order.


Compound Order

It is unfortunately nontrivial to figure out what the next compound "up" or "down" from a particular compound would be, as Raybestos' own literature is not completely clear on this subject.

Here is an ordered listing of Raybestos brake pad compounds from highest friction/temperature to lowest, as given to me by a Porterfield sales rep:

You will note that this does not necessarily mesh with the official Raybestos compound descriptions nor with the official Raybestos compound specifications.


Here are the same compounds in the same order with the specs:

Compound 1200 F Mu Bite Fade Noise Disc Wear Wear Temp
ST-47 0.480 8 1 2 0.009 5.8 1300
ST-41 0.440 8 1.5 2 0.010 7.0 1250
ST-45 0.400 6 2 2 0.022 4.3 1250
ST-43 0.380 5 3 4 0.013 5.5 1200
ST-42 0.290 4 2.5 2 0.012 3.1 1150
ST-38 0.490 8.5 1.5 2 0.010 8.0 1350


Here are the descriptions arranged in the same order, of friction coefficient:

ST-47 Has the highest friction and torque available to date. It has been engineered for long-lasting extreme heat situations and maximum rotor life. If you are looking for the most advanced performing road race brake pad that will simply outperform the rest, this is it.

ST-44 Remains consistent throughout a much wider temperature range, and suitable for practically all forms of motorsport use. Stops well when cold and driveable in wet or high heat conditions. Easy to modulate. Slightly higher friction level than the ST-43 compound.

ST-41 Maintains high mu level at extremely high temperature without sacrificing good wear - both pad and rotor. Needs some heat to reach its potential. Very rotor friendly. Friction levels are just under the ST-47.

ST-45 Lower friction level than the ST-47, could be used as a great rear to complement the ST-47 compound.

ST-43 This full race compound has proved to be one of the finest all around race compounds ever. Suitable for lightweight Formula cars up to GT racing cars in all conditions, cold or hot. Quick warmup, no rotor wear, and excellent pad life.

ST-42 Lower friction level than ST-41 and ST-43. Extremely stable average and in stop output over a wide temperature range. Has been very successful when used on the rear with ST-41 on the front. Best high temperature wear of all their materials.

ST-38 Slightly lower friction than ST-42. Wear not as good as ST-41. Good performance over broad temperature range with minimal rotor wear. Successful in a broad range of racing series.


Here is what I have found to work well, along with what people I know run on their cars.

Miata NA6

I love ST-43 on the front of my SSM race car. At the same time I drove a friend's stock 1.6 Miata with ST-43s on the front and the brakes were way too grabby and difficult to impossible to modulate. The owner also thought the brakes were too grabby.

Do not have a rear recommendation yet. I currently have the ST-43 fronts paired with a split Carbotech XP8/PFC 08 rear setup which works fine and the rear pads on a Miata last forever.

Miata NA8

ST-43 on the front for low to moderately aggressive driving styles or for street tires. ST-43 with street tires in rain seemed to have a little too much bite. ST-43 on R compounds felt a bit soft in the brake pedal.

I tried ST-45 in the front, specifically with R compounds in the dry. These had more bite and less modulation and I found them to have too much bite. I just about never pressed the brake pedal all the way into the floor with ST-45s on the front. Also, the wear of ST-45s seemed quite a bit worse than ST-43s. Porterield sales rep recommended ST-45s over ST-41s for a Miata, saying ST-41s would never get hot enough, but I am wondering if ST-45s are not meant to be run on the front axle.

No rear recommendation yet as I have a large stack of take-off brake pads to go through, especially on the rear axle. It seems that ST-43s in particular are on the softer/less grabby side of the spectrum because I had rear tire lock-up issues with DTC-60 and Carbotech XP8 paired with the ST-43 fronts. The rear lock-up happens only in hard braking zones into low speed turns while going over crests (Shenandoah and to a lesser extent Dominion Raceway are where this happens).

Miata NB Wilwood

This particular car has V8Roadsters front brakes (11.75" with Dynalite 4 piston calipers), Goodwin/949racing rear brakes (10.8" or 11", same size as Sport rotors with NA8/NB1 calipers) and in-cockpit adjustable brake bias. As such the car can get away with quite a bit of variance between front and rear brake pads. It has been a while since I drove it extensively but my feeling is ST-43 front with ST-42 rear can work OK but the car can use a softer front pad. I intend to try ST-42 front with ST-38 rear next.

Miata NC

An instructor friend of mine runs ST-43 front and rear on an NC Miata on R compounds (RA-1) and he has been happy with the combination. He previously tried Porterfield R4 which he found to be too grabby.

Miata NC Supercharged

Another instructor friend of mine started with ST-43s and eventually arrived at ST-47 fronts with ST-45 rears on his supercharged NC (I'm guessing 220-250 whp).