Why are my rear pads wearing out so quickly?

[squidrope]

92 vert
2050lbs
Stock rotors
Cool Carbon ST Pads
Motul 660
Adjustable Bias


We ran our first successful race last weekend and went through 1 set of rear pads between practice and the race. Fronts wore 50%.
The fronts always lock before the rears.
Previous car did the same thing with same set up.
Is this normal?

[TobyB]

Have you measured temps?
The rear rotors are pretty tiny-
you might need some ducting...

t

[tinoe30]

Couple questions:
Were the rotors and pads bedded in prior to the race weekend?
How long was the practice and race sessions?

If you wore out a set of rear pads and fronts 50% I tend to think the bias could use adjusting.

I don't know about the pads you are using. I wrench on my son's NASA Spec E30 and we race at Sonoma and Thunderhill. All we have ever used is Raybestos ST43 pads, stock rotors and calipers. Front brakes have cooling ducts. Are Raybestos pads expensive? Yes. Do they perform and last under grueling conditions. Absolutely.

[Etfren]

Any chance your rear calipers are sticking? For a while my rear wheels were getting dirty before my front wheels from brake dust on my daily. I replaced the rear calipers and now everything is back to normal.

[squidrope]

Haven't measured temps, and like the ducting idea.

Rotors and pads were bedded prior to race/practice. Practice was 5-6 hours Race was 14.5 hours. The bias seems good as the fronts lock just before the rears. Set of Cool Carbons are pricey too $250/set

Doubt the rears were sticking as car pushes easily and all calipers are new/rebuilt. Both rears also wore evenly. Previous car had the same wear issue and r/l wore evenly as well.

[tinoe30]

Okay, things are making more sense. You didn't mention endurance racing. That's a different animal. Curious, what group are you running with? American Endurance Racing? World Racing League? Champcar? Why such a long practice?

Considering these conditions I'd say you are doing okay then. Second the idea on measuring temps and ducting all 4 corners. if you really want to see what is going on with the car over such a long race it would be a good idea to have an AIM system installed for data collection.

[TobyB]

Practice was 5-6 hours Race was 14.5 hours.

Oh.

Yeah.
Um.
That.

Might.
Have...


....some....


effect.

on, er, like, longevity?

You have good front pads if they're lasting that long.

t

[radr]

Are you running the same compound on both axles?

[squidrope]

Are you running the same compound on both axles?

Yes Cool Carbon ST

[squidrope]

Okay, things are making more sense. You didn't mention endurance racing. That's a different animal. Curious, what group are you running with? American Endurance Racing? World Racing League? Champcar? Why such a long practice?

Considering these conditions I'd say you are doing okay then. Second the idea on measuring temps and ducting all 4 corners. if you really want to see what is going on with the car over such a long race it would be a good idea to have an AIM system installed for data collection.

We run 24 Hours of Lemons. Practice is all day on Friday and we like getting as much in car time as possible, even if it's only practice. Will try and get ducting in place for the next race in October. Duct to the center of disk?
Anyone else running endurance series? What pads are you using? One of my crew thinks we should switch to Porterfield. I just hate changing something that seems to be working well.

[1990m3]

pick a hawk endurance pad from the catalog. I've not liked the Porterfield pads I used in the past, but I'm liking the Hawk DTC-70s now. I would search their catalog and see what is their endurance pad -- or search other brake threads on here, a lot of guys run lemons style races in e30s and don't have brake problems.

[agent]

Anyone else running endurance series? What pads are you using?

We just did the ChampCar 24h at VIR; we use PFC-08s. The only time we've had to change brake pads or rotors is the first year we ran it when we didn't start with fresh ones.

[moatilliatta]

PFC - 08 /\ is where it is

[TobyB]

Will try and get ducting in place for the next race in October. Duct to the center of disk?

For a solid rotor, it's harder-

you need to get air to both sides of it.

https://www.amazon.com/Engineer-Motorbooks-Workshop-Carroll-Smith/dp/0879381868

http://160592857366.free.fr/joe/ebooks/Automative%20engineering%20books/Brake%20Handbook.pdf

I had good luck just slotting a metal tube, capping the end, and making a
bracket to hold it in place. Then feeding air via flex tubing.

Scoops hang down under the rear subframe- and yes, they get knocked
off from time to time.

hth

t
PF08's now, too.

[pandaboo911]

Why are my rear pads wearing out so quickly?

pick a hawk endurance pad from the catalog. I've not liked the Porterfield pads I used in the past, but I'm liking the Hawk DTC-70s now. I would search their catalog and see what is their endurance pad -- or search other brake threads on here, a lot of guys run lemons style races in e30s and don't have brake problems.

This. We run Hawks and they can’t be beat for price / performance. Front pads typically last about 2 races or 30 hours. Rear pads last 3+ races. We run a Miata though which may be lighter and slower so yours may wear faster.

We used to run strictly HT-10, but the new DTC-60/70 series last a bit longer. They have a bit too much bite but the longevity makes up for it. Pad choice makes a huge difference.
For 24 hour races we run a raybestos pad to ensure it lasts the complete race, but those races don’t really happen anymore.

We’re not sponsored by hawk or anything. I just genuinely think they make a good product. Some of my buddies knock them for being “cheap” but honestly..If they work and theyre cheap that’s a win in my book.