Rear brake shoes... are they doing anything?

RSTPerformance

RSTPerformance

New member
Some say the theory is that: “My front brakes do all the stopping, the rear does nothing, it doesn’t matter what shoes you run.”

We have experienced this theory to the fullest. We run stock shoes in the rear, and we have NEVER changed them in 4 years… they are doing nothing!!!

After talking with someone at Carbotech he implied that this theory is incorrect… he said that a lot of people think this way and just put any old shoe in the car… then the shoe gets “glazed” over and they do nothing. He said we would see a noticeable if not huge difference by putting “race” shoes into the rear. Obviously we would have to adjust our bias settings and what not, but it would help a lot in the stopping of the car, not to mention taking some of the work load of the fronts making them last longer as well.

What are your thoughts?

Raymond Blethen
RST Performance Racing

* My quotes from Carbotech may not be exact but that is what I got out of the conversation. The person I talked to was very good at not demoting other company’s products, which I admired a lot. Cudo’s to Carbotech as of now
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RST Performance Racing
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1st and 2nd 2003 ITB NARRC Championship
1st and 6th 2003 ITB NERRC Championship
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1st 2003 AS NERRC and NARRC Championships
 
I don't think rears do much on FWD cars.

I ran the same set of rear shoes for 5 years and they still looked like new. They showed no signs of glazing.

And if the rears DID work better, I'd end up reducing the rear brake bias to keep them from working as hard, so what's the point?

There are some cars that can and do use significant rear braking. A mid-engine or rear engine car comes to mind. Dad's old SSB Mazda RX3 used to eat rear shoes in 5 laps, but that was due to Mazda's terrible factory brake bias.
 
My preference is for my competitors to keep believing that they aren't important. I used to run stock pads, they lasted for years.

I most recently tried Porterfield R4s, and I can now lock the rears. In addition, they wear very fast, 20% of the available material during one 30 minute race at Laguna Seca. Now my problem is that the rears wear too much so they stop working again.

I have a set of green Carbotech's in my spares, waiting to replace the R4s after they wear out.

BTW, my VW GTI had great balanced brakes with stock type material on the rears.

ITB Capri
 
On a FWD car, you can use the rear brakes to help rotate the car into a corner, especially if you use trailbraking. The correct rear pad/shoe is important though, as you have to have a really sensitive foot and the ability to modulate the brakes properly to take advantage of it. The correct rear pad/shoe depends on what you're using at the front as well.

Depending on the track, track conditions, fuel load, etc., I would adjust the rear brake bias to maximize the braking effort at the rear. Some tracks, like Roebling Road, have no threshold braking zones. They're all 'turn and brake' corner entry so you had to be able to trailbrake without locking up the rears. Other tracks, like Summit Point and Kershaw, have a lot of threshold brake zones where ultimate stopping power is important and no trailbraking zones.

Once I matched the rear pads properly, I could usually go another 50 feet in most heavy braking zones than with "OEM" type rear shoes/pads.

I did get the rear shoes on the ITC Scirocco done by Larry at Carbotech. Again, the compound depends on what you're using on the front. I used the "silver streak" compound that Carbotech offers.

On the GP car, I tried several different compounds on the rear pads until I was found one that I was happy with regarding the modulation ability of the rear brakes.

MC



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Mark Coffin
#14 GP BSI Racing/Airborn Coatings/The Shop VW
Scirocco
Zephyr Race Coaching and Consulting
http://pages.prodigy.net/scirocco14gp
 
Like Joe, I ran stock shoes from Autozone on the rear of my Rabbit GTI. With the Hawk Blues up front, the brakes worked really well w/o a bias lever. A friend that ran an A2 GTI w/ the rear discs, said he had to go to a bias adjuster, and take out as much of the rear as possible to stop them from locking up.

I've got a brand new set of those Carbotech Rabbit shoes. I was going to try them on the HP car, but now that they've taken another 100# off the car, I just can't see needing anymore rear brake. I'll probably just sell them.

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MARRS #25 ITB Rabbit GTI (sold) | MARRS #25 HProd Rabbit
SCCA 279608
 
Originally posted by RSTPerformance:
greg, what type of shoes were you running? oem or "race" type ones?

Raymond
Click to expand...

OEM. I guess I never though about Mark's comment about making them easier to modulate. I suppose it might be worth a shot for better pedal feel, either for those tracks that you can trail brake, or for that matter, racing in the rain.

BTW - I was running Hawk Blues up front with the OEM rears since that's about the only thing that holds up at Blackhawk. Since I can't get them for my Honda anymore
frown.gif
I will be trying Carbotech 1109 compound. They'll get baptized at Blackhawk in a couple of weeks...
 
During my 2000 which was my first year racing
a Spec-7 (1985 Mazda RX-7)the rear had drum with Porterfield racing shoes & Hawk blue on the front. My first race at Blackhawk Farm the rear shoes had approx 5/8 shoe thickness remaining. Lets say two practice/qualifying sessions & a race. Maybe 10 laps into the race I'm third nose to tail with 1st & 2nd. I pull inside 2nd going into the last turn, see what's going on & figure I'll get 2nd free through his mistake. I back out of the inside move, get on the brakes & can you say NOTHING but floor. At paddock check there was nothing but partial shoe & DUST.

Ya rear brakes work. How much work I don't know but but shoes don't wear out from not working.

The Farm is a BITCH on brakes. Never raced again untill the car received a disc brake rearend & larger master cylinder. Now use Hawk blue all around with a proportion valve adjusted by track/conditions. Tried Hawk black on the rear but with 100% to the rear I could not lock it up.

Have Fun
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David

[This message has been edited by ddewhurst (edited April 01, 2004).]
 
Hawk Blue on all four. I keep the bias set so they all wear out at the same time. The rear brakes do 40% of the braking. I can drive the car in deeper and brake later and use the rear brakes to rotate the car.

Rick Thompson
# 99 IT7
 
Originally posted by Hotshoe:
Hawk Blue on all four. I keep the bias set so they all wear out at the same time. The rear brakes do 40% of the braking. I can drive the car in deeper and brake later and use the rear brakes to rotate the car.

Rick Thompson
# 99 IT7
Click to expand...

I tried Hawk blues on the rear of my GP car, but being a FWD car it is so lightly loaded back there that it was almost impossible to modulate. The Blues have so much initial bite that the line between braking and lockup was soooo fine I couldn't use it properly to trailbrake. And if I dialed the rear bias out so I could trailbrake I could tell I was giving up too much in the threshold braking zones. This was at VIR which has a couple of threshold braking zones and a couple of trailbrake zones.

I went to a pad with less initial bite and better modulation characteristics.

MC


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Mark Coffin
#14 GP BSI Racing/Airborn Coatings/The Shop VW
Scirocco
Zephyr Race Coaching and Consulting
http://pages.prodigy.net/scirocco14gp
 
I tried the greens and had the rears not only lock up .. but to the point of it seized up... not pretty...my theory is they grow in size making it almost impossible to adjust properly!! m glass
 
Yes, Larry warned me the green shoes will expand in size, so it is very important to set them up loose. I haven't tried them yet, only have tested the R4 shoes which so far work fabulous but wear too fast for my car.
 
Mark:
They make an inline valve that will dampen the initial pressure application. It will help with the "BITE" you are referring to, or, you can balance the brakes with the length of your brake lines. I have done both and prefer the latter on my car.
 
I think once we get the Audi's back to equal we will run one with "racing" rear shoes and one without. Since our lap times are within a tenth or so of each other under equal conditions we should be able to see if the racing shoes work better...

I will provide feedback later this season for those interested.

Raymond
 
Raymond, Talk to Dad about rear shoes. I believe we cut back the leading edge of the shoes in the Capri to make them do more work and even that braking problem more. I also remember braking the glaze after every other race to keep them working. Dad would probably remember exactly what we did on that. I know it helped to keep the front brakes longer when we started doing that.
Trish

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