[Fot] TR6 Porterfield R-4 Rear Brake Shoes - Carbotech relining

[Bob Kramer Gmail]

We’ve been running stock shoes on the ChampCar TR6 for a long time now. We‘ve needed the extra life to make it through a weekend. I’ve been running stock shoes in the vintage cars for decades. Occasionally one begins to crumble. I always err on the loose side of show adjustment and am probably giving up some rear braking.

On the endurance car, the addition of a splitter and a read wing last year has changed the brake dynamics. While we dropped lap times the  brakes can’t survive. We’ve cooked both the front and the back. 
We are going to have to upgrade to Wilwood all around. 

You only get one chance at life, make it a TRIUMPH.

> On May 23, 2024, at 9:04 PM, yellow04 via Fot <fot at autox.team.net> wrote:
> 
> My issues with Carbotech has not been the quality of the pads, it has been the shoes for the rear drums. I have had a couple of failures where the lining breaks up at the top or bottom edge, and once it starts crumbling, it is game over. I got to the point where I was mixing and matching shoes from different sets to actually get 4 shoes to wear out evenly.
> 
> Last year there was a thread here about running stock linings on the rear shoes, and the first thing in my head was that's nuts. But taking into account where those racers were finishing, I decided the worst thing that would happen is I needed to swap brake shoes in the paddock.
> 
> OK, I didn't go with the Moss Motors "who knows where they came from" shoes, I went to Rock Auto and spent all the money on a set of genuine Raybestos shoes, currently available for a whopping $32 plus shipping. I ran them for the first time at Summit Point last weekend and they seemed fine. Obviously, until I put eyes on them the jury is still out, but I really didn't think I could tell any difference in stopping power. Most importantly, my lap times were OK and consistent.
> 
> Thinking I probably had less coefficient of braking, I did nudge the balance bar a tad to the rear, and after the first session where I did a completely crap job of bedding them in, I never thought about them all weekend.
> 
> Henry
> 
>> On 2024-05-23 10:36, DAVE HOGYE via Fot wrote:
>> I used Carbotech a few times for front pads.  I had lots of problems
>> with them.  Quality control is/was terrible.  The backing plate was
>> ground down to the friction material at the sides of the pads and they
>> were not square.  So, there was far to much clearance in the caliper
>> slot.  This caused the piston to torque once the brakes were applied.
>> This makes the pads wear at an extreme angle and the pistons were
>> leaving a witness mark in the bore from the induced torquing and side
>> load.  The hot friction material was making contact with the caliper
>> casting.  I talked with Carbotech a few times about this and they were
>> completely defensive and said they sell a lot of these pads and no one
>> ever complained about this problem before.  They were not willing to
>> check quality control or make them correctly.  I took many photos and
>> some video of exactly what was happening and made a direct comparison
>> to standard pads and Hawk pads.  The standard pads were NOS from a
>> quality manufacturer, which I can't recall at the moment.  Standard
>> backing plate have a pretty tight fit in the caliper.  I think I found
>> .010" clearance.  I found that the Hawk pads have very consistent
>> production quality.  So I switched to Hawk.  I did like the feel of
>> the Carbotech pads, but they really caused problems.
>> I'll share some photos and later.
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