[Fot] brake pad and rotor discovery and update

[DAVE HOGYE]

Hello Friends,

I have been finding out quite a bit about the unusual and developing front brake pad, rotor and caliper issues that I have discovered on my TR3.

 

What I found was that the Carbotech CT-57 pads were causing the problem.

 

The supporting or backing plates of the pads had been ground down at Carbotech, far under the normal plate width that I measured in 4 other production pads that I have on hand.  Besides that, they were not ground down squarely.

  

This allowed the piston to take tremendous side load under braking causing the uneven and diagonal wear pattern in the pads.  This also caused the rotor to contact the caliper as the pads took on heavy uneven wear.

  

The slot in the TR6 caliper is 3.095" and the four non-Carbotech pads sets have a plate width of no less than 3.082".  The Carbotech plates have an out of square measurement of 3.030-3.050".  That's as much as .065" clearance in the caliper slot.  

The plates have too much clearance.  I found that a maximum of .010" backing plate to caliper slot clearance is more normal.  One set of pads have only .005" clearance. 

 

Furthermore, the corners of the Carbotech plates and pads were ground down far enough that the lower end of the pads hardly made contact with the caliper slot allowing more stress on the caliper piston.


I have been going back and forth with Carbotech on this matter and I will be sending back the badly worn set along with a brand set that have the same production issues.  I bought the two sets at the same time last August.  


What I found is that any backing plates that show evidence of sanding or grinding marks should be measured for proper clearance, but that really, there should be no sanding or grinding marks...ever.


All of the other pads I have show no evidence of sanding or grinding marks.  The previously shaped friction pads are cleanly attached to the backing plates and the backing plate is revealed around the friction material.  Only the backing plate makes contact with the caliper slot.  


It looks like I have to find another race pad supplier.  


Thoughts?


Dave H.

831-234-4928

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