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[Fot] brake pad and rotor discovery and update

Subject: [Fot] brake pad and rotor discovery and update
From: dlhogye at comcast.net (DAVE HOGYE)
Date: Wed, 11 Jul 2018 07:35:52 -0700 (PDT)
References: <1496073395.378283.1531254099121@connect.xfinity.com> <000001d4191c$23b6fac0$6b24f040$@gmail.com>
Hi Tim,

Just to clarify, the calipers on my TR3 are the 16PB TR6 units.  They are 
similar to the 16P, but the P calipers have 1/4" pins and the PBs have 3/16" 
pins.  The PBs also have a more durable flush seal design that I like.  I open 
the pin hole to 1/4" for easier pad selection.  If I get a set of pads with 
3/16" holes, I just open them to 1/4".  The PB caliper are sometimes referred 
to as "metric" because the mount holes and the bolt are metric sized.  

There shouldn't be any evidence of sanding or grinding marks around the edges 
of the pad backing plate or on the friction pad.  If there is, they are most 
likely undersize.  

I have 4 sets of other pads.  2 different Moss compounds, 1 Hawk Blue and an 
old set of Raybestos that are still new in the box.  None of these pads have 
any evidence of sanding or grinding on the plate edge.  The edges are cleanly 
sheared.  

Also, the plates should be well proud of the friction material and they are on 
these 4 sets.  On the Carbotech pads, the plates have been ground almost flush 
to the edge of the friction pad.  So the pad edge is making contact with the 
caliper slot.  Not good.  

It totally sucks that I have had to discover and study this matter.  This can 
be regarded as a serious oversight from Carbotech.   This could be potentially 
dangerous.  I noticed this through a routine check after an event when one side 
seemed to be dragging more than the other.  

Dave H.

> On July 11, 2018 at 6:36 AM timmmurphh at gmail.com wrote:
> 
> 
>     Thanks for this report.  We have had some issues with the Carbotech pads 
> on our TR4 at Blackhawk and the Kcup.  We use the CT2-XP10 compound.  I will 
> check our pad to caliper slot clearance.  Does anyone know offhand of the 
> slot on the 16P calipers on our TR4 is the same as the TR3 at 3.095??
> 
>      
> 
>     Tim Murphy
> 
>     #317 TR4
> 
>      
> 
>     From: Fot <fot-bounces at autox.team.net> On Behalf Of DAVE HOGYE via Fot
>     Sent: Tuesday, July 10, 2018 3:22 PM
>     To: Friends of Triumph <Fot at autox.team.net>
>     Subject: [Fot] brake pad and rotor discovery and update
> 
>      
> 
>     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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