[Fot] brake pad and rotor discovery and update

Wed Jul 11 11:21:25 MDT 2018

Thanks a lot, Ashley.  This is excellent information.
Dave H.

Sent from my iPad

> On Jul 11, 2018, at 9:49 AM, Ashley Page <apage at prosystembrakes.com> wrote:
> 
> All good points.
> I have been in the racing brake business for nearly 25 years and worked on them for the 25 prior to that.
> Just adding a few points that are industry standards in my work. Some have been pointed out in emails in this thread – all good. Hope you find this useful.
>  
> There should be some margin between the friction and steel back plate on the ends where the pad abuts the caliper.
> The pad should never be loaded against the pins that the pads hang from. The pins are there just to keep the pads from falling through -  not to take braking torque. Sadly some pads might need the oval holes opened a little to avoid this; so inspection of all pads is a must.
> The pad should have .5mm (.020”) float end to end in the caliper to insure against drag or hanging up at any temperature.
> New pads should also have after installed .5mm (.020”) float or slop between the caliper piston or brake rotor and the pad to prevent drag.
> The pads should be loose in the caliper and able to be removed with two fingers.
> Pad overhang (friction above the OD of the rotor) or under hang (below the ID of the rotor) is not good. If its not chipping away during track use then knock of the overhang after each event. It can cause piston knock back and a long pedal and or overheating – in the worst case. You can easily file the friction to the correct radius – at the expense of a cheep new file per box of pads depending on the friction and size. Don’t use your favorite file for this.
> Pad steel backing plates are made in several ways, stamping, fine blank stamping and, the best, laser cutting. The problem with worn tooling used to stamp or fine blank plates (unfortunately common with old pad shapes) is that the edges of the plate where they abut the caliper are not flat and square. Instead of a “fine” edge it looks like its been torn and the pad hits on a sharp corner. This starts to put a groove in the caliper abutment area which is not good. If your pads only have less than .020” float end to end and the plates look like crap on the ends then its advisable to file or belt sand the ends of the plates to be closer to square and flat. If the friction is even with the back plate end it can help cause delamination of the friction from the plate.
>  
> The pads we deal with are very old shapes and for the most part today not subject to inspection by OEM’s such as Ford etc. In other words they are just made in small quantity or in some cases carved out of a larger donor pads and sadly some that do this don’t pay attention to details.
>  
> But I am not throwing stones at random. The pads mentioned are all good and work well in the vintage and club racing world. Its just that some pads slip through with problems mentioned. Just a few things to look for in addition to all mentioned prior.
>  
> Also with some brands if you notice a loss of stopping power look at the pads. If they look glazed over then find a smooth piece of concrete somewhere in the paddock or driveway and using a figure 8 pattern lightly grind away the shine on the friction and in most cases they will perform like new. Only takes 2 or 3 figure 8s to clean them up – don’t overdo it.  
>  
> When the pads are new mark them so that they spend their life in the same place – i.e. left outer, left inner, right outer, right inner. If you move them around to even out taper or for other reasons you will create a friction surface that is not flat and that is not good.  
>  
> Ashley Page
>  
>  
> From: Fot <fot-bounces at autox.team.net> On Behalf Of DAVE HOGYE via Fot
> Sent: Wednesday, July 11, 2018 10:36 AM
> To: timmmurphh at gmail.com; Friends of Triumph <Fot at autox.team.net>
> Subject: Re: [Fot] brake pad and rotor discovery and update
>  
> 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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