Has anyone found front brake pads that fit a TR properly? | FerrariChat

Has anyone found front brake pads that fit a TR properly?

Discussion in 'Boxers/TR/M' started by Steve Magnusson, Nov 22, 2021.

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  1. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    25,144
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    #1 Steve Magnusson, Nov 22, 2021
    I know that you'll probably all say that "they are all that way", but I wanted to ask anyway before I install my new front rotors and a set of new front brake pads. The stock TR front brake pads that came off my 1991 TR (at ~33K miles and I bought the car with ~13K miles so pretty sure that it came from the factory that way) were/are very much like this TRW GDB270 brake pad where the friction material extends out just to a line joining the edges of the mounting holes:

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    However, this results in the friction material extending out past the OD of the front brake disk by about 1.5mm. This photo is with a set of HAWK brake pads which are even worse for this issue, but it was the same situation with the stock front brake pads (and even with Magneti Marelli BP0099 pads that are on the car now that I bought from a very reputable F parts supplier which they marked as 134848):

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    Consequently, I got all excited when I found this Brembo P 06 003 P pad on ebay (that seems to fit a slew of BMW) that has the outer edge of the friction material positioned much further away from the mounting holes, but it has an overall thickness of 19mm so won't fit into a TR front caliper:

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    The "best" 15mm overall thick front brake pad that I've found so far for this issue is this ATE 20092 pad that seems to have the friction material a tiny bit further away from the mounting holes, but I think it will still overhang a little:

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    So my challenge to you DIYers and F part suppliers is: "Where can I get a set of TR front brake pads that don't overhang the front brake disk OD?". I'll probably go with the ATE 20092 if nothing else is suggested/found.
     
  2. turbo-joe

    turbo-joe F1 Veteran

    Apr 6, 2008
    8,931
    southwest germany and thailand
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    romano schwabel
    #2 turbo-joe, Nov 22, 2021
    hello steve
    can you please make a sketch with the right dimensions you need. I have hare an old textar and also ATE catalog with the pads scale 1:1 so I could check
    also I wonder a little: the first pad you put in here is 89,6 x 70,5 x 15, the brembo is 89,7 x 70,5 x ?? and the ATE 20092 is 89,8 x 70,5 x 15
    what are the dimensions of the pads you have been inside? between 89,6 and 89,9 it is a little differnece and mab the you always hear a "clack-clack" when braking?
     
  3. vincenzo

    vincenzo F1 Rookie

    Nov 2, 2003
    3,373
    #3 vincenzo, Nov 22, 2021
    I’d bet a grinding wheel will make short work of the remaining edge as it wears down. Presumably it won’t hurt anything one way or another. Do you foresee an issue which I am missing?
     
  4. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    25,144
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    #4 Steve Magnusson, Nov 22, 2021
    Last edited: Nov 22, 2021
    Hi romano -- I wasn't worrying too much about those small dimensional differences of the back plate because no tolerances were given (e.g., one manufacturer might be giving the nominal value while another manufacturer could be giving the maximum value). I would accept a little "clack-clack" if the friction material didn't overhang the disk OD ;), and, likewise, if I needed to grind a little off, I could live with, and do, that.

    With regard to where the friction material needs to be away relative to that line joining the edges of the mounting holes, something like 2mm would be better than anything that I've found so far, and something like 5mm would probably be ideal.

    And, of course, the overall thickness of the pad can only be 15mm. I've had problems with that in the past where I bought some EBC greenstuff pads where they said it would fit a TR, but the overall thickness was 18mm (so wound up just throwing them out).

    TIA for the help.
     
  5. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    25,144
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    #5 Steve Magnusson, Nov 22, 2021
    I haven't had a functional problem with it -- the edge on the friction pad that sticks out as it wears is so thin that it tends to break off as it grows so never gets that long -- but I just don't like the idea of the friction material rubbing on the OD of the disk (which usually has low runout, but is not something guaranteed to have low runout). I'll probably wind up in the same situation, but wanted to ask if someone had found something that fits better.
     
    vincenzo likes this.
  6. EDoug

    EDoug Karting

    Apr 19, 2005
    190
    Southern Florida
    #6 EDoug, Nov 22, 2021
    Steve, I am sure that all of the "Shell Answer Men" will step up here. I do not know what the supply chain was for the '91 TR, but here goes for my 1986 Testarossa. I removed my original 3,400 miles pads to replace them with low dusting pads, and the front pad slightly extended beyond the disc as you describe.

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    The original pads were Galfer 1725 FF and not ATE.
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    I don't think the overhang was too bad. Image Unavailable, Please Login

    Please remember that if you go with a too much shorter pad, you could introduce an unintended consequence. On my MBs, they use shortened pads as you describe. What I find is that while the pad is fully utilized, the disc is not. As such, a lip on the disc outer edge develops because there is no pad material to wear it down like the rest of the disc. The lip can cause an issue for future maintenance. The pads inside the caliper cannot just slide off over the disc lip without pushing in the caliper pistons to compensate. I discovered this when replacing the MB OEM pads with Brembo pads. The following picture shows the lip formed on the MB disc.

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    I chose to go with Porterfield pads front and back Image Unavailable, Please Login

    The pads have an anti-squeal shim bonded to the back, and the front pad thickness allowed it to just slide in without any sanding. I tried taking a good picture showing where the pad material lines up with the outer disc edge. It is tough to see and I would have to remove the pins and spring to really show you. I think it is right on the money though. I will pull the pins and spring out if you want a better picture.

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    The inside diameter of the pad it is essentially exact to the disc wear marks as shown in the pictures that follow.

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    Also remember that the disc outer edge has a little chamfer that may produce a little overhang, but I am not sure?

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    For completeness, the rear Porterfield pads were just slightly too tight, and I had to sand them down to about 14.5mm. I used self-stick sanding pads to the bench top surface progressively finer as shown. Just by hand with varied circular motion, and vacuuming the discs a lot as I went. No big deal.

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    Steve, I hope this all helps. EDoug
     
  7. turbo-joe

    turbo-joe F1 Veteran

    Apr 6, 2008
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    #7 turbo-joe, Nov 22, 2021
    I agree with you steve,but friction materiel is also important. friction is not equal to friction.
    when I started repairing F about 40 years ago ( first car from F has been a 308 GTB ) I have been absolutely negative surprised about the prices for the pads and decided together with the customer to use not the pads F was offering, we took some from ATE matching also BMW in the front and after about 1 week the customer returns and told me that there is big fading after not even 2 times heavy braking. those pads have been matching from the size perfectly. but I then put the pads in from F and there was no fading anymore.
    I think it is better when the friction will be a little larger than the OD from the disk, so there will be never an edge at the discs and so less squeeking noise
     
  8. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    25,144
    30°30'40" N 97°35'41" W (Texas)
    Full Name:
    Steve Magnusson
    #8 Steve Magnusson, Nov 22, 2021
    That makes some sense as the TR WSM shows the Galfer brand and part numbers for the front and rear pads (although they don't match what is shown in your photo of markings on the front pad backside, but manufacturers often have a whole bunch of different numbers for the same thing ;)). There are a lot of silkscreened numbers shown on the back of my original front pads (that are now all illegible), but nothing like your (much more legible) stamped markings so there must have been some evolution/change during TR production.

    No argument that that creates an outer ridge on the disc, but I'd say that's the "normal" situation for almost all automotive brake designs. Thanks for mentioning the Porterfield R4-S AP82 option -- I'll keep that in my thinking/decision.
     
  9. qwazipsycho

    qwazipsycho Formula 3

    Oct 30, 2004
    1,176
    Utah
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    Scott
    #9 qwazipsycho, Nov 25, 2021
    FWIW - Every time I need brake pads I go to Napa and tell them I need pads for an 89 BMW. I can't remember the model but I just take an old pad with me and match it up. They have always worked phenomenally. I made the mistake of ordering those crappy Yellow Stuff pads once and hated the result. It drastically altered my braking performance. Back to the BMW pads and all is well. You should know by now if there is a less expensive solution I'm going to find it. Call me cheap but I still drive a TR.
     
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