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Since I had so much fun with my u-joints I decided to go through the brakes. On my 96 I had old (PO) PBR brand brake pads. On the rear the inside and outside pad are clearly different in size and shape. My new Carbotech rear pads are all the same exact size. The back side of the old PBR's are marked differently while the Carbotech's are all the same. Can anyone explain what is going on? Thanks!,
Let me ask a little less open ended question. Anyone that has done rear brake pads on a late model C4 were the inside and outside pad the same? Dan
I've owned four different C4, and have never touched the rear pads on any of them. The 85 has 53xxx, and the ZR-1 had >45xxx miles and both retained their OEM pads with about 50% life remaining. The 92 has about 55xxx since the PO changed the pads, and they have about 30% life remaining. So no, I haven't had an opportunity to observe the rear pads on my C4s.
BUT. Anticipating that I would eventually need pads for the 92, months ago I purchased a set of Delco from rockauto. Your post intrigued me, so I went out to the shop and took a pic of a pair of the rears. I have no idea why the shape of the friction is different for the inner and outer, but the Delco replacements I have are the same shapes as the take-offs in your pic. I note that only one pad has a "squeaker" wear indicator, and I presume that that is the inner pad? Interesting. Cheers.
Out of the box Delco "Professional" 413 rear pad pair.
Yes, the wear indicator goes on the inside. The Carbotech's come without any wear indicator. Also, note in my picture of the Carbotech's that the rivet holes are spaced differently on each pad. I asked Carbotech about it and they said it would not make any difference. Not good for about the most expensive pads out there. Dan
I agree that differences in friction shape will not "make any difference" because the driver won't detect any differences in braking performance or characteristics because of friction shapes between pads and pad manufacturers. The rear brakes don't contribute much to overall braking anyway. The friction shape on the rear is a nothing-burger. Don't fret over it.
Regarding the rivet spacing on the Carbotechs: Are there two pads each with the different spacing? If = yes, and the rivets protrude on the backside, be sure that the rivets don't contact or interfere with the caliper casting on the outside or the piston on the inside. My guess is that the narrow spacing goes on the outside, and the wide spacing goes on the inside. Cheers.
One more thing. While the front pad set has the rivet way down in a hole the rear set only has a little more than1/16" of pad wear before I am down to the rivet. This can't be right. Dan
I agree that differences in friction shape will not "make any difference" because the driver won't detect any differences in braking performance or characteristics because of friction shapes between pads and pad manufacturers. The rear brakes don't contribute much to overall braking anyway. The friction shape on the rear is a nothing-burger. Don't fret over it.
Regarding the rivet spacing on the Carbotechs: Are there two pads each with the different spacing? If = yes, and the rivets protrude on the backside, be sure that the rivets don't contact or interfere with the caliper casting on the outside or the piston on the inside. My guess is that the narrow spacing goes on the outside, and the wide spacing goes on the inside. Cheers.
Of the four pads 3 have narrow spacing and only one has the wide spacing. Carbotech said the plate must have shifted when being drilled but it would have to have shifted twice. I am waiting for Carbotech to get back about the rivets not being deep. Dan
It isn't. That's a QC issue. That pad should have been rejected at the first inspection station. For the price, it should have gone straight to the reject bin, not out the door.
I remember Adam and his hitting the board, every forum, every day pimping Carbotech pads. I took the time to investigate them, saw the price, and never paid attention again. I like the characteristics of some compounds better that others, but generally stock-ish pads are good enough for the way I drive my cars. I don't need anything exotic, nor do I want to pay exotic prices for something like a brake pad. OEM compounds are generally satisfactory for my street driven cars, which is all 7 of them.
If you favor boutique pads, have you investigated Porterfield? I put Porterfields on the Aston Martin I did a pad change on a few weeks ago. The owner's complaint on her new-to-her car was "The brakes squeak. Can you change the pads?" I didn't anticipate any trouble changing the pads, they were Brembos, nothing exotic but I didn't know what or where to source pads for it. She had done her research, and the A-M forum guys recommended Porterfield. If they're ok for the A-M crowd, they're probably good enough for a C4. I don't know what she paid for them. Cheers.
It isn't. That's a QC issue. That pad should have been rejected at the first inspection station. For the price, it should have gone straight to the reject bin, not out the door.
I remember Adam and his hitting the board, every forum, every day pimping Carbotech pads. I took the time to investigate them, saw the price, and never paid attention again. I like the characteristics of some compounds better that others, but generally stock-ish pads are good enough for the way I drive my cars. I don't need anything exotic, nor do I want to pay exotic prices for something like a brake pad. OEM compounds are generally satisfactory for my street driven cars, which is all 7 of them.
If you favor boutique pads, have you investigated Porterfield? I put Porterfields on the Aston Martin I did a pad change on a few weeks ago. The owner's complaint on her new-to-her car was "The brakes squeak. Can you change the pads?" I didn't anticipate any trouble changing the pads, they were Brembos, nothing exotic but I didn't know what or where to source pads for it. She had done her research, and the A-M forum guys recommended Porterfield. If they're ok for the A-M crowd, they're probably good enough for a C4. I don't know what she paid for them. Cheers.
Thank you. I have done searches for Carbotech rivet problems and this is not a new problem. Carbotech claimed, in these old posts, that the rivets are brass and will wear down with no damage to the rotor. I don't believe it. Many post their rotors were gouged. I just wanted a real upscale pad just for fun. I am disappointed in the quality control. I have officially asked to have them exchanged for a set with the rivets lower like the front set. I will know tomorrow if they will. They can always sell these to some other guy who doesn't care. Dan
It isn't. That's a QC issue. That pad should have been rejected at the first inspection station. For the price, it should have gone straight to the reject bin, not out the door.
I remember Adam and his hitting the board, every forum, every day pimping Carbotech pads. I took the time to investigate them, saw the price, and never paid attention again. I like the characteristics of some compounds better that others, but generally stock-ish pads are good enough for the way I drive my cars. I don't need anything exotic, nor do I want to pay exotic prices for something like a brake pad. OEM compounds are generally satisfactory for my street driven cars, which is all 7 of them.
If you favor boutique pads, have you investigated Porterfield? I put Porterfields on the Aston Martin I did a pad change on a few weeks ago. The owner's complaint on her new-to-her car was "The brakes squeak. Can you change the pads?" I didn't anticipate any trouble changing the pads, they were Brembos, nothing exotic but I didn't know what or where to source pads for it. She had done her research, and the A-M forum guys recommended Porterfield. If they're ok for the A-M crowd, they're probably good enough for a C4. I don't know what she paid for them. Cheers.
I have use Porterfield's on my vette and other cars for years. Never had any issues.
I have officially asked Carbotech for a return label for these pads. I have got no response yet. Even though the rear pads are defective I bet they still hit me with all the shipping and 20% restock charge. I will see. I have lost all faith in Carbotech's quality control. I will try the Porterfields. They seem to have very good reviews. Dan
It isn't. That's a QC issue. That pad should have been rejected at the first inspection station. For the price, it should have gone straight to the reject bin, not out the door.
I remember Adam and his hitting the board, every forum, every day pimping Carbotech pads. I took the time to investigate them, saw the price, and never paid attention again. I like the characteristics of some compounds better that others, but generally stock-ish pads are good enough for the way I drive my cars. I don't need anything exotic, nor do I want to pay exotic prices for something like a brake pad. OEM compounds are generally satisfactory for my street driven cars, which is all 7 of them.
If you favor boutique pads, have you investigated Porterfield? I put Porterfields on the Aston Martin I did a pad change on a few weeks ago. The owner's complaint on her new-to-her car was "The brakes squeak. Can you change the pads?" I didn't anticipate any trouble changing the pads, they were Brembos, nothing exotic but I didn't know what or where to source pads for it. She had done her research, and the A-M forum guys recommended Porterfield. If they're ok for the A-M crowd, they're probably good enough for a C4. I don't know what she paid for them. Cheers.
The head tech man at Carbotech said the rivet is correct. He said it is the same rivet depth as the stock pads. I have never seen stock pads. Did they really have rivets and was the depth of the rivet really just 1/16"? I am returning all the Carbotech pads. I just checked and the Porterfield's do NOT use any rivets. Dan
I will try the Porterfields. They seem to have very good reviews.
Here's another "good review":
After the A-M's owner had ordered the pads and received them, she called me to set up the work. Because of my experiences with pad replacements on Porsches where the wear sensors are generally not reusable, I asked her about "wear sensors". Did she know if I was going to have to also replace the sensors? She called Porterfield, (she said a human answered the phone), and got her answer for her question. Their response was "The sensors should be reusable. They can be transferred." They were right, too.
The pads didn't include break-in instructions. I almost called them, but didn't. I did (6) 60 to almost 0 MPH hard applications in sucession, then drove without stopping for another 15 minutes to let the rotors cool. I drove it again a couple hours later and the brakes were really nice. I liked the results on the A-M, I think you'll be pleased with yours on the 96.
After the A-M's owner had ordered the pads and received them, she called me to set up the work. Because of my experiences with pad replacements on Porsches where the wear sensors are generally not reusable, I asked her about "wear sensors". Did she know if I was going to have to also replace the sensors? She called Porterfield, (she said a human answered the phone), and got her answer for her question. Their response was "The sensors should be reusable. They can be transferred." They were right, too.
The pads didn't include break-in instructions. I almost called them, but didn't. I did (6) 60 to almost 0 MPH hard applications in sucession, then drove without stopping for another 15 minutes to let the rotors cool. I drove it again a couple hours later and the brakes were really nice. I liked the results on the A-M, I think you'll be pleased with yours on the 96.
Thank you!!! Your review counts more than ones on the web that might be fake. Dan
Well, I got my new Porterfield pads today. What a difference. Where the metal part of the pad is painted it looks like some kind of tough powdercoat, The Carbotechs are just painted red with a spray can getting overspray on the sides of the pad. It chipped up just during the shipping, Here is the front side of the front pad. It shows the wear indicator the Carbotech did not have one.
The back of the front pads have a ribbed rubber membrane covering most of the back side. The Carbotech was just metal. The wear indicator is securely mounted.
The front side of the rear pad.
The rears also have a wear indicator that the Carbotech's did not.
The back of the rear outside pad has an extra sheet metal backing. I suspect for sound. The Carbotechs did not. The pad material on the inside pad is thicker to make up for the piece of sheet metal.
These seem like very good pads. And no rivets!! Carbotech claims that a rivet 1/16" deep on the rear pad is dictated by GM specifications. This is hard to understand as GM has not used rivets on stock pads since the 1960's. Like half a century ago. I find it hard to believe that GM would have a specification for rivet depth on aftermarket pads. Rivets were used on model A brake linings but I thought they were a thing of the past but I sure could be wrong. Thanks to IHBD for this suggestion. My Carbotech experience will cost me at least $150.00 as I have to pay shipping each way and also pay 20% restock fee. Oh well- Alls well that ends well. Thanks for reading. I forgot to mention these are $100.00 less than the Carbotechs. Dan
Well, I got my new Porterfield pads today.
These seem like very good pads. Dan
I'm pleased that you are pleased with the Porterfields. I didn't know about Porterfield until my friend did her research and found the recommendation for her exotic. I didn't take any pics prior to installation, but the A-M's pads had the same quality characteristics as you show and cite. I browsed through the Porterfield offerings and will probably try them on which ever personal car next needs pads. (Other than the 92 of course, as I already have them on the shelf.)
I've never seen a set of Carbotech until you posted your pics, but from your description of your Carbotechs, I won't consider them in the future. That rivet depth deal is just crappy QC, and their response is a fabricated excuse, not a bona-fide explanation.
You mention a difference in rear pad 'thickness' between the inner and outer pad. While scrutinizing the Delco's I posted pics of earlier, I noticed that the friction of the Delco inner pad was thicker, same as the Porterfields. Just for curiosity I looked up the rear pads for the 85 (84-87 C4) and they are a different P/N, but the shape of the backing and mounting is identical. I posit that the difference in OEM P/N is that the early P/N is for drum-style park brake, the later P/N is for the caliper-actuated park brake. Porterfield lists the same P/N for both C4 applications. << I'd consider this a nothing burger.
After you get them bedded and have driven it for awhile, please report back with your evaluation of the Porterfields. Are you also replacing the rotors, or re-using the existing?
I seldom make "recommendations" in lieu of "suggestions", but I have had great results by using Permatex 80077 "Disc Brake Quiet" on my last (3) pad change outs, ( Porsche 911 and Maccan; the A-M Vantage). The reason I use "great" is that the owners (amusingly all women) haven't complained of any noise. My neighbor across the street had been reluctant to drive her 1986 Carrera for years because of an unusual noise no one had identified. I finally deduced it was from the front brakes, but had never heard this particular noise before from any disc brake. Long story still long, the Permatex fixed it, she's driving her 911 again regularly.
The 80077 goes on the backing plate. Not the friction. I turn the pads friction face down on a sheet of paper, apply two coats about 10 minutes apart and let it sit for at least a couple of hours before installation. I will definitely continue to use this stuff on my pad changes. It may not be necessary, but no one likes squeaky or noisy brakes. Cheers.
Brake pad question
