Auto Brake Pad Selection

http://www.kwik-fit.com/free-brake-check.asp

I know people are out there can do it. I can do it myself. Just looking for insight into the various materials used and the pro's/con's of each. Kwik-Fit is just another assembly line car shop. We have tons of them in the U.S.!

Hey Stinky! Remember the song?

'You can't get thicker then a thick git fitter...'

But seriously, Jim, what are you using the thing for? Discs warping due to heat? No chance, not if you mean through heavy braking. I have never been able to achieve a warped disc in all my years of abusing cars and bikes round race tracks. What I have done is got the brakes nice and hot, come in under a red flag without letting them cool down and sat with my foot on the brakes for a few minutes. This had the effect of transferring pad material, sintered of course, onto the disc. From then on, every time I braked I had a judder from the front wheels caused by the change in properties of that part of the disc. On closer inspection, there was a pad shaped discolouration on both sides of the disc, the only way I could rectify this was to spin the disc down. To be honest, a new set of discs only cost about £60, only £20 more then the work. No brainer from the safety aspect.

I have had brakes hot enough for the heat transfer to the wheels to melt the plastic centre caps in a set of Superlights! So, warped discs? I don't think so.

As to brake pads, If you can get Ferodo I would recommend them, if not I have had great success with EBC green stuff for road use.

Good luck!

You can easily warp disks and Jeep is proud to provide the user with an easy way to do it.

I have seen Porsche 944s warp rotors if you abuse them.

Put a heavy load on a Jeep and start going down hils and you will warp rotors very quickly.

No engine braking then? Or do you all drive automatics?

Even automatics, when driven correctly, can provide engine braking.......

My personal take on warped disks is that they were probably made badly in the first place and not correctly de-stressed before being planed.....

I'd like to see 944 rotor warped. How much deflection was there? These are fairly big vented discs, Have you got a picture you can post? Did the pads catdh fire? I've seen 944's set fire to pads before, never seen a genuine warped disc, though...

Easy to do. When I bought my second 944 the previous owner took it for one last joy ride before delivery.

The brakes are big, but not immortal!

My current car's rotors are larger than 13" front and rear and I bet if you abuse them enough they will warp, too. However, you really need to work at it! These brakes make the old 944 look like motorcycle brakes.

It doesn't take much warpage to render rotors bad. 0.025" will easily be felt in the steering wheel. You won't see it by looking at them, but I do remember looking at the 944 rotors and could visibly see the annealing from the heat. Turning them is senseless since the metal is annealed.

The last 97 Jeep Grand Cherokee Laredo I had warped the rotors and it was just used for highway driving. My old Chevy Blazer was used to tow my boat often and I never had problems with the brakes. It is hard to tell what was done to the rotors before I bought the Jeep but they warped badly. Brake shops are bad for turning rotors even when they don't need it!

Jeep is notorious for warped rotors and all the parts stores know it!

Interesting that you don't seem to mention stopping sfficiency at all...maybe then you should go for teflon pads...very hard wearing...no dust!

Seriously I'd rather the pad wear than the disc...ceramic seems daft to me... it costs v little to have new pads fitted ... but new discs

And why worry about dust on what is essentially an off road vehicle??????

Maybe, being a Brit I just don't get it?

Del

In Europe I agree with you totally and I always use the OEM pads, never from other companies as they usually end up wearing the disks first!!

Typical that the Big Three undersize their brakes!

Heat is the enemy! Ceramics will take more heat, but it isn't the pad that warps. Ceramic will insulate the heat from the disk brake calipers and keep the hydraulic brake fluid cooler, but that will not help you. In fact, it will make the rotor's job of bleeding off heat harder!

I think there are upgrades you can get for the Jeep's front brakes, but that is going to be expensive, I assume.

The softer pads will probably give you the best performance and be the kindest on your rotors.

If it were me, I would not keep any SUV, but I am biased. I would look into buying a car and rent a truck on the occasions you need to move the boat. The money you save on gas alone will easily pay for the rental!!! Let alone the cost of maintaining the Jeep.

Del & Hero make great points. Stopping efficiency is what I would view as a critical factor. I don't care about dust.

The first response refers to the assembly line brake companies that charge once for doing a brake job. Where they make their money is not in replacing the pads, it's when you have the rotors warp or wear to a point where they cannot turn them down and you have to have them replaced. They love to have you come back for this. This is NOT covered in the lifetime warranty they boast about. Shure they will replace pads but they make money in the rotors wearing out!

Back to my original question about the brake material you would like on your car ... are the softer, cheaper, quicker wearing, dust generating pads better than the ceramic pads? Does the softer pads stopping efficiency perform better than the ceramics? Do we sacrafice stopping efficiency for cost?

I didn't know if there were any automotive engineers out there who may have participated in brake material testing. Just what are the pro's & con's in the various pad materials?

Well put.

In Europe, so called "Grey imports" of US cars ate often slated for bad brake performance, where the legal import version brakes work fine.....so manufacturers ARE aware of the difference.

So for US citzens, it might be a good idea to get hold of Export brake parts from your manufacturer.....

In Europe you get the braking distances for each vehicle for 100KMH and good braking cars are under 40 meters.......so it is easy to compare....they also test repeated stops to see if fading sets in, some good cars actually brake BETTER when the brakes are hot!!

Hola Jim

I JUST studied this for my Yukon that needed the first brake job at 90,000 miles last week, asking my best pal who is a fleet mechanic for one of the largest general contractors in the US. They do not use ceramics as they grind up the rotors. Ceramics have a lifetime warranty as ceramic is one of the hardest materials around. Semi-metallic is what I'm using exclusively now, and he as well for hundreds of vehicles. Regarding warped rotors: Ford rotors warp from sunlight it seems. All of us 'mechanics' know this and have jokes about when, not if, they will warp. On all my Fords I just swap out the rotors for aftermarket and I've never replaced them again. And I never had a Ford rotor NOT warp. Normal 'soccer mom' driving for our Explorer, normal little old lady driving for my mom's Mercury Topaz, and my 80 YO neighbor's Lincoln Town car. All warped; all changed, all fixed. Ford knows this and put air scoops on their trucks. Unfortunately it scops up all the dirt and rocks also.

So; semi-metallic and find rotor species: non-warpimusmaximus [Latin]; after market rotors.

I'm still scratching my head here, I'm starting to think I'm up against the language barrier! By warping, I understand you to mean that the rotor has heated up in use, expanded at differing rates so as to become rippled or bent, and then cooled, staying out of shape? I've never seen that! I have seen inconsistent material properties on some discs, so that they wear unevenly, and very quickly, leaving a low spot on the face of the disc. Soooo...has anyone actually measured an allegedly warped disk for trueness with a DTI acrossed the whole surface? or is this uneven wear?

I've always accepted the term 'warped' discs and had vehicles that have suffered form brake judder that has disappeared when I replaced the discs/rotors. I think I may have even dial-gauged one in the past. I can't see how you can so adamantly discount the possibility of thermal distortion in a part which is intrinsically unstable in shape (planar), is not a single crytal of homogenous material and which eats heat for a living.

On the other hand I think that uneven wear in discs is probably responsible for much more judder than warpage, but is probably referred to as warpage in common parlance. Would it not be possible for hardness variation to creep in to the manunfacturing process, not to mention temperature variation in service due to thickness and material consistency?

Did the wheel bearings get replaced /tightened during the process?

I believe discs can warp..but I too have never personally met one, but I've met several worn wheel bearings.

It seems odd that Ford can get away with presumably substandard parts....if these were Chinese cars our US members would be shouting the roofs off!

Are we missing something? Do US drivers use the brakes more as they are generally driving automatics??? ( Don't tell me... Ford buy 'em in from China!!?? )

Ideas anyone? Maybe It's the brake disc fairy?

Del

'uneven wear in discs is probably responsible for much more judder than warpage, but is probably referred to as warpage in common parlance'

Thats what I'm trying to say in my usual incoherent manner! Are they warped or are they worn unevenly?

Yes, I understand your point about planer instability, but I've seen discs made blue by binding pads that have boiled the grease out of the wheel bearings, to the point where they were welded to the stub axle, and the discs still ran true! I've measured discs that had 0.2mm variation on one side, and 0.001 on the other, that the manufacturer said were OK! (Bad material!)

But to reiterate - Never have I seen a genuinely warped disc!

PS. I just remembered, I use AP Lockheed pads on aftermarket discs on my daily driver, a Honda accord, and they work better when warm.

Rotors will warp due to a combination of things.

1. Improper torque of wheel lug nuts.

2. Possible material defects (as you mention).

3. Over heating, especially in cold/wet climate (after parking) where some parts of the rotor is covered by the caliper and will cool at a slower rate than the exposed surface.

Not sure but this I only my 2 cents

Get the ceramic pads and replace the rotors with new OEM units. Never turn rotors unless it's just a clunker you want to keep on the road.

Warping of rotors is caused by heat. Alot of car companies use cheap rotors.

Did you have this problem when the Jeep was new? If not the answer could be to replace the robber brake lines from the steel line to the caliper. When this line fails, it usually does not leak, at first. The lining inside of the rubber hose leaks and when the 2500 PSI+ pressure is applied to the stop the car, that lining allows the fluid to leak between the layers, which still has pressure. This pressure remains for a little while after the brake is released and in affect over time create something simular to a pressure check valve. This creates the same effect as someone rideing the brakes down a long hill. The heat created then warps the rotor. PS, it will also cost you $$$ at the gas pump.

The real fix would be to put premium slotted rotors and ceramic pads. This would be especially true if there is extreme braking, like on long steep hills, if someone simply rides or lays their foot on the brake pedal.

Don't know about 'leaking between layers', but older hoses swell 'up' sometimes, on account of absorbing the fluid, untill the inside dia closes. (the rubber inner is prevented from swelling 'out' by the braiding so its swells 'in' instead. This leads to brakes that are inefficient, requiring considerable pressure to come on, and subsequently stay on, in extreem cases indefinitely. Greatly accelerated wear and bad fuel consumption and heat damage to surrounding parts results.

The swelling is created when the inner lining has failed.

If by 'failing' you mean the inner lining has become punctured or porous but not swollen, that wouldn't explain the hose closing off and requiring excessive pressure to force fluid through it.

It can, if the leak is bad enough. I have had it happen twice on a 1994 Chrysler and a 1965 Chevy Pickup. The Chrysler warped the rotors because they wear so thin that the OEM replacements only lasted about 6 months! That's when I redid the repair myself and found out they had not replaced the the brake hoses. I lso went to a thicker rotor that only costed $50 more. The total bill was half what the repair shop charged the first time. 75,000 miles later I have had no problems.

Excellent. So much for OEM's dire warnings about not buying your spares from them!

I would recommend "bedding" your brakes after a brake job. Its essentially a way of tempering the rotor material to not deform during driving, as well as breaking the pads in to mate to the rotor surface. Rather than a drawn out explanation, this link should give you the basics. http://www.zeckhausen.com/bedding_in_brakes.htm As far as pad choice, ceramics wont hurt, in my opinion, but may be overkill for regular driving conditions. I saw someone say they didnt like the EBC greens, but they worked pretty well on my Xterra after bedding and bleeding. I drive 60 miles a day in So Cal bumper to bumper, and pull a good sized trailer with 4 motorcycles on it, and have had no problems thus far.

I see you are from Indianapolis. My guess is that you have no steep hill except when you pull your boat to come to the good water in KY.

Happy boating

Thanks for that, but......tell me about noise!

My brother is a service manager for a chevy dealer in Texas. He had a corvette come into his shop once 3 weeks after he had rebuilt the pads with completly new calipers hoses rotors and pads. The OEM brake pad linings on all 4 wheels had delaminated and detatached from the metal backing plates.

The pads supplied by the parts house I deal with have dent on the metal plate that secure the pad better than the OEM.