Sintered Brake Pads & Rotor Warping

[denydog]

I'm ready to order Vesrah sintered pads all around. But just one question. Has anyone experienced rotor warping from increased heat using sintered pads?

I've been through all the old brake pad threads, and have not seen this particular question specifically addressed. I'm nervous about disk warping from my experience with my bike in the first year or so from when it was new. I had rotor warpage two times that caused a definite pulsing feel in the brake lever (actually, the whole front end). Rotors were replaced both times under warranty. They've been fine ever since. I think I've been running a set of standard EBC's or something since the latter 80's.

I'm just asking because I really don't want to go there again. I would like increased stopping power of sintered pads, but not if the extra heat and wear is too much for the old GS rotors.

FYI - Here's a detailed EBC application chart (3.5mb PDF) I ran across today. It contains cross references to SBS, Vesrah, and Ferodo also. http://www.ebcbrakes.com/Assets/USA2006MCcat.pdf

[bonanzadave]

Ditto Deny,

Im on my 3rd..............maybe 4th set of rotors. The first set like yours was under warrenty. 2nd and 3rd I bought. The discs Im running now came with a whole wheel I found after I somehow dented my orig wheel. I really should have paid more attention to the brake pads. Always got them at the Dealer. Im gonna rip the whole front end off soon for head bearings, fork seals, springs and oil. Ill be watching this thread and do the pads at the same time.

[Pearson]

If you're worried about it and there seems to be some truth to the warped rotors, I'd stay away from the sintered pads. Can they truly add significantly to your braking ability? Perhaps a less risky upgrade would be to add new braided brake lines that are said to improve braking performance.

[denydog]

If you're worried about it and there seems to be some truth to the warped rotors, I'd stay away from the sintered pads. Can they truly add significantly to your braking ability?

That's what I started this thread to find out. Is there some truth to sintered pads and warped rotors? My original rotors warped with stock pads. I already think that sintered pads will add to braking performance. Will they add to disk warping (or greatly accelerate wear)? That is the question!

But you are right. I am a little worried about it. One thing, I don't brake as aggressively as I used to. But I'd like a little more bite when I want it.

Perhaps a less risky upgrade would be to add new braided brake lines that are said to improve braking performance.

I have already installed braided brake lines, and rebuilt the calipers. Pads choice is my last task before ordering in the next day or two. I've searched forums all over the internet, but most of the info is for pads on current model sport bikes. I may have to flip a coin. Heads = Vesrah sintered, tails = Vesrah Semi-Metallic.

[Boondocks]

That's what I started this thread to find out. Is there some truth to sintered pads and warped rotors? My original rotors warped with stock pads. I already think that sintered pads will add to braking performance. Will they add to disk warping (or greatly accelerate wear)? That is the question!....

So-called warped rotors are usually the result of high heat brake pad deposition on the rotor surface, not a physical warping of the rotor itself. The pulsing felt is the result of the brake pad running over the deposits, which add width at the deposit spots. The OEM organic pads are more likely to cause this condition, and also more likely to fade than sintered pads.

Sportbikes use sintered pads because of their high performance and fade resistance. They are more abrasive than organic pads, but nothing to be concerned about. The sintered pads are less likely to allow the condition called a "warped rotor", because the extra abrasiveness scrubs the disc and helps prevent pad deposits on the rotor.

Sintered pads are a premium pad with premium performance.

[denydog]

So-called warped rotors are usually the result of high heat brake pad deposition on the rotor surface, not a physical warping of the rotor itself.

May very well be a problem, but I don't think it was the case with my original rotors. They looked clean as a whistle, and the shop checked and found the run out exceeded tolorance.

Well, no feedback to suggest that sintered pads are a problem. Anyway, I just ordered the sintered version.

http://www.repairmanual.com/motorcycles/1982/62//5617/8984

I double checked my current pads, and they are EBC M 723, or maybe 223, made in Holland. I couldn't find any info on that type of part number. They looked like they had some copper particles in them. I screwed up a bit when I rebuilt the calipers, by mixing up the old pads. The brakes weren't real strong, and I just noticed, as I had suspected, that the pads aren't in full contact with the rotors. The pad looks like only 2/3 shows a wear pattern in the current position. I could just continue using them to wear them in, as they are only less than half worn, but new pads will fix that sooner.

I'll post after I get a chance to try the new pads.

[Commodus]

So-called warped rotors are usually the result of high heat brake pad deposition on the rotor surface, not a physical warping of the rotor itself. The pulsing felt is the result of the brake pad running over the deposits, which add width at the deposit spots. The OEM organic pads are more likely to cause this condition, and also more likely to fade than sintered pads.

Sportbikes use sintered pads because of their high performance and fade resistance. They are more abrasive than organic pads, but nothing to be concerned about. The sintered pads are less likely to allow the condition called a "warped rotor", because the extra abrasiveness scrubs the disc and helps prevent pad deposits on the rotor.

Sintered pads are a premium pad with premium performance.

Not to be argumentative, but I have seen rotors that were actually warped from high temperatures. So it is possible, though as you say the majority of 'warped' rotors may well be due to these deposits you describe.

[Boondocks]

May very well be a problem, but I don't think it was the case with my original rotors. They looked clean as a whistle, and the shop checked and found the run out exceeded tolorance....

See The "Warped" Brake Disc and Other Myths of the Braking System for information on why discs are measured and found to have runout and be "warped". The deposits are often not visible. The article concentrates on cast iron discs, but SS discs manifest the same behavior.

[denydog]

See The "Warped" Brake Disc and Other Myths of the Braking System for information on why discs are measured and found to have runout and be "warped". The deposits are often not visible. The article concentrates on cast iron discs, but SS discs manifest the same behavior.

I read that article, plus I looked at several other sites that, in some cases, seemed to repeat the information from that site, and in some cases word for word.

You are right that the information seems to deal with cast iron discs, and cast iron car discs at that. I did not notice any hard information concerning our SS motorcycle discs in my brief search.

I still find it hard to imagine I couldn't have seen deposits that exceeded the thickness limits (.24 in.) and run out limits (.012 in.) of my discs. But I suppose anything is possible.

Bottom line is, the fact that pad deposits can mimic warped rotors (or vice versa), does not mean that my rotors were not heat warped. Thanks for the information none the less. It was interesting.

[Commodus]

See The "Warped" Brake Disc and Other Myths of the Braking System for information on why discs are measured and found to have runout and be "warped". The deposits are often not visible. The article concentrates on cast iron discs, but SS discs manifest the same behavior.

Interesting, I have "resurfaced" many discs that appeared to be warped with an angle grinder equipped with a wire wheel, using enough abrasion to score the rotor itself, and not corrected the problem.

If there were deposts causing the issue, I have to think they would have been removed by that process - but perhaps not given what he says in that article.

[themess]

Conservation of energy requires that the enthalpy produced by stopping a moving object be equal to the kinetic energy of that object. Enthalpy is the sum of heat, physical work and chemical work. Physical work would be lifting an object or flexing a spring, or transferring momentum to another object. Chemical work could be a phase change or breaking chemical bonds. Almost none of either occurs during breaking - if it did, brake pads could only last for a few tens of stops. So most of the energy must be converted to heat. The inescapable conclusion is that stopping an object from a give speed releases almost exactly the same amount of heat each time. If the object is stopped in the same time from the same speed, the heat released will be the same. A brake pad with a higher coefficient of friction should require less pressure on the brakes to stop at the same rate, but the heat released has to be almost exactly the same. Some brake pad materials certainly wear faster than others, or have different coefficients of friction when dry or wet. But if pressure in the braking system is adjusted to maintain the same stopping distance, the heat released will be essentially the same.

[AOD]

I'm running a set of Ferodo Platinum pads on the front of my 1100E. Not sure if they're sintered, but they're soft. Check out www.vintagebrake.com and talk with Michael there, he's knowledgeable.

~Adam

[denydog]

Since this thread popped to the top again, I'll just mention that I installed the Vesrah sintered pads today. It may be a combination of the new pads being flat (I got my old pads mixed up a while back, and they don't lay perfectly flat in the new positons.). and the new pads being grippier, but the front brakes seem to have about twice the stopping power. I have a firmer brake lever as well. I think the old cocked pads were causing a lot of caliper flex. I could actually see the left caliper flexing as I applied the brakes. That was the one that had a pad that was only 3/4's contacting the rotor, as indicated by the wear pattern.

The rear brake is a little weak, but I've only ridden a couple of miles trying to seat them in with several hard stops.

We'll see as time goes by. I have a 400+ mile, group ride, scheduled next weekend.

[denydog]

Conservation of energy requires that the enthalpy produced by stopping a moving object be equal to the kinetic energy of that object. Enthalpy is the sum of heat, physical work and chemical work. Physical work would be lifting an object or flexing a spring, or transferring momentum to another object. Chemical work could be a phase change or breaking chemical bonds. Almost none of either occurs during breaking - if it did, brake pads could only last for a few tens of stops. So most of the energy must be converted to heat. The inescapable conclusion is that stopping an object from a give speed releases almost exactly the same amount of heat each time. If the object is stopped in the same time from the same speed, the heat released will be the same. A brake pad with a higher coefficient of friction should require less pressure on the brakes to stop at the same rate, but the heat released has to be almost exactly the same. Some brake pad materials certainly wear faster than others, or have different coefficients of friction when dry or wet. But if pressure in the braking system is adjusted to maintain the same stopping distance, the heat released will be essentially the same.

You know, I've been kind of thinking the same thing, but in much simpler terms. More friction=less brake lever pressure for the same deceleration during normal stops, resulting in the same amount of work, or heat. Like you said. Now if I start doing stoppies, then all bets are off. :-D

[posplayr]

Very interesting read

Boondocks
Posts: n/a



Quote:
Originally Posted by denydog
May very well be a problem, but I don't think it was the case with my original rotors. They looked clean as a whistle, and the shop checked and found the run out exceeded tolorance....

See The "Warped" Brake Disc and Other Myths of the Braking System for information on why discs are measured and found to have runout and be "warped". The deposits are often not visible. The article concentrates on cast iron discs, but SS discs manifest the same behavior.