brake pad/rotor question

[650mark]

the front brakes on my 15,000 mile '80 xs11 special pulsed a bit when stopping so I had my machinist friend turn both rotors. the right side was only out of spec .002 but the left was out .005. he now has both within yamaha's spec and I anticipate the brakes will be nice and smooth next time I can ride. might be a while, it's going to be 118 here in phoenix tomorrow! my question is should I install the new EBC brake pads I have sitting on my work bench even though the ones on the bike right now (same EBC) have plenty of material still left on them? thanks

[bikerphil]

I would use the new ones. Old pads won't stop as well as new fresh linings will. I think they harden up over time. EBC brake pads should have the manufacture date stamped on the package. JMHO

[WMarshy]

I second that, use the new pads. The old pads have the profile of the old rotors surface cut into them. If you put the old pads on the new surface it wont wear as evenly (smooth) across the rotor. I wouldnt expect it to groove them but it could depending how grooved the old ones were...both the pad and rotor will wear into eachother until their profile match eachother, its better to start with a new flat/smooth pad on that nice surface your buddy just cut on your rotors. Just remember to seat them lightly for the first hundred miles or so.

[TopCatGr58]

Hey Mark,

My special OEM brakes would also pulse when I would use them, but I just put up with them, knowing that the rotor doesn't have much thickness and are also fairly hard to "turn"/lathe. Then I did my FZR600 dual piston caliper MOD expecting them to still pulse, and was pleasantly surprised that they didn't pulse! So...it turned out that the rotors were NOT warped. I then learned that having BENT caliper securing/mounting bolts will cause the brakes to pulse! I remember taking the calipers off previously and had found that the mounting bolt had gotten bent...just everso slightly, but was still BENT, yet I put it back in when reassembled.

A recent member had reported pulsing brakes, and after replacing his bent bolts his brakes didn't pulse anymore. SO...you might want to remove one fo the bolts and inspect it to see if it IS bent, and if so, replace it. Of course you have already had your rotors turned/lathed so you know that they are now true/flat, so if you don't check the caliper bolts but just do a test ride and AFTER your new pads have broken/seated in, that if your brakes still pulse, then you'll know that your caliper bolts are probably bent and need to be replaced.

T.C.

[Bonz]

I don't think the new pads are a bad way to go either.

But being me... I would think a person can sucessfully and simply sand down the surface of the old pads to remove any "grooving" or glazing, and be good to go. You will expose new virgin brake material as well. Put some gritty sandpaper on a flat piece of wood as your sanding block. That is what I would do and never look back.

Are you sure the pads weren't glazed to begin with, and thus your pulsing? .002 and .005 are pretty small tolerances to cause a pulse IMO.

[650mark]

before machining the rotors were both very smooth,not grooved or scarred at all. the old pads are not either, nor are they glazed. I did notice when I took the calipers off that the long bolts were not very tight, just snug. are they supposed to allow the calipers to move about a little or should they be tightened down?

[TopCatGr58]

The mounting bolts go thru a steel metal sleeve that is inside the caliper housing. The mounting tension on the bolt should be fairly tight. There are rubber orings on the large washers that keep the calipers snug yet still allow them to SWIVEL while they work. I don't have the torque values for the bolt handy, remember there is also a locking NUT that goes on the end of the bolt on the fork side.

T.C.

[WMarshy]

I don't think the new pads are a bad way to go either.

But being me... I would think a person can sucessfully and simply sand down the surface of the old pads to remove any "grooving" or glazing, and be good to go. You will expose new virgin brake material as well. Put some gritty sandpaper on a flat piece of wood as your sanding block. That is what I would do and never look back.

Are you sure the pads weren't glazed to begin with, and thus your pulsing? .002 and .005 are pretty small tolerances to cause a pulse IMO.

Keep in mind, the specials use a tapered pad unlike the standards. I personally would not choose to sand pads because you could lose that taper angle on the special pad and grit might get embedded into the pad material... Im sure its been done before without ill effects though.

[650mark]

son of a gun, turns out one of the bolts WAS bent! replaced them both, installed the new brake pads, now just waiting for a cool morning(under 100) to go for a test ride. thanks for the tip TC.

[Bonz]

It would be a simple thing to sand the special pads, just keep the pad surface flush with the sanding block and apply even pressure.

Grit isn't an issue in the amount it would be left behind on the pad surface IMO.

I haven't sanded my pads, but how many times do you read about guys scuffing pads on any type of vehicle with sandpaper to break glaze? It is done all the time.

Good luck with the test ride once you get under 100 degress out there! Wow, it is HOT for sure.