gs550t front brake rotor warped

[Fishman]

I experience some mild pulsing in the brake lever when stopping, although it stops just fine. I suspect my rotor is slightly warped. What options do I have? Anybody know of some aftermarket rotors that are available? The part is discontinued from Suzuki, and I haven't come across any on Ebay. It's just the single disk on the front.

I don't think it's a huge deal, but please feel free to correct me on that. I'm also concerned that it may not pass inspection that way.

[Nessism]

First thing is to figure out which bikes used that same rotor part number; you can go to Alpha Sports and look through the parts fishe to see. The 750T also used a single rotor so that would be a good bike to check. After you figure out which bikes have the rotor you need, hit ebay and do a search. Shouldn’t be too hard to find what you need.

[Suzuki mad]

I suspect that the 550 and 650 will be the same. Its unlikely the 750/850 will be.

Suzuki mad

[Nessism]

The difference will follow whether or not the bike had one disc or two. The single disc rotors are larger - this is what you need. There are 650L and 750T bikes that had one disc. That is where I’d start the search, along with the 550L and 550T models.

[Fishman]

Thanks guys. I gather there isn't an aftermarket rotor available then. I'll work harder on the ebay thing.

[Suzuki mad]

Post a Suzuki part number for the disc and I will see what other bikes it fits. That will open up your search.

Suzuki mad

BTW the UK GS550T had twin front brakes so UK shops supply pairs, not singles.

[Fishman]

Thanks Suzuki Mad, but hey, I just got lucky! Picked up a gs550t rotor from an ebay store that was just listed. $25, shipping included so a good deal I think as long as it isn't warped too. I've checked at least a dozen times prior to this, but all of the sudden . . . I'm thinking instant karma from my friends at the GSR!

[Fishman]

Update: Well the replacement rotor appears more warped than the original. I replaced the pads as well but that didn't help. One thing I did notice was that the PO slightly crossthreaded or overtorqued the top bolt attaching the front caliper to the bike. It looked like it was overtorqued to me because I thought I could detect a "slight" wobble on the bolt, but I am not sure. I ran a tap which didn't really seem to do much, and I ran the bolt in the opposite way, which seemed to clean it up very nicely, eliminating the tight spot with every revolution of the bolt.

Question: would the possible damage to the rotor fastening system cause some misalignment of the caliper. It really looks like there is no problem there, but I want to be sure. Two rotors not working might be more than coincidence.

Otherwise, can a brake rotor be resurfaced like a car's? Both rotors are in really nice condition, with very little obvious wear.

[srsupertrap]

The GS rotors cannot turned with a brake lathe but can be resurfaced to OEM specs with a rotary surface grinder . . . had mine done by an EBayer up there in Washington. Use the search function I posted the details in Tips sections

Have not seen his listing in the last 6 months

[Nessism]

My old 550E had a bent rotor when I bought the bike. It’s very easy to measure a bent or warped rotor if you have a surface plate and dial indicator; remove the rotor and lay it on the table with the brake surface up, then indicate off the braking surface and rotate the disc. You may have to pay someone to measure it for you if you don’t have this stuff but it’s worth it in my opinion since it will take the guess work out of diagnosing the problem.

[chef1366]

I would make sure it is a warped rotor with a dial indicator. Use a caliper to measure it.
If the rotor isn't warped it could be bad bearings, bad tire and/or bent rim.

[rphillips]

I took a pair to a llittle local machine shop, they found both were slightly warped, trued them both, now smooooth again. $25 CASH

[Fishman]

I have a caliper but no dial indicator, nor have I ever used one I'll do a search to see how exactly they are used.

I guess with just the caliper I can measure if the disk is of uniform thickness all the way around. It's a very high quality caliper so I'll have faith in it.

I'll let you know what I find.

[srsupertrap]

I would suggest measuring the following two dimensional attributes: flatness & parallelism. Flatness is measured again itself which sounds confusing. So the precise way to measure flatness is to use a surface plate, 123 blocks (3X) & dial indicator. Support the rotor surface on three equally spaced 123 blocks, zero the dial indicator to the rotor surface being supported by the 123 blocks and sweep the entire surface (360 degrees back n forth) with the dial indicator. The range of the deflection is the flatness. The other way of measuring flatness is to place the rotor on the surface plate and use different size feeler gauges; slide the biggest feeler gauge you can between the rotor OD & surface plate which gives a ball park figure. Why because you are really only measuring the gap that exists at the rotor OD, but close enough for many.

To measure Parallelism you place the rotor back on the 123 blocks & surface plate set up and sweep the rotor side that is facing up with a dial indicator. The range of the dial indicator deflection is the parallelism.

[Fishman]

I still haven't come up with a dial indicator, but I did measure the thickness of the disk with my dial caliper. The spread of the measurements was .006 inch. Does that mean anything?