my brakes have issues

[TDodge7]

i'm still trying to get my 80sg on the road but i'm having a little trouble with the brakes . they aren't very good despite the new fluid , ss lines , and proper bleeding . besides not stopping well i can feel pulsating thru the lever . the disks feel waxy but no ammount of scrubbing with brake cleaner removes the waxyness . the rear disk was the same way but it seems to be working pretty well now and there's an inch wide stripe of shiny disk on it so i guess it wore thru whatever is on the disk . the front brakes however doesn't seem to be wearing thru whatever is on the disks . and i can't explain the pulsating in the lever , i've had the bike up on the stand and spun the wheel and neither front disks appear to be warped . i tried riding around with the brakes on to see if i could wear away at it but the disks don't even get hot . anyone have any ideas ?

[XS1100 Newbie]

I don't know about any coating on the rotor, but it sounds to me like you may still have a bleeding problem on the front. Sometimes air gets trapped at the "y", and it is hard to work out. It looks like you have all the air out, but you don't. Try rebleeding the front.

[Larrym]

Sheeny pads?

On my first XS I had a leaking fork seal which contaminated the brake pads. After fixing the fork seal I removed the pads and tried to clean them with brake cleaner. It apparently worked on the surface of the pads and the brakes would grab like they were supposed to....for a while. Then it was back to slippin'-and-a-slidin when the pads wore down a little bit. Fix was to install new pads. Don't know if the old pads failed due to oil contamination or just being as old as the hills.

As far as the lever pulsating, anyone with steel brake lines is going to feel any irregularities in the system more than the guy with the rubber brake lines. That's what the brake lines do: they smooth out some of that pulsing. Take a look at someone's rubber brake lines when they pressurize the system and you'll see the lines actually expand a little bit.

If you are going to check the rotors for "runout" then the naked eye just isn't good enough. A dial indicator that reads in thousandths of an inch is required. I supposed if you had a micrometer then you could take measurements at different places around the rotors and see if the rotor is varying in thickness.

[TDodge7]

there is no Y , i have 2 stainless lines running from a dual banjo . i'm sure they're bled right , they have plenty of pressure ,just no stopping power , like the disks are glazed . they did pulsate before i changed to the ss lines , but i'm wondering if the pulsating isn't from whatever is on the disks .

[fredintoon]

there is no Y , i have 2 stainless lines running from a dual banjo . i'm sure they're bled right , they have plenty of pressure ,just no stopping power , like the disks are glazed . they did pulsate before i changed to the ss lines , but i'm wondering if the pulsating isn't from whatever is on the disks .

Hi '7,
I developed a forearm like Popeye when my SG's front pads got contaminated with fork oil.
Did you install new pads?
If you didn't and the old ones are oil contaminated the more you wipe off the disks the more the oil soaked into the pads will re-coat them.

[John]

Quite often the air bubble will be trapped at the banjo bolt at the master cylinder. I have found that by removing the M/C from the bars, and with a helper holding it so the lever is pointed up, removing and compressing a caliper piston into it's bore will force the air past the M/C plunger and into the reservior removing it from the system.

[bikerphil]

I remove the glaze from my rotors every so often by using some 80 grit on a rotary sanding wheel. 80 might be a little aggressive if you've never done this before, you could try a finer grit. Disclaimer: Your rotors might not look as nice as they did before, , but they will stop better and not squeal. YMMV. I would look at the pads though.

[TDodge7]

thats the thing , they don't squeal , the disk almost looks like it has a light coat of grease on them , but it doesn't wipe off on your hand .how common are warped rotors on these ? i've had a lot of motorcycles but never came across one with warped rotors .

[Larrym]

Mirror-rorriM

Warped rotors are as common as they have to be. What I mean is that although 1000 other owners don't have warped rotors it means very little to the one owner who does have a warped rotor.

Even if the rotor is perfectly flat and non-warped it is still attached to the front wheel of the bike. (Conveniently this allows the stopping of the rotor to stop the wheel as well...) I believe 6 bolts per side per rotor. If any of these fasteners were loose it could cause a "runout" which might cause your "pulsing". It could also be that some "crud" is between the rotor and the wheel itself which would cause the wheel to roll straight and true but the rotor to "wobble" as it turns.

Dial indicator tests for this but you have to remove the wheel to do the test.

That "mirror smooth" surface on your rotor is a good thing. "the disk almost looks like it has a light coat of grease on them" might be an optical illusion. Take a clean cloth and see if there really is a light coating of grease on the rotor. If I know grease and dust....you'll get something to confirm whether the rotor is contaminated or whether your rotor is a "mirror" smooth surface.

[petejw]

Hi Larry,
As bikerphil said, rub the rotors with sanding paper,
it wont hurt the rotors at all, ive done it using an orbital sander.

Did you install new pads? new pads need bedding in.

And as John said,try bleeding the master cylinder, i do it on the bike
with a rag wrapped around the banjo bolt to catch the brake fluid.

With the pulsating, the only thing that could cause that is a warped disc,
how do the wheels free turn when the bikes jacked up?

[XJOK2PLAY]

TDodge7,

A friend of mine suspected he was having the same issue w/ one of his newer bike's rotors being warped. It was under warranty, so he took it to the owner/ mechanic of the bike dealership to see about having it replaced. He took a 5" section of small wire, bent a 90 in it, held it against the fork firmly and placed the tip against the rotor, (bike on center stand) and spun the tire. If the rotor is warped bad enough to pulsate the brake lever, you'll see & hear the wire intermittantly scraping the rotor. If not, it'll stay against it all the way around.

Pretty quick & easy way to confirm one way or another, w/o having to tear it down and putting it on a lathe.

JAT.

[TDodge7]

yesterday i got some more work done on the xs . painted my top triple tree , put on new bars , grips , and mirrors , new shocks , i have a new seat cover that will go on soon . anyway i worked on the brakes some more too . tightened 3 loose rotor bolts , removed both calipers , lightly sanded the pads , brake cleaned the hell out of the rotors . re-bled just to make sure (since my bleeders love to weep fluid if i don't wrench the hell out of them ) and took her for a spin , i'm still getting pulsating and the disks still look like crap even tho they're clean . there's almost no stopping power . i don't have a center stand yet or i'd be able to try the wire trick . here's some pictures of the disks , the last one is the rear to show the difference , the rear is mostly mirrored with a stripe or two of whatever makes the front ones look so bad . also some pics of the bike just for the hell of it .

[Ivan]

Severely warped rotors will cause loss of braking power, but I would suspect if they are that bad on a scoot, it would nearly break your fingers trying to squeeze it. The pulsation in the handle is a good indication that you have a warped rotor though. If you were running with some of the bolts loose, the uneven torque will cause the rotor to warp.

Are your calipers floating on the pivot properly? It could be that the caliper is not self adjusting and you are only getting pressure from one pad on the disk. Also, check the side that has the pinch bolt on the axle, and make sure that rotor is centered in the slot of the fork. One other suggestion, you might have a stuck piston. I would pull the calipers with the pads still in place to keep the piston from coming all the way out, and gently squeeze the lever several times to make sure that both pistons move correctly.

Basically if you have good lever feel and no brakes something is blocking fluid flow or keeping the pistons from moving freely.

[TDodge7]

both calipers are floating and working just fine , but it's like the pads just slide on the disk without grabbing it , and the pulsating of course .

[Larrym]

Basics..

Thanks for the pics. It's always nice to see the bike being cared for. I can truly appreciate your concern with the fact that now the bike runs down the road under it's own steam you'd like to be able to come to a controlled stop. (That's half the fun cause then you have to accelerate again!)

It's fundamental that the pressure you exert on the lever is transfered to the pistons/calipers-to the pads-to the rotor. This pressure then stops the rotor due to the friction co-efficient of the pads on the rotor. If in fact the pressure is being transfered properly from the lever to the "pinching" of the rotor by the pads then all that's left is the lack of friction between the pads and the rotor.

I take it that you have degreased/cleaned the rotors with brake cleaner and wiped them off. This leaves the brake pads themselves as the likely suspect. Unfortunately the only way to determine if the pads are the bad guys here is to take the pads off and replace them with new ones. If the brakes work like they're s'posed to after this then it confirms that the pads are bad and need to be thrown away. (You can put them back on to confirm that they were indeed the problem but only guys like me are anal enough to do that sort of thing...)

As far as the Pulsating goes, I believe that this just ain't natural. I don't have the slotted rotors and mine don't pulse but if the slots are done right then it shouldn't be an issue. The lack of a center stand really is a stumbling point here. If my brakes did what yours are doing (pulsating) I would remove the front wheel entirely, remove the rotors themselves, and check the rotors for warpage along with ensuring that there isn't anything between the rotor mounting surfaces and the front wheel. While I had the wheel off I'd re-pack the front wheel bearings as well.

Yup. Sounds like a lot of work. But it's all just part of doing what's needed to make sure everything is right before hitting 90 MPH and trying to stop the bike's forward motion.