Front brakes pulsating?

[G21forme]

So I did the pads and lines over the winter and they felt awesome, unfortunately as of late they have been pulsating from 5mph to a complete stop. At speed they feel fine and this is after 2 trackdays and 3000 if that helps, thanks in advance.

eta

Ok Stupid me should have done a search first so it looks like I have a ton of things to check, I just can't get why i only feel it 5mph-stop? And that they felt great last week?

[Jim]

could be shitty pads, happened to me last season. or a slight warp in your rotors. try to find someone with your bike & see if they'd swap pads, rotors, then wheels for road testing purpose....go from there

also, front wheel could be out of balance.

[Currently]

Find out what the spec is for your rotor thickness ... they may be worn down and start warping when they heat up.

Pulses usually mean worn rotors.

[Uncle Snake]

Slow speed pulsing can also come from sticking piston(s) in your calipers.

[G21forme]

Slow speed pulsing can also come from sticking piston(s) in your calipers.

Good to know, I pulled them apart and cleaned/serviced them when I did everything else.

Now for the dumb question, I washed my bike about a week ago (I never wash it) and it's probably a coincidence it started right after but there was a bit of rust here and there and am wondering if it's possible I gummed them up?

[TheIglu]

Your buttons (little round dealies that hold the rotor on your rotor carrier) are gummed/frozen. You should be able to turn them by pinching with two fingers on opposite side of the rotors and turning. If you can't, they probably need some love.

Blast them with brake cleaner, turn them with your fingers, repeat. Mind the brake cleaner near your bearings.

If they are stiff/frozen, then your rotor can't "float" any more.

Also, the other situation typically is that you have a spot of grease/residue on part of your rotor, usually the bottom when you wash the bike or where the calipers/pads hide the rotor from being washed. If both have a little leftover soap/grease in that one spot, you'll get pulsation at slow speed since the brake pads won't have as much grab right there. Get your front end off the ground and use a nice clean rag/paper towel, spray a rotor liberally with brake cleaner and spin the wheel while holding the rag to one side of the rotor. Repeat. Then repeat again. Keep doing it until your rag isn't pulling off any color. Then do the other side. Then when you think you are done, do it again. Then use a new white paper towel and repeat. Do this until you are sure they are clean. Then do it once more.

Let us know how this works out.

[DuncanMoto]

Greg.
Are you using HH pads on factory rotors?
It does sound like it could be a button issue, but I have the same pulse in my rotors.
High heat from the track warped mine slightly. It only pulses when cold.
There's a reason why Galfer and EBC rotors are made of thicker, steel carbide.

[Uncle Snake]

Greg.
There's a reason why Galfer and EBC rotors are made of thicker, steel carbide.

Huh? Galfer rotors are made from 420 Stainless steel. It's got a higher carbon content than many stainless' but no carbide. I don't know about EBC....

[darkduc7]

Your buttons (little round dealies that hold the rotor on your rotor carrier) are gummed/frozen. You should be able to turn them by pinching with two fingers on opposite side of the rotors and turning. If you can't, they probably need some love.

Blast them with brake cleaner, turn them with your fingers, repeat. Mind the brake cleaner near your bearings.

If they are stiff/frozen, then your rotor can't "float" any more.

Also, the other situation typically is that you have a spot of grease/residue on part of your rotor, usually the bottom when you wash the bike or where the calipers/pads hide the rotor from being washed. If both have a little leftover soap/grease in that one spot, you'll get pulsation at slow speed since the brake pads won't have as much grab right there. Get your front end off the ground and use a nice clean rag/paper towel, spray a rotor liberally with brake cleaner and spin the wheel while holding the rag to one side of the rotor. Repeat. Then repeat again. Keep doing it until your rag isn't pulling off any color. Then do the other side. Then when you think you are done, do it again. Then use a new white paper towel and repeat. Do this until you are sure they are clean. Then do it once more.

Let us know how this works out.

i think your buttons may need some love. thats how i fixed my slow speed pulsing. when youre hauling along, there is enough force to move your rotor like its supposed to, at slow speed the rotor might not move, causing pulsing.

[Cheese]

Also, the other situation typically is that you have a spot of grease/residue on part of your rotor, usually the bottom when you wash the bike or where the calipers/pads hide the rotor from being washed. If both have a little leftover soap/grease in that one spot, you'll get pulsation at slow speed since the brake pads won't have as much grab right there. Get your front end off the ground and use a nice clean rag/paper towel, spray a rotor liberally with brake cleaner and spin the wheel while holding the rag to one side of the rotor. Repeat. Then repeat again. Keep doing it until your rag isn't pulling off any color. Then do the other side. Then when you think you are done, do it again. Then use a new white paper towel and repeat. Do this until you are sure they are clean. Then do it once more.

I've heard that rotors don't warp as often as we think. Instead it's as you mentioned, the rotor surface develops inconsistencies which causes pulsing and confuses us into thinking they're warped. Anybody else hear this or want to call complete BS?

[G21forme]

Thanks everyone! I'll give them some TLC as soon as I pull the bike out of the back bedroom LOL, and yeah Ted I'm running the galfer HH pads on fact rotors.

Hoping it's a simple cheap fix

[RandyO]

I had low speed pulsing on my SV once, turned out not to be warped rotors or sticky pads or anything to do with the brakes, it was a bent (not visible to the eye) front wheel

had the wheel repaired at McWheel over in Swansey, fixed the pulsing

[DuncanMoto]

Thanks everyone! I'll give them some TLC as soon as I pull the bike out of the back bedroom LOL, and yeah Ted I'm running the galfer HH pads on fact rotors.

Hoping it's a simple cheap fix

It is a free fix......
Just don't go slow and they won't pulse.

[DuncanMoto]

But seriously folks.
HH pads need a certain ammount of heat to give full bite. If you're talking about pulsing on the street, let me know if they pulse once you've had a couple of warm up laps at Loudon.

[Degsy]

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Find out what the spec is for your rotor thickness ... they may be worn down and start warping when they heat up.

Pulses usually mean worn rotors.

I have never, ever seen a bike rotor worn anywhere near minimum spec. And pulsing from the front end is almost never warped rotors.

The clue was in his post about cleaning the bike. There is an area on one rotor where the surface is contaminated with something (oil, cleaner, rust etc) and it has got into the steel. A good cleaning with brake cleaner might fix it. Might need a beadblast or light sanding to fix it. I can't tell you how many warped rotors I have seen that are perfectly straight once I get a dial gage on them.

[Currently]

My spare set of wheels have rotors with 42k miles on them are at less minimum spec.
There is a ridge on the outside that measures .18 inches with a vernier caliper but if you use a micrometer and measure inside the ridge, they are at .151 and minimum spec is .16 inches or 4mm. Factory manual calls it a service limit. <shrugs>

My other set that is on the bike has .176 inches and they have about 16k miles on them.

Wear seems to be accelerated when you use the racing compound brake pads. I plan on replacing those rotors with Galfers this fall.

Bedding the pads when I swap wheels shows noticeable performance difference for about a tankful of fuel.

[Degsy]

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I stand corrected. I have never seen a set worn that bad.

[Jim]

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I stand corrected. I have never seen a set worn that bad.

I was just thinking about that honda dirt bike that you replaced the rear rotor

[Currently]

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I stand corrected. I have never seen a set worn that bad.

You do have a point though ... they still don't pulsate unless they get very hot. Even though they are that badly worn. They do heat up quick though.

I was waiting for them to pulsate to change them. Someone told me that Galfer is having their Xmas special in July.

If I can come up with the money, I may do it at the end of this month.

[Degsy]

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I stand corrected. I have never seen a set worn that bad.

I was just thinking about that honda dirt bike that you replaced the rear rotor

Ok. I have never seen the rotors worn past the service limit when the bike owner used brake pads. If they elect to stop the bike using just the brake pistons then anything can happen.