Pulsing front brakes

2008 with 7000 mi. Front brakes started to pulse a while back, pulled calipers and sprayed with brake cleaner pads and all, look really clean. No rain rides on bike. Rotors are clean and look new. Any ideas?

warped disks ?

bit of crap on one of the disks is also possible... but warped rotors most likley.

Warped discs are the usual culprit for me but I've also had what felt like pulsing front brakes from worn out Michelin Pilot Road 2 front tyres which develop a curious serrated profile.

Try new pads and deglaze the discs, some brake pads deposit material on the disc surface that can cause pulsing......
Also give the disc buttons a good spray with brake cleaner, these can get full of brake dust which stops the disc floating as they should,
Might save you a lot of money

novice rider, i doubt i have ever got the disks very hot. Will try to check for true. And then try new pads if so. $160 for pads, ouch! hope it aint rotors. Will check rotor buttons as well Thanks

Try re-bedding in your brakes, it's the first thing I do when I feel a brake shimmy/pulse and has worked many times... and it's FREE!

Well checked rotors by putting zip Ty on fork and putting tag end up to rotor and spun them, they seem perfect. Spun all buttons and sanded rotors 80 grit wet/dry paper tryed to get cross grain scratches to maybe true the pads. Whent out for 50 mi blast all around Mt Tam in Marin CA unreal twisties!! 70 degreas and sunny. The new S20's are the best tyres I've had yet. no chicken strips super grip. Any way no change in brakes getting worse at slow speeds like pulling up to a red light.Thanks

Searched quite a bit and followed various past suggestions to resolve pulsing front brakes, but still with the issue. Took the rotors off, inspected the wheel for casting defects (none apparent), lightly sanded both sides of the rotors, re-torqued rotors back to wheel w star technique, even spun each of the floater 'buttons'

I don't have an accurate way to measure run-out but visually cannot see any obvious warp to the rotors when I spin the front wheel up on the stands...considering the bike has <6k miles on it, i find it hard to believe the rotors could be warped, but is there any other cause for the pulsing outside of what I've already looked into?

I'm reluctant to buy new rotors unless i've gone over every potential cause w these oem ones first

Are all the caliper pistons freely moving back and forth?

PBRnr - you can crudely measure if there is any run out using a sharp pencil. Place tip against the disc and shaft of the pencil braced against suitable surface that wont move like the fork leg or brake calliper. Then rotate the disc slowly and see if the tip moves off the disc or breaks off depending on if the disc moves away or toward the pencil......

its crude but it works - may take a couple of attempts to brace the pencil properly.

Good ideas, will check pistons and pencil runout method. Cheers!

Also - have you changed the front wheel recently?


Ignore this - i've just reread your post

I had the issue and nothing showed any signs of warping or Ill fitting rotors.

I went ahead and filed the castings and refitted the rotors, no more issues.

I think sanding is not going to help, you need to use a file.
I used a small hand smooth file and that did the trick for me.

Sent from my SM-G950F using Tapatalk

A build up of pad material on the high spots of your disc can cause pulsing, also if your worried with the alignment of the callipers to the disc, loosen the calliper bolts, hold your brake (brake lever) hard in, so pistons lock to disc, then tighten the calliper bolts while the brake is locked on, you could put a zip tie on the brake, or get someone to hold it on.

thx. I forgot to say I lightly sanded the rotors when they were both off the rim. Just today cleaned off the pistons. maybe 1 of 4 were slow but all were mobile initially. Didn't have time to take a test ride after bolting things back together today

Fingers crossed.

Maybe the next step would be to swap out the brake pads tho the oem brembos on there right now have lots of meat left...

Good to know. I don’t understand why brembo pads seem to be so harsh on rotors...on my ‘83 bmw, they eventually wore grooves into the rotors around the cross drilled holes. Maybe they’d do better on higher grades of steel? At that rate probably higher performing pads out there as well...

Tried to start bike, dead battery. Wanted to swap the lead acid for my shorai from the previous bike anyway, so did that. Took the bike to the shop to get a toolkit as the bike was missing it when I bought it.

Good news, no pulsing brakes! I think the cleaning of the rotors and pistons seems to have worked.

Bad news, bike died about 2 miles from home

Doesn’t appear to be charging the battery as it ran flat and now has not enough juice to run over.

Sigh

One kicker is that the oem toolkit doesn’t include a 5mm Allen key to even take off the battery fairing! KTM saw fit to include a bottle opener though as a final F U it seems as I sit here without power and without beverage

I tried but didn’t want to chew up the bolts so decided not to...

No wonder there’s more black and orange around my home than green