Pulsing from front wheel under slow braking?

[usherc]

Hi all... New to forum and straight in for some advice.. sorry!

Month's back I started noticing a slight pulsing from the front wheel when I was slowing down (ak7 abs).. only noticeable between about 10-0 mph, feel like the brakes are losing grip..pads were fine, tyre almost new.. so assumed Discs warped, bought new wavy discs and pads and set about changing.  During the disassembly I noticed the left caliper had a completely seized pot, took it to a local garage and they charged me £100 to rebuild (fought them apparently).. when I got it back I refitted everything.. although the caliper slider/bracket still seemed pretty tight and I noticed that the previously seized pot didn't move as much as the other, but it is the one further from the fluid inlet so is that normal?

Anyway.. you've guessed it, about £250 later.. it's still pulsing!, gave the discs a good clean, no oil or shiny spots.. any ideas, could it be the wheel bearing?.. doesn't seem to have any play?.. is there a way for me to test ride without one of the calipers fitted so I can identify if that's definitely the problem?

Damned Frustrating.. any suggestions gratefully received!

Cheers

[frez]

I had the same on my wee. The mechanic checked the disks, calipers and pads and it was all fine, so I lived with it.

[kwackboy]

Sorry to hear you have problems.
Are you sure the should is from the front end ...? , sounds can be quite confusing and in some cases the problem can be at the rear .
wheel bearings can make noises even with no play in them , id suggest after all the money you have spent your next move would be to replace wheel bearings .

[spender]

I had an MOT advisory for pulsing brake...not front but rear !

The mechanic explained to me that the usuall reason is corrosion between the disk and its backing mount... he took disc off cleaned up the mating faces and all o.k.......hope this helps

[usherc]

Cheers for this chaps.

Yeah might look to do the bearing anyway.. see they're quite cheap to buy, what are they like to fit? I have no probs getting the wheel off (will look to clean mating face between disc/wheel while I have it off).. but are they difficult to press in/out.. would I be better walking the wheel into a garage and just getting them to do that?

know what you mean about the symptoms being a bit misleading.. I had thought I maybe feeling an unevenly stretched chain throwing a bulge round when I came off the power, but as it was close to limit, I replaced and pulsing still there..

Still suspicious of the rebuilt caliper, cause of how they'd said it fought them.. could they have damaged it.. could the bracket not sliding smoothly be causing?.. toying with the idea of disconnecting from mountings, putting a shim in between pads and cable tying it out of the way and going for a careful test drive.. appreciate the brakes won't be up to much with only one caliper/disc... but if no pulse, surely I've narrowed it down?

[Mick 85]

Worth a try. Make sure the loose caliper is well wedged between the pads. Do it on a sunday, on a quiet straight road, dry conditions, someone walking ahead with a red flag  etc etc etc

Might be worth checking the speedo sensor as well - mine needed some grease a while back, showing some of the same symptoms.

[usherc]

Speedo sensor's a shout.. I know it's not up to much cause the readings it gives are a bit dodgy.. If I pull away with some "intent" it reads 0 then bounces up a few secs later.. it hadn't occured to me that if it's failing internally the rotation could be uneven.. guess that's just a question of pulling it, then giving it a spin.. is the plug end under the tank easy enough to get to if I need to replace?

This place is a wealth of good ideas.. Thanks!

[Mick 85]

It routes up under the tank - the link below has pictures. But if it is the sensor, just a bit of grease on the sensor itself  (in the front axle) did it for me.
http://www.vstrom.info/Smf/index.php?topic=13622.0

[TLPower]

If you have a friendly MOT station, ask if you can put the bike on their brake tester. Clamp off 1 brake pipe at a time, there by isolating each caliper and hopefully showing which caliper/disc is causing the issue.

Or you could do the same and try it on the road. (Very carefully).

If it persists, remove the front brake lever and just rely on engine braking and the rear brake.........

[greywolf]

If it persists, remove the front brake lever and just rely on engine braking and the rear brake.........

You forgot the  

[krisv]

Hi usherc. I had the same problem. It was due to too much grime or a bit of rust between the disc and the bobbins which allow the disc to float. Simple fix if this is the problem. Take a bolt which would go through the bobbin and its matching nut.. Insert it through the bobbin and hand tighten it. get a can of brake cleaner. use a ratchet to rotate the bolt (make sure the bobbin rotates too) while spraying brake cleaner till the bobbin moves freely and then some more... and use a clean rag to wipe the rust/grime up.. Do it for all the bobbins (both discs) and this should go away. If this does not fix it, then there is something else wrong.