Brake pulse

[TonyG]

Hi,

I have a slight pulse from front brakes when braking gently to a stop. Bike is an M1100s with 8k miles. Brake pads look good and calipers not dirty. I've read some threads that say the bobbins lock up, and to try freeing them off. I've had a quick look and not a single one seems to turn using finger pressure. Is it worth doing the bolt and nut trick to just get them turning again, or are they not suppose to turn?

Thanks for any help.

[Mr Gazza]

I don't have much faith in the stuck bobbin theory myself, but that's not to say that there's no truth in it....Give it a try.

I can vouch for the less believable theory of "variable surface texture"...To give it a name of my own.

Brake pads seem to make patches on the discs in standing, particulaly after being wet.
These patches can be felt going through the pads at the late gentle braking stage, as pulses.

The cure (from my own experience) is to use the brakes as hard as possible (and safe!), for as long as possible, after a fast blast. That seems to recondition them very easily and cheaply.

Then again you could have warped discs. I managed to check mine with a dial guage mounted on a "L" bracket on one of the axle pinch bolts, with the wheel in-situ on the bike.
The tricky part is trying to find a path round the disc for the probe, missing all the drillings or slots.

Not sure what the max run out would be, but you will feel as little as 1 thou...I found 15 thou on one of mine....I felt that alright!!!

[TonyG]

Thanks Gazza,

I will give that a go. Not too sure I believe the bobbin theory either.

[markh]

My 1100 had warped discs that were only really noticeable at very slow speed. There was pulsing at the lever and a very noticeable pulsed braking effect. The discs were within limits according to ducati but they most definitely were not right and so were replaced under warranty.

[oldie54]

I have this as well on my 09 1100s. Tried the bobbin trick which seemed to make a slight improvement but I am already thinking this is warped discs. Dial gauge next but if it is has anyone got any good replacement leads or advice? Never had this problem on any of my bikes so never had to replace a disc.

[utopia]

I've had mildly pulsing front discs on my 750 for ages ... or at least I did have.
I must've had 3 or 4 mot advisories on them too.
But they ran true and the bobbins were free so I cleaned them up with scotchbrite and then with fine wet & dry (very carefully).
They still pulsed, but less so.
Then I did a trackday (my first and only, actually) involving regular hard braking.
After that they definitely felt a little better, so I persisted with them, and took a few opportunities to brake harder than I usually do.
The upshot is that they have consistently improved and now they are perfect.
Same pads all the way through, so no influence there.
My bike had two previous owners, neither of whom did more than 1000 miles, so the discs were probably never properly "conditioned" in the first place.
Also, the bike stood unused for longish periods .. probably with wet pads on more than one occasion.
Mind you, the pulsing wasn't there when I first got the bike so maybe my analysis of the cause is incorrect.
But either way, like Gazza suggests, I think that pulsing discs can often be reclaimed by periods of hard use to (re)condition the surfaces.

Also, when cleaning the bobbins, don't spin them with a drill as is sometimes suggested as this will just cause unnecessary wear .. just turn them slowly with a bolt/nut/allen key.
Its also effective to simply stick something appropriately sized in the bobbin holes to use as a lever (I used a T-bar allen wrench with rubber tube slipped over to provide grip and prevent damage) and then waggle the bobbins while spraying with brake cleaner.

My symptoms were exactly the same btw ... pulsing under very gentle braking at ultra low speeds.
At normal speeds I couldn't feel it at all.

[oldie54]

Not sure the track day solution is for me as I have just done 2 full days at Cadwell with plenty of hard braking and this didn't seem to do it. Going to check with a gauge next.

[Darren69]

I seem to recall that there have been quite a few posts regarding 1100 front disks warping, quite a few people have had them replaced under warranty I'm wondering if there is an issue with them possibly?

[oldie54]

Would this be a one year warranty? I am doubtful they would look at an 09 bike as still under warranty, shame. New discs are looking a bit expensive I must say. And if you want the thicker upgrade ones they are £200 each!

[Mr Gazza]

I replaced the warped brembos on my 900 with Arashi contoured discs from China via Ebay.

Just over £100 for the pair and I've been very pleased indeed with them so far, in fact they just seem to get better ( I use organic pads)

A friend of mine has some 6mm "Racing" discs for sale, on a Brembo wheel for an Aprillia RSV Mille, but I have no idea if they would fit an 1100?

[oldie54]

I replaced the warped brembos on my 900 with Arashi contoured discs from China via Ebay.

Just over £100 for the pair and I've been very pleased indeed with them so far, in fact they just seem to get better ( I use organic pads)

A friend of mine has some 6mm "Racing" discs for sale, on a Brembo wheel for an Aprillia RSV Mille, but I have no idea if they would fit an 1100?

I am not a real fan of chinese industry and would be a bit miffed and contact Ducati if I could better Brembo kit with Chinese substitutes. I am reading a fair few posts about this problem which have all been traced back to calliper problems rather than disc warping so I am thinking check runout on discs with gauge I have just ordered and then have the callipers apart to check all the pistons are running smooth and retracting when the lever is released. Trouble with buying new discs might be that it doesn't cure the problem I guess.