Disc pulse.

[Zombie Master]

After using disc brakes hard, or after a maximum effort stop I will not allow my wheels to stop turning, if only a bit to avoid a hot spot from occurring. Hear me now and believe me later.

[moosehead]

Steve D, check yoour wheel rim for warp....

Had same pulsing few years ago on my 82 RS...took wheel into my mates shop...discs checked out fine, flat and true as pancakes...then removed tire and checked rim...BINGO...rim had warp!

Brought in older rim...John checked it out...all OK...mounted discs and tire...went for ride.... no pulsing.

[SteveD]

Steve D, check yoour wheel rim for warp....

Had same pulsing few years ago on my 82 RS...took wheel into my mates shop...discs checked out fine, flat and true as pancakes...then removed tire and checked rim...BINGO...rim had warp!

Brought in older rim...John checked it out...all OK...mounted discs and tire...went for ride.... no pulsing.

Doing the close one eye, find a reference point then spin the wheel...the wheel seems ok.

I'll check it again. I do have another disc to replace the pulsing one.

[SteveD]

I suspect I've sorted why and fixed the pulse.

In removing the wheel and the disc, I found the large circular shiney washer between the wheel and the disc. That would put the disc further out by the width of the washer, and I'm presuming allow it to be too close to the pads and allow heat to build up.

Anyhow, a replacement disc, washers all in the correct place and my brakes are now pulseless. More life in them than before though!

#2 should be on the outside of the disc and acts as a washer for all bolts/nuts. No other washers are required. That is, if you use #2, then #4 isn't used on the five bolts. The picture might be seen as misleading as the second disc isn't there, but the second #2 is, and the small individual washers are included. I wonder if I've misinterpreted that when putting it back together? The info is in the parts list where it describes one or the other. Anyhow, just in case, others might not make that simple error if they read this.

[Jean]

Yep. they are bad to use One drawing to show ALL the alternatives...you have to read the printed table and see which arrangement your particular bike uses. Sometimes you think you lost some parts...

[moosehead]

Glad to see you got it sorted out...those parts diagrams are confusing as to what goes where. And, as Jean has pointed out, the parts list per model has to be paid attention to...

Anyways, happy braking

[SteveD]

Just as likely me being in a hurry to put it back together to get to work ....

[SteveD]

The pulse monster is returning!

Last time I made a few changes. The right disc was pulsing. The left was fine.
Things I did:
1. New disc (used but straight, no pulse)
2. Replaced the calipers with a better set.
3. New pads
4. Bled the system
5. Reassembled the lot correctly, using equal torque on the disc bolts.

The pulse was gone.
However, 6 weeks later, I'm starting to feel it return, very slightly.

The wheel rotates straight. I've even stood on the pegs to watch how straight it rotates at road speeds.
There appears to be no run-out. The disc still appears to rotate straight too, but without a dial gauge to get an exact measurement, I must presume it's not.

The wheel will rotate by itself if on the centre stand, but does slow quickly towards the end of rotation. Maybe some slight resistance from the pads. The axle bolt is not too tight, in fact I added a dab of blue lock-tite in case it might've been too loose.

I'm unsure what to adjust at this stage, in an attempt to reduce the rate of the pulse development.

[ME 109]

Are you sure it's not your heart Steve?

Perhaps try digital verniers around the discs to see if there is any variation in thickness.

[Jean]

Try lightly scrubbing the troublesome disk with some medium sandpaper. It might have some glaze on it.
Rub the sandpaper in little circular motions, not round-and-round the circumference.
Don't forget to do BOTH sides!!