Re: [ST] Brake pulsing

["collett_mc" <collett_mc@xxxxxxxxxxx>]

I used to have the same problem.  This explanation might not make sense, but
it's what I went through.

I had the 'pulsing' problem, I thought it was the brakes.  But I wasn't
convinced, because when I would brake and feel the shuddering, sometimes I
could let off and then brake hard again and the shuddering wasn't there.
Weird.  At first I thought that if it wasn't the brakes, maybe it was my
unevenly worn front tire (it started to get an uneven wear pattern in the
center).  But that wouldn't explain the on / off behavior.

Around this time I started to notice how the front brakes really lacked
power.  16k miles on the machine.  So taking the advice of fellow listers, I
cleaned the front brake pistons (little bit of brake cleaner, toothbrush, a
rag, and some squeezing out / forcing in of the pistons).  I also put on a
brand new front tire.

Results:  No more shuddering, (and much more powerful brakes now).  I don't
think changing the front tire fixed anything, it would have been nice to do
the tire and brakes separately just to see, but I like to keep the tinkering
to a minimum and the riding to a maximum.  Theory: the same problem which
causes weak brakes after time (dust buildup, causing pistons to stick) also
caused my brake shuddering.  The pistons were sometimes not squeezing the
pads evenly, which gave the pads enough room to move around and vibrate.

Just an idea, but I do know that my problems are 'fixed' for now.  I'll just
keep cleaning the pistons on a regular basis.

Mark Collett

Proverbs 3:5,6

><//>
- ----- Original Message ----- 
From: "Craig Moddle" <sailnorth@xxxxxxxxx>
To: <ST@xxxxxxxxxxxxxx>
Sent: Wednesday, December 10, 2003 5:03 PM
Subject: [ST] Brake pulsing


> Ok, this is my third try posting this message. See if it goes through this
> time
>
> >>> Hey folks,
> My mechanic and I are working on this but no luck yet. It's turning into a
> bit of head scratcher.
>
> When applying the front brake I'm getting a pulse or grab happening. The
> timing of the pulse changes with speed, so pretty much sure it's wheel
> related (pulse slows down as speed decreases). My first thought was .....
> something on the rotors, but no they're clean.
> Then I thought warped rotors. Mechanic checked them by mounting the wheel
on
> the bench and dialing them in. Yes slightly out (7thou. & 9 thou.) and so
we
> replaced them the other night along with the front axle which was also
ever
> so slightly out. Only had a quick ride to the store & back but ...... the
> pulse is still there. A bit different in feel but still a pulse .......
>
> I'm not sure if he actually measured the rim for true when he was doing
the
> rotors, so I think we should check that. Because otherwise I don't know
what
> could be causing it.
>
> Any ideas?
>
> By the way, lucky for me he had just picked up a written off ST, so I was
> able to get the rotors & axle for less than the cost of a single rotor
from
> the shelf. And yes the rotors were good, he put them on his Speed Triple
> wheel and dialed them in, only out by something like 1 or 2 thousandths.
>
> And apologies to those snow bound list members, while it's a bit wet here,
> still very rideable.
>
> cheers,
> jcm
> '99 RS
> Victoria BC
>
>
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