Re: [ST] Near miss Friday - Brake question

["Daniel Wallander" <triumph99@xxxxxxxxxxxxx>]

I think the problem with the front brakes is a basic design problem.  Gunk
builds up around the pistons and doesn't allow them to move properly.  This
causes two of the pistons to not extend when the brake lever is pulled or
two of the pistons are not allowed to pull back into the caliper as they
should when the brake lever is released.  Eventually this leads to mushy
brakes.  If you remove the calipers and spray brake cleaner and brush the
gunk off, then 'exercise' the pistons, the feel comes back for awhile. 
What this cleaning cannot do is clean around the seal further inside the
caliper.

Replacing the seals in the caliper at each major service as the Triumph
service manual recommends, makes you thoroughly clean the pistons, the
caliper inside and out and gets new seals around the pistons.  The seals
help pull the pistons back into the caliper as much as the rotors push the
pistons back into the calipers.  New seals do this better.

I have about 4000 miles on the seal replacements at this point, not enough
time to fully know if this did the job or not, but, the brake lever is
still solid and brake feel is back to what I remember when new, and that is
that this Triumph has very fine brakes.

Dan Wallander
www.danwallander.com
VP-TSRA, IBA, AMA, ABC, HSTA
1974 R90/6    1999 Triumph Sprint ST
Albuquerque, New Mexico


> [Original Message]
> From: Blake Sobiloff <sobiloff@xxxxxxxxxxxxxx>
> To: <ST@xxxxxxxxxxxxxx>
> Date: 11/12/03 7:24:46 PM
> Subject: Re: [ST] Near miss Friday - Brake question
>
> On Wednesday, November 12, 2003, at 06:11  PM, collett_mc wrote:
> >     My brake question is this - I've got that problem with the Sprint 
> > mushy
> > front brakes.  You know what I'm talking about - no amount of bleeding 
> > seems
> > to solve it.  The lever firms up with use but then flabs out if you 
> > don't
> > use it for awhile (i.e. cruising down the road like we were).
>
> I've only found treatments, not cures.  I unbolt the calipers, pump the 
> brake lever to fully extend the pistons, spray the pistons with some 
> carb cleaner and scrub with a toothbrush.  Then I work the pistons in 
> and out of the caliper several times to make sure they glide smoothly.  
> Seems to hold for about 3,000 miles or so.
>
> Dan Wallander seems to have had better luck in replacing the seals.  
> Triumph recommends their replacement every 12K miles, IIRC, but I don't 
> know of any dealers that really do that as part of a 12K service.
>




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