Triumphrat

Mojoinco · 07-22-2008

Hola all,

I have a TBS that has always had some degree of mushy front brakes. It doesn't seem to matter how much fluid I bleed through it, how I position the master cylinder angle, or the forks (left/right on the side stand) for the union (crossbar) tube. That includes periodically tilting the master cylinder and trying to work out any bubbles sitting at the banjo joint (sometimes you get a pocket there that just will not bleed out except by working the bleed off ports in the master cylinder -- very small movement of the lever).

I recently had to change the left caliper pads due to significant wear versus the right caliper. Today I verified that the left caliper doesn't appear to be sticking, though it is snug (what I would consider acceptable) versus the right caliper being loose (clearly a slight gap betwee the rotor and pads). I can see both calipers 'torque' or twist as I apply the brakes (meaning they move a bit as the caliper moves on the pins). These calipers are 2 piston floating calipers (meaning the pistons are on the same side).

The only thing (other than fluid changes) that has been changed is a new upper brake hose (braided teflon line).

It has been more or less mushy the 3 years I have owned it. I am really tired of having non-linear brakes (the last 1/4~1/2 inch of travel they come on strong, though confidence may sometimes make you give it a couple of pumps prior to a ride).

I know these are the same pads as a Honda Hurricane (CBR600F2 or 3), so I find it likely the calipers are probably the same.

Years ago I had a HD FLH that had a similar problem and got some help -- the mechanic bled the brakes backwards (pressurized the fluid from the bleeder back through the master cylinder). Messy, but it worked (a lot simpler system -- one caliper, one hose).

Any ideas?

KitNYC · 07-22-2008

I replaced the twin-pot floating calipers on my Trident with 6-piston Tokicos from a ZRX. It made a world of difference, as did going to braided stainless lines all the way around. It's a well-known mod for the sporty T3 bikes; the only problem I could see with a TBS is finding floating rotors to fit. I used Trophy rotors on my 'dent, not sure if they'd fit yours.

HTH, good luck,
-Kit

bradtx · 07-22-2008

Mojoimco, One of the 'fixes' is to pull the calipers, extend the pistons and clean with a brush and brake cleaner...works well on the Daytonas here. You may find that not all of the pistons extend properly.

Brad

Jhumphrey · 07-23-2008

I think Brad nailed it, pull the calipers and extend the pistons or remove completely and clean. Reassemble, and check bleed once again.

Mojoinco · 07-24-2008

Worth a try!
Thanks, Michael

Mojoinco · 07-24-2008

...And the try is complete. No changes, nothing apparent on disassembly. I wonder if I should try a different master cylinder or see about getting a rebuild kit. As the stock brake lines are already teflon, new lines wouldn't seem worthwhile (and the upper hose was replaced when I replaced the bars for a shorter reach).

Might have to head to the junkyard and see what I can find (maybe a larger diameter piston).

Mojoinco · 07-27-2008

Went to the local junk yard and bought a master cylinder from a 1998 Kawi 600 posrt bike (ZX600?). 5/8" bore, plastic remote reservoir. The lever has 5 detents, but the whole lever assembly swaps from my bike (4 position). Definitely applies the brakes with less travel! Now to take it for a test drive. Easy swap, just needed a clamp (adel style) for the handlebar (will finish it off with a planned handlebar swap as the hose could be shorter and the reservoir mounted closer).

Mojoinco · 07-29-2008

Wow! As expected, more effort, minimal travel. Do wish the lever was closer to the bar, will look around for a new lever that is bent a bit closer. As I lost the Kawi lever, I can't try it for fit (fell off on the way home).