Triumphrat

10-31-2006, 10:32 PM

My 1998 TBS with 29K miles has a weird problem. On cold mornings, the front brakes drag. As temps increase, the dragging disappears. This morning (39 degrees F), I tried to go for a ride, and found the front wheel to be almost completely locked (I took the car instead). By the time I returned from work (65 degrees F), the front wheel turned normally. No drag was evident even though I had done nothing. It's almost as if the brake fluid is expanding during cold weather, pushing the pads tight against the disk. Other than this problem, the brakes work great - no squeal, weakness, or sticking when warm. The pads were replaced at 22k miles two years ago. Does anyone have any suggestions or similar experiences? Thanks.

Mojoinco · 11-01-2006, 12:05 AM

I'd pull the calipers, then try and figure out which one is havng the problem. Then I'd probably change the fluid. You might find you have a binding piston and can go from there (rebuild kits shouldn't cost much; you may be able to clean the bore and reuse the two seals). I think the crossover parts list shows this to be the same as a Honda application if the dealer is too hard (or far away) to get one.

11-01-2006, 06:41 AM

Thanks. Do you know if it is possible to get new caliper pistons? Also, do you have the link for the crossover parts?

Normandy · 11-01-2006, 12:45 PM

If you find the brake is being applied by fluid expansion, the problem will be the return in the master cyl - not the wheel cyl.

Mojoinco · 11-02-2006, 03:06 AM

Look at the fiirst item in the listing for this forum. You may have some luck looking at bikebandit.com for drawings.

Speed3 · 11-02-2006, 07:08 PM

I have an easy solution that might work. Pull your calipers one at a time. Remove the pads. Put a socket between one set of pistons, holding it there with a pump of the lever. Pump the other set of pistons out until you see the ring of dirt,etc. Take a flat screwdriver, some brake cleaner and with one of your wifes best towels wipe off the dirt from the pistons. Repeat with the other 2, and then do the other side the same way, and you'll be amazed at the improvement. Do this every few thousand, and you'll be good to go.

[ This message was edited by: Speed3 on 2006-11-02 17:09 ]

11-02-2006, 09:22 PM

Regarding "I have an easy solution that might work. Pull your calipers one at a time. Remove the pads. Put a socket between one set of pistons, holding it there with a pump of the lever. Pump the other set of pistons out until you see the ring of dirt,etc. Take a flat screwdriver, some brake cleaner and with one of your wifes best towels wipe off the dirt from the pistons. Repeat with the other 2, and then do the other side the same way, and you'll be amazed at the improvement. Do this every few thousand, and you'll be good to go."

Thanks, but I tried that already to no avail. Does anyone know if the caliper pistons are available separately?

HeyMan · 11-03-2006, 09:08 AM

Yes they are. You can get just the pistons or a piston and seal kit. The pt nmbr for the kit is 2020050-t0301. It's about 75.00 I think

PaloAlto · 11-05-2006, 06:45 PM

I don't know that you've isolated the problem to the pistons. I appreciate the desire to 'do something' but what you've laid out doesn't necessarily point to the pistons/seals.

Since you exercised your pistons (as in your last post), sticky pistons/seals isn't likey the problem. And the stickly piston/seal problem causes soft brakes - it isn't possible for them to create enough force to nearly lock the front wheel.

Re brake fluid expanding: brake fluid is designed to NOT expand or contract with temperature changes. It's thermal coefficient of expansion is very low. Think of the problems in braking if its volume were to change much as brakes go from temperate to very hot in track conditions.

In addition, unless the master cylinder has failed, it's not really possible for the fluid to be under pressure when the brake lever is at rest - the check valve to the brake reservoir will be open.

A test to see if the brakes are indeed the problem would be pull the pads out when the bike is warm and working normally - this will ensure the pads CAN come out.

Then try to pull the pads out when the bike is in its locked mode. If you can pull the pad and the bike still doesn't go, then it isn't the brakes.

If you can't pull the pads when it's cold, then it is likely there's something going on with the brakes.

Another possibility is wheel bearings (?).

Good luck,
Bern

11-24-2006, 04:22 PM

Problem solved. The right front caliper was defective. A $15 used replacement solved the problem. Brakes no longer stick but still stop great.