Briefly: last weekend was riding and the clutch was spongy so I took it in. Shop replaced clutch fluid. I also had them change the plugs while it was there.

Picked it up yesterday. Clutch works great, but less than 2 miles from the shop the rear brake lever loses pressure. I can depress it fully with no effect. Pump the lever and pressure builds so much so that bike will barely coast (idle with clutch in).

Back to shop it goes. They say the brake system probably needs to be bleed/fluid replaced. My question is this: the brakes worked perfectly when I dropped it off but failed less than 5 minutes after picking it up. I know they’re 2 separate systems but it seems an odd coincidence that I now have brake issues after the bike is worked on.

What say you? Coincidence or did they jack it up somehow? For the record the bike is a 2004 Honda ST1300 ABS with approximately 85k on it.

I’m not a mechanic but I’ve got over 30,000 miles on this bike since I e owned it so I know how it runs/feels when things are right or wrong.

Thank you

Sounds like you might have a bad piston seal in the rear brake master cylinder

I say no connection to the bleed/flush on the clutch.

Agree, two separate systems. Flushing the brakes might help. Are you saying if you pump the brake and release it stays on or if you pump and the brakes hold until you release the lever. If it is sticking, you might have a problem with the caliper slides. If not sticking, I agree you probably have a bad seal either in the master or caliper.

If you are mechanically inclined either of these should be relatively simple IMO. If you are not mechanical, best to leave brakes to a more knowledgeable person.

I'm an automotive, not motorcycle, mechanic, so I do have knowledge of brake and clutch hydraulics, but not specific knowledge of this bike. But I have a hard time believing this is anything but a coincidence. The only thing I can think of that has any plausibility is if the brake and clutch master cylinders both share the same fluid reservoir and the reservoir was allowed to run dry during the clutch bleeding process. The former is unlikely, but the latter would be easy to do since the reservoir(s) are no doubt very small.

These kind of coincidences do happen. Just the other day I installed a door actuator in the heater case of a car and then the blower motor stopped working. I could hit the blower motor with my fist and start it again. There is absolutely no connection (pun intended) between the two, but explain this to the owner of the car.

Opinion: Coincidental failure. Happens more often than not. I can't see anyone tampering with a critical part like a braking system then turning you loose on the streets. At least in my opinion if that was their plan they would have "found" a leaking brake hose or pointed out that your rear brake was not working when they moved it around the shop. Why take the chance for you to crash just after you left the shop? Liability is too great to play those games even for a less than honorable shop. And if they were to disable your vehicle so you cannot leave that eliminates the possibility of you going elsewhere for the repairs.

I'm doubting that a brake flush is going to do much,possibly if the fluid was highly contaminated with water and the fluid got extremely hot it might boil off the water and cause that type of failure but I'm extremely doubtful this is the scenario. I'm going with a failing master cylinder.Remember, this is a sixteen year old part.

I've seen master cylinders in cars allow the brake pedal to suddenly go to the floor under braking but later all is fine. It happened to my El Camino years back. I replaced the master cylinder the next day. My advice is to either rebuild or replace the master cylinder ASAP. If it happened once even though you flush the brake fluid and it works fine it's going to happen again.

quote:

Originally posted by mojojojo:
What say you? Coincidence or did they jack it up somehow?

Did they "jack it up"? Who knows, and ultimately you have no means to prove they did anything wrong, so you're stuck accepting their position on it. This is a huge part of the reason I began doing all the repairs and maintenance on the BMW I used to own.

I will say unfortunate coincidence. Clutch fluid failing, 15 year old bike, 85K miles - if you don't know if it ever had a brake fluid change. Go get some brake fluid and replace it and see what it feels like.

Here is a guy replacing his clutch fluid on a ST1300 - as shown no connection to the brake fluid. Pretty quick and easy.


Here is a guy replacing his brake fluid on a ST1300 - again no connection to the clutch fluid. A little more work though.


Same guy that did the clutch - doing his ST1300 brakes. Different technique, than the guy using the vacuum tool, but again showing no connection to the clutch.


If you don't like unfortunate coincidences - unless someone accidentally cracked a rear brake bleeder before realizing they were on the wrong bleed fitting. That's just a guess on how it could have happened, not an indictment on this shop. I suspect there would possibly be some fluid evidence in a nipple cover it that happened.

And how are your pads?

clutch and brake systems. not related.
Assuming all they did is one, any change in the other is unrelated. But I happen to believe in circumstantial evidence. So its possible a dealer idiot briefly didn't pick the right bleeder and open the brake one. But in the end it simply doesn't matter. You have to fix the brakes and you can't prove a nor b. You should make sure the brakes work especially in a linked abs system.

Please post the outcome.
Have an 06 in the garage.