Spongy brakes after hydraulic switch installation

I've searched the forums and tried every tip I could find to no avail. Before I messed with it, the front brake on my DRZ was excellent. Firm and powerful, one-finger operation was not a problem. Now the lever will touch the grips with a moderate to hard squeeze. I'd really like to get back the good lever I had before installation of the DRC hydraulic switch. Is it possible that the switch itself is the problem?

I've tried:

Strapping the lever overnight

bleeding at the bolt

I have used the vacuum bleeder kit combined with:

Raising the caliper above the height of the master cyl.

grease around the threads of the bleeder screw and a clamp over the rubber hose at the nipple to ensure no air gets past

Tapping on the line to get the bubbles to rise

Does anybody have any other ideas as to what I might try?

Don't know specifics of the switch you are using, but if there's a way to get a few drops of fluid into the switch before it's installed it might help.

I doubt it is the switch, you probably still have air in there.

I used to bleed the "normal" way of pumping up /releasing, but I find this way much less hassle. You'll waste a bit of fluid, but so much less hassle.

- Get a bottle of fluid

- Connect a hose about a foot long or so to the bleeder valve, and loop it in a circle above the caliper and back down to something to catch the fluid. I used zip ties to hold it.

- Crack the bleeder, then pump slowly until the fluid is at the top of the circle in the tube. This keeps air from going back in the line if you stop pumping.

- Once you get it there, you can open up the bleeder a bit more and just pump the lever. MAKE SURE to keep the reservoir filled while you are pumping so you don't suck air. Watch it, it will pump out fast.

- Once you stop seeing bubbles, I pump a little more to be sure then tighten the bleeder valve.

I haven’t had a problem since I have been doing it this way, and its quick. I can usually do both front and rear brakes with one bottle of fluid.

Hope this helps.

Go to you local phymacy and buy a syringe and a hose to fit the bleed screw fill the syringe with fluid open the valve and pump till the master is half empty the fluid can now be forced back in to the caliper by useing the syringe and be pumped out leave the valve open youll feel the air at the point it clears and see it

Don't know specifics of the switch you are using, but if there's a way to get a few drops of fluid into the switch before it's installed it might help.

The bolt appears to be a "flow-thru" design, hollow core with two small holes at the top. I can't think of a way to fill it up before assembly.

I doubt it is the switch, you probably still have air in there.

I used to bleed the "normal" way of pumping up /releasing, but I find this way much less hassle. You'll waste a bit of fluid, but so much less hassle.

- Get a bottle of fluid

- Connect a hose about a foot long or so to the bleeder valve, and loop it in a circle above the caliper and back down to something to catch the fluid. I used zip ties to hold it.

- Crack the bleeder, then pump slowly until the fluid is at the top of the circle in the tube. This keeps air from going back in the line if you stop pumping.

- Once you get it there, you can open up the bleeder a bit more and just pump the lever. MAKE SURE to keep the reservoir filled while you are pumping so you don't suck air. Watch it, it will pump out fast.

- Once you stop seeing bubbles, I pump a little more to be sure then tighten the bleeder valve.

I haven’t had a problem since I have been doing it this way, and its quick. I can usually do both front and rear brakes with one bottle of fluid.

Hope this helps.

I like this idea and will get some clear tubing tomorrow. This sounds like it will clearly show me if bubbles are still coming out. Perhaps I've given up too soon. I have only gone thru half a pint of fluid total doing front and rear. The tubing I'm using is black so I have no way of seeing what's coming out of the system.

Go to you local phymacy and buy a syringe and a hose to fit the bleed screw fill the syringe with fluid open the valve and pump till the master is half empty the fluid can now be forced back in to the caliper by useing the syringe and be pumped out leave the valve open youll feel the air at the point it clears and see it

I'm a bit confused about this process. Are you recommending replacing lost fluid only thru the bleeder? Won't this method only exchange the fluid at the bottom of the system? What if the air is trapped in the loop near the master cyl (which is what I suspect)?

I'm not sure if this is what he means but you can reverse bleed using the syringe to inject the fluid into the bleeder and let it flow out of the master. This way the bubbles go up with the fluid instead of rising against the flow.

I'm not sure if this is what he means but you can reverse bleed using the syringe to inject the fluid into the bleeder and let it flow out of the master. This way the bubbles go up with the fluid instead of rising against the flow.

That makes sense. That is the reason I removed the caliper and elevated it above the master cyl. the last time I tried to bleed. I'm now convinced that I just wasn't patient enough and needed to run much more fluid thru the system. A clear hose will tell me if I'm getting results or simply wasting fluid. I'm hoping to get to buy some tubing today and give it another go.

You will be amazed at how long it can take to pump up a system after disassembly. I rebuilt my front calipers on my zx 7 last year and after 3 bleedings i still don't think it's where it could be.

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