In the immortal words of Mona Lisa Vito, "What a F***ing nightmare!"
I really dislike Avid brakes. All I needed to do was put a longer hose on the back brake. Avid doesn’t make one long enough. Mike and Shawn hooked me up with some stuff from Jagwire.
I finally got the hose replaced and everything bled. I have to say that Hopes are looking better and better all the time.
Okay. Got that out of my system. Now I can talk intelligently about tonight's process.
The replacement hose made by Jagwire is a hair thicker than that made by avid. The hardware for the caliper did not fit properly. I managed to wiggle the locking sleeve over the hose in just the right position so that everything would go together.
The locking sleeve wouldn't screw into the lever. It felt like the threads were the wrong pitch. I took the original locking sleeve and it threaded right in. These are supposed to be one-time-use, so I didn't want to use the old one. I tried one locking sleeve without the hose in it and it didn't want to screw in. These are spare parts MADE BY AVID for AVID Juicy 7 brakes. It ended up that the locking sleeves are not machined or cast accurately enough to match the threads on the caliper.
Out comes Mr. Dremmel. With a wire brush attachment, I cleaned the threads on the locking sleeve. I even buffed them a little to make sure they were smooth. The threaded right in. I used a claw foot wrench that SRAM includes with the bleed kit to attach the locking sleeve. The clawfoot wrench strips. Luckily the sleeve is okay. I finish tightening with my snap-on clawfoot wrench. On the very last turn, the locking sleeve starts to strip. I figure it is tight enough. It has taken me an hour to get to this point. I sure as hell am not going to take this out and start all over again.
I attached the rest of the hose and the Jagwire banjo fitting went perfectly into place on the brake caliper.
Now its time to bleeeed.
Avid's instructions seem okay, though I think they're out of order if you're replacing the hose. I figured you'd have to bleed the hose first if you had no fluid in it. I went with Avid's instructions. I figure they know what they are doing. They say to bleed the caliper first, then the hose, then the lever. That would probably work correctly if the hose had fluid in it. It didn't. Bleeding the caliper just sucked air out of the hose.
Soooo. I bleed the hose first, then I bleed the caliper. I then bleed the hose again. Finally I bleed the lever. There is no freaking air in the system anywhere. I move everything back where it should be and HOSANA! I have achieved brakes again. The hose is even the right length.
There's still a major design flaw with these brakes. The way the bleeding is set up, there is no way to easily flush the fluid from the whole system. Bleeding the caliper requires a suck/push/suck/push method that just wiggles the bubbles out the top.
DOT brake fluid absorbs water. When it absorbs enough, it breaks down and won't compress properly. It boils easily and introduces bubbles into the system. No braking system I'm aware of is immune to this. Car brakes are much more robust than mounain bike brakes and they require flushing the fluid every other year (though few people do this).
From what I can tell, flusing the fluid in the caliper requires dismantling the caliper and breaking it open to dump out the fluid. While you're in there, you might as well replace the seals. You then put it all back together with no fluid in it. Hook up the bleeding syrenge and suck/squirt/suck/squirt until you suck all the bubbles out and squirt all new fluid in.
No thanks. I'll run them for a while then sell them to someone who loves Juicy 7s. Once I can afford Hope MX4s, that's what I'm getting.
Sorry for the rant.
Pete.
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