Brake Bleeding

[2LZ]

Hey gang,
After it made such a huge difference on the TT250, I opted to bleed the brakes on the RX3 last night with some good quality DOT 4. Now, between the two bikes, the TT seems to have had either a really lousy DOT 4 or a DOT 3 in it, while the RX3 calls for DOT 4 right on the master cylinder plate. I wasn't sure how much difference bleeding would make but it was worth a try just to know that the stock stuff was flushed.

I can say that I got about the same response from the RX3 as I did the TT250. From spongy to solid...and most importantly, for the first time since I've owned it, the front brake feel much more normal. It has yet to pulse or chatter like it did on occasion prior to replacing the fluid....but I've only been on two rides so we'll see. So far, I'm seeing a great improvement. I'd suggest doing this if you haven't already.

[detours]

Good call on the brake bleed, 2LZ. That's going on my list.

How many miles do you have on your RX3? Was the RX3 brake fluid burnt or discolored?

[2LZ]

Originally Posted by detours

Good call on the brake bleed, 2LZ. That's going on my list.

How many miles do you have on your RX3? Was the RX3 brake fluid burnt or discolored?

Not a lot so far because I've been really concentrating on the TT and putting break-in miles on it. I think I'm up to about 1000+/- on the RX3? It's tough to chalk them up spending 3 hours a day in a car super-commuting. Really puts pressure on the evening riding time, especially around wrenching projects.

The fluid looked ok compared to the slightly milky stuff that came out of the TT. A little funny colored compared to the Napa DOT 4 I swapped it with though. The RX3 must come with DOT 4 due to that's what the master cylinders indicate....but I'm sure it's not the best stuff.

I took it out again yesterday after some more baffle testing and it helped. The front again, has yet to chatter or pulse like it had been....though it's not like "throw you over the bars" braking. I think inherently, either the disk is too small or I'm more inclined to think that the master bore is to small.... The new, more firm feeling fluid helped though.

Hell, the front you can basically gravity bleed. I had it all swapped out before Mrs. 2LZ got home to help me with the last "open/close" routine to finish it off. The rears you can do by yourself because you can reach both the caliper and the master. Just make sure and run a vac line off the bleeder screw into a can or cup so it's always submerged.

[BlackBike]

2lz 1.5 hrs that would about put you into sac for work. Each day? Take care man ( hard working man Brooks and dunn. I'm burnin' my candle at both ends 'Bout the only way to keep the fire goin' Is to outrun the wind)

Detours, like your avatar, "Red 5, treading water" BATTLE TESTED !

[Lee R]

I managed to boil the stock fluid practicing hard stops on my RX3 and completely lost the front brake until it cooled, I'd recommend everyone change that stuff out, especially those who are in traffic or the mountains.

[rjmorel]

I bled and replaced brake oil in my RX3 just now. Old fluid was still clear. My F brake master cylinder says to use quality Dot 3 or Dot 4 ???? So I used Prestone Dot 4 synthetic. My only observation is the front seemed like it was never bled ???? as it took a number of pumps before anything even came out the bleeder. They have always worked but been spongy and not like other brakes I've had on motorcycles. Early on I had the rotor stuttering problem. Replaced rotor and pads and its worked all this while but not as good as I liked. The rear brake always worked better and oil came out as soon as I cracked the bleed screw. I will go try it in a few minutes on the way home and report back tonight after I'm home from some meetings. rj

[2LZ]

Originally Posted by rjmorel

I bled and replaced brake oil in my RX3 just now. Old fluid was still clear. My F brake master cylinder says to use quality Dot 3 or Dot 4 ???? So I used Prestone Dot 4 synthetic. My only observation is the front seemed like it was never bled ???? as it took a number of pumps before anything even came out the bleeder. They have always worked but been spongy and not like other brakes I've had on motorcycles. Early on I had the rotor stuttering problem. Replaced rotor and pads and its worked all this while but not as good as I liked. The rear brake always worked better and oil came out as soon as I cracked the bleed screw. I will go try it in a few minutes on the way home and report back tonight after I'm home from some meetings. rj

Great news. I hope you notice a difference I have. Like I stated earlier, I just ran a vac line off the bleed screw into my measuring cup, opened the bleeder and let it gravity bleed for about 5 fills of the master (almost 3 oz). Then finished with the "open/closed" procedure when my helper showed up. Piece-o-cake.

Look forward to your report. Mine felt more firm, less spongy.

[rjmorel]

Well, after riding it I can't say I see too much difference. Feels more solid on the lever but still mediocre braking. Probably as good as my old DR650. Won't be doing any stoppies with it but in a way that's probably a good thing as if I have to cram on the brakes in an emergency my front tire won't lock up . Plenty good enough for the riding I do, rj

[2LZ]

rjmorel is about right on. I did about 4 hours of "dang hot" today. Did lots of twisties plus some local traffic in town. Got everything real hot.

The plusses:
The pedal and hand brake feel more firm, better, less squishy.
When not super hot, they do seem to work a little better. No real shutter, squeak or pulsation.
Mentally, I know it's good fluid in there now doing the best it can.

The minuses:
When hot, they still braked ok but that dang vibration sound and squeak came back. No pulsation though.

This is mind boggling, especially with the sintered pads. Q, while lighter, has a MUCH smaller front brake and it will almost put you over the bars.

[detours]

I just changed the front and rear brake fluid on the RX3 with new DOT 4. Easy job with my vacuum bleeder, but the rear cover bolts were hard to get to. I used a bit holder with a 1/4" u-joint to get in there. But it was still hard not to strip them.

Warning: the rear reservoir empties much quicker than the front. So keep it filled and don't let air in the lines like I did. I essentially had to bleed them twice, but the rear line is so short it was fast.

I still need to test them and we'll see if the brakes improve.

[detours]

It may be wishful thinking but I think the front brakes are stronger now. They feel the same at light modulation, but on firm stops, they have more grab. The rear was always strong and didn't feel any different to me, but it was good to fill the reservoir to the correct level.

Definitely worth doing if you're on the fence.

[2LZ]

Originally Posted by detours

It may be wishful thinking but I think the front brakes are stronger now....but on firm stops, they have more grab. Definitely worth doing if you're on the fence.

Thanks for mentioning this. I was wondering if it was wishful thinking too...but when not super hot, the front does seem to grab better under hard stopping.

Does anyone know for certain if the front brake upgrade truly "fixes" the issue? I'd hate to spend a bunch of $$$ on something that's just a mild improvement. For how inexpensive the CSC parts are, the big front brake is an investment.

[rjmorel]

I'm wondering if a SS brake line would help the front brake. Maybe the stock oil brake line is ballooning some on hard stops and not applying all the pressure it can to the pads ? The TT250 has one I think. rj

[detours]

I thought we already had SS brake lines. At least the original specs listed them as SS. That may have changed in production. Does anyone know?

[Juanro]

I think the brake lines of the RX3 are in fact Steel braided? They're too thin for a plain rubber line.