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

[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

[rtking]

Originally Posted by 2LZ

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.

The upgraded Big Brake Kit actually feels pretty darned good to me. It firms up the feel on the lever and makes it a two finger operation. It is an improvement over the stock broke rotor with the sintered pad. Just make sure to really, really clean the brake rotor well with carb cleaner (or other solvent) before mounting. That was my problem - I failed to clean it well and was not sure why it wasn't performing better. I cleaned it very well with solvent and then bed in the pads. Works great now and I get plenty of nose dive when applying a firm grip on the brake lever.

[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.

[david3921]

According to the specs and pictures the front line is SS. That means that it is a rubber hose wrapped in SS mesh. That reduces the bulging of the hose. The hose can still bulge if the mesh is not tight enough. It might be benificial to check the hose while aplying the brake to see if it bulges.

Edit-teflon is usually used as the inner core rather that rubber. I would still check the line for any movement while braking to eliminate that variable.

[2LZ]

All good thoughts and input!

I may pick up a Goodridge brake line next time I'm running errands in Sac. I ran them on my old Harley's front disks and they worked great. Not as costly as one may think either.

I do have a new master cylinder (and clutch lever assy) coming....if it ever arrives. I'm curious to see if (what's supposed to be) a larger bore may also help.

The curious part is the front rotor appears more than large enough to dissipate enough inertia and heat and the pads/caliper should be more than adequate for stopping a 250, even a fairly weighty one. It's not like we're trying to stop a fatty KLR here or something like that.

In all honesty, I don't ride near as aggressively as I once did so under regular riding, it's ok...but a front brake is pretty dang important when one really needs it to perform.