Overcharging TRP HY/RD brake system
I am looking for slightly shorter lever throw with my HY/RD brakes. Has anyone personally had experience overcharging the system?
For those that dont know, "overcharging" is the act of bleeding the brakes with the pistons extended slightly. This puts a little extra fluid into the brake system, reducing pad clearance to the rotor, and in turn, shortening lever stroke.
If anyone has experience with it, what is the most effective way to do it?
It almost seems like you could simply add fluid to the system, without a total bleed. Any ideas?
I look forward to your insight!
Raised in a Chicken-Coop by Chickens
I have not tried that. However, I was in the same point as you are, and I tried somethind different. I reversed the cable anchor bolt and bolted the cable under the actuating arm... and, more importantly, to the inner side of the bolt. This way, I get more movement of the actuating arm from my lever throw. The brake response has changed as I expected: quite shorter throw, some less power, and a different feel (more direct, less "chewy", but still good modulation). Overall, I really like the brake the way it works now, and I still get more than enough power to stop my 200+ lb. (specially since I usually brake from the drops of my Midge bars, so I get plenty of leverage).
I am sure TRP does not endorse what I have done, but, in my experience, the cable anchor feels and looks rock-solid. I guess a pic is needed:
Just my 2 cents, in case it may help you (disclaimer: do it at your own risk, I do not bear any responsibility if you decide to tinker with your brakes ). The best part is that it is an easy and quick modification to do... and undo.
Last edited by campaleches; 01-13-2014 at 03:36 AM.
Nice! This was my original idea until I learned about topping off the fluid.
Originally Posted by campaleches
However, I did not think about flipping the cable fixing bolt upside down! Thats a great idea. In the past I was planning on filing off some of that lip to allow the cable to be fixed to the top, inside of the arm.
Theoretically, you would have less power and modulation with this mod, but I think there is enough to be spared.
Raised in a Chicken-Coop by Chickens
That was exactly my first thought: filing a "channel" for the cable.However, I was not too eager to make an irreversible structural mod to the brake. Thus, looking at the caliper, I just came out with the option of reversing the bolt.
There is indeed less power than in the original setup, but the brakes are still more powerful (at least, more consistently so) than my old BB7s. As for modulation, I even like it better now, it just felt too "chewy" out of the box. And I have not lost any pad clearance.
FWIW, my levers are TRP RRL SR. I guess the experience with longer-throw Shimano levers may differ.
Any more feedback on these brakes? I've been considering these or the Spyre for my commuter bike since my bb7's are just a constant nightmare of adjusting, cleaning, and general noisy disappointment in braking power and feel.
I have looked at applying your mod to my callipers but it seems that with the cable clamped on the reverse side of the actuating arm the cable with interfere with the body of the calliper. Did you find this was the case and, if so, are you comfortable with that happening?
It looks like filing a channel on the correct side of the arm would work, but as you said, hacking away at a brand new $150 calliper is a brave move and irreversible!
I have only just fitted the callipers and have not tried a full test yet but the lever throw does seem to be significant in order to lock the wheels (almost touching the bars). I have SRAM Apex 10-speed Double Tap Shifters, so they may have different characteristics to others.
Initial thoughts with the standard setup are - much better than cr@ppy Avid BB5's, no rubbing, squealing or juddering. Lever throw will take some getting used to.
Responding to the old question in the OP, I did that at TRP's recommendation. Having already used the brakes for about 600 miles and being unhappy with the lever stroke, I simply took the top off of the caliper (along with the gasket inside), added a bit of fluid, and put the gasket and the top back on.
At first it was like magic, my lever went from bottoming out to engaging with nearly 2 cm of pull left. Unfortunately as the pads wore the lever steadily creeped back toward the bar. When it got bad I complained to TRP again and they sent me redesigned gaskets.
Once again that fixed the problem, but once again the problem came back as the pads wore. By 1325 miles my front pads were worn out (lots of riding in sloppy conditions). After I pushed the pistons in and replaced the pads, I couldn't get the brakes to engage enough to stop the bike quickly with me on it. This time TRP decided to send me new calipers under warranty.
I just installed the new calipers last night and broke them in on the way to work this morning. As expected, they were great. The best news is that they worked properly right out of the box -- no fussing with the barrel adjuster (which is a very bad idea with these brakes), no playing with cable routing. They just worked. That wasn't true out of the box with my first set (installed last June, probably very early production run).
TRP support has been great throughout this process. I absolutely love these brakes when they're working. The process of keeping them that way has been frustrating.
FWIW, I'm using them with 4600-series Tiagra levers, which I think have about the same cable pull as SRAM. They've got power to spare, so I don't think the longer cable pull of newer Shimano 105/Ultegra/DA levers would be a bad thing. A little less mechanical advantage might even improve the feel. On the other hand, right now I don't think I'd want the brakes to engage any earlier in my lever stroke than they are. Maybe with less MA and more modulation, I'd feel differently.
Pictures! I almost forgot I had these. From the first time I went through the "topping off" process.
The before shot was after leaving the bike in a warm garage for a few hours. They were even worse when I used them in cold weather.
Note that the before shot is from a slightly rear angle to show that there was a small gap. Had I taken that directly from the side as I did the after shot you wouldn't have seen any gap.
The before shot is close to where my original brakes were when I first installed them. The after shot is close to where my replacement calipers are today.
I have seen people do this successfully. If you do it and it backfires, I do have replacement arms here. Feel free to contact us with any questions or concerns.
Originally Posted by etlprws
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