Compressionless housing did not fix spongy cable disc brake
12-31-20, 11:51 PM
#26
Junior Member
Thread Starter
Another problem that can occur is the stiff cable housings fouling up the caliper centering and angle. I centered my calipers without the cables, actuating the lever by hand, then inserted the housing into the caliper. With the very stiff housing, this can be difficult.
I found that sqeezing the brake lever with the cable attached did not work because the rotors are not very stiff from side to side and the cable housing pushed with enough force to move the caliper.
Changing to hydraulic calipers is not likely to solve the problem and they are pricey at $250 for a pair of GT four piston calipers. I suspect the problem is mistaking freeplay for spongy.
I found that sqeezing the brake lever with the cable attached did not work because the rotors are not very stiff from side to side and the cable housing pushed with enough force to move the caliper.
Changing to hydraulic calipers is not likely to solve the problem and they are pricey at $250 for a pair of GT four piston calipers. I suspect the problem is mistaking freeplay for spongy.
One thing that has helped, was making sure there is no slack by both the shifter end of the cable and the caliper end. I used a pair of pliers to pull the cable taught while I fastened the cable bolt in the calipers. Although it didn’t appear to pull any extra slack, when actuating the brake level there was a better, less spongy feel, but it’s still not great.
Gonna try the pad centering advice of loosening the pad bolt and actuating then tightening it while actuating the brake level next.
01-01-21, 01:43 AM
#27
I am potato.
Join Date: Jun 2015
Location: Pacific Northwest
Posts: 3,116
Bikes: Only precision built, custom high performance elitist machines of the highest caliber. 🍆
Mentioned: 29 Post(s)
Tagged: 0 Thread(s)
Quoted: 1790 Post(s)
Liked 1,631 Times
in
934 Posts
The best way, as far as I'm concerned, is to disconnect the cable, remove the housing from the caliper stop, screw the barrel adjuster all the way in & pads all the way out. Now you are free of external influence.
Loosen the caliper adjusting bolts just a fraction, maybe 1/8 or so turn from set. The caliper should float ever so slightly. (The closer it floats to final installed position, the better.)
Now that you are at square one: Install a a short section of cable into the bare barrel adjustor, squeeze the arm between your thumb & forefinger. Tighten the cable fixing bolt and apply tension with the barrel adjustor.
The caliper is now perfectly aligned to the rotor in all dimensions. Torque the caliper bolts incrementally to avoid disturbing the alignment.
Once torqued, screw the barrel adjuster in to relieve cable tension, loosen the cable fixing bolt, remove the short cable scrap & rest assured the caliper is aligned perfectly & ready for any cable & housing you ever wish to install forever more.
Insert the cable & housing you wish to use. Take up some slack by squeezing the actuation arm between your thumb & forefinger. Secure the T-25 cable fixing bolt. Then screw in each pad adjustment screw one at a time until a "schwing" is heard when the wheel/rotor spins, & back off 1/8th turn. It should run silent. Repeat with other pad. Done.
Most any future wheel or disc can be accommodated by adjusting the pads.
Loosen the caliper adjusting bolts just a fraction, maybe 1/8 or so turn from set. The caliper should float ever so slightly. (The closer it floats to final installed position, the better.)
Now that you are at square one: Install a a short section of cable into the bare barrel adjustor, squeeze the arm between your thumb & forefinger. Tighten the cable fixing bolt and apply tension with the barrel adjustor.
The caliper is now perfectly aligned to the rotor in all dimensions. Torque the caliper bolts incrementally to avoid disturbing the alignment.
Once torqued, screw the barrel adjuster in to relieve cable tension, loosen the cable fixing bolt, remove the short cable scrap & rest assured the caliper is aligned perfectly & ready for any cable & housing you ever wish to install forever more.
Insert the cable & housing you wish to use. Take up some slack by squeezing the actuation arm between your thumb & forefinger. Secure the T-25 cable fixing bolt. Then screw in each pad adjustment screw one at a time until a "schwing" is heard when the wheel/rotor spins, & back off 1/8th turn. It should run silent. Repeat with other pad. Done.
Most any future wheel or disc can be accommodated by adjusting the pads.
__________________
I shouldn't have to "make myself more visible;" Drivers should just stop running people over.
Car dependency is a tax.
I shouldn't have to "make myself more visible;" Drivers should just stop running people over.
Car dependency is a tax.
01-01-21, 08:58 AM
#28
Senior Member
The above procedure might work, but I quickly found that the stiff cable housing pushing on the caliper made it impossible to get good alignment. Of course it depends on the cable routing. I have frames made for hydraulic hoses that are not as stiff as compressionless housing.
01-02-21, 02:07 PM
#29
Junior Member
Thread Starter
So one thing that I found has helped, was releasing the cable fastener bolt and then pushing the cable into the frame from the caliper side, and the pulling it out again. Not sure why this worked, my guess is it helped get rid of some kinks and after the turn by the bb.
Finally I took the bike for a ride yesterday, the wheels locks out with plenty of throw to spare before The break lever hits the handlebar, but the break lever it’s self can be actuated even after this point such that it hits the handlebar. When not riding the bike, this made the brake seem more spongy than it actually is.
Finally I took the bike for a ride yesterday, the wheels locks out with plenty of throw to spare before The break lever hits the handlebar, but the break lever it’s self can be actuated even after this point such that it hits the handlebar. When not riding the bike, this made the brake seem more spongy than it actually is.
