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-   -   Front Brake Problem - What Am I Missing? (https://www.bikeforums.net/bicycle-mechanics/856723-front-brake-problem-what-am-i-missing.html)

CACycling 11-08-12 12:47 PM

Front Brake Problem - What Am I Missing?
 
Rehabbing an '88 Trek 360 for our youth pastor. It was a CL giveaway and everything looked original except the front wheel. Finished everything but the brakes and ran into a problem. The front brake cable was sticking. Pull the lever, brakes activate. Release the lever, lever spings back fully and caliper immediately releases part way then slowly releases the rest of the way. On the lever end, you can see the cable tip is no longer seated when the lever is released then slowly seats back in place.

Original was Diacompe calipers and aero levers with original cable and housing. Started replacing things till nothing original is still there except handlebars and mechanic (me). Now have Tektro caliper, Shimano cable/housing and Pyramid aero lever (stuff I had laying around) and the problem is exactly the same. I've taped the housing tightly to the bars with strapping tape while the cable was under tension and have all bends as gradual as possible but the problem persists.

Frustrated, I decided to swap out everything for the rear brake (Tektro caliper, Bell housing/cable and Pyramid aero lever) and it set up perfectly on the first try. What am I missing?

FBinNY 11-08-12 01:01 PM

You have a friction problem. The slack at the lever end indicates that it's wither in the cable or the caliper itself. Start by flexing the caliper closed with your hand letting the cable go slack and slowly releasing and watching and feeling to see if the caliper fully springs back firmly, and with constant spring pressure. If not, try oiling the pivots, and the places where the springs meet the arms.

If the caliper is OK, tie it closed to the rim with a toe strap or piece of string, and work the housing back and forth on the now slackened cable to feel for smoothness or friction. Often friction happens even with new cables if the lead in at the lever isn't straight or you used the wrong ferrule. In some cases I've seen cables that were OK until taped down then binding because of poor lever lead-in.

fietsbob 11-08-12 01:02 PM

buy new cables and housing. die drawn cable is smoother.
so wont drag inside the lined housing.

dsbrantjr 11-08-12 01:58 PM

Make sure that the caliper moves freely with the cable detached. Then make sure that the cable moves freely by itself. Make troubleshooting easier on yourself and don't tape the cable to the bars until everything is working properly.

CACycling 11-08-12 03:14 PM

No resistance felt in caliper itself - opened smoothly when released - but oiled it anyway. Don't feel any friction when moving cable within housing. Same symptoms when I untaped it. Same symptoms before and after replacing everything.


Originally Posted by fietsbob (Post 14928132)
buy new cables and housing. die drawn cable is smoother.
so wont drag inside the lined housing.

I did install new cable and housing but think I may need to look for something with even less friction. Just strange that the rear, with a much longer run (all in housing), works beautifully with the cheap Bell cable & housing (Walmart $5 for full set of cables type) but front is sticking with new Shimano housing and cable.

Thanks for the help, I guess I'll spring for some high-end cable & housing and hope that solves it..

FBinNY 11-08-12 03:27 PM


Originally Posted by CACycling (Post 14928615)
No resistance felt in caliper itself - opened smoothly when released - but oiled it anyway. Don't feel any friction when moving cable within housing. Same symptoms when I untaped it. Same symptoms before and after replacing everything.



I did install new cable and housing but think I may need to look for something with even less friction. Just strange that the rear, with a much longer run (all in housing), works beautifully with the cheap Bell cable & housing (Walmart $5 for full set of cables type) but front is sticking with new Shimano housing and cable.

Thanks for the help, I guess I'll spring for some high-end cable & housing and hope that solves it..

It's almost unheard of for front brakes to bind because of cable friction, especially with new cables. Look for misalignment or bad ferrules, or friction in the caliper itself. It's also possible that the caliper has a weak or binding spring, so check that thoroughly before shelling out for new cables which probably won't solve it.

CACycling 11-08-12 04:20 PM


Originally Posted by FBinNY (Post 14928658)
It's almost unheard of for front brakes to bind because of cable friction, especially with new cables. Look for misalignment or bad ferrules, or friction in the caliper itself. It's also possible that the caliper has a weak or binding spring, so check that thoroughly before shelling out for new cables which probably won't solve it.

That's what my thought was. But I have literally replaced everything piece by piece and the problem remains.

cny-bikeman 11-08-12 04:58 PM

You have not discovered an exception to the rules of physics, nor is your bike haunted. The problem has to be either cable or caliper. Given the amount of friction that would be required for the cable to prevent release of a normally functioning front caliper it pretty much has to be the caliper. The caliper should not just open smoothly - it should be very difficult to close by hand, and snap open immediately when released if no cable is installed.

reptilezs 11-08-12 07:44 PM

brake housing ends finished properly? pig tail cut off and ground flat? could also be the lever

onespeedbiker 11-08-12 10:52 PM


Don't feel any friction when moving cable within housing.
When you are doing this test is the cable threaded through the brake?

CACycling 11-09-12 12:27 AM

Disassembled everything again and noticed a very slight kink in the cable about where it rntered the housing inside the lever. Was barely noticeable but went ahead and put in a new cable and that did the trick. Thanks for all the suggestions and taking your time to help presrrve my sanity.

onespeedbiker 11-09-12 01:42 PM

Si I'm curious, you said

I did install new cable and housing but think I may need to look for something with even less friction.
Did you replace this housing for the second time?

CACycling 11-10-12 10:02 AM


Originally Posted by onespeedbiker (Post 14932104)
Si I'm curious, you said Did you replace this housing for the second time?

No, once I noticed the slight kink in the cable, I decided to just replace the cable.


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