When I brake the bike in the front of red light. My SYM 125 rear brake will be locked and can’t be released when it almost stop. The front brake is normal. It suffer twice. I just change the brake about a half years ago. A year ago, the rear brake was not in function, the motor service guy told me that the rear brake need to be change. OK, fix it. A half years later, the rear brake will be locked sometimes. I go back to the motor service shop and ask the guy to change new one.
And now it happen again. Any suggestion? 
[quote=“Phoenix9826”]When I brake the bike in the front of red light. My SYM 125 rear brake will be locked and can’t be released when it almost stop. The front brake is normal. It suffer twice. I just change the brake about a half years ago. A year ago, the rear brake was not in function, the motor service guy told me that the rear brake need to be change. OK, fix it. A half years later, the rear brake will be locked sometimes. I go back to the motor service shop and ask the guy to change new one.
And now it happen again. Any suggestion? [/quote]
What kind brake is your rear brake?
Drum or disc?
I’d assume a Sym125 will be a cable actuated drum brake, because AFAIK, they all are.
IF the brake was replaced properly recently, the odds seem to favor a bad cable.
Frayed cable strands can act like harpoon barbs inside the cable sleeve, so it’ll tighten when pulled but wont release. You could probably check this without needing to take the drum apart. Release the cable at the drum end and see if your rear brake releases. If it does the cables too tight or binding. If it doesn’y the problems inside the drum.
Take it off and have a look for broken, dirty or rusty things. Clean, fix, or replace them. Or get someone else to do it.
It’s drum brake.
Sorry, I should describe much more clear. The rear brake won’t be locked when the bike still speed. But when it almost stops, my left hand releases the lever, the brake seems to be locked. I guess the lining shoe is still very new. I just change it a few months ago. Thanks!
[quote=“Phoenix9826”][quote=“macduff”]
What kind brake is your rear brake?
Drum or disc?[/quote]
It’s drum brake.
Sorry, I should describe much more clear. The rear break won’t be locked when the bike still speed. But when it almost stops, my left hand releases the lever, the brake seems to be locked. I guess the lining shoe is still very new. I just change it a few months ago. Thanks![/quote]
The return spring of lining is very important component for drum brake release. But, dunno if you changed the spring at the same time or not.
If the spring is not well installed or weary, it will cause the lining can’t separate well.
Disconnect the rear brake cable and check that the inner cable is free within it’s outer. With it disconnected it won’t hurt to run some motor oil or anything similar down, into the outer cable itself. Work the inner cable back and forth after lubricating to work the oil right into it.
Also, with the cable disconnected from the rear drum’s operation arm (pictured below this post), work the arm with your hand. If the arm fails to return fully, then it’s best the strip the brake assembly, pull out the lever-arm spindle and clean and lubricate it before slotting it back into the drum assembly (be careful to mark it’s position for easy reassembly) . You should apply a little grease to the arm’s spindle before assembly, as the spindle is typically steel and the drum assembly alluminium, and these tend to fuse together relatively quickly without any lubrication between them.
If you can’t strip the entire assembly to take the arm out for cleaning and lubrication, then you can try spraying a little penetrating fluid such as WD40 into where the spindle enters the drum assembly. Work it back and forth. If it’s very stiff, then you can try gently tapping it with a light hammer as you work it back and forth. Once free, then apply some light oil, or motor oil into the spindle, being careful not to run a lot of oil into the drum itself as this may prevent the brakes from gripping at all!
Once all is done, then reassemble.
If you have to park your bike outside a lot, and if this component is often getting wet, then a quick lubrication every few weeks should keep it relatively free.
These types of drum assemblies suffer the same common issue generally with sticking, and the lubrication methods I mention typically fix this type of issue the vast majority of the time. A full strip and clean should be done at least once or twice a year typically.
All cables on the SYM need replacement from time to time without performing any type of maintenance. I would say it’s quite typical, especially when parking in the elements that you’ll need a set of replacement cables around once a year or so.
BRAKE not BREAK please.
Two very different words.
[quote=“urodacus”]BRAKE not BREAK please.
Two very different words.[/quote]
But in this case the one is the other.
(OH alright…is doing the other)
Yea, BRAKE not BREAK, Thank urodacus
Thank Macduff, Ducked, and Sulavaca, To see what happen, I would have a check for the cable, drum, spring, level arm, … these days, If I can. and report.
[quote=“Ducked”][quote=“urodacus”]BRAKE not BREAK please.
Two very different words.[/quote]
But in this case the one is the other.
(OH alright…is doing the other)[/quote]
HAHAHA,
Rear brake is real break now. :roflmao:
[quote=“urodacus”]BRAKE not BREAK please.
Two very different words.[/quote]
Thank you.