Linear pull brake / V brake assembly has my brain broken
#1
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Linear pull brake / V brake assembly has my brain broken
Hey people.
I will preface this by saying I googled the heck out of this, watched several videos and still nothing.
I am a former mechanic but have taken about 2 years off and I don't know if I killed too many brain cells in that short time, but I cannot get this puzzle back together.
A customer brought in some partially assembled promax brakes on a bmx bike. He said he tried to fix them himself but couldn't, so he brought it in to me.
I tried reassembling it a multitude of ways, but the pieces don't go together in an intuitive way and every combo I've tried just feels wrong, you know? He said that adjustment was fruitless so I imagine the adjusting screws weren't hitting the springs. Here is a photo (attached) of one of the brakes and the assembly as I found it, in order.
1. Brake arm
2. rubber washer,
3. adjustment screw mount ring "thing" (proper name?), I showed the "open" and "flat" sides, though only one is installed per brake and the flat side is against the washer, open against the spring (of course)
4. spring
5. brake mount for the frame
Also included bolt and washer to seal the deal but didn't include that in the photo.
I have tried flipping part 3 but neither way has it lay flat against the spring. It has a small bit that juts out where the screw is, and it prevents it from sitting flush against either part, no matter how I orient it. When I tried bending the spring a bit to catch on the screw, it instead got caught on the pacman mouth esque cut out on part 5. Really it's a mess. I've never encountered a set of these that don't go back together nicely and I don't know if they are missing pieces or my brain is missing screws.
Sorry for my lack of knowledge on the proper nomenclature. Thanks ahead of time to any helpers.
I will preface this by saying I googled the heck out of this, watched several videos and still nothing.
I am a former mechanic but have taken about 2 years off and I don't know if I killed too many brain cells in that short time, but I cannot get this puzzle back together.
A customer brought in some partially assembled promax brakes on a bmx bike. He said he tried to fix them himself but couldn't, so he brought it in to me.
I tried reassembling it a multitude of ways, but the pieces don't go together in an intuitive way and every combo I've tried just feels wrong, you know? He said that adjustment was fruitless so I imagine the adjusting screws weren't hitting the springs. Here is a photo (attached) of one of the brakes and the assembly as I found it, in order.
1. Brake arm
2. rubber washer,
3. adjustment screw mount ring "thing" (proper name?), I showed the "open" and "flat" sides, though only one is installed per brake and the flat side is against the washer, open against the spring (of course)
4. spring
5. brake mount for the frame
Also included bolt and washer to seal the deal but didn't include that in the photo.
I have tried flipping part 3 but neither way has it lay flat against the spring. It has a small bit that juts out where the screw is, and it prevents it from sitting flush against either part, no matter how I orient it. When I tried bending the spring a bit to catch on the screw, it instead got caught on the pacman mouth esque cut out on part 5. Really it's a mess. I've never encountered a set of these that don't go back together nicely and I don't know if they are missing pieces or my brain is missing screws.
Sorry for my lack of knowledge on the proper nomenclature. Thanks ahead of time to any helpers.
#2
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where the spring that goes into part 1 and over 5 ?
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Ok, so I've taken some of these apart in the past and maybe able to help if my memory is right on track. First most coil spring V brakes have a thin metal bushing like number 2 in your pics but this type is different but the same ( if you get my drift lol ) I'm pretty sure. I would think that #2 goes on #5 First, then the spring followed by #3 with the open end facing the spring, the screw should push on the little tab on the round end of the spring that #3 sits up against. You may have to assemble them and do some tweeking to the spring to center them with the screws. When all else fails a cheap set of V brakes may be needed as a replacement. Some cheap V brakes don't like being taken apart and messed with and I have had fits myself dealing with them I always go for used if I have them in my bins which I have more times then not. Hope this helps.
Glenn
Glenn
Last edited by Glennfordx4; 04-26-18 at 08:49 AM.