cb450 rear brake like shit! with rear set.

[joevirus563]

Ok so I tried my cb450 with rearset on the road.
Rear brake is like no brake at... not even a slight friction.

No my setup is a rear set with an overtsize 3/8 rod with reverse rear brake arm and brand new shoes.

Is the reverse brake arm the problem??

 

[lingo]

With the stock location of the brake arm, when you push the pedal the arm rotates forward and the brakes are applied. With the brake arm in that position, the arm must be pushed the the rear of the bike to apply the brakes. I have a feeling that when you are pushing the brake pedal you are actually pulling the shoes further from the drum.

 

[joevirus563]

With the stock location of the brake arm, when you push the pedal the arm rotates forward and the brakes are applied. With the brake arm in that position, the arm must be pushed the the rear of the bike to apply the brakes. I have a feeling that when you are pushing the brake pedal you are actually pulling the shoes further from the drum.

I hear you, but if you take a look at the schematic:
Part 7 is the same on bolt side, so technicly it should brake the same if I pull or push on the arm no?

 

[lingo]

Ok, I just went and dug out my spare parts and there was a backing plate with a brake arm on it. And you are right the lever will actuate the shoes in either direction. Could it be adjustment or flex in the rod between the rear sets and the brake arm?

 

[rockcitycafe]

in stock form, there's a stop for the brake pedal and adjustment nut that keeps the cam positioned just shy of causing the shoes to contact the drum, I don't see that on your setup, maybe it's out of the picture, but it's needed otherwise you're spending most of your pedal movement taking up the slack before contact. also, the lever ratio of a stock rear brake is probably much higher than what you've got, the way stock is, the pedal is a really long lever, maybe 12" or so, hence the pivot being behind the foot peg, and the arm on the pedal is really short, maybe an inch at the most, so you've got a huge mechanical advantage (an inch of pedal movement only moves the brake arm 1/8" or so) but that's what slows the wheel. your setup looks like it might be a 2-1 or even 1-1 ratio, which means you're braking power is probably 1/4 to 1/8 what it should be at best

 

[joevirus563]

in stock form, there's a stop for the brake pedal and adjustment nut that keeps the cam positioned just shy of causing the shoes to contact the drum, I don't see that on your setup, maybe it's out of the picture, but it's needed otherwise you're spending most of your pedal movement taking up the slack before contact. also, the lever ratio of a stock rear brake is probably much higher than what you've got, the way stock is, the pedal is a really long lever, maybe 12" or so, hence the pivot being behind the foot peg, and the arm on the pedal is really short, maybe an inch at the most, so you've got a huge mechanical advantage (an inch of pedal movement only moves the brake arm 1/8" or so) but that's what slows the wheel. your setup looks like it might be a 2-1 or even 1-1 ratio, which means you're braking power is probably 1/4 to 1/8 what it should be at best

1- The stop ? Do you have a picture of what it looks like?
2-braking rato... any way to add more power to it? Because right now its next to useless...

 

[lingo]

1. I just looked at both on my 450s and neither one of them has a lever stop (or anywhere for one to be).

2. To gain more mechanical advantage you need to lengthen the lever on the pedal or shorten the lever on the brakes. Neither one is going to be easy.

My rear sets should be here this week. So I have been thinking about this myself lately. I am going to reuse the factory brake pivot. I am going to cut the lever off of it and weld a lever to it for my clevis to bolt to. I know that I going to lose some mechanical advantage but I going to try to use as short of a lever on the pivot that I can so that I can lose as little as possible.

 

[yorkie350]

Hi fella's i had the same idea and same probs when i used rear sets & original brake , stops like hittin a wall now ,check out how i got round it in my thread cb350f 1st project agh! if ya need any help throw a reply up in that thread and ile answer ya questions

 

[joevirus563]

I want more!

Do you have a list of all required stuff?


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[teddpage]

What Sean (Roc City) was talking about, was a stop for the rear brake lever.
See my shitty attached picture. I had a similar issue on mine, but am away from my bike and cant take a picture.
You need to have a stop for the lever, so you can essentially add "preload" to the braking rod, thus reducing the amount of travel needed to engage the brakes. What I would do is drill and tap a hole for say a 6mm hex head screw where you want your brake lever to be, so that it rests against the bolt when the brake is not engaged.
EDIT: Found a pic of my fix on my own bike. I made mine adjustable...its a little ghetto, but it works!

 

[joevirus563]

Well that's one good idea! So you drill and tap a screw in the drum directly?

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[teddpage]

NO! Not into the drum. Just behind your rearset lever. Looks like you have your levers mounted on nice big aluminum plates. Either do like I did, and make it adjustable, or get your brake lever where you want it and make a permanent brake stop by adding a bolt.

 

[cavity.]

NO! Not into the drum. Just behind your rearset lever. Looks like you have your levers mounted on nice big aluminum plates. Either do like I did, and make it adjustable, or get your brake lever where you want it and make a permanent brake stop by adding a bolt.

while this is useful and a good idea, I'm not sure it will solve his problem.

if you pull (or push) the brake drum lever with your hand in either direction do the shoes make contact with the wheel?

 

[joevirus563]

while this is useful and a good idea, I'm not sure it will solve his problem.

if you pull (or push) the brake drum lever with your hand in either direction do the shoes make contact with the wheel?

Yes it does, either way. If you check the actual brake arm, it has the same shape on both side so it will make contact.

What they sead might be my problem. My pedal just hit the pipe before it take up all the slacks of the lever.

I'll give it a try and post back.

 

[teddpage]

I know for a fact it works. I am able to lock up the rear tire of my CB450 with my setup.

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