Rear brake: Pedal travel

DrJ said:
Nice parts you've made, very sano.
Click to expand...

Yes, very nice parts.
Can you make a brake pedal lever stop to keep the pedal in 1 relaxed position? With the set up now, when you try to adjust the slack out of the brake shoes, it will only alter the brake pedal height (and the pedal travel will remain the same). With the brake pedal having a stop to keep it at the relaxed position (brake off), you would be able to adjust the slack out of the brake shoes by altering the length of the rod (giving you less travel at the pedal).
DG
 
dgfischer said:
Yes, very nice parts.
Can you make a brake pedal lever stop to keep the pedal in 1 relaxed position? With the set up now, when you try to adjust the slack out of the brake shoes, it will only alter the brake pedal height (and the pedal travel will remain the same). With the brake pedal having a stop to keep it at the relaxed position (brake off), you would be able to adjust the slack out of the brake shoes by altering the length of the rod (giving you less travel at the pedal).
DG
Click to expand...

Yes, an adjustable brake pedal lever stop is handy to have. The stock brake setup has one. As I mentioned previously I fabbed one on my rearset. It does take up the slack so you can adjust the travel distance of your brake pedal. It also gives the brake lever a snappier, more positive feel. A return spring also helps.
 
Many thanks gents (and Shannon)! Below is my solution to the pedal stop problem. As the shoes wear, I can take up the slack with the rod. 3/8" or so to engage the brake. I'm well happy.

BrankPedalStop.jpg


--Chris
 
How are you taking up slack? I retained the original rod with the threaded end and needed to take up about half the adjustment before I got the brakes working nicely.
 
I attached a couple pics of my set up to my last post. I hope you don't mind if it's not from a cafe racer (I have about 3 1/2 CB750s & really wanna build one though).

I'm curious to see if this set-up passes the DrJ snifff test. My vertical arm portion has two different mounting heights. Originally I had just the taller one when I roughed it out. Then I found I had more than enough travel so I drilled a lower hole, figuring the closer I am to pivot point the better my leverage - I can always cut off the excess later.

I don't have the arms parallel like the Dr recommends but thats a matter of grinding out a few more splines at the back. I've already taken out about 2 extra. When first installed the lever points back some then I take up a whack of travel before locking the set screw on the brass arm and its canted forward some by then.

Anyway it appears to work...in the garage. It would be nice to test the theory if it stayed cold for a week and we got some ice.
 
First, your method of attaching the pullrod to the foot control scares the shit out of me. To put it lightly, that is a horrible idea. Besides introducing stress on the pullrod as the control travels through its arc, there is a good chace it will just pull free of the brass bung. You really need something that 1.) allows the rod to rotate and 2.) uses something other than a set screw.

You can get small, female rod ends. These don't have to be fancy aircraft spec ones like I used. If it were me, I'd tap the pullrod and thread it into a female rod end.

--Chris
 
Good points. Yes the rod connection at the front needs to rotate or else it will bend each time the brake lever is pressed. Overall the construction quality is very good, looks like you used 1/2" aluminum and you've incorporated a stop and return spring. The levers aren't parallel but that's looks close enough. Parallel is optimum for function and appearance. But it's all about performance so if you can lock up the rear tire on dry pavement with this setup then you've succeeded.
 
Oh Please Mr Chris give me some credit. Of course the brass section pivots.

As to the set screw it happened to be in the brass part when I found it. I thought it might need a second set screw but I can stuff my foot into hard as I might and it don't move.

As an added bonus my set screw set up allows me to take up all the travel I need. (If memory serves me correctly that was something your approach struggled with). As well this adjustment and my travel stop allow me to set where I want the starting position of the pedal. I may rotate it forward a bit so the toe piece is a little lower.

Horrible? I think thats a stretch. A little bit ugly maybe - the shape could have been nicer but I tried to use the shape of the plate I had rather than make more cutting work for myself. I was chewing through this with a jig saw (actually 3/8" DrJ) and got lazy.

Part of the challenge of building these ice bikes was to start with a beater and not spend more than 30$. The shiny gold studs took me over the limit a little......

DrJ are you buying my shorter lever better mechanical advantage approach? At some point I may move it back to higher mount hole just to feel the difference... or maybe not. It works now and other projects are calling.
 
Yes, I'm all for the shorter elbow section. I'd say a ratio of 1:2 is good, elbow section being half the length of the hub lever. Also shorter elbow equals longer foot pedal travel. But if it works just as well with the pivot on the top hole then go for it.
 
zixxerboy said:
Oh Please Mr Chris give me some credit. Of course the brass section pivots.

As to the set screw it happened to be in the brass part when I found it. I thought it might need a second set screw but I can stuff my foot into hard as I might and it don't move.

As an added bonus my set screw set up allows me to take up all the travel I need. (If memory serves me correctly that was something your approach struggled with). As well this adjustment and my travel stop allow me to set where I want the starting position of the pedal. I may rotate it forward a bit so the toe piece is a little lower.

Horrible? I think thats a stretch. A little bit ugly maybe - the shape could have been nicer but I tried to use the shape of the plate I had rather than make more cutting work for myself. I was chewing through this with a jig saw (actually 3/8" DrJ) and got lazy.

Part of the challenge of building these ice bikes was to start with a beater and not spend more than 30$. The shiny gold studs took me over the limit a little......

DrJ are you buying my shorter lever better mechanical advantage approach? At some point I may move it back to higher mount hole just to feel the difference... or maybe not. It works now and other projects are calling.
Click to expand...

Ok, that came off a bit unconstructive; that was not the intent at all. Consider this though, if that brass bit can spin, it can likely come loose. Not a good thing. I do stand by my statement that the set screw holding the pull rod is a bad idea. A second screw won't really improve the situation.

The taking up slack issue I had is not really comparable to the brass bit/pull rod issue. If you were to install a rod/rod end solution like I used, you would not have the problem I had because you welded a little bracket to stop the foot control from pivoting up. Once I figured this out, I didn't have a slack issue. I went for a ride a few nights ago and the difference is night and day.

In the end, we work with what we've got. No harm in that.

--Chris
 
Ok Chris you just won't back off so you have this coming. QUIT BEING A JERK.

You're making comments about stuff you can't possibly know from looking at a picture.

1) Although the brass part spins you probably can't see from the picture that theres a lock/bolt/nut affair to keep it in place.

2) Perhaps you don't understand how a set screw works especially since you say a second one wouldn't help. Utter nonsense. One DOES hold it just fine thanks. Were you in my garage stomping on it for all you're worth?

3) The pedal stop is bolted in place not welded - thus I have pedal position adjustment.

4) I think the "take up slack " issue is relevant. Your rod end might take up maybe an inch at either end. I can take up as much as I need - 6 or 8 inches if it was required - regardless of where the pedal stops.

Rants over let's go for beers.
 
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