Author Topic: hydraulic system with rear drum (Read 6981 times)

tamk · « **on:** March 19, 2011, 10:20:56 AM »

Hello all

Long time follower first time poster. There are a lot of very skilled builders on here so i thought this would be the place to ask. I have a 75 CB550 that I'm Cafeing up. Being the cheap guy that I am I'm building my own rear sets. Left side all but done with no trouble. Now I'm moving over to the right side little different story.

What I've been looking for is a Hydraulic master and slave system that could be used to pull on the rear drum rod. The reason for this isn't better breaking its to clean up the look and to reduce the clutter and weight of the bike. I can build the master and slave but was hoping to save the time for other things. I've tried the search function and googled tons of different ways but to see nothing I'm looking for. So if any of you know or have done this type of conversion I'm all ears.

Thanks again to all, this is really a fun place to spend my evenings. There are just tons of really good ideas

Terry in Australia · « **Reply #1 on:** March 19, 2011, 04:49:05 PM »

Harley used a hydraulic rear drum brake from 1959 to 1972, you may be able to adapt something mate, but why not just use a cable setup? Cheers, Terry.

tamk · « **Reply #2 on:** March 19, 2011, 06:57:20 PM »

Terry
Never thought about going with a cable system. Would you happen to know where I might be able to find some examples of that you are talking about? Really what I'm looking for is to be able to cut all that old hardware off that was used with the old system.

To convery to hydraulic system isn't much trouble other than i need about .700 travel with the drum breaks.

rangelov · « **Reply #3 on:** March 19, 2011, 07:04:32 PM »

I THINK the old late 70s Honda XL250 used a rear cable actuated brake drum.

I might wrong, since I last rode one in the early 1980s, when it was stolen.

Roach · « **Reply #4 on:** March 19, 2011, 07:53:19 PM »

why not ditch the drum and go and stick a 750 swing arm and rear wheel on with disk? save allot of troubles

2nd idea cut off all the old stuff flip the arm upside down and attach the arm via a rod right to the brake pedal..

I'm really not sure what the purpose of going to a hydraulic is with the old drum system

3rd idea is just leave the old stuff on and attach your rearsets to it? for the weight you cut off it really isn't much.. probably less than a pound of metal

FunJimmy · « **Reply #5 on:** March 19, 2011, 08:40:42 PM »

Here's a mechanical pull rod rear-set setup that replaced all the factory crap.

tamk · « **Reply #6 on:** March 19, 2011, 08:41:27 PM »

Roach
I guess the reason I was trying to go this way was to do it different that what you see all the time. That's part of why I do all the one off type of stuff I do. Anyone can have a given bike but unless your willing to change things up then your bike is just like the next.

I work in the firearms industry and I can't think of one gun I own that is like anyone else. Not that it makes them any better but no one else has them. I have always liked the cafe look and wanted something different. Just to make things even more so I have a 1976 CB550 frame with a 1975 CB400f motor mounted into it. Some will ask why I just figured it will be mine and nothing like you will see anywhere.

I was hoping to find another crazy person to do things just a little outside of the box that's all. The other season I am headed this way is I have a good friend with a full machine shop so it makes it pretty easy to build just about anything.

tamk · « **Reply #7 on:** March 19, 2011, 08:45:45 PM »

FunJimmy

looks like some nice work. I'll have to talk with you a little. My current set up is using the rear peg mounting points so I'm a little farther back. Nice work though.

Have to take my son to see battle of LA I'll be back in the morning hope to talk more about how your cleaned up the mess.

FunJimmy · « **Reply #8 on:** March 19, 2011, 08:52:36 PM »

Quote from: tamk on March 19, 2011, 08:45:45 PM

Have to take my son to see battle of LA I'll be back in the morning hope to talk more about how your cleaned up the mess.

Let me know about the movie too.
My son and I are planning a viewing soon.

Cheers

scottly · « **Reply #9 on:** March 19, 2011, 09:31:07 PM »

As far as slave cylinders, you might look at automotive clutch units? Can't see how a hydraulic system would be any lighter than a simple rod, though.

tamk · « **Reply #10 on:** March 20, 2011, 09:28:56 AM »

Let me know about the movie too.
My son and I are planning a viewing soon.

Cheers
[/quote]

Jimmy the movie was a good shoot em up kind of show. Good father son kind of time. Not sure how hold your son is but there are a couple pretty violent spots. Have you ridden your bike with your rear set break set up? If so I would like know what kind of downward pressure it takes to get a sold stop. The reason I ask is the original set up has quiet the mechanical leverage long travel but lots of force.

Scotty,
Your right it would be heavier but so much cooler and cleans up that side of the bike.

FunJimmy · « **Reply #11 on:** March 20, 2011, 10:42:56 AM »

Quote from: tamk on March 20, 2011, 09:28:56 AM

Have you ridden your bike with your rear set break set up? If so I would like know what kind of downward pressure it takes to get a sold stop. The reason I ask is the original set up has quiet the mechanical leverage long travel but lots of force.

Yup. Been riding with this setup for the past two summers and it's been pretty good, but not perfect.

I’ve got lots of good stopping power on the front and tend to favor front brakes over rear anyway, but the short arm of this setup leaves the rear brakes feeling a bit wooden. It’s my intention to shorten the pull arm that the pull rod attaches to for more leverage and replace the brake shoes with some fresh ones when I get a bit of free time.

FJ

tamk · « **Reply #12 on:** March 20, 2011, 06:06:54 PM »

Quote from: FunJimmy on March 20, 2011, 10:42:56 AM

Quote from: tamk on March 20, 2011, 09:28:56 AM
Have you ridden your bike with your rear set break set up? If so I would like know what kind of downward pressure it takes to get a sold stop. The reason I ask is the original set up has quiet the mechanical leverage long travel but lots of force.

Yup. Been riding with this setup for the past two summers and it's been pretty good, but not perfect.

I've got lots of good stopping power on the front and tend to favor front brakes over rear anyway, but the short arm of this setup leaves the rear brakes feeling a bit wooden. Its my intention to shorten the pull arm that the pull rod attaches to for more leverage and replace the brake shoes with some fresh ones when I get a bit of free time.

Correct me if I'm wrong but shorter lever requires more force and less throw, longer lever requires more throw but less force. That is the reasoning behind hydraulic conversion high force with minimual travel of your foot. Oh and the cool guy factor!
FJ

FunJimmy · « **Reply #13 on:** March 20, 2011, 06:13:14 PM »

Tamk

You gotta get the quote feature to work better dude.

You are correct in that a shorter brake lever would require more pressure to achieve the same transfer of power to the brake shoes, but I'm referring to the arm that the pull rod is attached to, not the brake pedal itself. A shorter throw on the other arm will increase the leverage applied to the pull rod and require more travel of the brake pedal. Just like you said.

tamk · « **Reply #14 on:** March 20, 2011, 06:34:57 PM »

Jimmy your right this is my first go at a forum so I'll get it in time sorry for the messy words. Just checked out your bike build nice job!!!

I still think I'm going to try and put together a hydraulic breaking system for the rear drum. Just had a thought and maybe you could help as I haven't had a drum set apart. do you feel there would be enough room to build a small slave cylinder and fit it inside of the drum? Much like trucks or cars use.

Flying J · « **Reply #15 on:** March 20, 2011, 06:51:28 PM »

WOW. Your probably right not many people have put a 400 in a 550 frame. Im all for making things different but you might want to think of a reason to do it besides "its original". Otherwise you might want to try running no rear brake at all. That would really clean things up and lighten the bike. Not to mention there are not many people doing that as well.

Total sarcasm and try not to be offended. I like that you are trying to think outside the box but try to find a purpose and direction then go with it.

tamk · « **Reply #16 on:** March 20, 2011, 07:15:51 PM »

ffjmoore,

The 400 is in and mounted in place. Had to build a couple motor mounts but other than that it was pretty straight forward. There is a very long story as to why I did this but the short story is a went through a couple of 550 motors and didn't find a good one locally and ran into this 400 which was running. So I'm not sure if it was determination of frustration but I now have a running bike.

I have a direction just not sure how many turns are in the road is all.

All was taken as sarcasm but I think I'll keep the rear brake. The plan is to have all the build done and rideable by the end of this summer then tear down and make things all pretty.

FunJimmy · « **Reply #17 on:** March 20, 2011, 07:46:53 PM »

Quote from: tamk on March 20, 2011, 06:34:57 PM

I still think I'm going to try and put together a hydraulic breaking system for the rear drum. Just had a thought and maybe you could help as I haven't had a drum set apart. do you feel there would be enough room to build a small slave cylinder and fit it inside of the drum? Much like trucks or cars use.

I can't remember how much room there is inside the drum for a slave cylinder, but that sure would be keul!
Maybe you could use the hydraulics from a single piston caliper and keep it really narrow.
Just tinking out loud.

Flying J · « **Reply #18 on:** March 20, 2011, 08:02:04 PM »

At the cam part is like 3/4 inch. Here are the internals.

tamk · « **Reply #19 on:** March 20, 2011, 09:15:18 PM »

Quote from: ffjmoore on March 20, 2011, 08:02:04 PM

At the cam part is like 3/4 inch. Here are the internals.

Hope I got this quote thing figured out. I will take my rear brake apart tomorrow and see what kind of travel is needed to engage the brakes. This might turn into something. The way I see it happening is a dual actuating piston probably built from scratch and using the shaft hold as the connection point as well as the point of the banjo connection. Might just have to skip work tomorrow to figure this one out.

Flying J · « **Reply #20 on:** March 20, 2011, 09:33:03 PM »

Nice you have the quote thing down like a pro and your on track for something real cool. Do you have any experience with hydraulics?

tamk · « **Reply #21 on:** March 20, 2011, 09:45:11 PM »

I've built cylinders in the past but nothing anywhere near this small. Man now i won't be able to sleep tonight trying to work this out in my head. But what better reason to loose sleep over?

Flying J · « **Reply #22 on:** March 20, 2011, 09:49:23 PM »

Couldnt you just put a hydraulic cylinder where the spring is on the cam side? It would retract the pads when you let off the brake and you would only need a single one because it would apply pressure evenly between the 2. Plust it gives you a little more room to work with.

tamk · « **Reply #23 on:** March 20, 2011, 10:16:11 PM »

That might work also but I think you will need the spring to retract the pads. But there is nothing saying the cylinder couldn't hold the spring to retract the piston. Good idea more minds are always better. Thanks

754 · « **Reply #24 on:** March 21, 2011, 08:59:05 AM »

I would leave the spring side.
Remove the 2 metal pins or maybe just cut them down. Excellent mounting points.
Cut 1/2 the eye off the shoes on the pin ends, then mount double acting cylinder there with 1/2 rounds(with a lip) against the shoe. Then add another spring to the shoes, on the cylinder end.
Now your original end can be a wear adjuster., cylinder is closer to front and brake line can run up along swingarm.

simple, eh..

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Author Topic: hydraulic system with rear drum (Read 6981 times)