Modern rearsets and drum brakes

Shaun6691

New Member
Well I'm aware that it's takes some creativity and fabbing but I'm hoping to see some examples of modern rearsets attached to rear drum brakes. Also, what's a better route? The universal type rearsets sold everywhere or adapting modern sportbike rearsets? Gathering ideas for my gs450

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I feel your pain. I found it hard to navigate 20 pages of per build to find one good example. Search on here and google will be your best help!
 
Here's my setup.
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What I did was use the previous mounting holes and studs for the pegs and made that my pivot spot. Using the stud, I welded a tab on one side and notched the other so the tab wouldn't move on the other side and secured it with a nut in case I needed to take it apart for lubrication. On the brake lever, because it's pushing the arm instead of pulling, the spring would compress instead of actuating the brake. So I just put a nut on the brake linkage as a stopper and it works ok.
 
that thin long rod is not meant to be in compression. it will bow quite easily, seems a bit reckless.
 
it would be in tension if it was setup stock. He put kz650b wheels on his C which has rear disk. hes says "On the brake lever, because it's pushing the arm instead of pulling, the spring would compress instead of actuating the brake."

seems risky to me
 
sorry man,
I missed the part about running it backwards......which is VERY sketchy to put it politely
 
The trouble you will find is that modern rear sets for disc brakes simply don't have the parts needed for ready adaptation to a drum set up. That means you will have to make (or adapt from other drum brake rear set parts) all the bits in between. This is the case for most "universal" set ups as well because even though most bikes with drum brakes have nearly identical set ups, the specific small differences make the connecting parts too various.

Mostly this means retaining the original factory pivot and crank arm that pulls the long rod that actuates the brake. This is far more important than is evident to most people. The reason is that the location of the joint where the crank arm pulls on the rod is very critical. That joint must be as close to the swingarm pivot as possible and along a line drawn between the swing arm pivot and the rear axle. Even a small deviation will result is noticeable oscillation at the pedal when braking over bumps. Actually, at the stock location there is still oscillation, but it is so minor it is not a problem. Remember, I'm talking about the pull rod-crank arm connection, not the pivot for the brake pedal. That pivot can only be in two places: Either directly above or directly below the pull rod joint. (or very nearly so) So you need to leave all that intact and connect up your new pedal to a new crank arm attached where the old pedal was attached. This is invariably splined, so a ready solution is to alter the pedal into a new crank arm. This can be connected with a rod and heim joints (spherical rod ends) and it is vastly better to load this arm in tension than compression but if it is robust enough compression is ok.

All these problems can be overcome with a cable system, but the cable must be pretty stout. They are pretty simple, but finding/making proper parts can be a lot of trouble. And the routing of course is very important as the suspension moves a fair distance and often violently. But cables are completely immune to the kinematics of the suspension and are far easier to engineer. The other thing is that once you get all the cable bits sorted out, you can simply relocate the whole works anywhere you like and only have to make new mounting points and possibly a new cable if the length can't work. Very often moving the pegs a bit up or down, or more to the front or back has huge benefits, and this easy relocation capability can be a huge asset. Such a system also migrates to another completely different bike pretty easily for what it's worth.

Here is a cable set up on a bike I did a while back:
 

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Kamn said:
sorry man,
I missed the part about running it backwards......which is VERY sketchy to put it politely
And why couldn't the crank arm just be put back stock in the "up" position? Than at least the long pull rod would be fine. The short rod on the pedal may be a bit minimal, but I'd be a bit concerned about the orientation of the crank it drives.
 
Another point to add for cable routing is to make sure you create a path with gradual curves. As evidenced in the image, you don't want tight kinks and you may have to use a longer cable to get the necessary sweep:

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Cable set ups are simple to do.

And, you can call Motion Pro and have them make a cable for you, pretty inexpensively.
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doc_rot said:
it would be in tension if it was setup stock. He put kz650b wheels on his C which has rear disk. hes says "On the brake lever, because it's pushing the arm instead of pulling, the spring would compress instead of actuating the brake."

seems risky to me
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My reasoning behind looking past the rod bending was that being that it's drum and the rear, I'd be breaking mainly with the dual disc front, but I guess I can fab another pivot arm like the one above that when pushed by the brake lever it would then pull the drum lever..
 
I follow your reasoning. I almost never use my rear brake, but i think that it should be in good functional order for that moment when you need it. (gravel, oil, water on the roadway)
If you have room there what you suggest should work, but dont forget what JP said;
jpmobius said:
the location of the joint where the crank arm pulls on the rod is very critical. That joint must be as close to the swingarm pivot as possible and along a line drawn between the swing arm pivot and the rear axle. Even a small deviation will result is noticeable oscillation at the pedal when braking over bumps. Actually, at the stock location there is still oscillation, but it is so minor it is not a problem.

when the suspension compresses it will pull on the rod and cause the rear wheel to brake when you hit a bump. I think using a cable would be the easiest way, or using that existing pivot hole to fabricate a crank that puts the rod end up high near the swingarm pivot point.
 
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