Topic: Building Rearsets from scratch.

[Pinhead]

I'm currently in the process of building ultra-cheap (free so far) rearsets for my CM400T. The project epitomizes the phrase, "I've gone so long with so little I can make almost anything with virtually nothing." So far I've only used scrap pinsetter parts (that's a bowling machine for those that don't know lol).

The first pic shows the bike as it sits (rattle can paint and all). The second shows the left-side rearsets and mounts. Just need to make a few final adjustments and bend a bracket here or there. I'll try to get a pic with them on the bike.

The brake side, however, is proving to be a real bear. I know how/where to mount the pegs but the linkage/brake system is the part that I'm stumped on. Does anyone have a CM400 with rearsets? Anybody ever seen any pictures? I'll try to get closeups of the brake linkage area for brainstorming.

[Pinhead]

Both my CB650 and my CM400T have 12 inches of brake pedal leverage from the pivot point to pedal. How the heck are you rearset guys getting enough leverage to make your brake system work right? You'd have to have the lever pivot point behind the passenger pegs!

[Pinhead]

Now HERE's an interesting and simple yet effective way of doing it... Wonder where I could get a strong enough cable.

[Industrial Rat400f Killer]

I'm not at home or I'd provide pics but I'm flipping the brake drum lever upside down, pointing up, and then running one 1/4" aluminum rod from the pivot on the peg to the brake drum lever. It'll have to have and "S" shape to clear everything but I've seen it done so I know it works. Hope that helps.

[Alan F.]

Now HERE's an interesting and simple yet effective way of doing it... Wonder where I could get a strong enough cable.

A clutch cable from a small car should do the trick.

[MCRider]

Now HERE's an interesting and simple yet effective way of doing it... Wonder where I could get a strong enough cable.

Many bikes have had cable actuated rear brakes. The CB77 Superhawk comes to mind. It was a powerful double leading shoe brake.

[mystic_1]

I'm not at home or I'd provide pics but I'm flipping the brake drum lever upside down, pointing up, and then running one 1/4" aluminum rod from the pivot on the peg to the brake drum lever. It'll have to have and "S" shape to clear everything but I've seen it done so I know it works. Hope that helps.

Careful, that setup mean than your suspension travel will affect your brakes action.

mystic_1

[Industrial Rat400f Killer]

I'm not at home or I'd provide pics but I'm flipping the brake drum lever upside down, pointing up, and then running one 1/4" aluminum rod from the pivot on the peg to the brake drum lever. It'll have to have and "S" shape to clear everything but I've seen it done so I know it works. Hope that helps.

Careful, that setup mean than your suspension travel will affect your brakes action.

mystic_1

Hmm, is that because the pivot isn't located at the same point as the swing arm pivot? I talked to two people who have done this and neither of them mentioned it having any effect on the brake action.

[MCRider]

I'm not at home or I'd provide pics but I'm flipping the brake drum lever upside down, pointing up, and then running one 1/4" aluminum rod from the pivot on the peg to the brake drum lever. It'll have to have and "S" shape to clear everything but I've seen it done so I know it works. Hope that helps.

Careful, that setup mean than your suspension travel will affect your brakes action.

mystic_1

Hmm, is that because the pivot isn't located at the same point as the swing arm pivot? I talked to two people who have done this and neither of them mentioned it having any effect on the brake action.

I think virtually all set ups, the brake action is affected by the swingarm moving up and down. (Exception is hydraulic or cable actuated brake.)

With the CB750 for example, if you could hold the brake pedal in a positon relative to the frame. and move the wheel up and down you would see the brake lever move relative to the brake plate.

Especially, when depressing the rear brake, if you raise the rear wheel the brake will tighten up as though you were pushing harder on the pedal. As a practical matter we all just "feel" this and compensate. Usually when braking the rear rises, wheel drops relatively, and the rear brake becomes less effective, which is a good thing.

The key is simply to be aware.  If its too bad, you'll have to change something.

[mystic_1]

Yes, the further away the end of the brake rod is from the pivot point of the swingarm, the more effect swingarm deflection will have on brake action.

My original post should have said "... more than the stock setup".

In extreme cases, hitting a bump or dip in the road could result in the rear brake applying itself.  So, try to keep the two pivots as close to each other as possible. 

In stock configuration, the brake rod end pivot (where it meets the pivot arm that goes through the frame) is quite close to the swingarm pivot point, like within in inch or so, and in a plane connecting the rear axle to the swingarm pivot.  This position gives minimal deflection on the brake arm when the swingarm moves.

As Ron says, just something to pay attention to.  Remove your rear shocks and raise the swingarm to it's highest deflection point to see what effect it might have on your brake linkages.

mystic_1

[Pinhead]

I drove the bike today to work with both pegs mounted in their new position. I haven't yet moved the brake lever back, though.

A little background. When I first got the bike I removed the grab rail and rode it around for a while (rode the bike, not the rail ) and noticed that anything above 55 was extremely unstable. It felt like the entire bike frame was flexing like a slinky. I quickly went back home and re-installed the grab rail. Stability increased greatly; 70 to 75 mph was now achievable. Above 75 mph, however, tended to easily induce a wobble. It seems that the CM400 frame is inherently flexible.

Adding the aluminum plates (that are holding the rearsets) has stiffened the frame enough that it has increased stright-line highway stability by another noticeable amount.

I recommend this mod for anyone that is driving a CM400. Even if you don't install rearsets, I strongly recommend adding the plates to help stiffen the frame.

[Green550F]

Swingarm motion doesn't affect the brake action as the function is related to the cable end vs the mounting points. since the mount at each end moves with the relative location of the cable end there is very little effect. In fact the only effect will be changing of the radius as the swing arm moves. This will be less than the normal free play at the pedal.

There is far more effect with a rod actuated brake which still works fine.

My rearsets are from a 2000 Buell M2. Fitted to a CL350 frame. I found the origional mounts did not have enough strength so I had to add a backer to them. It works great but the shifter didn't work so I flipped over a second brake for the shifter pedal.

[Steve_K]

I built rear sets for my Hawk GT and I decreased the leverage about 15% because it was easy to lock the rear up under heavy braking.  It had a disk brake tho and not the same as a drum.  I will be building rearsets for my 550 this winter and I have not got around to checking the leverage yet.
Steve

[Industrial Rat400f Killer]

Yes, the further away the end of the brake rod is from the pivot point of the swingarm, the more effect swingarm deflection will have on brake action.

My original post should have said "... more than the stock setup".

In extreme cases, hitting a bump or dip in the road could result in the rear brake applying itself.  So, try to keep the two pivots as close to each other as possible. 

In stock configuration, the brake rod end pivot (where it meets the pivot arm that goes through the frame) is quite close to the swingarm pivot point, like within in inch or so, and in a plane connecting the rear axle to the swingarm pivot.  This position gives minimal deflection on the brake arm when the swingarm moves.

As Ron says, just something to pay attention to.  Remove your rear shocks and raise the swingarm to it's highest deflection point to see what effect it might have on your brake linkages.

mystic_1

I think virtually all set ups, the brake action is affected by the swingarm moving up and down. (Exception is hydraulic or cable actuated brake.)

With the CB750 for example, if you could hold the brake pedal in a positon relative to the frame. and move the wheel up and down you would see the brake lever move relative to the brake plate.

Especially, when depressing the rear brake, if you raise the rear wheel the brake will tighten up as though you were pushing harder on the pedal. As a practical matter we all just "feel" this and compensate. Usually when braking the rear rises, wheel drops relatively, and the rear brake becomes less effective, which is a good thing.

The key is simply to be aware.  If its too bad, you'll have to change something.

Thanks for the tips, I will keep these in mind when I get around to finishing my rear sets.

[Alan F.]

I drove the bike today to work with both pegs mounted in their new position. I haven't yet moved the brake lever back, though.

A little background. When I first got the bike I removed the grab rail and rode it around for a while (rode the bike, not the rail ) and noticed that anything above 55 was extremely unstable. It felt like the entire bike frame was flexing like a slinky. I quickly went back home and re-installed the grab rail. Stability increased greatly; 70 to 75 mph was now achievable. Above 75 mph, however, tended to easily induce a wobble. It seems that the CM400 frame is inherently flexible.

Adding the aluminum plates (that are holding the rearsets) has stiffened the frame enough that it has increased stright-line highway stability by another noticeable amount.

I recommend this mod for anyone that is driving a CM400. Even if you don't install rearsets, I strongly recommend adding the plates to help stiffen the frame.

That's a great one PH, you should post that one on the twins forums too if you get the chance.
-Alan