Rear Wheel Question....Will it fit?

[Arnie]

Noel,

If you don't have a "brake arm" or have the caliper or hanger keyed to the swingarm, then the hanger and caliper will rotate about the axle.  Anchoring the brake arm to the swingarm, the footpeg bolt, or to a frame cross member will restrict this rotation.

[ribbert]

Noel,

If you don't have a "brake arm" or have the caliper or hanger keyed to the swingarm, then the hanger and caliper will rotate about the axle.  Anchoring the brake arm to the swingarm, the footpeg bolt, or to a frame cross member will restrict this rotation.

That's my very point. If the brake arm is fixed to the frame, as opposed to the swing arm which moves in an arc around the frame, The caliper must rotate as the arm moves up and down.
I've only had 2.5 hours sleep in the last 2 days, perhaps my brain is addled, but that's how I see it.

My point is, mounting the caliper stay to the swing arm vs the frame. If it's mounted to the arm, it all moves as one. If the stay is mounted to the frame, the caliper has to rotate.

Noel

[Pat Conlon]

I agree with Noel...

With the different pivot points (brake arm vs swing arm) the caliper will move back and forth as the swing arm pivots up and down.

Is it a problem? The folks who have the brake arm anchored to the frame report no quirks.

Although it is best to have the brake arm anchored to the leg of the swing arm to negate the movement of the caliper when the rear suspension loads and unloads..

[FJmonkey]

I mounted the rear brake stay to the underside of the swing arm with a custom bracket when I did my GSXR rear wheel swap. I did not want to consider what happens if connected to the fixed frame, under hard braking and having the rear wheel navigating rough road. But with the connection points being as close as they are and the rear braking providing 20% or less of braking effect, I am guessing this is a 98% fix. If you are not gonna track the bike or ride it like you stole it, the rear passenger should work well.

[Mark Olson]

Swing arm mount is best for the brake stay .  You do not want it moving around on the axle and swingarm.

[X-Ray]

I have to add that I have never been 100% happy with the brake arm bolted to the footpeg bolt, it can't be done up super tight as that is actually a pivot point now for said brake arm. Fixing the brake arm to the swingarm is on my to do list, 

[ribbert]

I agree with Noel...

With the different pivot points (brake arm vs swing arm) the caliper will move back and forth as the swing arm pivots up and down.

Is it a problem? The folks who have the brake arm anchored to the frame report no quirks.

Although it is best to have the brake arm anchored to the leg of the swing arm to negate the movement of the caliper when the rear suspension loads and unloads..

What I don't understand is, on my bike (and I amagine others ) the caliper is wedged between the spacer and the swing arm and when the axle is tightened, it can't move, as we all agree it must do as the swing arm rises and falls if the stay is attached to the frame.

?

Noel

[Pat Conlon]

Actually the caliper isn't wedged to anything, it just bolted to the caliper arm. The lower point of the caliper arm is squeezed between the wheel and swing arm...it acts as a spacer.
Yes, the caliper arm is squeezed when the axle nut is torqued but that force is not enough to resist rotation when the caliper squeezes the rotor. That's why the brake torque arm (aka stay arm) is needed.
Rest assured if your torque arm comes off and you apply the back brake, the force from the rotor on that cantilevered caliper arm will spin that bad boy. Exciting things will happen.

Some bikes don't need a torque arm. They have a dovetail or key arrangement  where the caliper arm is connected to the leg of the swing arm and the resistance to rotation happens thru that dovetail/key connection.

[fj johnnie]

 Some GSX-R rear calipers are designed to have the stay attached to the frame. The torque arm has a bearing which allows the caliper to move freely about the axis of the axle. It is designed to rotate. As the bike moves through the suspension, the position of the caliper changes .All the Yamahas I own have the stay attached to the swing arm. When the axle is tight, the caliper does not move about the axis. However, as Pat says, if you apply the brakes it will rotate. Thus the need for a stay to prevent rotation. The Yamaha application does not allow movement at any time.

[The General]

I agree with Noel...

With the different pivot points (brake arm vs swing arm) the caliper will move back and forth as the swing arm pivots up and down.

Is it a problem? The folks who have the brake arm anchored to the frame report no quirks.

Although it is best to have the brake arm anchored to the leg of the swing arm to negate the movement of the caliper when the rear suspension loads and unloads..

What I don't understand is, on my bike (and I amagine others ) the caliper is wedged between the spacer and the swing arm and when the axle is tightened, it can't move, as we all agree it must do as the swing arm rises and falls if the stay is attached to the frame.

?

Noel

Haaaha....I find chicken trolling better than prawns, esp if they`re on the nose, but a thick worm hooks them best.   

[Pat Conlon]

Awwww geeze, I think I've been had.....

[Bones]

Noel,

If you don't have a "brake arm" or have the caliper or hanger keyed to the swingarm, then the hanger and caliper will rotate about the axle.  Anchoring the brake arm to the swingarm, the footpeg bolt, or to a frame cross member will restrict this rotation.

That's my very point. If the brake arm is fixed to the frame, as opposed to the swing arm which moves in an arc around the frame, The caliper must rotate as the arm moves up and down.
I've only had 2.5 hours sleep in the last 2 days, perhaps my brain is addled, but that's how I see it.

My point is, mounting the caliper stay to the swing arm vs the frame. If it's mounted to the arm, it all moves as one. If the stay is mounted to the frame, the caliper has to rotate.

Noel

Noel, When everything is tightened up and the torque arm is disconnected, the caliper will rotate easily because there's a bush on the hanger where the axle goes through, also on the torque arm where it connects to the frame there's a rotating ball.



and again on the caliper there's a bush where the other end of the torque arm connects.



So when all connected and tightened, everything is free to move to compensate for suspension travel. You could probably mount the torque arm to the swing arm somewhere if you wanted to weld a mount on it, but the arm is pretty long so you might have to shorten it to fit. As it is standard, it lines up well with the bottom foot peg bolt, so that seems to be the easy way out and why people mount it there. I just put a longer bolt in, spaced it out a bit from the frame so it doesn't hit, and lock tighted the nut on. Seems to work ok for now, but maybe in the future I'll look at mounting it different.

                                                                             Tony.

[ribbert]

Noel, When everything is tightened up and the torque arm is disconnected, the caliper will rotate easily because there's a bush on the hanger where the axle goes through, also on the torque arm where it connects to the frame there's a rotating ball.



and again on the caliper there's a bush where the other end of the torque arm connects.



So when all connected and tightened, everything is free to move to compensate for suspension travel. You could probably mount the torque arm to the swing arm somewhere if you wanted to weld a mount on it, but the arm is pretty long so you might have to shorten it to fit. As it is standard, it lines up well with the bottom foot peg bolt, so that seems to be the easy way out and why people mount it there. I just put a longer bolt in, spaced it out a bit from the frame so it doesn't hit, and lock tighted the nut on. Seems to work ok for now, but maybe in the future I'll look at mounting it different.

                                                                             Tony.

Thank God, at last, the answer I was looking for, without a lesson on terminology or the fact that applying enough force to anything will move it whether it's meant to or not.

Thanks Tony, that is exactly the answer I was looking for. I have an FZR600R wheel and brakes and the caliper clamps firmly between the hub and the swing arm. A brake stay bolted to the frame would not work with this arrangement but you have clearly shown how it works with the Suzuki bits.

You have provided the information I needed, thankyou.

Noel

[ribbert]

Awwww geeze, I think I've been had.....

No, not at all Pat. It was a legitimate question for the reasons just mentioned in the previous post.

The General, being privy to certain information, is naturally suspicious of any questions I post.

Noel

[ribbert]

Actually the caliper isn't wedged to anything, it just bolted to the caliper arm. The lower point of the caliper arm is squeezed between the wheel and swing arm.

Pat, this effort gives you an unassailable lead in "Pedant of the Month"

BTW, it's never referred to as the "arm"   

Noel