bled the air out of rear OK but a ?

[6m459]

Hi,

 

OK, so I finally found some time to get down to bleeding the air out of my (new to me) red bike's foot brake front line.

 

Despite all my worry about difficulties of the job, it went pretty well and I managed it without a helper. Took a bit of planning and required some odd contortions on my part, but not too difficult overall. I worry too much.

 

The brake pedal feels nice and firm now and brakes work so much better. I notice though, that the rear brake pads drag a bit now.

 

When I first took a road test, I noticed lots of dragging and hot rotors, so I returned to base and, as per advice here, took some fluid out of the reservoir to make a larger air space in the reservoir. No doubt about it I had overfilled it at first. Now the fluid level is below the bottom of the threaded plug channel btw.

 

This helped and there is less dragging now, but there still seems to be some that I wonder about. (Unfortunately the bike is not licensed as yet, so I have to keep my road testing to a minimum and only on the QT cause I have neighbours who are policemen & women.)

 

My driveway is on about a 15 degree incline. At the first test, the bike wouldn't roll back on its own when I had it pointing up hill on the driveway in neutral. After losing some fluid, it will now roll back OK. Also, originally I had high heat on both the rear and front left rotors but after loosing some fluid only the rear sounds like its dragging and the front rotor came back from road testing quite cool.

 

With the bike on the centre stand, I can rotate the rear wheel with my foot but there is some resistance coming from the brake (I lifted the caliper up off the rotor to confirm this).

 

My other '84 xvz12, with lots of road miles in my care, has very little resistance to the rotation of the rear wheel by foot.

 

In the course of looking this bike over, as it is new to me, I have had the brake pads out of the rear and front left calipers to inspect them for wear etc. I cannot guarantee that the pads were re installed on the same side of their respective calipers, or if they are now swapped around. Thus presumably there could be some wearing in to do all over again.

 

My question is, does this light drag seem normal, or should I be looking to improve it somehow?

 

Thanks,

 

Brian H.

[mini-muffin]

Muffinman says that light drag is ok and will work itself out with some riding time. It may just be like you said the pads are reversed.

 

Margaret

[rhncue]

Just riding and using rear brake may well fix the problem. The problem could be the pads as you suspect or it could be a stiff and sticking piston in the caliper. If after a week or so of usage you still have the problem I would pull and rebuild the caliper. Easy to do and not expensive.

 

Dick

[Venturous Randy]

Just riding and using rear brake may well fix the problem. The problem could be the pads as you suspect or it could be a stiff and sticking piston in the caliper. If after a week or so of usage you still have the problem I would pull and rebuild the caliper. Easy to do and not expensive.

 

Dick

 

RandyA

[bongobobny]

When I read the title I thought maybe you farted and had a little more than air come out...

 

Make sure you still have a little free play in the brake pedal, else wise the rear brake will not completely release and cause drag. You may also end up rebuilding the rear caliper as the piston may be a little gummed up.

[skydoc_17]

Hey Brian,

With the cost of a rear rotor hanging in the balance, plus a rear caliper lock-up due to a overheating rear caliper, I would not risk running a dragging caliper myself.

I have had really good luck using compressed air to "pop" the pistons from the caliper, (I use a stack of paint stir sticks between the pistons, blow air in caliper where the brake line attaches, remove a stick or two and blow again.) until the pistons come out. Remove the cap screws to split the caliper into halfs. Pick up a Brake Cylinder Hone at any auto parts store.( $10.00) When removing the seals from the caliper halfs there are two different seals in each piston bore, the front seal is a wiper and the second is the actual seal. Keep the seals separated. Lightly hone each piston bore, clean the pistons, (I use scotchbrite for this) Yamaha makes a brake piston lube that works great and I use it a lot. If you don't want to spring for the new seals you can reuse the old ones as long as you don't tear or break them when you remove them. I have done this "cheapy" caliper rebuild several times and have had excellent results with a very minimal cost.

If you decide to skip the caliper rebuild, carry a 12MM wrench and a 5/16 wrench because when that caliper drags you to a stop the only way to get going again is to let off some of the fluid pressure from the caliper, if this doesn't work, take the 12MM wrench, remove the caliper bolts, rock the caliper back and forth to spread the pads re bolt the caliper, and ride home but don't apply the rear brake. If you have questions about the rebuild, PM me.

Hope this helps,

Earl

[Condor]

It could also be that the rear line is plugged and not allowing expanded fluids to retun upstream to the reserve. I might also add that there isn't a sight glass on the L.front/rear reserve. He might be mistakenly looking at the right front and not addressing the problem.

[6m459]

I might also add that there isn't a sight glass on the L.front/rear reserve. He might be mistakenly looking at the right front and not addressing the problem.

 

Say what ?

[6m459]

When I read the title I thought maybe you farted and had a little more than air come out...

 

Make sure you still have a little free play in the brake pedal, else wise the rear brake will not completely release and cause drag. You may also end up rebuilding the rear caliper as the piston may be a little gummed up.

 

I'll have to be a little more careful in titling my posts from now on I guess. Sorry for the confusion.

 

I did compare the pedal position and free play between bikes. They both seem to look and feel the same now.

 

Also, I did use a C clamp to retract the pistons at reassembly. Both seemed to move freely and didn't take too much force. Actually I was surprised how nicely they retracted as I was expecting a struggle. I made sure to push on the centre of the piston by putting a socket inside and using it as a spacer.

 

Thanks,

 

Brian H.

[Condor]

Say what ?

 

My Bad.... I should double check all long posts before commenting. Disregard my previous post...

[Yammer Dan]

Is there less drag when cold?? If so you still have too much fluid in the rear reservior. And as mentioned here it could be not enough free play in brake linkage. When it is dragging can you adjust free play til it is not. Keep wrenches and paper towels with you when you try it out. Brake fluid not nice to paint!!!

[bongobobny]

I'll have to be a little more careful in titling my posts from now on I guess. Sorry for the confusion.

 

I did compare the pedal position and free play between bikes. They both seem to look and feel the same now.

 

Also, I did use a C clamp to retract the pistons at reassembly. Both seemed to move freely and didn't take too much force. Actually I was surprised how nicely they retracted as I was expecting a struggle. I made sure to push on the centre of the piston by putting a socket inside and using it as a spacer.

 

Thanks,

 

Brian H.

 

Hmmmm, I just used my thumbs to reinstall my pistons, but I did take the time to polish the pistons prior to reassembly, using a buffing wheel. Did you replace the seals as well?? The original ones are quite old!!

 

Did you also rebuild the rear master cylander?? Could be IT is not returning smoothly.

 

 

BTW Skydoc, that is EXACTLY how I disassembled all my calipers!! Started with 3 paint sticks because they fit perfectly between the slots, then removed one at a time and finally removed all of them!!

[Condor]

BTW Skydoc, that is EXACTLY how I disassembled all my calipers!! Started with 3 paint sticks because they fit perfectly between the slots, then removed one at a time and finally removed all of them!!

 

Good idea. I just used a piece of plywood with a shop rag over it to cushion to blow.