Is this normal? Front disk

[Paul57]

Hi all. I have replaced the front pads and master cylinder on my '80 XS400. Today I had the bike propped up and tried spinning the front wheel. It will turn, but it's snug, for lack of a better word. It certainly doesn't spin freely. I'm just curious if this is normal.

 

[xschris]

The pads will have a bit of drag to them. As long as you can grab the brake and then release it and it still turns with little effort your good.

 

[stormtracker]

Check it again after a test ride to be sure. It will probably be ok after they get seated after a test ride.

 

[16VGTIDave]

The pads may be hanging up in the carrier. Sticking or bent slider pins can be another cause of dragging brakes. Another possibility is a sticking caliper piston. There should be very little drag from the brakes, the caliper piston seal is designed to retract the piston slightly when the brakes are released.

Also check the adjustment of the brake lever. There should be some free play between the adjuster screw and the piston in the master cylinder.

 

[Paul57]

Thanks for the advice. So here's an update. Today I went out and dropped the front disk brake pads in case I had a rock stuck in there (I live on a gravel road). All seemed fine and the wheel spun loosely.

Then I took it out for a ride. Within a few miles, I could hear a squeak. I was worried it was bearings, so I cut my ride short. When I got home, I could tell that the front caliper was pretty tight on the front disk, and that was causing the squeaking. Again, I could turn the wheel by hand, but it wasn't loose by any means.

After it cooled for a while, things loosened up and when I turned the wheel, I could hear the disk lightly brushing against the pads. If this "tightness" is normal with new pads, then I'll live with it until they wear down a bit. My main concern is having the wheel seize while I'm rolling. The pads are new and are supposed to be the right ones for this bike.

Thoughts?

 

[Scorpio1963]

I think you should try bleeding your master cylinder.I had this problem with my bike and had them seize while riding.Fortunately I wasn't going very fast and I jumped off the bike before getting thrown off it.I checked my pads and could find anything that looked out of the norm.I bought a new set of pads and it was still dragging.Come to find out my caliper wasn't retracting back like it should.I rebuilt it and then had a problem with MC.After bleeding it and the brakes problem is fixed.

 

[Yamaguy55]

Sounds like the the caliper piston is hanging up. Be absolutely sure you have bled all the air out as well. If any is in the caliper, it will expand and apply the brakes.

The runout of the disk and the "grippyness" of the piston seal retracts the pads enough that they just skim the disk as you ride. If they heavily drag, I'd start by pulling the caliper, using a c-clamp and push the piston all the way in. Pul the master cylinder cap , mop out the old fluid, being sure not to get it on paint, as it is a great paint remover. Fill with clean fluid from a sealed container( brake fluid sucks moisture out of the air like a sponge) Remount everything, then after pumping up the system with the lever a few times, bleed the system until clean brake fluid comes out the bottom.

If it still drags, rebuild/replace the caliper. The chrome on the pistons often peels and then the piston pits, hanging up the piston. I think MikesXS sells the pistons separately.

Good luck. Old brakes are often a real pain. If the hoses are originals, replace them with the braided steel type. Hoses are only good for 4 years, so I'm guessing yours are older. Replace it all.

 

[XSLeo]

On the M/C there is a tiny bleed hole. When you release the lever the piston retracts enough to uncover this bleed hole and lets any pressure in the line bleed back into the reservoir. If this bleed hole is plugged it can give you these symptoms.
I might suggest a tear down and cleaning of the M/C. Or better yet a new M/C with a 11 mm bore. This will greatly improve the braking over the stock 14 mm bore.
Leo

 

[motoTrooper]

Yep, total rebuild is what I'm having to do as well. Not very expensive or difficult either.

 

[XSLeo]

I was just looking at my XS650 book and it says that some brake drag is normal.
If you hook a scale to the spokes out near the rim. and turn the wheel by pulling the scale. 2-4 m-k gs. I think that means kilograms per meter. My manual has a conversion formula to convert kg-m to ft-lbs. 14 to 28 ft-lbs.
I think as long as it turns with out to much force then it's ok. Given a good hard spin and it stops in less than one turn is a bit much. The same good hard turn it should spin a couple turns.
Leo

 

[drewpy]

if I had to leave my bike for any length of time, it would partially seize. A good kick on the caliper body usually releases the pads off the disk.

best to take them off and open up the dust seals where you will find that the alu has corroded. Just need to clean it.

No need to take off the hoses

 

[Yamaguy55]

Be sure to check the condition of the pistons while you're there. They often pit the chrome plating and that makes them dig into the bore and seals. The old fluid often congeals in both master and wheel cylinders. A good disassemble and scrub work wonders. If they clean up well, reassemble and bleed and they should be fine.

The fun of old bikes. Just be happy they are only 30 years old. Try 45-50 years old. They're even more fun.