Typical Brake Drag

[BrilliantMove]

Came back from a quick test drive after reassembling my 87 XR250 and the front disk was hot to the touch.

Spun the front wheel and it barely moves without brake applied.

What is typical drag on a front brake? Similar to a pedal bike where you want very little, or like a car where you want a bit?

Any advice would help.

[Reformed Wheeler]

If your rotor seems good and your caliper and brakes are normal... I guess I would be looking at the spokes... If your wheel is all trued up...

[redhurricane]

IF the rotor is straight and true, next step would be to grease the bolt that the pads ride on- if it is dry and/or corroded the pads will not move freely and will generate more heat from contact with the rotor. 

[Trailryder42]

To elaborate on the greasing brake pad pins that your see a lot of folks mention. They don't mean, to slather on a thick coat and leave it that way. After you file / sand the rust off the pin, just a light film is all it needs. Anything more and its going to collect dirt. In fact, I prefer to use anti-seize, as I think it impregnates ( ? may not be the word I'm looking for) the metal better.

 

Don't confuse the pad carrier pin with the caliper carrier pin.

[BrilliantMove]

Thanks for the tips!

Ill check the disk integrity and the pin situation.

But what's the ideal drag? None at all?

[BOAB]

If your rotor seems good and your caliper and brakes are normal... I guess I would be looking at the spokes... If your wheel is all trued up...

 

Isn't the rotor attached to the hub?

[Trailryder42]

Thanks for the tips!

Ill check the disk integrity and the pin situation.

But what's the ideal drag? None at all?

 

Well it should spin several revolutions, even with a light drag. Barely spinning with no brake applied is not right.

 

Be sure the reservoir isn't overfilled.

 

Stand on the left side of your bike, hold the handlebar, put your foot against the brake caliper and push to compress the caliper piston. Does the wheel spin freely now?

[Reformed Wheeler]

Isn't the rotor attached to the hub?

Yes good point, I should have mentioned the wheel bearing... I think I thought it, but didn't type it...

[BrilliantMove]

Okay update:

Tried the foot on caliper thing..still drags.

Also seems to be a slight warp, but not enough to cause the drag.

Next I bled a bit from the upper reservoir. No change in drag. Closed it up.

Then I loosened the bleeder on the caliper and wabam! Drag reduced. So I tightened it up. And tested the brakes. Breaks grabbed just fine.

But then, they didn't fully release to the ideal drag I found d by loosening the caliper bleeder. Instead it returned to previous drag...

Removed the two pins with flathead and no sign of corrosion.

[BrilliantMove]

Well it should spin several revolutions, even with a light drag. Barely spinning with no brake applied is not right.

Be sure the reservoir isn't overfilled.

Stand on the left side of your bike, hold the handlebar, put your foot against the brake caliper and push to compress the caliper piston. Does the wheel spin freely now?

Actually, I tried this again and it helped. But just like I mentioned in my last post the drag returns after I use the brake... So, what does this mean?

[JoeRC51]

Be sure the little holes in the master cylinder don't have crap in them and make sure the MC piston is retracting fully. Somewhere you're not releasing the pressure back to the MC. Sometimes old brake hoses delaminate internally and cause blockage.

[piltoyougram]

Check the 2 activation pistons in the in the caliper, they just may need cleaned or replaced.

[MadMat]

Try to lubricate the caliper pin where it slides in the caliper bracket with silicon or dielectric grease. Worked for me.

[BrilliantMove]

Swapped the discussion and I'm getting less drag.

I'll lubericate the pins too. Both the pins and the cylinders seem to have a good amount of dirt.

Thanks!

[FFMan]

next stop - split the caliper and remove the pistons, polish and reassemble with new seals i.e. a caliper rebuild.

 

generally works wonders, and is required on most bikes from time to time.

[puddytat]

next stop - split the caliper and remove the pistons, polish and reassemble with new seals i.e. a caliper rebuild.

 

generally works wonders, and is required on most bikes from time to time.

What he said....all the brakes that I have had drag, were the pistons seizing .

[BrilliantMove]

What he said....all the brakes that I have had drag, were the pistons seizing .

Yeah that's a good point, even from the outside I can see very dirty grease in that area. I'll do a rebuild.

I'll post pics and lessons learned for future generations!