Dragging front wheel after brake bleed

[headtube]

So, I bled my ATE front brakes today (79 RS). I adjusted the bearing bolt on both calipers so that the inboard pads were flush with the disc/s. Also loosened the front axle and bounced the suspension several times to seat everything, then cinched it up. I know some drag is probably expected, but it seemed a bit much to me. So I checked the MC and slackened off the cable a little from the piston rod so that the pads would return to a "resting" position.

After all that... still dragging excessively. Rotors are not warped. Any thoughts?

[Stagehand]

I always needed to bleed them again and again when they drug on me, after such brake mechanicking.

Maybe it was just a bubble in my head, though

[Big Bamboo]

There is a U shaped tool on the factory feeler gauge for setting the free play at the master cylinder. Also, did you get the pads parallel with the disc?

[ozmoses]

A) Bleed again. And again.

B) Could be your pads are not adjusted properly with the eccentric bolt.

C) Crud in master cylinder return port(s)

D) caliper needs a rebuild.


E) Brake lines not allowing fluid return.

[headtube]

I went over this pretty thoroughly. I did rebuild the calipers. Cleaned the inside of the MC with Q-tips - being very careful not to introduce lint. The pads are parallel with the discs. Free play at the piston rod is correct. Even removed the clamp holding the under tank MC to remove more air. The lever is pretty firm when applying the brakes, but the pads don't release as they should. At least not for my liking.

What a ridiculous system. I can see why BMW switched to the Brembos up front. There's one out back, and it bled just fine with no issues.

[Stagehand]

Then just bed them in really well?

[One Less Harley]

if you have old brake lines that could be your problem.

[_cy_]

another vote for collapsed brake lines ... go to your local brake re-builder. they usually can make up new hoses that match up very closely with OEM. at a fraction of costs of OEM

[Kai Ju]

Take a magic marker and draw about 6 evenly spaced radial lines on both sides of the rotor. i.e. hub side and fork leg side.
Spin the wheel and see where the marker has been rubbed off.
It shouldn't wear anywhere until brake pressure is applied.
Where ever marker has been rubbed off, that's where your pads are touching.
Adjust the caliper so that the inside pad wears the line off evenly across the face of the rotor with light pressure applied.
The outside pad self adjusts and should only wear with brake pressure applied.
If it wears the marker off without brake pressure applied the caliper is misadjusted and touching the rotor, causing brake drag.
Adjust as needed.

If you determined that the caliper is adjusted properly but you still have brake drag the most likely option is that the compensating port hole is blocked and needs to be cleared. It's the smaller of the two holes visible at the bottom of the master cylinder reservoir and is the one closest to the brake hose.
When you push the caliper piston in you should get a little geyser of brake fluid coming out of that hole in the master cylinder. If you don't you need to find out why.
It can either be insufficient cable clearance forcing the piston to cover the hole or simply dirt/rust etc.

Clear the hole and see if your brakes work as designed.

[00_Green]

What fluid did you use? Brake light staying on? That might indicate trapped pressure. Had a friend do a bleed on his and he added a DOT 5. it reacted with the old 3/4 and caused the master to hold pressure on the calipers.

[headtube]

Good advise from everyone. I will use the marker to establish where the rub is located. I will also look for a blocked venting hole/port. Thanks. Dot 4 - new bottle.