Stiff Sticky Brake Pedal

Stiff Sticky Brake Pedal:
My brake pedal got very stiff and sticky over the last week and I wasted a lot of time on the rear caliper since it was showing corrosion from the winter's riding. After moving on to the master cylinder I disconnected the linkage and found it was all in the main pivot bolt of the pedal. After buying a metric hex set and adapter for my impact wrench I finally got that stubborn bolt loose and the friction immediately disappeared. I then tweaked it with a ratchet so it moved easily without rattling. Don't know what caused that after 11 years and 54,000 miles but I'm not going to the trouble of removing the cotter pin and pulling the bolt unless I need thread-locker to keep it just right. This was an unexpected problem so it took me awhile to figure it out (or I'm just slow) but maybe I can save others time and trouble if they have the same problem.

I don't understand what you're getting at.

Do you mean that the pedal was stiff until you backed off on the pivot bolt a bit?
Do you mean that the pedal will now only move freely if you leave the pivot bolt backed off a bit?

Yes.

It's simple sense that a tighter pivot bolt will cause more friction but there was no way it tightened itself. Maybe corrosion though none was visible, I won't know unless I remove it and check and there's a hard to get at cotter pin that would need to be pulled first.

Yes, I believe you are going to have to remove that cotter pin and remove the pivot bolt.

Reason being is that, unless you fell over and bent something, the likely reason you're having a stiff brake pedal is that the grease that was once lubricating your pedal and pivot bolt junction is now no longer in the building.

The pivot bolt has a shouldered length to it that is a wee bit wider than the brake pedal so you should be able to torque that bolt down properly and not bind the brake pedal movement.
Having to run it loose is a good indication that you need to remove the pivot bolt for an inspection.

Ok I found a diagram showing it is indeed a shoulder bolt but the fact that the friction is sensitive to bolt torque indicates it's caused by a vertical surface and not lubrication. So the proper solution would be to put a shim at the threaded end or grind down the surfaces of the washer at the head of the bolt, which may be a bit swelled by corrosion. It's only backed out a tiny fraction but it does seem to have loosened a bit from my 20 mile backroad ride yesterday so I will have to deal with it eventually like you said. Don't know about greasing a part that's subject to so much dust but if there's grease already then I'll clean and regrease.

speedfiend wrote:

Ok I found a diagram showing it is indeed a shoulder bolt but the fact that the friction is sensitive to bolt torque indicates it's caused by a vertical surface and not lubrication. So the proper solution would be to put a shim at the threaded end or grind down the surfaces of the washer at the head of the bolt, which may be a bit swelled by corrosion. It's only backed out a tiny fraction but it does seem to have loosened a bit from my 20 mile backroad ride yesterday so I will have to deal with it eventually like you said. Don't know about greasing a part that's subject to so much dust but if there's grease already then I'll clean and regrease.

I had a similar issue with my DL650.  In the end I needed to clean away the corrosion and lube the bolt/joint.

Seems the corrosion is wearing away for me. Last time I tightened the bolt I could snug it lightly without friction but a good tightening would still cause it. A little more braking and vibrating might get it back to good.

But next spring's snowmelt/roadsalt mix may well resurrect it. Oh well, why worry now?

I don't understand why you refuse to remove the cotter pin.

A good mechanic has the patience to wait for problems to fix themselves. ;-)

And apparently I am a good mechanic, at least in regards to brake pedal pivot bolts. Torqued tight and moving freely for some months now.

Still waiting for my chain to shrink back to its original length and the knobs to grow back on my tires.