Grabby Brakes

Back in mid May I did a brake bleed and replaced the front brake pads on my Oilhead. Didn’t do a lot of riding on the Oilhead but the brakes operated fine.

Just took a 2000 km trip with the R1100RT pulling my one wheel trailer. Haven’t used the trailer during the past two COVID years. On this trip the front brakes became “grabby” when coming to a stop. Hadn’t experienced this in the past with the trailer. Thought I possibly overloaded the the trailer although I doubted that as I hadn’t packed as much as my usual camping gear.

Once I arrived in Winnipeg and dropped the trailer at the in-laws, I tested the brakes and found them to still be grabby when stopping.

Any thoughts as what changed and how to eliminate the less than stellar stops, especially before I leave for the trip home?

Paul:

What do you mean by "grabby"? Do you mean:

1. The brake has more bite and effectiveness than you expect for a given amount of lever pressure?

If so, did you use OEM pads or an aftermarket? If aftermarket perhaps trying a different pad material or reverting to OEM might be the answer.

2. The brake doesn't seem to completely disengage, i.e. drags a bit, when the lever is released?

If so, maybe the calipers have picked up enough crud to be restricting free movement of the caliper pistons. In that case I'd be tempted to pull the caliper and pads and give the caliper a good wash with soapy water and a toothbrush.

Good luck and enjoy the rest of your trip!

stooie said:

Paul:

What do you mean by "grabby"? Do you mean:

1. The brake has more bite and effectiveness than you expect for a given amount of lever pressure?

If so, did you use OEM pads or an aftermarket? If aftermarket perhaps trying a different pad material or reverting to OEM might be the answer.

2. The brake doesn't seem to completely disengage, i.e. drags a bit, when the lever is released?

If so, maybe the calipers have picked up enough crud to be restricting free movement of the caliper pistons. In that case I'd be tempted to pull the caliper and pads and give the caliper a good wash with soapy water and a toothbrush.

Good luck and enjoy the rest of your trip!

Click to expand...

#1. More bite than anticipated as the final pressure is applied to complete the stop
aftermarket but not being home, I am reluctant to taking stuff apart.
having camped in campgrounds with sandy & gravel roads, that sounds like a possible cause.
will examine and attempt some cleaning.

#2. This has not been an issue.

Thank you for your suggestions.

Paul

1 - Have you upgraded the front brake hoses? If they're stock, I could envision a piece of internal hose crud (highly technical term there...) partially blocking a line, and moving as pressure is increased.
2 - The disc may be a bit warped; you may be able to see some runout viewing from the front and manually spinning the wheel.
3 - May be some crud has imbedded itself into a pad.

On the one hand, most front calipers are pretty easy to pull if one has the correct wrench.

On the other hand I'm not familiar with the Oilhead's pad setup and some pads and their retention pins can be trickier than others. I also am completely sympathetic to the feeling of "working without a safety net" trying this far from home.

Good luck!

Easy to pull, but the fiche also shows a few different "mounting parts" sets - if the wrong one was used, or has come a bit loose, that may cause those symptoms too. (Insert "Grrr" here.)

Pauls1150 said:

1 - Have you upgraded the front brake hoses? If they're stock, I could envision a piece of internal hose crud (highly technical term there...) partially blocking a line, and moving as pressure is increased.
2 - The disc may be a bit warped; you may be able to see some runout viewing from the front and manually spinning the wheel.
3 - May be some crud has imbedded itself into a pad.

Click to expand...

1. The lines are Spegliers.

2. New discs were installed about 30,000 km (18,000 miles) ago. Should be OK.

3. If crud should be embedded onto pads, would gently passing emery paper against the pads serve as a means of cleaning crud without removing the pads?

All suggestions are welcomed. I am trying to avoid drastic stops. Even though the trailer and cargo are only about 140 pounds, and under normal conditions the trailer weight is invisible when stopping, currently with the abrupt stop with final applying of the front brakes, the possibility of a tip over is all too much of a reality, which I do wish to avoid. (Successfully avoided so far)

For now the trailer is unhitched until tomorrow afternoon when we all head out of four days of camping together before I begin the 2,000 km trek home.

Obviously after checking the brake pads, emery paper could not be slid in to do any cleaning.

However after rotating the discs, there was some grit on them which I removed. I assume there will be a bit more after a few more rotations. Rain looks imminent so l’ll wait until it passes. Would blasting the calipers and pads with a hose have any effect at removing any remaining grit? (Riding in the rain made no difference yesterday.)

I neglected to mention that problem only began on the 3rd and 4th day of the four day ride and up I have been camping in sandy provincial campgrounds.

Any other suggestions are welcomed.

Cheers!

Blast 'em with high-pressure air. Wear eye protection and do not breathe the asbestos.

Pauls1150 said:

Blast 'em with high-pressure air. Wear eye protection and do not breathe the asbestos.

Click to expand...

That sounds like it might work.

Thank you, Paul !

Upon Examination

I was invited to visit Dieselyoda in Winnipeg who examined my braking problem. Apparently the aftermarket front discs have rings in the rotors which aren’t rotating. There also seems to be a lack of free play between the rotors and the brake pads. As well the brake, throttle and clutch cables appear to need replacing as they are much too tight.

I have for now pretty much eliminated the jerky or sudden slow stops. I am braking normally with mostly front brakes and some rear brake. When the actual stop is about to happen, I am using one finger on the front brake with a touch of the rear. With this method, stopping has been less stressful.

When I return home, I’ll make an appointment with a dealer to replace the mentioned cables and to check my front braking system.

I very much appreciate Dieselyoda‘s help in going over my R1100 and showing what things are and are not up to snuff. As things things deteriorate slowly over time, I failed to notice the changes.

Nice.
om

Brake cables too tight???

I knew oilheads used old technology, but cable brakes?

I also don’t understand the throttle cable and clutch cable being too tight. They are adjustable.

98lee said:

Brake cables too tight???

I knew oilheads used old technology, but cable brakes?

I also don’t understand the throttle cable and clutch cable being too tight. They are adjustable.

Click to expand...

My cables were very tight compared to Dieselyoda's. As for the clutch, I adjusted the freeplaym to 7mm before the trip, so it is within specs, but tight compared to his Oilhead. My main concern is the braking; hence the main reason to having a dealership mechanic to check this issue.

I do the 10,000 and 20,000 km services on my bikes but unlike many on this Forum, unfortunately I am no mechanic.

Perhaps the throttle and clutch cables are just worn or corroded inside (or "lubed"); also check that they're not getting "bent" too sharply or clamped tightly, at any point, as that would create unwanted friction.

Another perhaps is that the aftermarket rotors are actually too thick - my manual says the factory rotors are 5.0 +/- 0.1 mm (0.1969") thick, with a minimum of 4.5 mm (0.1772").

When you say "rings in the rotors", are you referring to the "wave" washers in the disk mounting points? They must exhibit a little free play, as they are part of the "floating disk" setup. That might be another sign that the disk is too thick, or maybe has excessive runout.

Pauls1150 said:

Perhaps the throttle and clutch cables are just worn or corroded inside (or "lubed"); also check that they're not getting "bent" too sharply or clamped tightly, at any point, as that would create unwanted friction.

Another perhaps is that the aftermarket rotors are actually too thick - my manual says the factory rotors are 5.0 +/- 0.1 mm (0.1969") thick, with a minimum of 4.5 mm (0.1772").

When you say "rings in the rotors", are you referring to the "wave" washers in the disk mounting points? They must exhibit a little free play, as they are part of the "floating disk" setup. That might be another sign that the disk is too thick, or maybe has excessive runout.

Click to expand...

It has been close to 100,000 km since the throttle cable was replaced and in the 135,000 km that I have ridden this bike, I don’t recall the clutch cable being replaced, unless that is part of a clutch replacement.

Couldn’t recall the proper term for the “wave” washers so yes, I called them “rings in rotors”.

I believe the aftermarket rotors were installed about eight years ago but of course there was no riding on this bike during the first year of COVID and maybe only seven or eight thousand km during las summer’s COVID’s season.

Needless to say, I am anxious to have a BMW tech check these items to return to normal stopping.

I was in awe, when I saw Paul's mileage.

Yep, Paul got some mileage on his R1100RT and such a gentle soul in person, makes me think of Dr. Hyde and Mr. Jeckle. I might have that backwards, or I might have it right?

Right off the bat, absolutely no movement in the rotors. The rotors need to move as the calipers are fixed. Hence, the rotors and in particular, the buttons, with c-clips, didn't move, at all.

Something has to float, calipers, rotors, anchors or whatever.

I don't think this was Paul's first notice of the issue. I would bet a box-o-beers or several, that coast to a stop caused a lurch.

Clutch/throttle, wow, those needed some hand strength, way beyond what is left in my hands. I can't imagine just a few K/miles as hard as they were.

The brake cable, damn if I didn't look hard for it!

I guess it was the oldzheimers thing looking for it to be under the fuel tank.

I really enjoyed meeting Paul and for sure, if you find yourself in the centre of North America (just 40 miles from me) and you got an issue, or maybe you don't, shop be open, beers in the fridge and street hockey about 7 of 7 days a week.