Jump to content

1st of 2 things - rear brake rotor dragging?


sbeec

Recommended Posts

So here's the subject - 2018 RT with 6000 miles.  I've had it for about 3 months.  All scheduled maintenance has been done by the BMW dealer.

One thing that I've noticed is that I think my rear brake is dragging slightly.....here are the indicators...

- I can smell brake or clutch lining when I get back to the garage.  Clutch isn't slipping and the riding was normal.

- even after a short trip with 75% front brake use, the rear rotor is mildly hot (not burning, probably a 7 out of 10) to the touch and the front rotors are cool to warm.

- and...I just washed the bike/rims and even after a short (7 miles) in town trip with minimal braking, there is already brake dust on brake side of the rear rim

 

I know that the rear brakes are tied to the use of the front brake - but I'm not sure what the precent proportioned is.  

 

What are some other experiences?  What is normal to expect?

 

Rich

Link to comment

A few things to check.  First the obvious:  Is your foot touching the brake pedal inadvertently?   6,000 miles is very low miles but the bike is over two years old.  I would not trust that the dealer replaces and flushed the brake fluid.  If you have a brake fluid tester, then test it.  If not, do it yourself so you know it is done.  Since you are doing that, you might as well pull the rear caliper and clean it to within an inch of its life with the pistons extended a bit.  Lube the pins too.   Then go for a ride.   
 

where are you located?  Maybe someone nearby can assist in person.

Link to comment
3 hours ago, Carlisja said:

 

where are you located?  Maybe someone nearby can assist in person.

Thanks James....I'm in Bremerton WA- west of Seattle on the Olympic Peninsula 

What brake system flushing tool do you use?

Link to comment
10 hours ago, sbeec said:

So here's the subject - 2018 RT with 6000 miles.  I've had it for about 3 months.  All scheduled maintenance has been done by the BMW dealer.

One thing that I've noticed is that I think my rear brake is dragging slightly.....here are the indicators...

- I can smell brake or clutch lining when I get back to the garage.  Clutch isn't slipping and the riding was normal.

- even after a short trip with 75% front brake use, the rear rotor is mildly hot (not burning, probably a 7 out of 10) to the touch and the front rotors are cool to warm.

- and...I just washed the bike/rims and even after a short (7 miles) in town trip with minimal braking, there is already brake dust on brake side of the rear rim

 

I know that the rear brakes are tied to the use of the front brake - but I'm not sure what the precent proportioned is.  

 

What are some other experiences?  What is normal to expect?

 

Rich

Morning Rich

 

Sounds pretty normal as the rear brake is linked to the front brake so it is applied every time you use the front brake lever. 

 

The front to rear proportioning is computer controlled so there is no magic number, the proportioning bias is learned based on braking forces &  vehicle loads.   

 

Link to comment

If still in warranty take it to the dealer. Some of the symptoms you describe are similar to mine and some are not. The factory pads are dusty. I get a lot of dust in front and especially the rear

 

Heat and smell on the rear is dissimilar to my experiences. 
 

Put it on the center stand in neutral and see how easy/hard it is to spin the rear by hand. If really difficult it may be dragging

 

No special tools needed on the wet heads to change brake fluid. I do use a catch bag I bought from speed bleeders but not required. I would recommend changing brake fluid annually. It will cost you less than $6 and should take less than 30 min. The only thing I need help on is the rear brake. I can’t reach the rear brake pedal and bleed screw simultaneously. The wife helps push the pedal down

 

I don’t use speed bleeders however as there has been some experiences where they break and that creates a whole new set of problems. Brake bleeding is simple on the wetheads

  • Thanks 1
Link to comment

sorry.  It seems we are on opposite sides of the country.   Check out JVB Production videos for some well produced maintenance lessons for your bike.   The list of special tools required to maintain your bike is very short. Most every task is within the skill level of a noob that can follow directions.   My best advice is to pay attention to torque values.   

Link to comment
10 hours ago, Skywagon said:

The only thing I need help on is the rear brake. I can’t reach the rear brake pedal and bleed screw simultaneously. The wife helps push the pedal down

 

 

Have you tried with the rear wheel and side bags removed?

 

Mine is a GS, maybe the lack of bodywork makes it easier. I pull off rear wheel and have bags off.

Link to comment
22 hours ago, Skywagon said:

The only thing I need help on is the rear brake. I can’t reach the rear brake pedal and bleed screw simultaneously. The wife helps push the pedal down

 

Morning David

 

You don't need to reach the brake pedal and bleed screw at the same time if you use a bleed bottle or catch bag with the hose terminating "below" the top of the fluid level in the catch container.

 

With the hose end terminating below the fluid level the  fluid in the catch container acts as a sort-of check valve, so just open the bleed screw then pump the pedal until clean fluid comes out through the hose. (it will work just like you have a one way valve in the bleed hose). 

 

Then if you elevate the catch container above caliper level for the last few pumps that prevents seeing those small evenly spaced air bubbles in the bleed hose from leaking bleed screw threads when you quit pumping the pedal.    

 

 

Link to comment

Thanks DR...will have to try that next time.  I just did brakes a week or so ago for the year.  Would the hose also have to be full too?

Link to comment
6 minutes ago, Skywagon said:

Thanks DR...will have to try that next time.  I just did brakes a week or so ago for the year.  Would the hose also have to be full too?

Afternoon David

 

The hose will fill as soon as you start pumping the pedal with the bleed screw open. 

Link to comment

great feedback -and good tips!

someone reminded me if it's still under warranty......as much as I like to do my mechanical work - I'm going to see what the BMW shop evaluates and addresses- might as well.  I'll post the results - taking it in next Saturday.

Link to comment

No matter what you use if you loop the drain line you form a trap and that will stop air. 

 

I use speed bleeders and a IV bag and it is so easy to do I do it every year and it takes an hour to turkey baster the old brake fluid out, wipe them out, fill with fresh fluid and start the bleed process.

 

It is very easy to do and something I am religious about on car and bike.

Link to comment
31 minutes ago, LAF said:

No matter what you use if you loop the drain line you form a trap and that will stop air. 

 

Morning LAF

 

Are you sure? Basic hydraulics says it would require an air inlet or vent at the top of that loop to stop any siphoning effect if the catch container is below the level of the caliper.

 

They suck the air in at the caliper bleeder screw threads so even with a loop in the line if the catch container is below the caliper bleed screw threads it will still suck in air.

 

Now if it had a vent in the top of that hose loop that would allow atmospheric air entry & break the siphon. To vent that loop without leakage when pumping the brake pedal would require some sort of pass-through vent container or a one way check valve type vent (seems a lot simpler to just elevate the catch container to be above the caliper) 

Link to comment

Well with a IV bag it does.  I guess I should have been specific.  Even reused I roll them to get old juice and air out best I can loop the silicone hose, lay a small weight on the loop and never have had a problem.  Same as the end of the hose in fluid.  Back in the day it was a baby food jars but once I found IV bags it has been smooth sailing.

Link to comment
  • 2 weeks later...

Follow up gentlemen.....  the BMW dealer in FIFE - south of Seattle found that the REAR master cylinder had failed mechanically and did not release all the pressure from the caliper when pedal was released.  Kept a small amount pressure on the caliper.  Dealer replaced rear master cylinder, brake pads and rotor (showed signs of over heating.) - in warranty .

 

My wife is right - as always LOL!!  she said let the dealer fix it !!!   ha ha!   Anyway -moving on from that....  when I was doing my trouble shooting.....  I noticed the rear did NOT overheat when I used only the front brake....even with the front / rear connected with computer which cleared the rear caliper from being the problem.  only leaves the rear master cylinder as the problem.

 

Plus - shop technician compared the amount of drag on my bike  when rotating rear wheel off the ground to a new bike rear wheel.

 

Rich

Link to comment

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...