Odd front brake behaviour

Mellow

Joe
Admin
Joined
Dec 1, 2004
Messages
18,819
Age
60
Bike
'21 BMW R1250RT
2024 Miles
000540
Are you sure the spacers are installed on the correct side on the front wheel?

Here's the right-clutch side:



The other side is the longer spacer... typically however, you don't get far if this happens so it may be more of an air in the lines issue or the sliding pins on the caliper allowing it to 'float' are stuck/dry.

from an article by @jfheath HERE

You can see the spacer orientation:

spacers.jpg
 
Last edited:

Highrider

Part time mechanic
Joined
Jun 30, 2005
Messages
870
Age
68
Location
Barlett, Illinois
Bike
2005 ST1300
STOC #
5560
Is just the outer pad wearing different and the inner pad looks normal? Sounds like something on the right side is misaligned or the 3 caliper pistons are not working as they should.
Could be air in one of the circuits.
 
Joined
Jan 8, 2011
Messages
7,066
Location
Arizona
Bike
2007 Honda ST1300A
Air in the brake system!
Did half a dozen brand new bikes in the last couple months...some with only 600 miles on them...same thing, alot of air was found in PCV and SMC circuts. Almost all shops use vacs to do setups to save shop time and $ and you should know how I feel about that :rofl1:
Simply use a check valve type bleeder and flush the system..this may fix your problems.
If not..I would pop out the pistons and clean underneath the seals with a plastic pick.
 

Firstpeke

NT1100D
Joined
May 23, 2009
Messages
1,689
Location
UK
Bike
Honda NT1100
STOC #
7764
I would agree on air in the system, but it I seem to remember there is a delay valve in the front circuit too, just can't remember the layout..... may only be form the rear pedal circuit, slider pins may also be contributing too.

As Igofar says though, most likely air.....
 
Joined
Nov 10, 2007
Messages
1,607
Age
61
Location
Vancouver, British Columbia, Canada
Bike
1&2 2005 ST1300ABS's
STOC #
8562
My money is on air in the system too.
I would also remove, clean and re- install those pads. Could be an assembly error.
Also check the wear on the other pads as they have to work harder due to those not functioning.
 

dduelin

Tune my heart to sing Thy grace
Site Supporter
Joined
Feb 11, 2006
Messages
9,634
Location
Jacksonville
Bike
GL1800 R1200RT NC700
2024 Miles
006739
STOC #
6651
The primary front brake circuits are the shortest on the bike and are fed from the front master cylinder. I tend to discount air in the lines because if there was air in the circuit(s) the lever would be soggy and then pump up hard with two or three strokes. You are very familiar with the ST1300 and would know this symptom of air in the lines but you didn't mention it after riding in the mountains and on the brakes all the time.....but you did describe unsymmetrical pad wear on the right caliper. I would strip and clean the RH caliper with an eye toward why the front outer piston or entire caliper does not return to the at rest position. Excessively worn outer pads on the leading edge of the pad describe the front outer piston not retracting all the way, or the caliper is hanging up on the upper slide pin. My thoughts anyway.
 
Joined
Nov 10, 2007
Messages
1,607
Age
61
Location
Vancouver, British Columbia, Canada
Bike
1&2 2005 ST1300ABS's
STOC #
8562
I always want to do a test and keep forgetting to do it.
I own an infra red thermometer gun.

Day1
I was going to just use the rear brakes, say riding around in hills and flat areas and then measure the temperature on all 3 rotors.

Day2
Only use the front brakes.
I do the above using the same path I traveled on the previous day and the same time riding and measure the temperature on the rotors.
This would give me a bench mark on the temperatures these rotors see. Then if I suspect any problems with the braking system.
Do this test again and see if the numbers are consistent.

Just thought of this before I posted this,
use both front and rear on the same circuit and then measure the temperature.
 

dduelin

Tune my heart to sing Thy grace
Site Supporter
Joined
Feb 11, 2006
Messages
9,634
Location
Jacksonville
Bike
GL1800 R1200RT NC700
2024 Miles
006739
STOC #
6651
Let me clarify. Without symptoms of excessive air in the front brake circuits (soggy lever initially but firm feel after two or three quick pumps) I discounted that as a causal factor for the asymmetric pad wear that seemed to be the subject of the original post. That said, I'm always pleasantly surprised how good the brake levers feel after a 12,000 mile flush and bleed service even when the brakes were feeling and working fine prior to the service. Hopefully the original problem is resolved between adjusting the spring clip and bleeding the system.
 
Joined
Jan 8, 2011
Messages
7,066
Location
Arizona
Bike
2007 Honda ST1300A
If air was allowed in the rear system it would effect the entire brake system, by being pushed from circuit to circuit. The clip may have been dislodged due to the pistols in the calipers not working correctly, or you could just have the wrong clips installed since new, I have found this already. The assembler may just have grabbed the wrong part. If you check the parts fisch you will see different part numbers for the newer longer front caliper they are now using etc.
Do keep in mind....just because you can't feel symptoms of air in one CIRCUT does not mean you don't have air somewhere in the system. It can hide in several places.... and just be pushed from one area to another....as you have found.
Glad you resolved your brake issues...Ride safe and enjoy your new bike.
I have whispered and discredited the non believers :rofl1:


update: spring clip part number-old style - 45108MZ2-016
spring clip part number-new style- 45108-MBT D52

I don't have any more new ones in stock to compare the differences for you, but I do have several new old stock of the first part number if you need measurements etc.
 
Last edited:

Blrfl

Natural Rider Enhancement
Joined
Aug 24, 2005
Messages
5,602
Age
55
Location
Northern Virginia
Bike
Fast Blue One
STOC #
4837
Day1
I was going to just use the rear brakes, say riding around in hills and flat areas and then measure the temperature on all 3 rotors.

Day2
Only use the front brakes.
The rotors cool quickly enough that you don't even have to make a day of it. Five minutes of riding with some hard stops and a little bit of dragging here and there will get you what you need. I usually stop just after bedding in a new set of pads and make sure the temperatures aren't insanely high and that the fronts are more or less in the same neighborhood. Stop for 30-60 minutes between runs and the rotors will have cooled completely.

--Mark
 
Joined
Jan 8, 2011
Messages
7,066
Location
Arizona
Bike
2007 Honda ST1300A
The rotors cool quickly enough that you don't even have to make a day of it. Five minutes of riding with some hard stops and a little bit of dragging here and there will get you what you need. I usually stop just after bedding in a new set of pads and make sure the temperatures aren't insanely high and that the fronts are more or less in the same neighborhood. Stop for 30-60 minutes between runs and the rotors will have cooled completely.

--Mark
:plus1:
 
Top Bottom