Glitchy front brakes

[Eddie Green]

On a GTR1400, I've had an ongoing problem with rotors that give uneven braking - like parts of the rotors grab better than others.

The surfaces appear regular, and while spinning the wheel there is a slight runout to both but not enough to cause them to bind.

I had no problems with the first set of OEM rotors, problem started with EBC iron rotors which started doing this over the first winter. I replaced them with new OEM's and recently they've started to exhibit the same condition.

I suspect that corrosion or dust buildup is preventing rotor and carrier from floating.

I've been able to free up the 'floating' pins on a previous bike which has cured this type of effect, however on both the OEM and EBC rotors I have the pins are not floating and appear to firmly bond the rotor to the carrier.

My questions are -

has anyone experienced the same issue and how did they resolve it?

Are the pins supposed to freely rotate (ie floating) and how can you release them.

Are there any replacement pins for these rotors - along the lines of those in this video

Thanks

 

[Freddy]

and while spinning the wheel there is a slight runout to both but not enough to cause them to bind.


That needs to be measured with a dial gauge to see if out of spec. The OEM 'pins' do not rotate freely. To do so, a bolt and washers need to be tightened thru the 'pin' and rotated using a spanner and cleaning fluid. - one at a time. EBC use square 'pins' these days.

I have had a slightly warped OEM C14 disc 'machined' by a bike brake disc repairer to correct it. The friction disc was removed from the hub piece, reground flat then re-riveted to the hub piece.

 

[Eddie Green]

Thanks for comments regarding freeing the pins - that's the technique I'm familiar with and I'm just off out to do them now.

I'd contemplate their removal and re-enginnering if left with no other solution, finding it difficult to understand how, having bedded in discs and pads and not being a heavy front braker, I'd have warped them in the first place.

 

[Eddie Green]

Well, I seem to have resolved the issue by freeing the floating pins using a bolt/locknut arrangement as in the photo below, assisted by a dropper bottle filled with isopropyl alcohol to flush out the joint as each pin is rotated.

What came out seemed quite grainy, like fine silt, and dried grey so would also have contained brake dust. There was a fair amount of this removed.

Once the task was completed, the wheels rotate much more freely and the braking issue has now disappeared.

I'm still interested to know whether there are dismantlable pins available to replace the pressed-in ones. The task of maintenance would be much easier if I was able to dismantle them and clean the components more thoroughly.

The bolt/locknut I used was an M10x45mm with one locknut and one standard nut, as shown below:

 

[runnerb0y]

I have a similar problem with the braking on my 2012. What are the "pins" you're talking about and how do I go about 'freeing' them up to see if it reduces the pulsing when braking?

TIA for any help!

 

[Freddy]

They're not actually pins but the large rivets that holds the steel disc to the disc carrier.

Brake shudder has been an issue for some owners since day 1 - me included. Like City Slicker, I'm not heavy on the brakes. Kaw said it was because of this that pad material transferred to the disc face which caused shudder, not warping. Measurements of disc run-out always showed to be in spec. Kaw said that ZX14 riders don't have the same issue even tho they had the very same brakes because they ride/stop hard and burn off the crud. Kaw has had 3 goes at front pads to rectify the issue iirc, with different part numbers for them. I've found that sand/bead blasting the discs (after removal) solves the problem temporarily (a year or 2). I've had no such success using an abrasive by hand on the disc face.

I've also had a disc which had a 0.002-3" thin area on it (about a 2-3" area on the face) when measured with a micrometer - after blasting didn't fix it. I sent it off to a bike brake specialist to be ground flat. They removed the disc from the carrier, ground the disc and re-riveted it to the carrier.

 

[Eddie Green]

I call them pins, some people refer to them as bobbins or rivets if they happen to be of the fixed variety. They allow the disc to float laterally to the axis of rotation but prevent movement around the axis.

On some bikes these pins are serviceable, on many others they are pressed into place and have to be drilled out.

This is how the riveted variety look:

Here are some aftermarket pins that are removeable:

 

[Eddie Green]

Has anyone got the measurement for the diameter of the pins in the OEM rotors?

I've seen a couple of varieties of these, for example on AliExpress but don't know if the diameter would fit.

Maybe Freddy might be able to ask the people who did his rebuild what diameters are used whether it's standardised, what pins to fit on the GTR rotors?

 

[Eddie Green]

Sorry, forgot to fully answer runnerBy's question -

The bolt I use is sized to be inserted through the eye of the pin and tightened. Once tight you'll be able to rotate the bolt and pin together using a wrench. You'd keep rotating and use brake cleaner or other high flashpoint solvent to flush out any accumulated dirt in the faces of the pin.

You'd rinse and repeat for each pin and for both rotors.

 

[Freddy]

Has anyone got the measurement for the diameter of the pins in the OEM rotors?

I've seen a couple of varieties of these, for example on AliExpress but don't know if the diameter would fit.

Maybe Freddy might be able to ask the people who did his rebuild what diameters are used whether it's standardised, what pins to fit on the GTR rotors?

It was nearly 4 years ago, so I doubt they'd remember it.

 

[runnerb0y]

Thanks to City Slicker and Freddy for the explanation. I'll take a look at mine and see if I can't improve/reduce the pulsing.

 

[Tundra]

I'm grateful for all the information here and this was a good thread.
With the risk of being the bummer here and not a contributor, I've been severely disappointed with my brakes since day one. Hands down worst motorcycle brakes in 42 years of riding. Mine is a 2012, I call them WONKY BRAKES. I have ridden newer model years and they feel and work completely different (perfect) My assumption is the brakes are improved on newer models? I've heard of break issues with the 2012 model although that was a simple recall repair/improvement to there rear. I just realized my post does not address city slickers original issues in his post. I will leave the post and see if there is any confirmation regarding Wonky Brakes on 2012 model year, seeing as his issue has already been so well addressed
Real nice post City Slicker, great description and pics to easily follow. Freddy nice explanation. Honestly guys, after reading this post I have decided to renew my membership, which I let go for personal reasons. This is the type of useful reading I really enjoy, as it helps others in the GTR community.

 

[Freddy]

The recall you refer to was on the early 08 & 09 bikes only, which was a new metal shield on the m/cyl to prevent pebbles getting lodged in there.

Is it the linked brakes that are causing you grief? They have for lots of folks. Kaw recalibrated the 'link' in the ABS ECU from 2015 on to make it less intrusive rear to front.