06 unified brake system

[Fencer]

I put "IT" on the center stand and grabbed the front brake. The rear tire still moved freely. Is this right? I reread Yamaha's ad for the brake and if I am reading correctly, only the rear is linked to the front, not front to back. I guess I am just looking to confirm my interpretation.

 

[kaitsdad]

I put "IT" on the center stand and grabbed the front brake. The rear tire still moved freely. Is this right? I reread Yamaha's ad for the brake and if I am reading correctly, only the rear is linked to the front, not front to back. I guess I am just looking to confirm my interpretation.

Was it in gear, and running?

 

[Fencer]

I put "IT" on the center stand and grabbed the front brake. The rear tire still moved freely. Is this right? I reread Yamaha's ad for the brake and if I am reading correctly, only the rear is linked to the front, not front to back. I guess I am just looking to confirm my interpretation.

Was it in gear, and running?

In neutral, both running and off. "N" because Im checking free spin vs brakes

 

[Warchild]

What you are observing is indeed correct behavior for the 2006 FJR's linked brakes. When you squeeze the brake lever, it has ZERO effect on the rear brakes.

Instead, it activates 6 of the 8 cailper pistons up front. That's it. It activates nothing on the rear caliper.

When you step on the rear brake lever, both rear caliper pistons activate, as well as the remaining two pistons on the right front caliper only.

So, in reality, the FJR's linked brakes are not "fully" linked like the Honda LBS system; they are only linked when using the rear foot lever.

 

[odot]

Ow.....my head hurts. That's complicated. :uhoh:

 

[Fencer]

thanks Warchild

 

[Warchild]

Ow.....my head hurts. That's complicated. :uhoh:

Actually, it's a pretty primative system, truth be told.

At least, compared with the 3rd-generation LBS system that Honda uses... now *that* is a fairly complicated system! Fortunately, it's pretty refined at this point... the 1st-generation LBS system came out in 1991, so they have had a decade and a half to refine it to the level it is today.

Not to turn this into a debate, but if I had a 2006, I am pretty sure I would de-link it. If I squeeze the brake lever in earnest due to a "situation", I want all eight caliper pistions doing the job, not a 75% best effort the current system offers.

Doesn't mean you '06 owners can't bring your FJRs to a screeching halt, mind you.... you just have to use both brakes to obtain 100% effort from the front calipers. Using the front brake lever only nets you only 75% of the *possible* braking power of the front brakes....

 

[odot]

Um....we need some "stick" drawings in the dirt for this to be explained to me. Let's hunker down and stick a stick in the dirt.

 

[Dallara]

Not that I want to get into a debate with Dale (Warchild), but...

First off, I am seriously thinking of *de-linking* the brakes on my 2006, but only because I don't like the idea of the rear brake pedal having anything ot do with the front brakes. I rarely, if ever, use the rear brakes, but if I do it is usually to settle the chassis in certain situations, and in those I particular instances I don't want any front brake at all.

But on the subject of needing all eight front caliper pistons "doing the job" in a "situation"... It's really unnecessary. If the 2006's didn't have ABS it would be easy enough to fully lock the front wheel at just about any speed with only six of the eight caliper pistons, so any more would be redundant. In fact, I imagine only one of the two discs would easily get you into lock-up.

With the ABS system the point becomes even more moot... It's not going to allow you to use as much braking force as you potentially have (I hate ABS systems on motorcycles, by the way... and will disable mine if I can do so without any side effects to other systems) onboard, anyway. Yamaha's ABS seems to have a pretty early threshold, too - i.e. it actuates way before impending lock-up. It does have an accelerometer, and my guess is it triggers the ABS at about 1-G of deceleration... Waaaaaaaaaaaay to soon. I get my 2006 into the front ABS all the time, and actually have to *fool* in order to brake as hard as I like on corner entry, by releasing the front lever just an instant after the ABS kicks in, and then hammering it again, and repeating that modulation as needed.

No offense, Dale... But in this case, six pistons or eight pistons, doesn't really matter. It's irrelevant.

Thanks!

Dallara

 

[ionbeam]

Heading down the slippery slope

Not debating to ABS or not to ABS --- >

ABS systems are triggered by 'slip angle' and not G force. When a tire's rotational speed becomes some percentage less than it should be for the vehicle's road speed, (typically it is 87% of tire speed vs vehicle speed) ABS engages. The pressure pump will cycle to maintain 87% slip angle under most common traction situations. There are some situations *well outside NORMAL driving* conditions where this does not work such as wet ice. At 86% slip angle the tire is starting to skid, at 88% slip angle there is some amount of traction still available.

This information comes directly from an automotive engineer (and personal friend) that was in charge of GM's R&D development to create GM's fleet ABS systems.

Edited to add:

Road tests show that the '04 & '05 ABS does engage a bit early and a professional rider under controlled situations can out-brake the ABS system by a distance difference larger than other bike brands with ABS. A typical rider can practice emergency braking but they can't practice panic braking or unpredictable traction situations.

 

[twowheelnut]

Hey, ionbeam... Was that a splash I just heard? Snigger. :good:

 

[Fencer]

Dale & Dallara.

And so we don't have the ABS debate (which I think we can discount for this question) assume no ABS

Help me out here, This is the reason I was checking to see if the rear would spin with the front brake applied in the first place.

We have established that the 06 system works rear brake to front only in the link process. Would it not be a better system as you stated to have 100 % front brake power and THEN link 25% or so to the rear rather than Vise versa? I may be wrong but isn't that how the BMW systems work?

 

[Dallara]

Ionbeam,

You are 100% correct when discussing automotive ABS systems, but literally every single motorcycle ABS system currently produced also employ multi-axis accelerometers for ABS triggering, too...

And most are set to "engage a bit early" relative to what the slip angle of the tire is (and this is from a development engineer for Honda). Why is a bit of a mystery to me, but apparently it is actually for liability reasons. They do, in fact, use accelerometer sensor data, along with differential wheel and engine speed sensor data, to determine not only slip angle, but decel rate. Evidently, according to my sources, the manufacturers believe that if their ABS systems were allowed to brake as hard as the tires and bikes are capable of that it would be so abrupt and disorienting to some riders that they would release the brakes, or something else untoward - hence the desire to keep braking at or about 1-G.

If you want to see just how early ABS on most bikes does engage, grab a friend's BMW R-1150-GS or R-1200-GS. On those you can switch ABS off (though not the damnable BMW servo-assist). Hammer the brakes on both settings and see just how much waaaaaaaaaaaaaaaaaaaay before lock-up the ABS engages.

Your friend at GM wouldn't be named Barry, would it?

FJRFencer...

I think that Yamaha chooses their linked braking approach aiming at the lowest common denominator rider - i.e. one who doesn't use the front brake and only uses the rear pedal. With Yamaha's set-up those riders at least get some front brake, which of course we all know is far more effective that the rear. BMW has two systems, and they are used on different models. One operates where the front and rear are always linked, pedal and lever both work all the brakes to some degree. The other is split just as you describe.

Thanks!

Dallara

 

[Rickster]

I would think that if there's not already a conversion to de-link the brakes, there will be soon.

My thoughts -- for a sport bike, and on the track -- i definately want full control.

For a sport-tourer, having linked brakes is fine for me.

I haven't received my FJR, but the CBR1100XX I had did have the Honda version of LBS (but no ABS), and it was fine for what the bikes intended purpose is. I considered de-linking the XX, but that system is more complicated (i.e. Front lever gets 2/3 of the front, delays and then applies some rear. Rear petal gets the other 1/3 of the front, and applies the rear IIRC)

Having 3/4 of the front, and the other 1/4 applied with the rear should be fine for a sport tourer, and I like the fact that it's much simpler than Honda's LBS. For full stopping ability you need to apply both anyway -- so should be just peachy

As far as the ABS, I've posted before that it would be nice for there to be a switch to turn it off, but I would think you could farkle an on/off switch for the ABS -- For a wet cobblestone or brick road conditions, the ABS and linking may be dicey for me, but all will be ok.

 

[FJRski]

Why debate we we can descend into an all-out pissing match?

I wasn't happy about the linked brakes on the '06 BEFORE I got my bike.

I had to grab a handful this morning when a nimrod changed lanes into my space.

However they work, these brakes are awesome.

NO COMPLAINTS - but I am learning a lot. :yahoo:

 

[v65]

Seems to me we are missing something extremely important, if an '06 owner from a dead stop were to grab the front brake, crank the throttle, and then release the clutch the result would be? From what Warchild says one smoked rear, clearly what Yamaha had in mind when they didn't link the rear to the front

 

[mech 1 twa]

If you don't like ABS just disconnect a speed sensor at either wheel. This will trip ABS light.

ABS has a FAIL-SAFE mode. Anytime it CODES the ABS is deactivated. This gives normal braking in event of ABS failure. Its a back up so brakes still work.

 

[Rickster]

If you don't like ABS just disconnect a speed sensor at either wheel. This will trip ABS light.
ABS has a FAIL-SAFE mode. Anytime it CODES the ABS is deactivated. This gives normal braking in event of ABS failure. Its a back up so brakes still work.

Anyone farkled an on/off switch for the speed sensor at a wheel? (Looking to allow ABS/Non-ABS with the flick of a cockpit switch)

 

[Fred H.]

The linked brake on this bike really is pretty simple. Here is a diagram of the system on the GL1800 Gold Wing for comparison. It has the front brake linked via a secondary master cylinder mounted on the left caliper. When you apply the brakes, the left caliper pivots up from the braking force on it, and actuates the secondary master cylinder, that then applies two pucks on the rear brakes. It all works pretty slick and the bike just squats when you brake.

As for disabling the ABS, I really can't see how that would possibly benifet anyone and I don't understand the logic for wanting to do it. It makes no sense.

How many times in 100 miliseconds can you modulate the pressure to both your front and rear wheels while your brain is fixated on the vehicle about to hit you?

Anyone who has ridden any amount at all has at one time locked up the rear wheel on a bike. Why would you not want a system that can prevent you from locking up the rear wheel?