Un-Linking Front Brakes on 2nd Gens (and later)

[eflyguy]

Having not given it much thought, as there appears to be plenty of stopping power, but if I had to hazard a guess, I'd think it would be about forcing a little bit of a weight shift forwards when the rear is applied by itself.

Of course none of us who know how to utilize the brake system effectively would find this useful, but I have personally never found it to be intrusive. I'd also be curious to know "what were they thinking"..

 

[Fred W]

Here's the blurb from the "Features" section of the 2nd Gen FSM:

OUTLINE OF THE UNIFIED BRAKE SYSTEM The Yamaha unified brake system is a system that operates one set of pistons in the front brakes together with the rear brake when the brake pedal is depressed. Compared to conventional brake systems, the ability to slow the vehicle using the simple operation of the brake pedal is improved.

It sort of insinuates that because of the unified braking you could (simply) only use the rear brake pedal to brake, but doesn't come right out and say that. In fact there is a disclaimer later in the description:

CAUTION: • The unified brake system is a system to assist the brake operation. However, both the brake lever and the brake pedal must be operated for maximum braking effect.

 

[RossKean]

Looks like it is a "Feature" to improve the survivability for riders who still believe that the use of front brake is dangerous!

 

[Cosmin]

My conclusions after reading several debates on this topic:

1) obviously such a mod like 'de-link' is addressed only to those who are totally aware of the risks, are very familiar with the bike and ready to adapt the riding style to get used to the new behaviour;

2) apparently there is nobody on the forum who did this mod, so we cannot get feedback from a genuine user of the delinked FJR;

3) depending on the parts I can procure, my plan is either to delink (if I find all the needed lines etc) or, at least, to eliminate the proportional valve (which, judging by the schemas and pictures in FSM, is quite easy to do) in order to increase the amount of brake force from the rear brake.

 

[Bounce]

My conclusions after reading several debates on this topic:
1) obviously such a mod like 'de-link' is addressed only to those who are totally aware of the risks, are very familiar with the bike and ready to adapt the riding style to get used to the new behaviour;

2) apparently there is nobody on the forum who did this mod, so we cannot get feedback from a genuine user of the delinked FJR;

3) depending on the parts I can procure, my plan is either to delink (if I find all the needed lines etc) or, at least, to eliminate the proportional valve (which, judging by the schemas and pictures in FSM, is quite easy to do) in order to increase the amount of brake force from the rear brake.

1a) Those who take the effort to de-link need to also restore OEM function before selling the bike or provide a proper disclaimer form with signature of both themselves and the buyer to notify the buyer of the change and wash themselves (as the seller) of any future liability claim.

As to 3: Increasing rear braking power may not result in what you expect. The Gen1s were occasionally panned for having too MUCH rear brake and the change (Gen2) was to address that.

 

[FJReady]

Fred,

Regarding post #9 above: Area of the piston varies with the square of the diameter, therefore the ratio is not linear.

For your first example (33.96^2 - 30.23^2)/(30.23^2) X 100 = 26.2% not 12.3%

Cranking through the rest of the equations is left to the student.

JSNS

 

[Fred W]

Ah yes, of course. Area is what maters.

So the increase in brake caliper clamping power (as well as brake lever throw) from adding the small 4th pair of pistons to the front brakes would be more than I calculated too.

Thanks.

 

[08FJR4ME]

So that 4'th set of pistons that is activated by the rear braking system would have to be independent from the front braking lever correct? My observation of this effect is because of the two bleeding screws. Wouldn't you only need one bleeder if they were not independent? So the pressure required of the front brake should not change. That's my assumption at this time.

P=F over A if I remember correctly. It's been awhile.

Dave

 

[RossKean]

^^^

I think the plan is to disconnect the fourth front piston pair from the rear brake line and splice it into the plumbing for the front brakes. That way it is activated by the front brake lever.

 

[Fred W]

Yes, that was the plan as originally stated. To use that 4th pair of cylinders for the front, like a normal bike.

Thinking more about the intended use of the unified brake system, it would seem that they designed it so that an inept rider can just mash that rear brake pedal and allow the ABS to cycle on the rear caliper circuit to keep the wheel from locking up, meanwhile producing some braking power on the front unified brake cylinders which are on a separate ABS circuit.

I suppose one could just remove the hollow banjo bolt from the front right lower hydraulic line and (after retracting the two unified caliper pistons) replace it with a solid one. That would effectively disable the rear pedal linkage to the front and not change how the front or rear brakes or ABS works from stock. The only difference would be no front braking effect from the rear pedal. That would also make the change very easily reversible. The down side is that you would have reduced the total front braking power when both front and rear are used together.

 

[mcatrophy]

...The down side is that you would have reduced the total front braking power when both front and rear are used together.

Since even I can activate the front ABS on a good dry road relatively easily just using two fingers on the lever, I fail to see why you would need the "extra" of the rear's pistons acting on the front over what the normal front ones can give you anyway.
One of the first things I noticed about the FJR's brakes over my previous Trophy's was something of a "planted" feel when using just the rear brake pedal when cornering. I immediately put this down to the small braking applied to the front. I liked it from the start, and have never been in a situation where I thought that the linking was a disadvantage.

Even if my insurance wouldn't be invalidated by such a modification (which it would), I can see no point in doing it, certainly not for me.

 

[K_Flyer]

One of my concerns about going to the FJR after the '07 K1200GT was the difference in the braking system. I was used to a tap on the rear brake to set up a corner and, sometimes, to give a little extra braking without using the front brake which tends to stand the bike up. I find that the setup on the FJR still works well for this technique. Now the only thing I miss is the self-cancelling turn signals!

BTW, Theresa has finally decided that she likes the FJR better than the BMW which is a big step for her.

 

[Niehart]

Like

BTW, Theresa has finally decided that she likes the FJR better than the BMW which is a big step for her.

 

[Powerman]

After riding other bikes that the linked braking sucked, I figured it would have to go on the FJR.

I soon found it much better, and liked it for trail braking.

A lot of folks don't use back brakes?

 

[Cosmin]

One of my concerns about going to the FJR after the '07 K1200GT was the difference in the braking system. I was used to a tap on the rear brake to set up a corner and, sometimes, to give a little extra braking without using the front brake which tends to stand the bike up. I find that the setup on the FJR still works well for this technique. Now the only thing I miss is the self-cancelling turn signals!
BTW, Theresa has finally decided that she likes the FJR better than the BMW which is a big step for her.

Although last year I took the decision to keep the FJR since the BMW K1300GT I wanted to buy would have created too many problems plus significantly increased maintenance bill unjustified, I still think the GT brakes are better than the ones on FJR (not only since they fullfil my obsession of totally separated rear brake but also as stopping power overall). On the other hand once you get used to FJR it's preferred as a bike which always takes you where you planned as alternative to the K1300GT which always might bring unexpected surprises on the road.

PS: @K_Flyer - nice to meet you on this forum also (last year you gave me some useful advice in GT versus FJR comparison and decision on the BMW forum)