Braided lines on a 92 ABS

[magge52]

I'm scoping out replacing the front brake lines and found a puzzling situation. The line from the front m/c goes to what appears to be a junction block which I assume is part of the ABS system. Another line goes from there to the junction block for the fronts. I can't see if the rear line connects but I'm assuming it does at this point. Would I need to replace the front & rear lines or just the fronts? I wonder if the distribution to the front would be affected by the old rear rubber line. It looks like the front fairing would have to be removed to get at all of this.

[FJ_Hooligan]

What you're seeing is the front line leaving the master cylinder and joining a metal line (like the clutch) which runs past the engine and to the ABS pump by the rear shock.  A return line parallels the m/c line back to the splitter which sends a line to each caliper.

The rear is similarly routed.  Master cylinder goes to ABS pump with return line directly back to rear caliper.

[yamaha fj rider]

Most of the ABS brakes quit working in the first year or two. May be time to remove all the ABS stuff and get new lines that go from the masters to the calipers. Improved mine brakes greatly. Hope this helps.

Kurt 

[magge52]

After thinking about it I realized the brakes aren't linked so the rears shouldn't affect the fronts. I'll work on replacing the front lines. It looks like the louvered panels that butt up against the tank can be removed separate from the fairing. That should give good access to that junction-next weeks project.

I'm not a huge fan of abs but it must be a lot of work to remove all the hardware and plumbing. I'll search for more info but I'd rather spend my time riding.    So I'm heading out for northern NH & VT this weekend. My first overnight on the FJ. Oh boy!!

[yamaha fj rider]

The front and rear brake lines are connected to the abs pump. So the brakes are linked. Also the lines will be less expensive if they just go from the master cylinder to the caliper. I like having the least number of joints or connections in the brake lines, less to go wrong. Hope this helps.

Kurt

[magge52]

The front and rear brake lines are connected to the abs pump. So the brakes are linked. Also the lines will be less expensive if they just go from the master cylinder to the caliper. I like having the least number of joints or connections in the brake lines, less to go wrong. Hope this helps.

Kurt

Sounds like replacing the front & rear lines would be in order if I keep the ABS. I'll have to decide which way to go as I don't want to replace the lines a 2nd time down the road. It would be a weight loss of something like 25 lbs and it would give much easier access to the rear shock...hmmm

[FJ_Hooligan]

The front and rear brake lines are connected to the abs pump. So the brakes are linked.

That's not correct.  The front and rear brakes are NOT linked.  The ABS pump has a separate circuit for the front and rear brake systems.

[yamaha fj rider]

So how could you engage only the front brake and have the rear brake pedal go down?

Kurt

[FJ_Hooligan]

I don't understand the question?

Are you saying that whenever the ABS activates it pulses BOTH brake systems?

If so, then it's just unsophisticated 1993-era ABS technology.  The pump may modulate both ends but it should only pulse the one nearing lockup.  Either way, the brakes are not linked hydraulically.

[yamaha fj rider]

I am saying, at slower speeds. When the ABS was working. When applying front brake only, it would also apply the rear for you. Happened many times to me. The rear bake pedal would drop when this happened without being touched. The brakes had to be connected some how. If not hydraulically then electronically. When this quit happening was one of the ways I knew the ABS stopped working.

Kurt     

[magge52]

I am saying, at slower speeds. When the ABS was working. When applying front brake only, it would also apply the rear for you. Happened many times to me. The rear bake pedal would drop when this happened without being touched. The brakes had to be connected some how. If not hydraulically then electronically. When this quit happening was one of the ways I knew the ABS stopped working.

Kurt     

Kurt, this happened under normal braking or when the abs kicked in?

[FJ_Hooligan]

If you were activating the ABS pump with the front brakes only, then what you're feeling with the rear pedal is the pump cycling pressure in the rear line also.  It's not applying the rear brake, it's releasing pressure.  Since you weren't applying the rear brake, there is no pressure to release thus you would feel the rear pedal drop.

My ABS never worked.  I only assumed it was sophisticated enough to activate the front and rear separately.  But, what you're describing indicates that when it kicks on it will cycle both ends regardless of which brake is locked up.  Interesting. 

[yamaha fj rider]

Yamaha only did the ABS 92-94 then dropped it. I remember a lot of problems with it. Seemed like, it would work for about two years then quit. Maybe just enough time to get some water in the brake fluid. Wasn't it ten years before it came out again from Yamaha? Modern ABS seems to work great. First gen NO. I think that mine worked just long enough to get passed the warranty.

Kurt

[yamaha fj rider]

I am saying, at slower speeds. When the ABS was working. When applying front brake only, it would also apply the rear for you. Happened many times to me. The rear bake pedal would drop when this happened without being touched. The brakes had to be connected some how. If not hydraulically then electronically. When this quit happening was one of the ways I knew the ABS stopped working.

Kurt     

Kurt, this happened under normal braking or when the abs kicked in?

Only when the ABS was engaged.

Kurt