FJ Mods. Please explain?

[ribbert]

My own post got me thinking as I was typing, why will rubber brake lines on a car do a million k's over thirty odd years and still be considered serviceable while the bike's have a scheduled replacement.
The bike's get a bit of UV but are better protected than car's.
Anyone want to venture and opinion?
Noel

[craigo]

http://www.fjowners.com/index.php?topic=3380.0

Here ya go. My GSXR Wheel Conversion. There are others that I used to do mine, but as I did my conversion, I took pics. This is for the 3CV and a 1990 GSXR wheel pack. As the monkey said, best to get all the parts from the same donor bike. Otherwise, you'll be playing with a lot of unknowns and end up looking like this:



On another note, someone here told me (Arnie?) that I was overthinking this mod. It really is not that difficult.

CraigO

[craigo]

Noel,

As to automotive brake lines vs bike brake lines, I don't know what the difference is. However, there sure is a lot more risk involved if you bike's brake line fails vs the cars. I have seen cars brake lines fail and they do give some warning that not all is well with the brakes. The bike, not so much. And the last thing you want is a ruptured brake line while braking hard.

I seem to remember reading someone's post here where their brakelines failed. It didn't end well...

CraigO

[fj11.5]

I thought most cars only had rubber brake lines at the wheel end/s only, with copper , stainless , ect going from the mc to the wheel area

[Pat Conlon]

My own post got me thinking as I was typing, why will rubber brake lines on a car do a million k's over thirty odd years and still be considered serviceable while the bike's have a scheduled replacement.
The bike's get a bit of UV but are better protected than car's.
Anyone want to venture and opinion?
Noel

Sure, cars made in the US after 1957 have a dual master cylinder system. The floor pedal activates 2 master cylinders. One master cylinder activates the right front wheel and left rear wheel, and the other master cylinder activates the opposite left front and right rear wheels.
Failure happens in cars where the rubber lines split, just as on motorcycles, however the loss of line pressure will only affect 1/2 of the system (2 wheels) you will still have brake line pressure in one front wheel and one rear wheel.

We know on motorcycles, ~80% of our stopping power comes from our front brakes. We know that (most often) the rubber line failures, splits, happen where the rubber line is connected to the banjo fitting.
So lets count the potential failure points on a early FJ with anti dive forks...
What do you get? 11 potential failure points? Any split will cause loss of pressure on a front brake system that supplies 80% of your braking power?

So the question posed: What's wrong with 25 year old rubber lines?  My answer is: Are you feeling lucky today?

[fj11.5]

Clever system for cars, even back then ,, anti dive was one of the first things I replaced completely , with 89 forks  ,, and ss brake lines, , the 88 rubber brake lines were that bad they were almost crunchy , Oi had even taped them up as the rubber was splitting  , now has newish xjr lines for now,,

[moonrunnah]

might be a dumb question but what exactly is the antidrive is that the things on the bottom of the forks and also most cars are diagonoly split some are front rear and cars much like bikes the front do 75% ish of the braking , ads copper should never be used as brake lines seeing how the run over 300psi and over 2000psi on abs cars (just my 2 cents)

[Arnie]

You may have a question or three in that amazing run-on sentence.  Want to try re-writing it in standard english (or american) ?

Arnie

might be a dumb question but what exactly is the antidrive is that the things on the bottom of the forks and also most cars are diagonoly split some are front rear and cars much like bikes the front do 75% ish of the braking , ads copper should never be used as brake lines seeing how the run over 300psi and over 2000psi on abs cars (just my 2 cents)

[moonrunnah]

You may have a question or three in that amazing run-on sentence.  Want to try re-writing it in standard english (or american) ?

Arnie

might be a dumb question but what exactly is the antidrive is that the things on the bottom of the forks and also most cars are diagonoly split some are front rear and cars much like bikes the front do 75% ish of the braking , ads copper should never be used as brake lines seeing how the run over 300psi and over 2000psi on abs cars (just my 2 cents)

never been good in english
what is an anitdrive system......how does it work

[FJmonkey]

The Anti-Dive was on 84 to 87 years and many claim it never worked. It was an attempt to restrict fork dive by using pressure in the brake lines to affect a valve that controls fork oil flow. They add weight and only looked cool in 84 because it was new technology. It can be bypassed  a few different ways.

[moonrunnah]

how can i bypass it i dont think it works because under hard braking it still dives a lot

[Arnie]

Moonrunnah asked, "what is an anitdrive system......how does it work? "

An anti-dive system is intended to increase the damping and/or spring rate of the forks when you are braking.  This is intended to keep the bike on a more even keel and prevent the steering head angle and trail from changing when you brake, which does change handling characteristics.  Several anti-dive systems were used by racing bikes and the Yam system looked like them.

The system Yamaha put on the early FJs restricted the flow of fork oil in the forks when there was pressure in the brake system.  It was supposed to allow soft(ish) fork action at most times while maintaining handling while braking.
It never did much.  This is probably due to Yamaha  not wanting to upset IN-expert riders with drastic changes in fork feel.
(read possible lawsuits and liability)

Removing the Yam system and replacing with blanking plates is no real loss.  It also allows you to use 2 or 3 brake lines instead of 5.  This saves you $$ on brake lines while getting more feedback at the lever.

Arnie

[moonrunnah]

thank you arnie
where would i get these blocking plates or do i need to make them

[FJmonkey]

So the question posed: What's wrong with 25 year old rubber lines?  My answer is: Are you feeling lucky today?

A little Dirty Harry going on there, I like it Pat.... Did I fire 5 shots or 6?

[ribbert]

I thought most cars only had rubber brake lines at the wheel end/s only, with copper , stainless , ect going from the mc to the wheel area

They do, between the front rail and the wheel, that's the bit I was referring to.