anti-dive forks

Hey Guys,
I have 2 XJ900´s
a 1984 and a 1985 model

the front end of the ´85 model looks like this

and this is the ´84 model


Looks like the ´84 model has the anti dive contraption on the front of the forks but it is not connected to the brakeline so it is just a dead weight as far as I can tell.

Main question - is it possible to connect up the anti-dive with a short brakeline as it is in the ´85 model?
Am going to redo the brakelines anyway so it could be a good time to do this.

I guess I would need another hollow bolt (longer) to accomodate the second banjo fitting.

Any comments on this?

 

Yes.

Yes!


P.S. really like the yellow dust cap..........

 

Someone disabled the anti-dive unit on your '84 by disconnecting the line ot it. My recommendation is to tear down and inspect the anti-dive units on that bike before reinstalling the brake lines (you will need to drain the fork oil to remove the anti-dive units). I doubt that you will find anything wrong, but they will need to be cleaned out to make sure the pistons move freely, otherwise they won't do anything.

 

Can you think of a reason why someone would have disconnected the anti-hero on my bike?
Are there down sides to this technology?
Could there have been some technical reason to motivate the previous owner to do this?
Not having much experience with these bikes yet, how did the anti-dive perform on the XJ's

 

1. It stopped working
2. The line ruptured
3. They didn't like it
4. They didn't want to use it
5.they didn't want to rebuild it
6. They didn't want something to possibly go wrong with it

I Can keep making up scenarios, but until you actually go in and see what it's like, it's just anyone's guess at why a previous owner would do something, unless they documented it for you-------

 

I did some reading and found that anti-dive tech was all the rage in the 80´s
but I read that today modern motorcycles do not use it any more.

Reasons I came across are:

• difficult to bleed and service
• braking on uneven ground becomes problematic
• more prone to leaks and failure.
• Riders found it alters the behaviour of the bike in negative ways under braking

 

The last bullet point is really just a matter of expectations. Once you get used to the anti-dive, and have it set up for your weight and riding conditions, it becomes a non-issue.
Anti-dive systems are still used on big touring bikes; notably the Honda Gold Wing.
One reason why anti-dive isn't used elsewhere comes down to tht last bullet point. Motorcyclists are generally a conservative type of thinker; we tend to not like things that don't behave how we expect them to behave, even if that thing makes an improvement in some way.

The point about braking on uneven ground being problomatic really does not apply to the Yamaha anti-dive system (or the modern Honda system). The method of actuation is progressive, and there is a pressure valve that allows the fork to continue to do it's job over bumps. The other anti-dive systems didn't have that particular feature at the time.

 

No more difficult than bleeding the rest of the brake system!

Hmmmm.....

Literally true, since there are more physical connections/possible points of failure, but true nonsense nonetheless.....

Especially if the system is not maintained (i.e. bled, serviced periodically) and/or adjusted properly (per service manual instructions).


In other words, just like any other "system" on these bikes, they require that:

a) instructions be followed
b) maintenance be performed

These "mechanical" systems are not used any more because they have been replaced/updated with newer technology systems and/or electronic controls. The control and responsiveness of suspension systems has advanced greatly over the years; it does not mean that early systems were lacking, they were merely more "primitive" in comparison to the current era.


Remember, these bikes are basically de-tuned (for street use) race bikes (of that era), and as such, the nut that holds the handlebars is usually the weakest link!

 

hehehehehe.
Such wisdom
thx