Anti-dive mechanism

[Arfdog]

I am going to try remove the rusty nipple on top of the anti-dive mechanism this evening. If I bugger it, I might remove the anti-dive completely.

Three questions:
Is this an anti-dive, considering that there is only one mechanism on one fork, nothing on the other?

What is the easiest way to disable/remove anti-dive?

If I remove it, will my bike start diving much more?

Thanks

https://i112.photobucket.com/albums/n190/arfdog/SIDE.jpg

https://i112.photobucket.com/albums/n190/arfdog/FRONT.jpg
____________________
I'm a lover, not a fighter.

[Paddy Blake]

That is the anti dive and if you remove it the oil will piss out.To remove
the bleed screw use a socket that has six sides and not the other
ones that are more likely to round the screw.

Paddy.

[Arfdog]

Hi Paddy, the nipple has already been rounded. It was so rusted that the corners basically crumbled. It is VERY solidly fused in. I couldn't budge it with heat and molegrips, so I'm giving it a couple of days of WD40 application, then trying again..
____________________
I'm a lover, not a fighter.

[finpos]

By the looks of it you'll need to remove the link jhose and replace the double banjo bolt on the caliper with a single banjo. You might get away with cutting one banjo width off the original bolt - never tried it but it should work.

edit - actually, you can just re-use the single banjo bolt off the anti-dive end. duh.


Then an ordinary bolt to plug up the anti-dive banjo hole (after you have drained it of fluid - you don't want it to lock!). Unless you are removing the whole thing, but then you'll be left with an as yet unidentified hole in your forks.

finpos.

[Arfdog]

Drain the fluid?

I don't know the mechanics of exactly how this thing works, which is a problem. If sealing off, I would have thought it would have to be sealed whilst full of juice, and bled of air too, as this is the configuration they would normally exist in when the brake is not being pulled. The only difference after removal is that pressure would not increase when the brake is pulled.. If I drained it of juice (or even left juice in but didn't bleed the air out), then surely the fork would be unexpectedly floppy?
____________________
I'm a lover, not a fighter.

[finpos]

Inside there there's a piston - on one side of it is brake fluid, so when you press the brake lever the piston moves exactly like your caliper piston. Other side, there's a big spring to return it.

On the suspension side, there's basically two different routes for the damping oil to go when the fork is compressed - one that allows normal damping, one that is stiff damping (i.e. antidive mode).

When you press the brake, the piston moves and blocks off the normal route, leaving only the anti-dive route.

So, if you leave the brake fluid in the anti-dive unit and screw a bolt in t' hole, you run the risk of compressing the fluid, shifting the piston and putting it permanently into anti-dive mode.

i.e. it doesn't work by fork oil pushing back against brake fluid pressure.

And if you rip off the unit, you'll possibly expose some oilways, or at least a delicate diaphragm or something. You'd need to make up a metal plate to replace the unit with.



finpos.

[Arfdog]

Aaaaaaaaah I see!

Ok excellent, thats cleared things up for me now.

Thanks
____________________
I'm a lover, not a fighter.

[finpos]

Yes, one day anti-dive will make a triumphant and popular return. Then all those hours I spent figuring out how the hell they were supposed to work* and fixing them** will not have been in vain.

finpos.

* This was before we had the interwebmong thingy you could just ask people on.
** I know I should have just knocked 'em off with a chisel and thrown them in the bin, but they were very popular at the time. Damn you marketing department.

[Tarmacsurfer]

Anti dive (on the GPz series at least) was pretty good, when it worked. The problem being that it rarely worked for more than a few thousand miles between rebuilds

Looks to me like one fork has been replaced at some point, and so they are mismatched. If that's the case I'd hope that the system is already disabled otherwise it's going to lead to some interesting handling... What's the bike? The RXS100 doesn't have an anti dive system as far as I'm aware

Most important thing to remember if removing the system though, is fit progressive springs and sort the oil weight out, or the front endwill be utterly fubar.
____________________
I'm immortal. Well, so far.

[crazymotorbik...]

Hey,

Completely remove the anti-dive, when they work there good, but in my expereince they never do work properly and are expensive to get bits for.

Just make a metal blanking plate, put some form of gasket in between and the jobs a gooden.

You'll never notice the difference.

Cheers,
Shaun.

[Arfdog]

Ok I removed the bleed nipple finally and got a stainless replacement, but it turned out the anti-dive nipple is about 2mm longer than ther brake bleed nipple, so I can't plug the hole!

So, I disconnected antidive hose, drained fluid, and sealed it back up again, so antidive is disabled and brakes are now hard as rock. I also opened the mechanism to see inside, and the piston was stuck in permanent anti-lock. I loosened it so it moves again, but there is no spring (on the top side anyway), so I hope it stays up.

Next problem, before removing the correct bit, I removed the incorrect bit of the antidive, the bast part. I lost about 3 teaspoons of fork oil which was behind it, before sealing it up.

So now I'm thinking I should replace fork oil in both forks so I know they're sound. Question is: the manual I have does not cover models with anti-dive forks.. so how much fork oil should I put in each, especially considering that one fork has a newly disabled anti-dive? I'm guessing unequal amounts in each fork, but equal level from the top in each, since one fork will probably have a bit more space atthe bottom due to anti-dive.

Thanks.


* Oh, if anyone has a haynes manual for the 1986 gs450, could they please have a butchers and tell me if it says anything about fork oil levels specifically on anti-dive forks? thanks **
____________________
I'm a lover, not a fighter.