Anti Dive gotta go

I had an an issue the other day with stopping quickly and the forks compressing (diving) all the way. I am now ready to remove the anti-dive units. (I researched the forum and there are lots of directions...however, I am resolved to eliminate the anti-dives.)

I am also going to install SS brake lines and progressive springs.

But first, I need to blank off the anti-dive and remove the extra brake lines. My question:
1. Does oil need to flow (full flow) between the two ports of the anti dive?
or
2. With the ports blanked off; Will the oil flow through the inner oil lock assembly at the flow rate required for progressive spring dampening?
or
3. Do I need to replace the oil lock assembly? With what?

Thanks to all, greg

 

Good questions.

I'm going to speak in terms of the Venture which I believe has a similar anti-dive......

It appears to me that oil flows through the anti-dive in normal operation. The closing of the anti-dive during braking shuts that passage, increasing the compression damping.

I suspect the oil lock is supposed to move against that little stack of springs to provide a type of pressure relief valve so the forks aren't locked up.

Now there is a guy on the VentureRider site that sells a block off plate like you describe for the Venture. I asked him the same questions you are asking and I got some mumbo jumbo about fork springs in reply.

There are a number of people there that have installed his block off plates and seem happy with them. That leads me to conclude that one of the following must be happening:

1) I have a complete misunderstanding of how the ant-dives work.

2) People are reluctant to recognize they made a mistake (and talk about it).

3) Anti-dives don't do much to begin with. Or they've all been worn out or broken.

I suspect #3.

 

Why not keep the anti dive, provided it is working of course. From what you describe, sounds like your springs are dead. Replace them with a good set of progressive springs.

 

If you problem is forks compressing (or "diving" all the way), then I think you'd want ANTI-dive forks :twisted: . That's exactly what the brochure says they're for! People doubt their effectiveness, but they won't CAUSE your forks to compress any more.

You should consider servicing both the forks side and the brake side of the anti-dive units. And your forks, as Super suggested.

EDIT: I see you are planning on installing new springs and brake lives. For just a little more you could buy the lower brake lines and whatever seals are available, and a little elbow grease would have them functioning properly.

Or your could always get a really cheap set of forks off ebay from a non-anti-dive xj with dual calipers, and rebuild those, if you're concerned with oil flow. I agree with MiCarl, it would appear necessary for oil to flow through those passages.

 

I defeated mine, I'll post some pictures when I get home but I think it's possible to use the anti dive unit to make adjustable compressing damping
+1 for the block off plate, that part needs to pass oil

 

a completely shot anti-dive operates the same as no anti-dive at all. Why go from "kinda maybe crappy" to "garunteed crappy"

If you insist on tearing it off at least sell it here, don't pitch it in the bin.

 

I'd disagree with that statement. If someone really doesn't WANT anti-dive, there are people who've removed it and you can take their advice. I personally reconditioned it.

Anti-dive units, when not serviced, could cause inconsistent fork damping between the two forks. If the brake side is still connected and not serviced, gunk trapped in them can contaminate the brake fluid and trap air bubbles.

But definitely keep 'em with you, even if you blank them off, never know when they might be of some use to you.

 

the black part needs to stay, i tried blocking it off with a plate and the fork barely moved.
the aluminum part on top replaces the brake fluid part and covers the piston that moves under brake fluid pressure.
the adjustment would be a set screw in the top aluminum part to push the piston down like the brake fluid pressure would originally do, that's all theory, never tried it.
the adjustor on the bottom still seems to have some effect, i moved it once and it seemed to stiffen it up but never really got into it any deeper

 

^^^
Smart and simple. However, the anti-dive unit will still need to be cleaned out to make sure it isn't all plugged up.

What does that aluminum block do? There shouldn't be any fluid coming out of there, but I imagine the usefulness of making the damping adjustable.

 

oh yea there was a lot of rusty gook in mine that needed cleaning.
the aluminum block just covers the little piston thats steel if i remember right, that piston and a o-ring is all that stopped the brake fluid and fork oil from mixing and now it's holding the fork oil in, a gasket under the aluminum thing is a little extra insurance it stays in

 

I just left my anti-dive units on and plugged the brake line opening when I removed the lower lines. My forks work good without the anti-dive units and don't dive much at all.
If they were a good idea, they'd put them on more bikes today, but they don't! So what does that say about them?!!

 

My opinion:

Clean them up so they work as intended, add a fancy new set of stainless lines, so they LOOK GOOD and WORK BETTER and you will have maintained the uniqueness of these machines and made it safer to ride. I'm very happy with the rebuilt forks, calipers and ss lines on mine. The anti-dive units are the subject of curiosity for many that look at my bike.

Dave

83 900

 

From an engineering stand-point, I think they work as a SYSTEM. Anti-dive + early 80's spring and fork technology = a better braking system than other late 70s-early 80's tech. Today's fork technology is good enough that anti-dive doesn't add anything. Remove anti-dive in a Seca and you're back to just 80's tech. Throw in progressive springs and you've probably helped things. But it's still 80's oil flow tech in there.

I for one have never had my anti-dive forks bottom out on me while braking.

 

Ah yes...did not know such great responses would come forth. Here's the rest of the story:

Forks rebuilt, anti-dives cleaned/pistons move, brakes rebuilt, lines flushed put it all back together. Anti dives work..stiffen at highest setting, less compression at lowest. For normal riding I use 20 wt and 5 psi which tends to ride like a rock. My 210 lbs girth keeps the forks compressed with only 2 inch of travel. When braking with any bumps...I'm just trying to hang on cuz the front hard as rock. Alternately, when I lessen the anti dive to smooth the braking, I start dipping to the bottom end of travel. Which of course makes the spring absorbtion terrible.

Coupled with the spongy brakes and brake fluid pushing a dive piston instead of the calipers...I was grabbing all of my brakes and could not stop near quick enough. This event happened 2x. The 1st time I missed a head on with luck and the 2nd time I hit dirt and went down. Now I have to repaint...that's the rest of the story AND the ugly part.

So I agree with earlier posts. Fork oil needs to move between the two anti-dive ports to get into the lower oil lock valve assembly. There is a company named Traxxion that makes a "emulator valve" to replace the oil lock assembly which would allow the anti dive to be blanked off. BUT, they want $150 for the valves...plus springs...plus spacer...+++.

I like the aluminum block to replace the brake connection. This will allow oil to flow past the anti-dive valve and the adjuster should still work to regulate the oil flow into the bottom oil lock assembly.
- Where can I get the brake section cap or block off?

 

My forks already had progressive springs and I modified my anti dive units making them just an adjustable compression dampening valve.

 

"- Where can I get the brake section cap or block off?"
i'am going to make a few after work, pictures later

 

When I blocked off my anti-dive units, I used a short bolt, threaded the same as the brakeline and a nylon washer to seal it. Hasn't leaked a bit since and the forks are far from bottoming out. Actually, the forks are even a bit stiff, which is good.

 

Gregu, I'm sorry to hear you took a spill! And you must have gained weight since last we met. I'll try to whip out a set of block-off plates for you here in the shop (including the bypass channel for pressure transfer). Give me a call when you get a moment.
Darkfibre, I'd LOVE to get pics or a diagram of your adjustment mechanisim. It would be nice to add to the block-offs I'm going to make for Gregu.

 

Hey Robert...I just LOOK skinny...been 210 since college. Hey if you are building block-offs with the adjuster, I'm ready for a pair. I'll call you this weekend.

 

My adjusters work as a replacement for the hydraulic activator. All it does is push down the existing piston on the anti dive. The valve still needs to be operational.

Cant find any pics of the underside, but I made a single (13mm by memory) plunge cut to about 2mm depth so the plate didn't depress the piston.