Anti Dive Settings

[SIR tricky]

[Guest]

Okay, so help us out here. The repair manual is VERY vague on the operation of the anti-dive unit, so I'm going to make a couple "assumptions"...I know! I know!
Setting #1 offers the least ANTI dive. I'm guessing this would allow more oil to by-pass, allowing the forks to travel further in a shorter period of time. So #1 would allow more flow? The higher you get in number settings, the more restriction to flow, allowing less travel in the same period of time.
BUT......Wingman's observations don't bear this out. He got most flow in #2 and #4 settings. Even though he has the wrong dive label, why would there be more flow on #2 than #1?
It's a puzzlement. :?

[WingMan71]

Yup, I’m with you glhonda. It makes no sense to me.

Even looking at my flow results for my left fork only (which has the correct number ring on it), the #1 setting should have had the MOST flow, not the least. Then the 2, 3, and 4 settings should have proportionally less flow, with 4 being the least flow (most restriction). That would match the Honda chart on the effect that the setting has on anti-dive.

It would be nice to have the next member of our forum who replaces his springs/fork oil do the same flow test that I did when draining the oil and see if they get the same results.

The problem is that this flow test only works correctly if your fork caps are removed. Otherwise there is too much vacuum in the forks for the oil to flow freely when draining.

[wayne peppers]

I need to replace my fork seals and dust caps.. do those $25.00 kits sold on ebay typically come with all the seals needed to make the repair?

Wayne

[SIR tricky]

(T)orque ®eactive (A)nti-dive ©ontrol TRAC


I have had the the anti dive mechanism apart but never really looked at how it worked only that it was clean.

My assumption is that the higher the number the flow would be restricted from outer fork slider through the smaller orifice back into the inner piston (not necessarily) to the drain plug.

My take on the member with the wrong anti dive on one fork is that one of the 2 PO's had either damaged or had replaced the mechanism (unknowingly) with the wrong part.

I cannot see it happening at the factory, we would see a lot more of it if this had been the case.

One thing about Honda is that their quality control is quite good.

[William_86]

Thanks... i have set my antidive to 4 and it still dives a lot, actually. the suspension compresses 100% on fast stops. im running 20W fork oil

[WingMan71]

All,

After much recent discussion on Honda’s TRAC system, I wanted to find a really good description of how TRAC actually works. I found a great one in an ’82 Cycle Magazine write up. Here it is below.

Note: The road test results were written for TRAC on an ’82 Night Hawk 750, so keep that in mind when deciding on what setting to use on your Goldwing, which is a much heavier bike and has TRAC on both forks.

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Honda's Torque Reactive Anti-Dive Control (TRAC) system actuates differently than the Suzuki and Yamaha anti-dive front ends. Those setups use front brake hydraulic pressure to control a valve that closes the fork's compression-damping oilways, and they can have two drawbacks. First, additional brake-line plumbing and increased brake-lever ratios can produce a spongy feeling at the brake lever. Second, those systems are either on or off - there's no modulation of antidive effect.

Instead of being triggered by a rise in brake-fluid pressure, Honda's TRAC activates mechanically-independent of brake-system hydraulics-through the torque reaction of the brake caliper. The brake caliper hinges behind the fork leg on a pivoting link. When the pads grip the disc surface, the disc tries to drag the caliper around with it. The caliper pivots, pressing against the anti-dive mechanism's activating valve and closing off the fork's compression-damping oil passage. This valve, in the shape of a piston, is normally held open by a spring. In a very simple non-TRAC system, applying the front brake would cause a valve to close and increase compression damping, which would reduce front-end “dive”.

TRAC is more elaborate. Forward weight transfer during braking compresses the fork, raising fork oil pressure against the underside of the TRAC activating valve and, through the valve, pushing against the caliper's braking torque. These two opposing forces - fork-oil pressure and braking torque - interact through the valve to provide progressive anti-dive. Hitting a bump causes a sharp pressure rise in the fork. This rise can cause the valve to push hard enough against the opposing force of the caliper to open, partially or fully, the normal compression-damping passageway. This opening allows the fork to respond to a bump. Moreover, TRAC's design provides a constant modulation between fork anti-dive and bump response.

Not everyone wants or likes a certain anti-dive setting. A rider can dial in the anti-dive effect with a four-position adjustment on the fork leg. The adjuster controls a small secondary oil passageway parallel to the main compression damping passageway. This secondary passageway provides a way to bleed-off fork-oil pressure from under the anti-dive valve. The rates at which this bleed-off occurs are controlled by orifices, the size of which can be controlled by the external adjuster. Position 1 corresponds to the largest orifice, which offers the least resistance to the passage of fork compression-damping oil; positions 2 and 3 expose progressively smaller, more restrictive orifices, increasing fork damping pressure. Position 4 exposes no hole; all fork-oil pressure comes to bear on the valve's underside and against the braking torque.

Normally, a fork has much lighter compression damping (one-fourth) than rebound damping. In the TRAC system, when the anti-dive seals off the main compression-damping passageway, compression damping becomes two or three times stiffer than normal when the adjuster is set on position one. On successive settings the compression-to-rebound damping ratios become increasingly biased toward compression.

So much for theory, how is it on the road? There is little feeling of anti-dive effect when the adjustable orifice is set on position 1; the fork compresses much like a conventional fork under hard braking, but there's some travel available for bump response. On position 2 the fork resists the front-end braking dive, and the fork's bump response is firmer. The difference is small but obvious. Position 3 gives a noticeably larger increase in anti-dive effect, producing firmer resistance to front-end squat from braking and stiffened reaction to bumps. The fork still dips when the brakes are applied, but slower; it still responds to bumps, but it delivers a firmer jolt. Position 4 produces more substantial effect in the same direction.

Riders who use their front brakes without any particular vigor will find the first two positions useful. These allow the fork to respond nicely to bumps during braking while giving a wonderfully smooth cruising ride. Our staff testers preferred position 3 for rush-about riding. It provides a measure of squat resistance and yet responds nicely to most surface whoops. Those who stand their motorcycles on headlamps during braking will like position 4. It gives generous resistance to front-end dive and responds to hard bumps.

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Hope that sheds some light on the subject!

The picture below shows the Anti-Dive valve system. (Brake caliper shown is a Night Hawk caliper, not a Goldwing caliper. Anti-Dive valve is the same though.)

[Guest]

Thank You VERY much!!
I has always wondered how the system worked, but never investigated 'cause I've never had a problem. (Let sleeping dogs lie)
I've always run setting #2. Maybe I'll fool around with different settings just to see. Maybe I'd better leave 'em where they're at, we have a lot of pot holes around here.
Thanks for your effort.

[seminolejoe]

I hate to say it but my anti dive settings for my 1200 aspy are the same as wingman's. my left side the #1 setting is in the forward position with the #2 setting at the top which gave me the fastest flow when draining. The right side has the #1 position to the rear of the unit with #2 likewise at the top but the best flow on this side came from the #4 setting which is at the bottom location. This gives both sides the same look sitting there looking straight at them. #1 to the left #2 on top #3 to the right and #4 at the bottom. Now if I rotate one of the number rings 180 degrees then I have the same number with the highest flow on both sides, which is #2 on the left and #4 on the right at the present time. I will have to do another flow check to be sure but I believe if I set the #1 position at the bottom on the right fork and at the top on the left fork I get the faster flow at what is now the #1 position on both and the slowest flow on what would be #4 with this senerio. I'll check that out and get back to you. I also noticed that the number ring does move around rather freely. Not enough to change positions but it does have some play in it.

[HarrysToy]

So are you guys getting at (the settings are incorrectly marked)??
I have to wonder, I havent tried the flow test yet, however ive tried mine on settigns 1-2-3 and had no differance in front travel at all.........
Maybe I need to play with this a little more hock:
I just figured mine wasnt working, my friends got his set at 3 and has very little suspension travel under front braking........ :?

[WingMan71]

SeminoleJoe,

Thanks for verifying your anti-dive settings vs flow rates for me. Makes me think that I'm not way off base by myself here!

Harry,

Yes, I am saying that the anti-dive settings stamped on the numbered rings don't match the actual flow rates, at least on my bike. See the following thread for my test results and what started this discussion.

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I'd be curious to know if the numbered anti-dive setting rings on your bike match mine, or Tricky's.

[seminolejoe]

I'll see if I can get a picture of mine and try to post it.

[WingMan71]

I'll see if I can get a picture of mine and try to post it.

Based on your earlier description of your anti-dive valve numbered rings, the position of the numbers on the rings exactly match mine on both sides.

[seminolejoe]

Well, it doesn't seem that I'm gonna be able to get the photos of my anti-dive settings posted. Every time I try to post them it sends me to the login screen after I do the login it sends me back here but the reply screen is blank and I have to start over. I'll try to post just this message and see what happens if it goes through I'll try to post the photos in another reply

[seminolejoe]

[attachment=0][attachment=1] I'll be d@#$%* I did it.