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anti dive fix GL1800

11899 Views 17 Replies 12 Participants Last post by  choppas
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In the past I have had a problems with the anti dive system on my GL1800’s, until I fixedthem.
The history
I have two medium mileage GL1800’s (2003) one for me and one for my wife, both bikeshave suffered with an anti dive problem. The brakes operate a slave cylinder that activates an anti dive actuating valve on the left hand side of the front forks, this slave cylinder only functions when the bike is moving.The slave cylinder has been changed twice on one bike and once on the other leaving me to believe that GL1800’s suffer with this problem. I have ridden many other 1800 wings and least two of them had the same problem but the owners were unaware anything was wrong until they rode my bike! My bikes are regularly serviced and the brakes have had the brake fluid replaced twiceto date.

The symptoms:

While riding along normally the bikerides wonderfully smooth until I had to slow down or stop. The anti dive valve stays on until it decides to relax; during this time the front end of the bike becomes skittish at very low speeds or while cornering. Theproblem is also evidentwhilenegotiatingspeed humps in the road, I always slow as I approach them and then release the brakes before I make contact with them, but the suspension remainsfirm and seems tobounce over the speed hump. The result is that the suspension can finish up almost fully extended after crossing a series of speed humps. I once stopped after crossing one of these speed humps and put the bike on its side stand and waited almost 10 minutes for the front forks to relax back to the normal position.
On the third time this started to happen I (being an engineer) decided to take a look for myself.

The Fix:

The brake slave cylinder is the problem, it forces a 5mm pin into the anti dive actuator tolock upthe left fork during braking. This slave cylinder is supposed to return upon releasing the brake lever but it doesn’t always behave as it should, it cantake some time to return to its resting position. I took it upon myself to effect afix that works better than ever and has been working well for the past year. Myfix was to fit a small rubber 'O' ring over the pin and remount the slave cylinder to its rightful place, that’s it!

Method 1:
The rubber ‘O’ ring is 2.5mm(0.098”) in section x 5mm(0.196”) bore and 10mm (0.393”)O/D made of black silicone rubber, it sits in a void between the slave cylinder and the anti dive actuator. It doesn’t impede anything or prevent anything working it just helps the plunger to return to its rightful position.
To get at both the slave cylinder and the anti dive actuator is simple… first, remove the top front portion of the mudguard (top front fender) by unscrewing the four recessed (5mm) socket screws. This brings the two units into view on the front of the lower left fork leg, There are two (4mm) socket screws, one each side of the slave cylinder. Undo these… (don’t worry the two items can be separated and there should be no leaks, springs or nasty surprises) and insert the ‘O’ ring, checking first that your ‘O’ ring fits comfortably, without friction, over the 5mm pin on the slave cylinder and in the 10mm recess in the top of the anti dive actuator.

Method 2:
You can use two ‘O’ rings instead of the one.(above) The first ‘O’ ring dimension- 1.8mm (0.070”)in section x 5mm (0.196”) bore x8.5mm(0.334”) O/Dand theSecond ’O’ ring dimension- 1.8mm(0.070”)in section x 6mm(0.236”) borex 10mm(0.393”) O/D, bothblack silicone rubber.The smallest ‘O’ ring sits on the 5mm pin without friction and the larger ‘O’ ring sits in the recess on top of the anti dive actuator, one on top of the other when assembled. Note: when putting the two units back together be sure the ‘O’ rings are still in place. This gives a slightly slower anti dive reaction under very light braking. I favor this fix.

You can, if you’re daft enough, (yep that’s me) ride the bike with the two units separated!!! but the bike will dive every time you use the brakes.:cool:

:shock:. If you try to fill the void between the two units with rubber the anti dive becomes next to useless. If your bike is still under warranty let Honda sort it. If you have found a leak of any kind from either unit STOP what you’re doing and inform your service centre.

Happy riding :action:

[align=center]Photos and their descriptions
Here are the pictures I hope they are useful Below is a description of each picture

The front mudguard (fender) removed 4x5mm socket screws

Using a 4mm Allen key to detach slave cylinder

The slave cylinder detached and not leaking

The top of the anti dive actuator showing the recess

The two rings I use are still in good working order and the only two tool required for the job

The largest silicone ring in the recess

The smallest ring over the 5mm pin - indicated by a screwdriver

Care taken to place the two items together

Securing the slave cylinder into place using the 4mm Allen key

Replacing the front mudguard (fender) using the 5mm Allen key

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Good post Paul.
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Paul, could you pull one of the units apart and take some pics of the location and fitting of the 0-rings? As this will clarify the text of the fix a lot more clearly.

Once you've done this then maybe Steve could add it to the tips page and the index.
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Great post, and with the possibility of pictures this sure would be appreciated.

Thanks again,

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This post is now indexed and will be in the FAQs after folks have seen it for a while.
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I'm a bit busy at the moment but I will se what i can do about the photos:waving:
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The piston on mine was stuck out so the antidive was on all the time. Talk about a rough ride. I was able to push it back with a fair amount of pressure, but I didn't think I could trust it. So I made a spacer to disable it. Sounds like your idea will put some pressure on the piston to push it back. Will give it a try when I am in the fixing mood.
Thanks for the tip.
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As per Paul's request, I have inserted all of the pictures and their links should someone want to download the actual pictures.

A fantastic job Paul, Kudos for great work. :clapper:
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:clapper::clapper:This is good stuff Paul:clapper:eek:ver the last 4yrs,, ive spent £300 or more with my anti dive,,this would have saved me ££££££,,cheers:waving:
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Got to love it. New member with just 4 posts and he does this kind of work. :clapper:


Your inputs with the new pictures will make my winter project much easier plus taking a corrective action as well.

Again many thanks.

Now what is your next project? :cheeky1::cheeky1::cheeky1:

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I grumble a lot about the Speedo error on my bikes, they’re an average of 8% over optimistic, I'm pretty confident I can cure this one… when I find my BIG hammer.:cool:

I have also modified my front suspension with a simple little gadget I made. It adds extra handling and cornering performance for very little work and cost… Thing is I haven’t fully tested it yet... but I can say that I’m climbing all over the back of other bikes round the twisties…ohYes.:cooldevil:
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That's great work Paul, I will also add this to the workshop pages soon.
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Just the advice I needed, great.
And in the garage I´ll go...
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Has anyone else tried this fix? let me know how things went good or bad
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Great read, great pictures and very informative.

Excellent post,

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Hi all

I am writing to update my article “Anti dive fix GL1800” posted in August 19th 2009. Firstly thanks to all that have taken the time to post a message to me, I would also like to answer a few questions that I have been asked and I’d like to explain something about the braking system at the same time because this is relevant. People have written to me and told me that ‘the anti dive should only work while operating the rear brake’ that ‘the front end should bounce freely under stationary conditions’ and ‘a drilled nickel or washer will do the same thing’ I’ve seen a thin unsealed spacer placed in a loosened brake fluid retaining part of the assembly that has left me feeling uneasy.


The reason I didn’t isolate the anti dive unit completely is because the bike needs to be as stable as possible while being ridden. Under normal riding conditions the Goldwing is like any other machine, that is to say while in a straight line, on a level road and at a set speed beyond 10-15mph, it is in its most stable condition. Input a force on the machine and it becomes less stable; this force can be applied as acceleration, deceleration or a turn. With respect to the braking effect (deceleration) all machines will transfer its weight forward, under braking, onto the front suspension making the machine less stable. Honda must have decided during the testing stages and before general sale that the bike had a large degree of dive under certain braking conditions making the bike unacceptably unstable. The upshot of this is that to prevent the bike diving so much the boffins at Honda came up with the Anti Dive Device to best deal with the problem.

How does the A.D.D. work (or not) with the brakes.

Please bear with me on this because it may explain to most what is going on with the anti dive and why it does what it does and it may save you some money, so here goes.
The linked braking system on the GL1800 is in my opinion poorly engineered. It has two front disks and one rear disk and three master cylinders. One master cylinder is connected to the hand brake lever; the second master cylinder is connected to the rear brake pedal. One of the front disk brake callipers is mounted directly to a front lower fork strut, the rear disk calliper is also mounted firmly to the rear swinging arm. The complex bit is that the other front disk calliper is mounted on a radial swivelling bracket and is prevented from moving too, far when the brakes are applied, by the third master cylinder. I don’t want to get overly complicated here so I’ll try and keep it as simple as I can. In doing so I will not involve the Delay Valve and PCV in this discussion to keep it as simple as possible.
Each of the three disk callipers have a three separate chambers or cylinders activated by either the front brake lever or the rear brake pedal nine braking cylinders in all. The front brake lever operates two cylinders on the front right calliper and one cylinder on the left front calliper and that’s it, three cylinders.
The rear brake pedal operates one cylinder in the rear calliper and also one in the front right calliper and…two cylinders in the left hand calliper four cylinders, that’s seven cylinders in total so far. This leaves two cylinders in the rear calliper unaccounted for and in a simplistic fashion I’ll try to explain what happens now. If you apply both brakes while the bike it is stationary you will not really use anything other than the seven braking cylinders. But while the bike is moving forward applying either or both brake levers activates the brakes on the previously mentioned cylinders, but now because the machine is moving the left calliper grabs the disk and because it is on a swivel bracket it will activate the third master cylinder.
This third master cylinder acts like a power servo to the remaining two rear braking cylinders and by a combination of the unmentioned Delay Valve and PCV more braking force is delivered to the remaining cylinders, the braking effort is proportional to the effort placed on the system by the rider and by the amount of pressure the floating calliper applies to the third master cylinder allowing a greater than one third of a ton bike to be stopped relatively easily.
What has this to do with the anti dive? Well the anti dive is directly connected to this third master cylinder.

The anti dive mystery and my method on how to test it.

You will find it easier to understand how the A.D.D. can be tested if you have read the previous section Carefully. Firstly while aboard the bike hold the front brake lever and pump the front suspension up and down, the suspension should move freely. If it doesn’t or it only bounced once don’t worry, it’s possible that the left calliper is gripping better than the right one at this time, this is often caused by residual brake dust on the right disk or water if its just been cleaned. If the left calliper does grip the disk better than the right one at that time for whatever reason, the left calliper will activate the Anti Dive Device this will happen even if there is the slightest movement in the third master cylinder. Try this, release the brake lever and roll the bike backwards and forwards a few inches for a couple of times then redo the bounce test but this time give the front brake lever a real big grip to prevent any possible rotation of the front wheel how ever slight, then while still gripping hard redo the bounce test and the bike should bounce freely. If this time it still refuses to bounce you may have a problem with the anti dive actuator valve but its not yet confirmed because there’s two more tests you can do. Get the bike on its main stand and get some one to sit on the rear seat to hold the front wheel off the ground, spin the front wheel and check that the wheel spins freely and the disk pads only just skim over the disks with the lightest of friction then while the wheel is spinning grab the front brake to stop the wheel dead then re-spin the wheel if you hear only light pad to disc contact then there shouldn’t be a problem there. If there is a rubbing disk then you may need to get your brakes serviced. The next test is a riding test this has to be done over a gentle speed bump or something similar that would normally be encountered on the road like entering a driveway. While the road is clear of traffic approach the speed bump or driveway at a safe speed or the normal safe speed for that hazard and apply the brakes any lever will do to slow you down before the obstruction then release the brake lever one or two feet before you arrive at the hazard. The bike should soak the hazard up cleanly if the hazard was very firm and jolted you will find that the A.D.D. is well and truly in need of attention.

Now the update on my fix

In the summer of 2008 I had a go at fixing my A.D.D and was quite proud of my fix and I told the world a year later. Since then I have had countless emails thanking me for the fix suggestion and I promised to give you an update. So here it is.
Three years on and it’s still working fine in one of our bikes but, the other bike succumbed to the dreaded damp and road salt, needless to say that I investigated further. The anti dive actuator can be stripped down cleaned and returned for duty but I’m not going to tell any one how to do this because it only takes one person to get this bit wrong and people could die and I couldn’t live with that, but return it for duty I did and I left the original fix in place and it still works as it did when I first tested it. But this time I have sealed the two units from the elements using brake quality grease as a seal. Using brake seal quality grease should prevent any problems with the piston seals if they should somehow become contaminated.
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This last weekend on a very bumpy road, my front suspension got very stiff and did not loosen up until after I had stopped for a break. With 132K miles on my 2001 I decided to try this fix.

Being in the USA, I wasn't able to find any metric O-Rings without ordering them in bulk. I was able, at an ACE Hardware store, to find ones that were close and buy them individually.

For the 8.5mm X 5mm X 1.8mm I used a 5/16 X 3/16 X 1/16 #36 O-Ring
For the 10mm X 6mm X 1.8mm I used a 3/8 X 1/4 X 1/16 #5 O-Ring

I have installed them in the Bike and will see how they work.
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Thanks lepolgr, the o ring info is useful.
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