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Hi all


I am writing to update my article “Anti dive fix GL1800” posted in August 19[suP]th[/suP] 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.



Stability
[/b]
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[/b]. 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.
[/b]
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[/i], 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.
[/b]
You will find it easier to understand how the A.D.D. can be tested if you have read and understand the previous section.This method of checking is, I believe, a more involved test than the service manual and should help you get a better result. 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[/b]

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.



Finally[/b]



This fix is by no means a permanent fix, nothing will be. Adding the rubber rings will only act as spring assisters and their efficiency will deminish as they flatten slightly. The ring or ringswill do one, or the most part of four things depending upon where you live in the world as humidity, salt or both may contribute to some sort of deterioration. I live in the UK and the authorities throw salt all over the road in winter and this ruins anything remotely made of metal and this does effect the anti dive unit severely. The other thing I would say is, it’s the design of the anti dive actuator that is the problem. It is for want of a better description, an old fashioned brake cylinder unit, the 5mm plunger protruding from it is part of a larger piston on the inside. This piston has two brake quality seals on it to do its job. This piston moves up and down by a small amount, about say 5mm. This movement happens every time we use any brake. The problem is that the piston is steel the seals are as I’ve mentioned ‘rubber’ and they move up and down inside an aluminium bore. The steel reacts with any moisture in the braking system fluid and in the atmosphere also the rubber seals buff the cylinder walls within the anti dive activator body. Most of the damage, that’s what it is[/i], is dust from the regularly buffed cylinder walls reacting with the limited amount of rubber grease in the unit that forms a paste. This paste will react further with atmospheric moisture and this combination causes the piston to eventually stick in the 'on' position and it stops the suspension functioning as it should. Another problem is that the anti dive device on the lower left suspension leg hasn’t any springs to talk of to assist the plunger back in the first place.

Here is what thefix 'fixes'. First, the rings will take over that missing return to base spring action. Two, they will provide a more progressive anti dive. Three, the anti dive action deactivates immediately you release the braking effect. The forth thing is that they do ‘absolutely nothing’ when the paste mixture overcomes the returning action of the rings. I did mention that I have disassembled the anti dive actuator body and cleaned it but when I reassembled the unit I packed the piston and slider with brake grease and when I coupled the actuator to the anti dive valve I also smeared some of the grease around the 25mm spigot to act as a seal against the atmosphere while remaining as safe as possible from any potential threat that could result if the seals became contaminated by the seal friendly grease. The upshot is a superb braking effect that is super smooth and the cornering while braking combination that we should never do but sometimes do in a panic is much more controllable. I’m reluctant to tell anyone how to service the anti dive actuator body because if I leave only one small detail out people could die.
Regards



N.B.

I mentioned nothing will be permanent, but I believe I can do away with that part of the brake system assisted anti dive and replace it with a brake light switch activated electric solenoid for a faster and more reactive operation.

:cheesygrin:
 

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You have another master cylinder on the left side just above the anti dive unit. It works off the rear brake pedal. To test it, do each brake lever separately. one lever will allow the front fork to compress, the other one won't.
 

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Hi

thats right there are a total of three master cylinders and the third can be activated from both the front or rear brake levers.

:thumbsup:
 

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Not the one for the anti dive unit. That one is only operated from the rear brake. The front brake won't operate it.

If I remember correctly, it's just above the anti dive cylinder.
 

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hi wing-rider
take a look at your clymer, you'll see that both brakes will opperate the anti dive. you wil also see this happen if you do the rolling bump test as sugested.

cheers
 

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Very nicely done write up.
Wonder why my service manual tells me to lock the front brake, then "bounce" the front forks and they should move freely 2 or 3 times then fork movement will lessen as the ADV does it's job, if it's working correctly.
Also, since the Wing has a linked brake system, I would think using either the front or the rear brake would activate the ADV.
Am I missing something????
 

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I did and you're wrong. Only the back brake. I have the official manual.

The handlebar brake operates the front two calipers and the foot pedal operates both front and back calipers and the anti dive unit as well.
 

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Dear Wing-Rider
I also have the official service manual andmy copyonly mentions the official rear brake test via the secondary master cylinder on top of the left front calliper. By pushing the left front calliper upwards you will apply pressure to the secondary master cylinder, this in turn will activate the ADV as well as the rear brake via the top and bottom pistons and also the middle piston in the right hand front calliper however, you will have to push fairly firmly and you’ll need some one to assist you to do the full check. No part of the manual describes a test for the anti dive system beyond removing the unit and there is no mention anywhere in my manual that the anti dive is only controlled by the back brake alone.
Take a look at the diagram on page 15-A-5 and on page 15-A-6. These diagrams describe only what systems are activated while the machine is stationary, on a service ramp for instance. It does not show what happens when the brakes are applied during forward motion, i.e. normal braking. Look carefully at the at the diagram on page 15-A-5 then imagine for a moment that you are riding the bike along the road and you will note that when the front brake lever is activated the right calliper grabs the right disk also the left calliper grabs the left disk and if you look at the diagram closely you will note that this in turn activates the secondary master cylinder, doing so will activate the ADV as well as the rear brake via the top and bottom pistons and also the middle piston in the right hand front calliper as well. Conversely, if you look at the diagram on page 15-A-6 you will note that the rear brake pedal will activate the ADV again when the left front calliper grabs the left disk and thereby activating the secondary master cylinder once more. Therefore, it follows that any upward movement of the front left calliper during NORMAL braking will activate the ADV no matter what.
I have two GL1800's both of them have always activated the anti dive system when the front or rear brake is used I can't see two identical bikes having the same anti dive outcome and be as you would imply, malfunctioning in exactly the same way. Might I suggest that if you think your anti dive system only works when your apply your rear brake pedal that you have a fault in your braking system or if you bought the bike second hand it may have already been modified to prevent the ADV from working altogether. I can say that I have spent a lot of time and effort investigating this particular fault before I wrote the update to help other wingers I do understand what you see but its not the whole story even in the full service manual.
With the greatest of respect
Best wishes and may your road ahead be warm and dry
Paul Hopewell
 

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Well... I write manuals for a living, so I'm pretty good at reading them too. Decided to take a look.

I have the Honda GL1800 Factory Service Manual on DVD, and it states this on page 24-5:

--------------------------------------------------------------------------------------------------------
BRAKE SERVO-PRESSURE SENSING ANTI-DIVE SYSTEM

This motorcycle is equipped with the Linked Brake System (LBS). This system operates the anti-dive system on the left front fork by utilizing fluid pressure generated in the secondary master cylinder.

The secondary master cylinder responds to braking forces generated by the lever and/or pedal. When either brake is applied, the plunger is pushed by pressure from the secondary master cylinder and the anti-dive piston valve in the fork oil passage moves to block fluid flow.

[/b]As the flow of the fork fluid is reduced by movement of the piston valve, the system reduces compression of the front fork and thereby controls the nose dive of the vehicle.
--------------------------------------------------------------------------------------------------------

So...Honda clearly states that BOTH the front and rear brakes act on the secondary master cylinder and the anti-dive valve.

They also have a good set of pictures on that page that help to illustrate exactly how the system works. Don't have time right now to copy/post those up or I would. Just look at page 24-5.

Thanks for the update Paul.

***
 

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Hi WingMan71
Thanks for that it seems I do not have the entire manual because I haven’t this page in my book. Weirdly it stops at page 24-3. That’s by the by thank you very much I’m sure I would have got my facts out a little earlier if I’d found that page.
Have a nice day keep the rubber bit on the road and smile like you’re up to something.

Regards



By the way, I would love a copy.

:thumbsup:
 

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Again, you both are wrong. I don't know how to tell you that the hand brake lever is in no way connected to the rear wheel. If it is, you need to go tell my bike that. I went outside today and held the front brake handle and guess what? The rear wheel spun freely.

I have been searching for the section in the manual as to how to test the front fork dive unit. It clearly stated that the FOOT PEDAL ONLY operates the anti dive unit. I also saw the schematic of the hose routing and that too CLEARLY shows that the hand brake is not associated with the anti dive or the rear wheel.

So, if the manual said either lever operates both wheels, it's wrong. Hand brake lever is not connected to rear wheel.

If you folks insist that it is, go ask your bike. Take a friend out there with you. Put it up on the center stand and hold the hand brake lever and spin that back tire. It will spin. No ifs ands or buts.

I can also guarantee you also that if you were to hold the hand brake lever and try to compress the strut, it will. Then do the other one. Now it won't. That's how you test the system to see if it's working.

That should solve the problem!:shock::watching:
 

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Hi Wing-Rider,

So what is a linked brake system then?

I am lost.
 

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The linked part of the brake system is when you press the foot pedal to the rear brake it also operates the front brake.
 

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That's what I thought, but Wing-Rider is saying it doesn't. I am confused, hence the post.
 

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Wing-Rider wrote:
It clearly stated that the FOOT PEDAL ONLY operates the anti dive unit.
I'd like to see that reference in the HONDA Factory Service Manual copied and pasted here. I can't seem to find it.

I took the time to copy and paste the proper section out of myHonda Factory Service Manualand it cleary states that BOTH the front and rear brake act on the anti-dive valve. See that post above.

If you think about that for a minute,why on earth would ONLY the foot petal affect the anti-dive unit when the front brake on a bike offers the most braking force and will result in the most front end dive when applied. If anything, ONLY the front brake should act on the anti-dive unit (if you have to choose just one). Makes no sense that just the rear would act on it alone.

Let's please have chapter and verse that you are quoting from the Factory Service Manualso we can verify that. Andsorry, but I don't takeanything from a Clymer, or other non-factory manual, as gospel. Seen too many mistakes in those.

Different topic now... linked braking system:

Here's a direct cut-and-paste from the factory service manual regarding the linked braking system:


[align=left]This motorcycle is equipped with the following systems:[/align]

[align=left]– LBS (Linked Brake System) – that is designed to engage both front and rear brakes when either the brake lever or brake pedal is used.[/align]

[align=left]I can't imaginewhy that would be inthere if it is not the case. Not near my bike at the moment, but I'll go pull the brake lever and see what happens when I am. Also would like to take a close look at each of the three brake calipers and see if there are TWO or just ONE brake line hoses attached to each caliper. That would be aclue.[/align]


[align=left]***[/align]
 

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Wing Rider and All,

I just couldn't understand the disparity between the factory service manual Linked Braking System explanation and the "rear wheel spinning test" that Wing Rider was doing.

I've done some more research and the mystery is solved. They're both right! How is that possible you say? Well, read on.

It turns out that the rear brake system is linked to the front brake lever indirectly through the secondary master cylinder and controlled by the pivoting motion of the front left brake caliper when the front wheel is TURNING and the front brake applied causing the caliper to pivot upwards.

So, Wing Rider's observation that applying the brake lever with the bike on its centerstand does NOT stop the rear wheel from spinnning is right. It won't.

The centerstand method does not work, because the front wheel has to be moving when you put on the front brake.The left caliper then reacts to the brake action and pivots upward to initiatethe linked braking via the secondary master cylinder to two pistons in the rear brake caliper. But the bike has to be moving at some speed, for all this to work orthe left front caliper will not pivot and act on the rear brake system. See the diagram below:





This is also born out by the fact that there are TWO separate brake line hoses going into the rear brake caliper, one directly from the rear brake master cylinder on the brake pedal and one indirectly from the secondary master cylinder.

You CAN do a centerstand test if you do it properly using the left front brake caliper to activate the secondary master cylinder, and not by using the brake lever. Here's the procedure from the factory manual:


[align=left]Place the motorcycle on its center stand, stop the engine and shift the transmission into neutral. Move the left front caliper assembly upward while slowly turning the rear wheel. The brake system is normal if the rear wheel stops.[/align]
So, there you have it. Mystery solved.

Now we can all sleep tonight.

***
 

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I knew that!!!
 

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Hi. Thanks for the 16th and 17th post WingMan71 it is very much appreciated. I did write in my 1st post… “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….” This would imply that under stationary conditions only the front wheel would be prevented from turning not the back one.
On the next paragraph I also stated….”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…” again as demonstrated in your diagram this would imply that under stationary conditions the foot brake lever will operate the front disks and the rear disk. In my 9th post I probably overcooked the explanation in my attempt to explain what I’d gleaned from my copy of the factory service manual and my experimental experiences.
Thanks for the input and I hope the missunderstanding is now well and truly solved.
Regards
 

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That's the drawing! I was talking about the test side of it. That's correct that both hydraulic systems are linked mechanically together. I was going to post that picture.
 
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