Anti- dive fix for the 1800's - GL1800Riders
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post #1 of 35 (permalink) Old 11-30-2009, 08:32 AM Thread Starter
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Anti- dive fix for the 1800's

I take no credit for this article, I found it.

Scroll down for pics.

In the past I have had a problems with the anti dive system on my GL1800’s, until I fixed them.
The history
I have two medium mileage GL1800’s (2003) one for me and one for my wife, both bikes have 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 twice to date.

The symptoms :

While riding along normally the bike rides 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. The problem is also evident while negotiating speed 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 remains firm and seems to bounce 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 to lock up the 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 can take some time to return to its resting position. I took it upon myself to effect a fix that works better than ever and has been working well for the past year. My fix 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 x 8.5mm(0.334”) O/D and theSecond ’O’ ring dimension - 1.8mm(0.070”) in section x 6mm(0.236”) bore x 10mm(0.393”) O/D, both black 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.


WARNING
. 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




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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post #2 of 35 (permalink) Old 11-30-2009, 04:38 PM
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Torque value?

Thanks for the post Wingone. As a new (to Wings) rider, and one who also does much of my own work on my bikes, I have to ask. Is there a torque value for the anti-dive allen bolt?

Warmest regards,

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post #3 of 35 (permalink) Old 11-30-2009, 05:36 PM Thread Starter
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Quote:
Originally Posted by kindofblue View Post
Thanks for the post Wingone. As a new (to Wings) rider, and one who also does much of my own work on my bikes, I have to ask. Is there a torque value for the anti-dive allen bolt?
According to the Honda service manual, torque value for the "Anti-Dive Plunger Case Bolt" is

N-m (Kgf-m,lbf-ft)
3.9 (0.40, 2.9)

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post #4 of 35 (permalink) Old 11-30-2009, 09:55 PM
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I like this better than the disable fix.
post #5 of 35 (permalink) Old 12-01-2009, 06:26 AM
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"If your bike is still under warranty let Honda sort it."

Good luck with that.

Love 'em all... Let GOD sort 'em out!"
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post #6 of 35 (permalink) Old 12-01-2009, 06:46 AM
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I fix things for a living, from plumbing to a bike for a friend, but no living off fixing bike, other than a good time, a beer or two and some nonsense.

Problem with an O,ring under steady and repetive compression is it does take a set and will not continue to function. It is designed to be a seal and that is about it. Some will not withstand oil, or brake fluid, so you do have to pick those that will, others will not take the sunlight and quickly crack and deteriorate.

I have the perfect fix, a member on this site told me about using two little washers under and between the two halves of the anti dive gadget.

So I trotted off to Napa and got two small copper washers that will just fit between the two halves of the thing, naturally this leaves a gap so water and dirt can enter........so I placed an O ring around the top section, one that just fits, so now when the sections are bolted back together the o ring does compress enough to seal out the weather, but the washers do not allow it to compess too far, so now you have a good secure fix , with a weather seal.

This really does take most of the harshness out of the front end, not all of it, but a good majority of it. Makes a nice ride actually.

Does not totally disable it either, front will dive about 3/4 or an inch or so during an emergency stop and then the gadget works as it should.

This also takes the constant stress and tear off the left fork and the seals. And if you do choose to carefully use the front brake in a rough curve....not that you should, but sometimes it is cool......no more crowhopping around the corner.

Best .27 cent fix I have ever seen.

Kit

Oh the fellow who asked about what is the proper torque on the two allen head bolts.......well just secure, do not sweat the small stuff.....as a rule of thumb with any allen head bolt, small like that, I use a standard allen wrench.....no not a T handle that you can strip heads out with, just a regular allen, and when you see the shank of the allen just start to flex.....that is enough.
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post #7 of 35 (permalink) Old 12-01-2009, 07:08 AM
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anti dive

Best fix I have seen is using a home made piece of gasket material instead of the washers. You get the same result without worrying about allowing in dirt and water. You can use several thin ones and experiment with "tuning" for the ride you want. I'm going to try this method. Quick, cheap, easy.............ME !

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post #8 of 35 (permalink) Old 12-01-2009, 07:36 AM
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"this slave cylinder only functions when the bike is moving."

Huh?????????? Works whenever you activate the brakes, I thought, moving or not, right?
Maybe mine is the odd ball, but no problems so far. Not sure why the anti-dive is being rendered inop? It should not effect the ride at all unless the brakes are activated??
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post #9 of 35 (permalink) Old 12-01-2009, 09:29 AM
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Thanks Walter & Kit.

Warmest regards,

Doc Reid
08 BMW R1200GS w/ABS
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post #10 of 35 (permalink) Old 12-01-2009, 09:35 AM Thread Starter
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You're welcome,.

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