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Discussion Starter #1
So I suspect my anti dive may be stuck and I have new O-rings coming. I have ordered O-rings in two different materials, Viton (FKM) and EPDM. The Viton (FKM) will be fine if exposed to fork oil and the EPDM will be fine if exposed to DOT 3 brake fluid.

So here are the questions:
1) Does the fork oil ever come in contact with the lower O-ring on the Anti-Dive piston?
2) If I remove the piston to clean, remove and install new O-rings how much brake fluid or fork oil am I likely to loose?

I have read most of the posts on disabling the Anti-Dive, but at this time I am not considering disabling the Anti-Dive.

Thanks to all that respond.
 

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anti-dive stuck

Before tearing down the anti-dive valve may I suggest you pull out the two screws holding it on and using several plastic tie straps to secure it to the fork leg, take it for a ride to be certain it is stuck. No need to fix it if it ain't broke. The valve only has brake fluid in it but you will need to do a brake fluid flush and fill after.
billy
 

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I spent a lot of time playing with o rings and nearly as much as it cost to just replace the whole ADV valve (about $35). It's been 4 years and 75k miles with out an issue since. I do however fully flush and bleed my brakes every year.

Sent from my Moto Z (2) using Tapatalk
 

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So here are the questions:
1) Does the fork oil ever come in contact with the lower O-ring on the Anti-Dive piston?
2) If I remove the piston to clean, remove and install new O-rings how much brake fluid or fork oil am I likely to loose?
Year would be helpful ???

However, assuming that you are talking about a 2001-05, and since you are referring to repairing one, are you asking about the actual part that is on the slider, or the case plunger with the hose attached to it ???

See fishe #31.

https://www.mrcycles.com/oemparts/a/hon/5053ec48f870021c54be419c/front-fork
 

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Discussion Starter #5

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It is a 2013 and yes the item 31 the plunger.
Sorry if my memory cannot remember, but if I recall, the "o-ring" design ended in 2005. I also might add, that for most, the ADG plunders goes bad from lack of maintenance. 5th gens have serious issues when the brake fluid is not changed per Honda Maintenance Schedule.

Probably the easiest way to test your ADV is to remove the front fender and nylon tie the caliper covers in place. Unbolt the ADV plunger, nylon tie it to the the fork slider and go for a test ride.

I should have asked first, why do you think you have an ADV plunger problem ???
 

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There are two O-rings on the plunger piston. Between them there is a 1.6mm (1/16") hole to the outside world. The grease that is original equipment quickly stiffens and the 1.6mm hole clogs up with the stiff grease and the O-rings clag up with the grease too. I've serviced mine many times but the solution for me was to remove the lower O-ring completely and to pack the space with red rubber brake grease. Also be sure that the piston returns fully into the top cylinder under just thumb pressure.
 

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Discussion Starter #8
Sorry if my memory cannot remember, but if I recall, the "o-ring" design ended in 2005. I also might add, that for most, the ADG plunders goes bad from lack of maintenance. 5th gens have serious issues when the brake fluid is not changed per Honda Maintenance Schedule.

Probably the easiest way to test your ADV is to remove the front fender and nylon tie the caliper covers in place. Unbolt the ADV plunger, nylon tie it to the the fork slider and go for a test ride.

I should have asked first, why do you think you have an ADV plunger problem ???
OK I was not aware that the plunger design was changed, what are they using now? (post 2005 model)
Not to keen on riding around with parts zip tied to my bike, so probably will not do that.

I am experiencing a harsh ride that is noticeable in the handle bars, a common complaint of folks that have had bad anti dive plungers, thought I would experiment with possible fixes, first was to replace the o-rings (if my bike has them) , then maybe disable the anti dive if the new o-rings did not improve the ride quality.

My understanding is that the material Honda selected for the o-rings maybe was not the best selection as many have noted the o-rings were swollen when removed, a typical sign of rubber being incompatible with the fluid they are exposed to.
 

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OK I was not aware that the plunger design was changed, what are they using now? (post 2005 model)
Not to keen on riding around with parts zip tied to my bike, so probably will not do that.

I am experiencing a harsh ride that is noticeable in the handle bars, a common complaint of folks that have had bad anti dive plungers, thought I would experiment with possible fixes, first was to replace the o-rings (if my bike has them) , then maybe disable the anti dive if the new o-rings did not improve the ride quality.

My understanding is that the material Honda selected for the o-rings maybe was not the best selection as many have noted the o-rings were swollen when removed, a typical sign of rubber being incompatible with the fluid they are exposed to.
If I recall, the newer style uses more of a cup design instead of o-rings. My suggestion to nylon tie the plunger to the slider was to test ride it to see if your ride improves. Bad steering head bearings, too high of air pressure, poor tire choices, as well as other fork issues can cause a harsh riding too.

If you choose to test ride it with the ADV plunger removed, do this first. Find a man-hole cover nearby that causes harshness when you go over it. Test ride with the ADG in place first. Then remove it, as I suggested above, and do the same ... any change ???
 

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Discussion Starter #10
Thanks will consider all of the above.
 

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Sorry if my memory cannot remember, but if I recall, the "o-ring" design ended in 2005. I also might add, that for most, the ADG plunders goes bad from lack of maintenance. 5th gens have serious issues when the brake fluid is not changed per Honda Maintenance Schedule.

Probably the easiest way to test your ADV is to remove the front fender and nylon tie the caliper covers in place. Unbolt the ADV plunger, nylon tie it to the the fork slider and go for a test ride.

I should have asked first, why do you think you have an ADV plunger problem ???
I test mine by getting on it and doing the bounce test. Mine is a 2006 and I've never had an issue with it. Brake/clutch fluids get flushed every 2-3 years.
 

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Discussion Starter #13
My 2003 and my 2013 were of identical design but one of the O-rings was of different material in the 2013. It was orange on colour.
Thanks,

I wonder if they went to a silicone or fluorosilicone o-ring. that material is very chemically resistant and can be made in just about any color, other tech materials do not take to colors some times.
 

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Not to keen on riding around with parts zip tied to my bike, so probably will not do that.
Drill a hole in a nickel and put it in place under the ADV and bolt it back on. I did this today and only takes a few minutes.
 

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Discussion Starter #15
Drill a hole in a nickel and put it in place under the ADV and bolt it back on. I did this today and only takes a few minutes.
Yeah was thinking about that, maybe do that if i decide I want to disable the anti dive.

Did you notice any improvement in the ride quality?
 

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You can do it temporarily just to see if the ADV is an issue. Yes, mine was stuck and it made a noticeable improvement.
 

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Discussion Starter #17
Magic

So I got around to pulling the top section (section attached to the brake line that houses the push piston) of the anti dive system.
The push piston was stuck, once I got it freed up I lubed it just a bit and exercised it so it goes in and out fairly easily. I put a 5.8mm x 1.9mm Viton O-ring on the "stem" end of the piston so the piston can still extend it activate the anti dive system, but it should have some compliance when fully extended.

I took the bike for a short test ride to evaluate the ride quality and all I can say is , "That is pure MAGIC", it rides like a different bike.

I am going to monitor it for a few weeks and then check it again to see if the push piston is still free or if it is stuck again.
If I find it stuck, I will have to remove the nut where the bleeder valve is and remove the push piston and change the O-rings, I have new EPDM O-rings that I will install.

Stay tuned for further updates.
 

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If it continues to function reliably please post the source for the O rings size and part number if available, it would help a lot of is over time.

Sent from my Moto Z (2) using Tapatalk
 

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Discussion Starter #19
If it continues to function reliably please post the source for the O rings size and part number if available, it would help a lot of is over time.

Sent from my Moto Z (2) using Tapatalk
I can do that now, never hurts to be informed.

Bought them on line from Metric Seals, www.metricsealsinc.com
I purchased:
10 each 5.8 x 1.9 Viton 75 black, part #: P6 V75 BLACK
10 each 5.8 x 1.9 EP70, part #: P6 EP70

That size is what is needed to replace the O-rings on the push piston so they fit the little nub on the end of the piston perfectly.

Now for the bad news, they have a $10.00 minimum charge Plus shipping, the O-rings are 75 cents and 30 cents each respectively so I had to order 10 of each to reach the $10.00 minimum that plus shipping the order was $18.00 to receive a 75 cent O-ring.

The EP70 O-rings are suitable for exposure to brake fluid and the Viton are suitable for exposure to fork oil. If the system does not leak there should be no fork oil any where, but just in case that is why I used the Viton in the middle dry section.

I am going to keep 4 of the EP seals and 2 of the Viton seals for my self, if any one wants some of the others, PM me and I will send them to you, first come first serve until they are all gone.
 

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Pretty sweet, that's still cheaper than replacing the ADV itself.

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