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Discussion Starter · #1 ·
I changed the oil in my Monoshock today. I thought it had probably served long enough and I wanted to see if having the correct quantity of new oil would affect the ride quality at all. I will check that out tomorrow, but for anyone contemplating this job I have a few observations.



Firstly it is not all that difficult a job, but does require some way to compress the shock. It also of course requires a few other basic tools. I was helped greatly by what I read in the forum archives, and by a couple articles in the Google docs section. In particular the article here .



I also reused my seal, because I am cheap and didn't feel like springing for a new one. AFAIK GL650 Seals are still available to order for around $20-$25 from Honda Dealers. (discounthondaparts.com wanted $18 plus $12 shipping.)



First thing is to get the shock out of the bike, and I was able to do this without taking the whole exhaust off. I removed the mufflers and lowered the H box a bit in order to get one of the pro-link bolts out. Since I had just serviced the pro-link two years ago everything came apart easily. The top shock mounting bolt is easily reached with a flexible socket and extension through a narrow slot between the frame and the airbox.



I cleaned the shock up and removed the rubber bellows. Here is the shock upside down in a vise:




This shows the backup ring and the wire retaining ring:




In order to remove the seal first I had to drive the gold colored ring down a bit so the wire retaining ring could be removed. I used a big flathead screwdriver and a big hammer to pop it down 1/8" or so. Then a dental pick to pull out the wire ring.



Now comes the fun part, getting the seal out. I tried using the press I built into the wall of my shed to do it the way the manual says, but it didn't budge. Here is the press:




I wound up placing the shock in a bucket and applying 75# of air at the hose. With a bang the seal and most of the oil was out. I poured mineral spirits into the shock and swished it around a few times to clean out the remnants of the old oil.



I put the shock upside down into my vise and filled with oil. I used ATF (Dexron). The manual says the shock holds 669ml. I managed to get 500ml into it and had to stop because I needed room to install the bushing and seal. Reassembly was pretty much by the book except for the special fixtures on the press. I didn't have any of those so I put the seal back in with with gentle taps with a hammer and screwdriver, just like they tell you not to do! Worked fine. The above photo shows the filling of the remainder of the oil with the press.



Like the manual says, I pressed the shock with the valve removed and the end of the hose in a jar of ATF. Air bubbles come out when the shock is pressed and fluid is drawn into the shock when pressure is released. I repeated this step until no more air came out. The shock does hold 669ml or so of oil, but that amount fills the shock completely, with no air inside the shock. This is a problem because it puts the shock in hydro-lock, meaning it ain't compressing once the valve is put back on the hose! The manual says to push out 200ml of oil at this point, but I followed the recommendation of a poster on the Aussie CX/GL board and only pressed out whatever came out from one complete compression of the shock. This was right at 100ml. Less airspace above the oil should enable me to run at lower air pressure and hence have a smoother ride. I will find out tomorrow.
 

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Discussion Starter · #3 ·
Here is the results of my test ride today
:)etc



I am just sorry I did not do this 20,000 miles ago when I lubed my pro link. The suspension actually feels silky, smooth and supple now.




I ran 15 lbs in the rear shock and did not top out at all, even though I was riding on some roads that would shake my teeth out before. I used to pump my shock up to 50-60 lbs to keep it from topping out, which resulted in a very stiff ride. I had been blaming the rough ride mostly on the forks, but a lot of it was due to the rear shock. For one thing the oil was old and there was only about 400mls of it in there. I have 560mls now of new ATF, and my damping is very good. It did not give any handling problems at all on my ride today which included 100 miles of all kinds of roads, at speeds up to 100mph. This was with nothing in my saddlebags and riding solo (I weigh 220lbs).
 

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Here is the results of my test ride today
:)etc



I am just sorry I did not do this 20,000 miles ago when I lubed my pro link. The suspension actually feels silky, smooth and supple now.




I ran 15 lbs in the rear shock and did not top out at all, even though I was riding on some roads that would shake my teeth out before. I used to pump my shock up to 50-60 lbs to keep it from topping out, which resulted in a very stiff ride. I had been blaming the rough ride mostly on the forks, but a lot of it was due to the rear shock. For one thing the oil was old and there was only about 400mls of it in there. I have 560mls now of new ATF, and my damping is very good. It did not give any handling problems at all on my ride today which included 100 miles of all kinds of roads, at speeds up to 100mph. This was with nothing in my saddlebags and riding solo (I weigh 220lbs).
Which manual gave you the info? I have both clymer & haynes out of library but no such stuff. Is there a downloadable somewhere? Thanks,GJ
 

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Discussion Starter · #5 ·
Which manual gave you the info? I have both clymer & haynes out of library but no such stuff. Is there a downloadable somewhere? Thanks,GJ


There is a GL500/650 service manual available for download in the drop.io section. here is a shortcut



The shock rebuild article I link to in my post above is very informative as well. Much more so than the manual in fact. here is the link

It was originally a post on ADVRider forum. He goes much further into his shock that I did mine, I just wanted to change the oil. His shock is also a bit different than the GL650 shock, but the info relates well.



Some of the members here have great websites that show just about any repair service or mod you can think of. The Quick reference pages has links to a lot of these. here is a link to the quick reference pages



Once you learn your way around this forum info will be easier to find.



This service I highly recommend to anyone with an original mono shock.
 

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great help mr softie. i'll have to read this many.many time to get it in the brain... and then try it....muchas gracias
 

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I tried the hydraulic method described in the service manual. It didn't work. Your explosive method worked at 95 psi, then ...BANG! OK seal's out, fluid's out, but there's another issue now. the fluid that came out had a lot of little pieces of black stuff in it. Do I have a new problem? If so, can it be fixed?
 

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Discussion Starter · #8 ·
I tried the hydraulic method described in the service manual. It didn't work. Your explosive method worked at 95 psi, then ...BANG! OK seal's out, fluid's out, but there's another issue now. the fluid that came out had a lot of little pieces of black stuff in it. Do I have a new problem? If so, can it be fixed?


I don't know Dan, were the bits hard or soft? How did the fluid look? Do you plan on re using the seal or are you replacing it?



There is nothing that I know of inside the shock that would break up into small black bits. The shock is really very simple. I think there are just holes inside for the oil to pass through for damping. And a spring. The seal is black, but if that looks OK you should be able to reuse it. I would just clean the shock out by swishing some mineral spirits etc around in it until it comes out clear. Then I would proceed putting it back together and try it out. It has got to work better without those bits in it!
 

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I have a new seal. The old seal leaked. It wouldn't hold pressure or and slowly seeped fluid. aaaathink I'll go for it & see what happens. Thanks
 

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Just how stiff are these shocks supposed to be? On my makeshift press, I can exert over 800lbs of pressure, but I cannot get the shock to compress more than about an inch or less.



I've filled the shock, but have been able to compress out only about 75cc, allowing for some spillage, I still have almost 590-600cc in the shock.
 

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Hey Mr. Softie, good stuff in your re-build. Might need to to do to my "shock" in near future. The mono-shock loses some air after 2-3 days but the ride is still good (30,000mi) given the fact that it's a Trike with fat tires and low air prssure.



LT2
 

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Discussion Starter · #12 ·
Just how stiff are these shocks supposed to be? On my makeshift press, I can exert over 800lbs of pressure, but I cannot get the shock to compress more than about an inch or less.



I've filled the shock, but have been able to compress out only about 75cc, allowing for some spillage, I still have almost 590-600cc in the shock.


I think mine compressed more than 1", but cannot remember exactly how much more. Maybe an inch more or so? I was using a jack rated at 12,000 lbs, so you may have to up the pressure a bit to get it to compress more. You are compressing the spring inside the shock. Is your shock right side up while pushing out the 1 stroke worth of oil? I think I have about 570ml in mine.
 

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Discussion Starter · #13 ·
Hey Mr. Softie, good stuff in your re-build. Might need to to do to my "shock" in near future. The mono-shock loses some air after 2-3 days but the ride is still good (30,000mi) given the fact that it's a Trike with fat tires and low air prssure.



LT2




Thanks. The seal is still available for the 650, so unless the piston is scored you should be able to get the air leak fixed. The Schroeder valve and hose connection o-rings are areas that can leak as well.
 

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Discussion Starter · #15 ·
Just for reference, here is what I wrote many years ago: http://www.aegeansof...6,3997#msg-3997


Yes I read that post Bob when I was researching how to do the shock service. Thanks for posting that, it was one of the posts that helped me to be able to service mine. I think it is great how these old posts remain available for for our enlightenment years later. Pretty neat! BTW the shock is still working well, glad I did the service. I recommend servicing the shock, as it is probably neglected on lots of bikes. Mine was!
 

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Just how stiff are these shocks supposed to be? On my makeshift press, I can exert over 800lbs of pressure, but I cannot get the shock to compress more than about an inch or less.


Do not compress the shock any more than necessary to remove the o-ring.



They shocks move only about an inch and the Pro-Link multiplies the amount of travel.



That is one of the reasons that the spring is so strong ... as the weight is multiplied back to the shock though the Pro-Link.



If you compress too much you may damage the shock.
 

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Discussion Starter · #18 ·
UPDATE!





I just re read this thread and remembered how impressed I was with the ride of my GL650 after the oil change. The ride was much improved. Since then I have replaced the shock with a XVS1100 shock and more recently with a XVS650 shock. Each mod gave a noticeable improvement in ride quality.



This experience points out the wisdom of the saying " we only know what we ride". While the work I did on the stock shock did improve the ride considerably, I have found that replacing it with a more modern shock improves the ride and handling even more. I hope my work on the XVS shock conversions is of some use to other GL riders. It has made my bike even more comfortable and enjoyable than it was.
 

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Does the XVS shock bolt in directly or is some modification needed? I bought a much better original shock for mine last year (with rebuilt linkage at the same time & only a fluid change for the new shock I still can't believe how much better it rides 7000 Km later), but maybe next time......
 

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Just a note for others who might be re-building the stock shock. I was able to find the oil seal as part #91257-MA2-003 at http://www.powersportsplus.com. Price and shipping were reasonable to Oregon. This part shows up as NLA at BikeBandit, so we'll see if it actually gets shipped to me. If not, I'll update this post.



UPDATE: Powersports Plus just got back to me and the seal is NLA. I'm going to change out the fluid (I have a donor shock, and I believe the seal is good in it) until I can put in a modern shock.
 
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