monoshock question?

[Guest]

re: 1983 gs750e

I disconnected my hydraulic pre-load adjuster to replace the knob, and lost some fluid. The fluid was under a bit of pressure, and it seems likely that it should be replaced and possibly have any air bled out of the lines?

My questions are: What is this fluid? Brake fluid? Hydraulic fluid? How does one repressurize or bleed the shock once it has lost fluid?

It seems that this device is a simple piston that is moved forward or back in a bore when you turn the knob. Does it work just by moving a column of fluid in or out of the monoshock?

Thanks for any insights any of you may have.

silverhorse

[Anonymous]

I've never seen the shock in question but my CR250 had a tire valve on its shock. After a rebuilt it was possible to have it filled with Nitrogen at the local dirt bike shop. I'm not sure how they pump it up.

Steve

[silverhorse47]

Thank you Steve. I'm thinking my shock doesn't have nitrogen in it because fluid spurted out when I disconnected the line? Though perhaps the nitrogen was dissolved in the fluid? I don't know.
But, my shock doesn't have a valve on it to add either fluid or gas. Perhaps I need to add one...
Lordy...I hope not....!

[Dink]

It sounds like it is time to either replace that shock or have it rebuilt there is no fluid where you had it come out, so it may be terminal
Dink

[silverhorse47]

That is bad news indeed, Dink.

Does that piston/plunger adjuster increase/decrease gas pressure when it is wound in or out? The shock looks absolutely fine and it is hard to imagine how this fluid...which feels and looks like brake fluid, got into the line between the knob and the shock. Is there a fluid filled compartment in the shock that is supposed to be separated from the nitrogen maybe?
Any way...thanks.

S.

[Billy Ricks]

Silverhorse,
My 700 uses the same shock as yours. The spring tension knob is a hydraulic adjuster. I don't think you actually lost any oil out of the shock. It looks to me like the fluid in the knob only acts to compress the spring. Oil out of a twenty five year old shock would likely look pretty bad. As long as you are able to dial in the preload you need I wouldn't be concerned about it. The damper assembly is at the other end of the shock from the spring preload which is another clue shock oil isn't involved.

[silverhorse47]

Thanks a lot Billy...that sounds right. Thank goodness.

S.

[Anonymous]

Thanks a lot Billy...that sounds right. Thank goodness.
S.

I am sure Billy is right, too. I checked the factory manual for my 1983 GS750ES and it makes no mention of the parts in the preload adjustment mechanism or disassembling it. The only problem that I can see is if you now have air in the hydraulic line for the mechanism and end up compressing that instead of the spring. I am too chicken to take mine apart and see if there is a way of "topping off" the fluid and bleeding off any air.

[Billy Ricks]

If you find it won't compress right you may be able to add some hydraulic fluid. I would probably use hydraulic jack oil. Unbolt the adjuster after backing completely off the preload. Unscrew the knob with it pointing straight up and top it off. With the way it is set up if you got excess air in the system it should be near the top of the setup anyway.

[silverhorse47]

Billy yes, I did refill the line as well as I could before I reattached it to the adjuster...I used brake fluid. I'm going to have another look at it now that I understand that the hydraulic line is meant to compress/relax the spring. I'll be able to see if it is working or not.
I imagine that air in that line would get dissolved in the fluid eventually. I forget exactly how I reassembled the adjuster itself, but I think it required the use of the vice, and I know when I reattached the line some fluid dribbled out before I got it cinched up. I couldn't figure a way at the time of completely filling the cylinder on the backside of the piston in the adjuster, but your advice to lift it high and wait for the air to bleed out sounds right.
Thanks a lot.
S.

[silverhorse47]

Hello Simon re: your post,

*...it makes no mention of the parts in the preload adjustment mechanism or disassembling it*

Simon the manual has a pic of the guts of the adjuster on page 1-14 under 'general information'...but in the usual factory manual way the essential sentence is missing half its explanation...at least.

*I am too chicken to take mine apart and see if there is a way of "topping off" the fluid and bleeding off any air*

"Fools rush in...."

S.

[Anonymous]

Simon the manual has a pic of the guts of the adjuster on page 1-14 under 'general information'...but in the usual factory manual way the essential sentence is missing half its explanation...at least.
S.

By golly, Silverhorse, my copy has the same sentence fragment.....I had never noticed this before (but then I probably never read this part of the manual ). The diagrams, though very pretty, seem essentially useless. I have found one delightfully rude mis-spelling (at least to my fevered brain) in true Japanese manual fashion. Delicacy forbids me quoting this particular example, but I still recall the admonition in the manual for my old 1969 Yamaha 125cc (YAS-1) to "drain the float bowels" of the carbs......involves usage of a laxative in the fuel tank, I imagine.

BTW, Silverhorse, is it your understanding also that the monoshock damper for the 1983 GS750ES is not rebuildable, and there is no aftermarket unit available?