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Prolink (Showa) Shock Help

1299 Views 5 Replies 5 Participants Last post by  Fred in Napanee
My 1983 GL650i monoshock has failed in the collapsed or bottomed-out position. It holds air reliably and hasn't leaked any oil. I removed the exhaust system and all the linkages as well as the shock. I pressed or drove out all the pivot sleeves and cleaned and greased them and the bushings with a moly type grease.

I then tried to follow Sidecar Bob's directions regarding the shock. Using my 20 ton press I worked the shock through it's full travel multiple times, then inverted it and expelled 250 ml of oil and discarded it. Turning the shock upright, I worked it in the press to draw in 250 ml of mineral spirits. With this mixture I cycled the shock multiple times in the press and tried shaking it manually as well. I then used the press to pump out all the solution I could, which measured about 600 ml. I discarded all the old fluid. Turning it upright again I drew in about 600 ml of ATF. I followed Bob's directions to remove air from the fluid before reinstalling the shrader valve.

I was encouraged at this point as the shock responded well in the press. I reinstalled it in the bike and the rear suspension could be bounced again and I could put the bike on and off the centre stand again. With it collapsed it sat too low for me to be able to struggle it up. I put the exhaust system back on and everything else that had been removed. I put away my tools, tidied up and went for a ride. It was rather chilly and I only went 3 or 4 miles. Initially it rode great albeit a bit firm. I had charged it to 40 psi. Returning home I found the shock had again collapsed with no possible movement and I cannot again raise it onto the centre stand.

Has anyone else encountered similar problems and how did you resolve them? I have no choice other than to remove the shock again to replace or repair it. I've read reports of removing the main seal by cycling it in the press while full of oil or increasing air pressure to force the seal out. With the seal out I assume I can empty the oil more completely but is it possible to find and correct whatever is causing the shock to lock up. The spring is obviously fine as it functioned well in the press. I suspect the oil is restricted somewhere in the dampening passages. I think I found an aftermarket replacement shock made by Hagon which might be the simplest solution but not the cheapest. Has anyone experienced this issue and been able to repair the shock?
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Fit a new Hagon shock
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Muzza beat me to it … but I was thinking exactly that; I have a Hagon on my 500 Eurosport and it performs very well.
Does the shock still have the same air pressure? If it is and it doesn't extend something inside must be preventing it from extending.
Are you sure you cleaned all of the pivots in the linkage?
Is something keeping the swingarm from moving through its full range?

BTW: I wrote the article about the shock because I found the instructions in the manuals hard to understand, especially the part about how much fluid the shock should have when you're done (it doesn't actually say - it is the amount of air space left after you fill it and expel the correct amount of fluid).
I had my collapsed Showa rebuilt but it was not very effective and the new Hagon which replaced it was so much better. Eventually, after many years, the Hagon began to leak oil but after a rebuild it works better than ever.
Yes I found your article informative. There aren't a lot of other articles available. I initially hoped the problem was a binding pivot as that is alluded to in several reports. However all my pivot points move freely and I checked them by installing the brackets in the bike and moving the swingarm before mounting the shock. Even with the shock installed everything moved freely until I road tested the bike.
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