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Hi everyone,
I recently got my '87 GTR, and I notice that the suspension is getting a bit old. I plan on installing a set of progressive springs up front, but what are my options with the rear shock?
A new shock is horribly expensive. Is a rebuild doable?
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A rebuild, no as they are a sealed unit.
Many people have had very good results with replacing the oil in the stock rear damper (shock).
Remove the shock from the bike. Remove all the air. Remove the air hose. Invert the shock so so the oil will drain into a graduated container. Refill the shock with the SAME amount of oil that you drained out.
As to type of oil, I used oil for a Kayaba shock. Others will tell you to use oil of ?? style/brand/viscosity. The shock is a Kayaba shock, I use Kayaba specification oil for shock absorbers.
As to quantity, most drain out in the neighborhood of 6-8 ounces, or 200-250ml. I think it is critical NOT to over fill it. Refill with the exact quantity you drained out, unless your shock is leaking.
Another option is a Progressive brand shock, what I run now. If they are still available, I don't know. Then there's shipping/duty to Netherlands :-/
Rick
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Thanks a lot!
I've found a small workshop who can rebuild unrebuildable rear shocks. I think I'll first try to refresh the rear oil, upgrade the front suspension with progressive springs.
Are there any bearings I should watch out for/check when I have the rear shock out?
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Some riders on here have also put either a ZZR1200 or C14 shock onto the C10. The ride height is altered higher which may or may not be an issue. One of these is on my list to do one of these days.
As for your forks - most would recommend a straight-rate spring from Sonic (which progressive sells too). Most-likely the 1.0 rate but do call them to determine what is right for your riding style and weight of rider and machine. You can sometimes find them for sale here. Fork braces too.
Another great thing to do instead of buying new springs is to cut about 4 to 5 inches off the springs (the close wound section), add a spacer and washers to each to make up the difference cut off, and change the fork oil to 15W. You will get surprising results for only a few dollars. Of course a few have totally switched out the front end from a different bike like maybe the ZX-9 to get a more update front end. They'll probably post the info.
Most of this stuff can be found here by doing search's with words like springs, fork, shock etc., and will make for some interesting reading.
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Thanks for the help! I'll consider the options!
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I am running 50 weight in the front with Sonic 1.2 and emulators. The front is the best it is going to get without converting to a new front end with cartridges.
The rear is good with a new ZZr1200 shock but the spring is too soft. A C14 or ZZR shock raises the back up a little but when you sit on the bike it sags too much.
Someone figured out that a ZX9 shock can be re-valved and re-sprung and it fits a C10 but I have no more info on that.
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I am running 50 weight in the front with Sonic 1.2 and emulators.
50? (or 5 or 15?)
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Yup.. 50 and I still have too much rebound with 50. I could go thicker. That is the problem with the old damper rod technology in C10's. No way to control rebound except for going to thick oil. There are no valves or valve adjustments to control rebound.
With the thick oil I can adjust and soften the optional Gold Emulators for compression damping only.
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. . . and I still have too much rebound with 50. . .
Well, I have to ask. Is it possible the little white plastic rings are missing from the tops of your damper rods?
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I cant say I remember white plastic rings on the tops of the damper rod tubes but I might think it strange to see the Gold Emulators sitting on white plastic rings . I thought it was just metal damper rod to brass Emulator.
Oh, the ring that runs around the outside between the fork tube and the rod. I saw that. I assume that is the rebound damper seal.
Mine is probably worn out and no longer seals well.
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Alright, I ordered the progressive springs. And I'm going to do an oilchange for the rear-shock.
Are there any things I need to know, can check while I'm at it?
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Rebound flow with emulators bypasses the rings and goes by the outside of the emulator, which is why needing a heavy oil for rebound control is necessary. I'm running 30 wt, I could use more for rebound but then the compression starts getting harsh. I could probably mitigate that with the lightest spring, but haven't done it yet. Steve
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I can't remember if the Concours damper rod has rebound holes at the top. EDIT Dug up a C10 damper rod from the basement and there's no rebound hole at the top, so this can be safely ignored for the C10. /EDIT
When installing emulators, the SV650 people recommend closing up the rebound hole with brazing or JBWeld. Then all the rebound damping is from oil sloshing past the rings at the top of the damper rod.
This might help those seeking more rebound damping from the C10.