Bouncy shock after rebuild help

KILLASAN
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KILLASAN
Edited Date/Time 1/15/2019 8:59am
Any folks do their own shock work?
Ran into an issue. I rebuilt a shock and its bouncy as hell(was bouncy prior to servicing,however then it had almost no oil or air in the bladder). Shock head was replaced. Piston band looks good. Adjusters were cleaned. Bladder was charged at 150psi nitrogen and did not leak. What else could cause the shock to be bouncy. It feels as though there is no reisistance. Shock body is undamaged of which i can see. Its on a 98rm80.
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Kristen_Valentino 1/12/2019 5:58am
1/12/2019 5:58am
Turn in rebound adjuster, see if that helps, no burrs or scratches in shock shaft, piston was installed correct.
KILLASAN
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KILLASAN 1/12/2019 6:04am
1/12/2019 6:04am
Tried turning both adjusters all the way in and out. Felt no.difference. piston and shims were installed exactly as it was removed.i used a screw driver to.hold all items in the proper order. Unless the previous owner messed with it. Highly unlikely though. Not sure wat else it can be
slipdog
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slipdog 1/12/2019 8:01am
1/12/2019 8:01am
1st pic is the compression side which takes the shim stack with the larger diameter shims. The 2nd is the rebound side, that is the "top" or goes up The shim stack with the smaller diameter shims goes there then the washer and finally the nut that holds it all together.
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slipdog
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slipdog 1/12/2019 8:04am
1/12/2019 8:04am
If it was out of oil when you took it apart the shock body may be worn out.
KILLASAN
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KILLASAN 1/12/2019 8:07am
1/12/2019 8:07am
slipdog wrote:
If it was out of oil when you took it apart the shock body may be worn out.
It could be. Do you think a worn piston band may allow the fluid to bypass the piston itself? I have not changed the band.
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slipdog 1/12/2019 8:19am
1/12/2019 8:19am Edited Date/Time 1/12/2019 8:22am
Yes, if they are run with low or no oil the piston overheats and the band wears to the point of no seal and that leaves the metal piston itself to rub against the aluminum shock body wearing it out.

If you have a bore gauge you can take a measurement at the top, bottom and middle of the body. If the middle is more than just a few thou larger than the very top and bottom it may never seal well even with a new piston/band. I've seen that a lot with vintage shocks from the 80's.

It's hard to diagnose a problem like you have over the internet though. My first thought os like Kristen said and the piston or shim stacks gor flipped.
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slipdog 1/12/2019 8:27am
1/12/2019 8:27am Edited Date/Time 1/12/2019 8:28am
Although... that piston design looks like if you got them upside down it would hydraulic lock instead of losing all damping.
KILLASAN
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KILLASAN 1/12/2019 8:54am
1/12/2019 8:54am
Here is my shim stack.left is bottom all the way up to the nut.also is the shock head. Gonna try to measure the barrel



KILLASAN
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KILLASAN 1/12/2019 9:04am
1/12/2019 9:04am
Bore is smooth .no marks to suggest damage. I measured it in 4 places and it shows 33mm. Ah this is so confusing. Tha ks for all the help thus far

slipdog
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slipdog 1/12/2019 9:26am
1/12/2019 9:26am
Yes, that was all installed correctly. Measure the piston band with some calipers as well. It should be over 33mm. usually, XX.15mm is considered service limit on piston band size but even when I see them undersized like at 32.85 or so they will still dampen and not be a pogo stick. Over time with heat cycles the O-ring underneath the Teflon piston band deforms and goes flat or become square instead of round, that's what causes the loss of size/seal more than the band itself wearing down but you can't replace the O-ring without cutting off the band first.

I would assume in your case something else is going on.
KILLASAN
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KILLASAN 1/12/2019 9:32am
1/12/2019 9:32am
Piston band is almost exactly 33mm.i thinks it really is too worn piston ban and faiming orings l. I would close off this job here. I cant even seem to find showa 33mm piston bands. The band itself feels brittle. Tbh it looks like the oem one.
KILLASAN
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KILLASAN 1/12/2019 11:09am
1/12/2019 11:09am
4 and 5 seems to be the oring onthe shock head and circlip on the shock body. The bike is a 98 rm 80. I reinstalled eveything and will.get my light nephew to bump on it. If all esle fails i will look into using a heavier oil. Im using light 5 atm.
slipdog
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slipdog 1/12/2019 12:07pm
1/12/2019 12:07pm
KILLASAN wrote:
4 and 5 seems to be the oring onthe shock head and circlip on the shock body. The bike is a 98 rm 80. I reinstalled...
4 and 5 seems to be the oring onthe shock head and circlip on the shock body. The bike is a 98 rm 80. I reinstalled eveything and will.get my light nephew to bump on it. If all esle fails i will look into using a heavier oil. Im using light 5 atm.
You're right that #5 is definitely a circlip now that I look again. None of the Honda parts lists I looked at had piston parts available either and unfortunately, there's no direct Showa supplier to contact for that.

Kristen_Valentino 1/12/2019 3:04pm
1/12/2019 3:04pm
Did you use a seal head tool or plastic bag when installing seal head over shaft, sometimes they get cut
KILLASAN
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KILLASAN 1/12/2019 3:51pm
1/12/2019 3:51pm
Kristen_Valentino wrote:
Did you use a seal head tool or plastic bag when installing seal head over shaft, sometimes they get cut
Used some electrical tape. My bullet doesbr fit that thin of a shaft. However you can feel the ease during the rebuild. It doesnt have the force/suction when pumping the shaft. This is before setting the shock head.
jaredkeller96
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jaredkeller96 1/12/2019 10:43pm
1/12/2019 10:43pm
Make sure it has nitro in it...can leak out and cause it to be springy

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KDXGarage
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KDXGarage 1/13/2019 1:37pm
1/13/2019 1:37pm
I bet the piston band o-ring is shot to hell. As slipdog mentioned, they wear out underneath the piston band.


Look for Honda 52431-GC4-003 (unavailable). It is 33mm and might work.

Do a notch cut to get that band off and install a new o-ring.
KILLASAN
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KILLASAN 1/13/2019 2:34pm
1/13/2019 2:34pm
KDXGarage wrote:
I bet the piston band o-ring is shot to hell. As slipdog mentioned, they wear out underneath the piston band. Look for Honda 52431-GC4-003 (unavailable). It...
I bet the piston band o-ring is shot to hell. As slipdog mentioned, they wear out underneath the piston band.


Look for Honda 52431-GC4-003 (unavailable). It is 33mm and might work.

Do a notch cut to get that band off and install a new o-ring.
I highly suspect the same thing. Thanks for the part no. What bike would that be off?
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KDXGarage 1/13/2019 5:19pm
1/13/2019 5:19pm
Not sure if it fits, but worth a try

1989 - 1994 CR

Check years, not sure
KILLASAN
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KILLASAN 1/14/2019 5:28pm
1/14/2019 5:28pm
Good news . Called factory connection and they have instock. Just ordered hopefuy solves the issue
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KDXGarage
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KDXGarage 1/15/2019 8:53am
1/15/2019 8:53am
Sweet! Thanks for letting us know you found one there. I have heard a few people comment that Showa parts are harder to find than KYB. I know with KYB Technical Touch, the last ten years have made it easy to find most KYB parts.
KILLASAN
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KILLASAN 1/15/2019 8:59am
1/15/2019 8:59am
KDXGarage wrote:
Sweet! Thanks for letting us know you found one there. I have heard a few people comment that Showa parts are harder to find than KYB...
Sweet! Thanks for letting us know you found one there. I have heard a few people comment that Showa parts are harder to find than KYB. I know with KYB Technical Touch, the last ten years have made it easy to find most KYB parts.
That indeed is true. Showa parts are not readily available. I had recently restored a 92 rm and could not find a bladder anywhere. Even tried buyin a kyb one similar sized. (Didnt work as bladder shaped differently). Guys at fc responded and had 2 instock. Any parts i cant find it seems they got it. Now i just hope this solves my issue. Thanks guys ill report back wen i get it installed.

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