Author Topic: old koni shocks (Read 15022 times)

octagon · « **on:** May 09, 2011, 07:08:16 PM »

does anyone have a line on gasket rings for old koni shocks? i need two. the dimensions are 4mm thick, 27mm id, 33mm od. the rings are bevelled about 10 degrees but possibly i could do that with a sander.
contacted koni, and they don't have parts for this model (76f 1296)
a local industrial supply house says they can get gasket material of the correct thickness but i would have to cut or punch out the rings.
thanks for any help/advice.

crazypj · « **Reply #1 on:** May 09, 2011, 07:55:58 PM »

Is it a packing ring between top nut and guide bushing?
Any idea what it's made of?
Try hydraulic repair places, probably same a some piston seal?

octagon · « **Reply #2 on:** May 10, 2011, 05:46:34 AM »

that stepped piece in the picture seems to be there to help with dampening. the ring i think seals that piece in the shock tube. good idea on checking a hydraulic supply place.

Markcb750 · « **Reply #3 on:** May 10, 2011, 08:41:35 AM »

The "gasket Ring" is a simple O-ring, the bevel is not necessary. You should be able to go to any Hydraulic supply house for a replacement.

The key seal is the shaft seal in the top cap. if it is leaking you will need replacement and I believe Ikon has replacements for that seal.

Key to the shocks is cleaning all the little orifices in both the cylinder bottom and the piston. some holes are only about the diameter of a pubic hair and need a thin wire brush dia. wire to clean out.

The piston adjustment (extension damping) can be set once the unit is assembled. The bottom compression damper must be set before assembly and tightening the adjuster too tight or mis-assembling the control disks will result in very stiff compression/ harsh ride. I found a nice smooth compression point with 1 turn out on the piston damper felt good to me.

I used 15w fork oil, fill the cavity about 80% prior to inserting the piston, too much oil will make it bind, too little will make it inconsistent.

Here is a link to my thread, hope you find some useful info there.

Mark

http://forums.sohc4.net/index.php?topic=85827.0

octagon · « **Reply #4 on:** May 10, 2011, 09:13:10 AM »

aha. so the old o ring was shaped over the years by stepped place it sits in. thanks for the tip about cleaning as well.
i did checked with dave gardner at ikon usa on parts. there are two series of 1296 shocks, an older one and newer one - i have the older series, and they have no parts for it.
too bad because these shocks are a pleasure to work on, as they're so well made. the original oil in them certainly smells nasty though.
i have one bad shaft seal, but i was going to try and fabricate fabricate new ones anyway - i thought the o ring/gasket ring pieces were critical and didn't believe i could make them too easily.
appreciate the info.

Duke McDukiedook · « **Reply #5 on:** May 10, 2011, 10:06:26 AM »

You should be able to source rings and seals that will work for your purpose.
This guy on ebay might be able to readily source some seals for that model for you, he rebuilds old Konis on a regular basis.

http://stores.ebay.com/sdbikeparts

Markcb750 · « **Reply #6 on:** May 10, 2011, 10:17:29 AM »

Aha, I did not know the two age 1296 problem. I did not replace my seals as they showed no evidence of leaking. I would look in a hydraulic shop for something close (maybe in Viton) and figure out how to adapt it into the Koni shaft. Many hydraulic cylinders are metric sized shafts today and the nominal 12 mm shaft should be common.

I have a shaft seal from the donator unit, the exposed lip has some dry rot, but it might work. PM me a mailing address if you want it.

octagon · « **Reply #7 on:** May 10, 2011, 10:37:46 AM »

thanks mark for the offer on the seal but i'll try to find a way to put in something new when the shocks go together - slight hassle getting these guys apart.
i-d d, i sent an email to the ebay guy.

Silverback · « **Reply #8 on:** May 10, 2011, 10:49:57 AM »

Try these guys:
http://www.mfpseals.com/type.php?id=1

They have had everything I have ever needed as far as o-ring go.

octagon · « **Reply #9 on:** May 10, 2011, 02:49:44 PM »

thanks i'll check with them also

octagon · « **Reply #10 on:** May 11, 2011, 08:05:34 AM »

update - heard from the koniking guy on ebay - he prefers to rebuild them himself not sell parts - he gets fifty dollars a shock for a rebuild (which seems reasonable) "to save them for future generations" as he put it. on to the mfpseals guys.

Duke McDukiedook · « **Reply #11 on:** May 11, 2011, 09:24:42 AM »

Doesn't seem too bad a price if you don't want to do it yourself.
You would think he would want to make money selling the parts too.

octagon · « **Reply #12 on:** May 11, 2011, 10:29:19 AM »

i thought 50 was reasonable. new the equivalent is over 150 each.
maybe there's not enough profit in the parts sale to be worth it. can't blame him for that.
i already have mine apart and have a rough idea (thanks to the forum) of what to do, so i told him i'd push on.

crazypj · « **Reply #13 on:** May 11, 2011, 08:42:56 PM »

More than once I've used gear change shaft seals and made new holders (seal head) when seals were not available (lot of Suzuki MX bikes don't have any shock parts available)
Honda use 12mm shafts on a lot of bikes

Markcb750 · « **Reply #14 on:** May 12, 2011, 04:18:32 AM »

Quote from: crazypj on May 11, 2011, 08:42:56 PM

More than once I've used gear change shaft seals and made new holders (seal head) when seals were not available (lot of Suzuki MX bikes don't have any shock parts available)
Honda use 12mm shafts on a lot of bikes

The shaft seal on the Koni is packed via a beveled washer and spring between the inner cylinder cap and the top cap of the outer shell. Some hydraulic pistons use a similar seal. a standard 12mm shaft seal, intended to seal a low pressure shaft such as a gearshift shaft, will not seal well against the pressure spikes the shock will see.

Duke McDukiedook · « **Reply #15 on:** May 12, 2011, 07:35:04 AM »

Do these have to get refilled with pressurized nitogen like my more modern shocks?

Cyclone82 · « **Reply #16 on:** May 13, 2011, 05:06:47 AM »

Hi, I got a set of old Koni 76 shocks today.

So do you guys reckon the o-rings/seals are metric? When i spoke to IKON Australia some time ago they said Koni used some metric and some imperial stuff. When i measured up all my o-rings for my 1978 Koni 23 X remote reservoir gas shocks they all seemed to be imperial o-rings and i spent days measuring them to come to that conclusion. The main body o-ring on my 76F shocks is too far gone to get an accurate measurement from though.

On the 76 F shocks i got today my shafts measure 11.70mm roughly. I have to double check though. Mine have one combined seal/wiper in the top capa and the wiper lip is perished anc cacked a little. I want to do these shocks properly but i have no idea what to use as a seal. Its going to be a special size/shape for sure. Do other people upgrade to 12mm shafts?

Also my top out washers/rubbers are gone. Everyone says they disolve into the oil. What is the correct thickness of this item? I was thinking of using an Ohlins or White Power top out rubber. Did the Koni top out rubber just sit on the piston and float up and down in the shock? I did not seem to see a groove in the bottom of the shaft guide bush for a rubber to be retained.

What about piston rings? They have a thin metal ring on the piston. Coming from experence with Ohlins/White Power you always replaced these at a service which was easy as they were a flexible teflon band. If these were ignored and left to wear excessivley, you would end up with metal to metal contact inside the body and the shock would be a write off.

I have also askedd Koniking if i could buy some rebuild parts off him because i want to do the job myself and it is too expensive to send the shocks to USA from Australia. Shipping from USA to Australia is ok though. He does not seem to want to sell any bits. Someone could make a decent amount of $ selling rebuild parts for these Konis.

Anyway let me know how you get on. I will be watching this thread carefully

cheers

Duke McDukiedook · « **Reply #17 on:** May 13, 2011, 07:29:48 AM »

That's what I'm saying, you could make some money off parts as opposed to making no money because of cases like these.

It makes no sense.

Ikon should be willing to make parts (at least stock the seals) so people can rebuild their old shocks, they probably have all the old shop drawings and dimensions, just make the damn things.

Ugh.

Cyclone82 · « **Reply #18 on:** May 17, 2011, 05:21:19 AM »

Not having much luck yet. Its the damn 11.7mm shafts, anything else would have been easier.. Closest 'real' size is 29/64 which is 11.52mm but i have not found any seals that size yet either. Its about time someone starts offing rebuild kits for these shocks, gets the kits on ebay and starts reeling in the $$$ and i may know the person do it. He will see a need once i explain all this to him and he will suport owners of these vintage shocks 100% AND sell the parts on their own and not part of a 'rebuild only' I will see what i can do but will keep digging around first before suggesting it to him. Surely somone on this planet has done the hard yards and already had seals made or knows a suppler.

octagon · « **Reply #19 on:** May 17, 2011, 02:51:05 PM »

checked with mfp and they didn't have the seals - the guy there was very helpful and gave me the number of another place to try- will report back on that.
if anybody has a junk shock i could use either the whole shock or the the very last piece that threads onto the shock shaft before the bottom nut goes on. looks like a little cylinder with cutouts at the bottom on two sides.
i'm also wondering if these shocks are metric - a 7/16ths socket fits exactly on the bottom nut. will check on that some more also and report back

Cyclone82 · « **Reply #20 on:** May 18, 2011, 12:31:08 AM »

I may have found some 11.75mm seals in Italy today. I will see what comes of that. I actually measured the shafts and they are 11.75mm and not 11.70 as i first thought.

I have not stripped my shafts yet but i had a 11mm 1/4" drive socket and that fit fine when i did a test fit.

I am about measure up the cavity for the main body o-ring and that should reveal more if these are basically metric or imperial or a mixture.

Cyclone82 · « **Reply #21 on:** May 18, 2011, 07:04:20 AM »

Quote

if anybody has a junk shock i could use either the whole shock or the the very last piece that threads onto the shock shaft before the bottom nut goes on. looks like a little cylinder with cutouts at the bottom on two sides.

That would be the piston. Do yours have piston rings or just plain with no rings?

I tried to measure up the groove dimensions for the o-ring and run the specs through an o-ring calulator i have using some other o-ring groove specs but there really is not an o-ring that actually suits this groove properly unless Koni were using an oversize o-ring operating outside the specs for that o-ring cross section and thus compressing the ring a lot.

So far everything technically tells me it should be a 2.62 CS o-ring which suits the groove width, but the groove depth says it should be a 3.5, 3.53 or 4mm CS. I wish mine were not old and i could measure them as they just look like a big squashed and swollen ring at the moment. I will try and get an answer from Ikon.

All this is based on my assumption that the seal cap bottoms out hard on the shaft guide bushing under the seal and compresses up that wire spring when assembled and therefore creating the enclosed groove for the o-ring.

octagon · « **Reply #22 on:** May 18, 2011, 05:26:32 PM »

hi,
mine is a plain piston. i was also told by a local industrial supply guy that that an o-ring of that cross section isn't usually available for those id, od specs. my rings are also distorted, but i got measurements off piece it sits on.

Cyclone82 · « **Reply #23 on:** May 19, 2011, 04:18:37 AM »

Ok, thats what i was thinking, i could not see an o-ring that is right. Ikon say that the 7610 have 33mm bodies and use the same o-ring as the 76F so i will get some off them and meausre it up. To me, i think it has to be a 3 to 3.50mm cross section and they are using it outside of the recommendations. Ikon said it is a tight fit on the ID. I plan to post some info on the 11.75mm seal i found in the next few days, with some diagrams etc. Sorry if i wont be moving as fast for you as you would like and you want to rebuild yours and go riding next week, but i am just working ar my pace and im in no rush.

I will also be looking into machining a groove in the piston to take a modern flexible piston ring. That should not be an issue.

It looks like the main issue will be the shaft guide bush. It has some tiny holes right on the edge and there is NO room to bore it out bigger and then press in a modern shaft teflon DU bush or custom bronze bush without cutting into those little holes. Im not sure exactly what they do really. i need to study it further to see if those holes can be routed out wider. If not the only option really is to downsize the shaft but you would have to go to something like 9mm or machine up whole new bushes and get all those little holes done. Probably not that cheap or worth it but i know a guy who could do it.

Mine are not too worn though but im not thrilled about having to leave them. If i go with this new seal, it looks like it will eliminate the spring and cup washer and then i will have a gap of about 3mm which could be used for a 3mm thick bushing. Its only 3mm but at least it would allow me have that portion a good close fit on teh shaft and at least guide the shaft more truer than a half worn original guide. I will still have to work out what to do with those holes in the middle though and if i can design the extra guide bush to not cover those little holes right close to the shaft.

*edit - I think it may be possible to re-bush the original guide bush and then re-drill out the little holes. Would be a fiddly job but do-able. I am going to seek a second opinion on this from my shock expert mate and will probably send some bits to him to look at. He will know what to do for sure.

octagon · « **Reply #24 on:** May 19, 2011, 07:16:48 AM »

hi cyclone,
by shaft guide bush you mean the large stepped metal piece that the o-ring fits on right? what kind of wear do you have there?
on the piston, on my shocks, the piston is quite thin and brittle (as noted above i trashed one already) and it might be problematical to machine a groove in one.
for what it's worth, on the outside of the shock body, the large rubber "bumper" from a stock honda shock seems to swap over with no problem.

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Author Topic: old koni shocks (Read 15022 times)

Markcb750

Markcb750

Markcb750