Author Topic: Re building old koni 76f 1296 shocks (Read 8834 times)

rosewood · « **on:** July 20, 2018, 07:09:47 AM »

I came across someone selling these shocks here in NZ. They seller mentioned they would fit 550's and they were in good condition so i took the gamble and brought them not knowing anything about these old shocks..

turns out they are 76f 1296 after some searching on this site and made for 750's..I'm going to try rebuild them and see if I can get them fitted to my 550..

There were few guys talking about these old shocks a while ago but apart from that not much else out there. Are there any Gurus still around that know these shocks well?

Ive managed to get them apart but what i cant figure out is from this old post:

"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."

Does anyone have any info on this....what exactly is it and where does it go? not sure if mine had it originally but its definitely not there. Is this part needed and if so what do i use to replace it?

Any help much appreciated, ill post some pictures tomorrow of the dissasembly

cheers rosewood

Bankerdanny · « **Reply #1 on:** July 20, 2018, 07:26:23 AM »

You should talk to Nils at Resto Cycle in Arizona https://www.restocycle.com/.

He is a long time member here and the US rep for Ikon, which was formerly Koni. I know he can rebuild them for you, and possibly swap out the springs for lighter ones appropriate to a 550. He may also be able to sell you the seals and other parts to rebuild them yourself.

flatlander · « **Reply #2 on:** July 20, 2018, 11:34:18 AM »

or, a little bit closer to you are ikon themselves: https://www.ikonsuspension.com/contact-ikon-suspension.html
they're in australia. geoff, their boss is very knowledgeable about the old konis and can provide most of the parts still.

my name is nobody · « **Reply #3 on:** July 20, 2018, 02:09:55 PM »

The correct shock is the 1302 for an early 550. The 1296 will fit on the 550, but is about an inch longer. Some claim they work well on the smaller 550. My experience was that they (1296) were too tall, and changed front geometry. Opinions vary. I experienced a high speed tank slapper that nearly ended in disaster. I promptly removed them, and put them back on my 750, and trawled E bay for a long time till a set of 1302's became available for my 550. I had mine rebuilt by a guy named Robert Haag, in the usa. If you put them on a 550, TEST DRIVE CARFULLY ... rhaagusa@yahoo.com He specializes in konis for bikes,
and was very helpful

flatlander · « **Reply #4 on:** July 20, 2018, 02:26:49 PM »

you are right, 76K-1302 is the model for the 550. that's the number on my konis

by the way, here are pictures of a rebuild: http://www.zimmerframeracing.com/koni_shocks/index.htm
different model, but they are all very similar inside.

my name is nobody · « **Reply #5 on:** July 20, 2018, 08:13:03 PM »

That's an excellent article. Going in my favorites folder

NobleHops · « **Reply #6 on:** July 20, 2018, 09:44:24 PM »

With thanks to you Danny, unfortunately we cannot rebuild the 76 series. We don’t have parts and the 7610 seals I do have don’t fit.

The comments about the fitment of the 1302 and 1296 were spot on. We sometimes use the 1296 to lower a bike like a CBX, 1302 will do the same for a 750, but that is best done at BOTH ends, equally. Lower the rear by itself and the bike will handle like a chopper, have a tendency to run wide. Lowering the front by itself can cause a lot of instability, head shake, tank-slappers, or a full on debiking. When raising a rear end, caution is advisable. I personally suggest no more than 15mm.

P.S. We recently lowered a CBX as above, 1 inch, and found that 1/2” removed from the side stand below the spring was pretty much perfect to ensure safe storage, and in that case it still met the rubber pad on the muffler when retracted.

rosewood · « **Reply #7 on:** July 21, 2018, 04:58:01 AM »

Thanks for all the reply's and the warnings of using these on a 550...I am aware of screwing with the geometry for handling etc, a part of me was keen as this will be a cafe and will enhance the stance I'm after. It's a project bike and not intended to be ridden much but I will be very cautious if they do end up on the bike.

Thanks for that link flatlander I've been trawling the internet all day for something like that but couldn't find anything..

I did contact ikon in Aus and got the usual reply of no parts but offering me knew ones..

Nils would you be able to comment on the top out washers for the ones I have? there is no sign of them but I'm not sure if they if they ever had them or if they dissolved like mentioned in some other posts. I did read on a parts diagram that they may not have been fitted. http://forums.sohc4.net/index.php/topic,27828.0.html

If i were to make my own nylon top out washer and assemble it what would be its dimensions? Just above my piston there are a couple of small holes in the shaft, if the top out washer slid on the shaft and covered these holes would it be an issue or do they have a particular design?

My particular one doesn't come with a piston ring/groove on the piston either.

I am a bit hesitant in taking apart the bottom valve and piston assembly so far is there a trick to reassembling it? It was mentioned somewhere that the amount it was screwed back up could affect the operation..read this:

"There are three steel washers spaced by three tiny spacers on the bottom damper. From a fresh disassembly they alternate starting with one against the damper body.

I found the best setting was with the center screw snugged then backed off until the outer washer was clear a few thousands from the damper body. It took several assemble & test with small adjustments out each time to find this position.

You can create a lot of compression damping by turning the screw in just 1/4 turn, more then I wanted for street riding. Turboguzzi's comment confirmed this for me."

So far I've cleaned up the bodies and in the middle of painting them, I will dissemble and clean out the bottom valve and piston valve assembly then they should be able to go back together. I am not going to take apart the top gland with the seal incase I damage the seal...the shafts had a bit of wear on them but they didn't appear to be leaking..

Thanks again
rosewood

rosewood · « **Reply #8 on:** July 21, 2018, 05:14:38 AM »

heres a few pics for reference...

NobleHops · « **Reply #9 on:** July 21, 2018, 12:31:30 PM »

Quote from: rosewood on July 21, 2018, 04:58:01 AM

Thanks for all the reply's and the warnings of using these on a 550...I am aware of screwing with the geometry for handling etc, a part of me was keen as this will be a cafe and will enhance the stance I'm after. It's a project bike and not intended to be ridden much but I will be very cautious if they do end up on the bike.

You can mitigate that by being mindful of the aspect ratio of the tires you choose front and back. If you use a tire with a smaller aspect ratio in the rear you can easily lower the rear a little bit to end up with less than a full inch of height.

Quote

Thanks for that link flatlander I've been trawling the internet all day for something like that but couldn't find anything..

I did contact ikon in Aus and got the usual reply of no parts but offering me knew ones..

Well, Ikon sell and service shock absorbers, and given that they are unable to service yours...

Quote

Nils would you be able to comment on the top out washers for the ones I have? there is no sign of them but I'm not sure if they if they ever had them or if they dissolved like mentioned in some other posts. I did read on a parts diagram that they not have been fitted. http://forums.sohc4.net/index.php/topic,27828.0.html

I'm not clear what you are referring to. Koni used a 2mm or so split nylon washer atop the gland nut around the shaft, the main purpose for it was to provide a channel for air to escape in a bottom-out scenario, so that high-pressure air pumped from the bump stop wasn't being concentrated along the shaft and seal interface area. Ikon does not use that part on their current designs, but we do clean and reinstall it when we rebuild Koni 7610s.

N.

rosewood · « **Reply #10 on:** July 21, 2018, 07:39:26 PM »

Thanks for the reply Nils I fully understand these are obsolete now just trying my best to restore them..

Sorry if I am confusing people but Ive read about the top out washer dissolving and gumming up the small holes....I am just trying to figure out what that is and if mine came with it installed originally or if it did dissolve. This is the what i am referring too:

" +++++ A heads up to Koni buyers and owners: Old style 76 series KONIS that have not been serviced get gummed up by an internal soft rubber/ plastic rebound top out bumper washer (that sits on top of the piston) that dissolved into goo over the decades, and gets sucked into and plugs up the damping mechanisms. This is visible in the photo of the internal parts. So if not jammed already, they'll usually get stuck after trying to pump them. Don't force them or you can do damage including bending the shafts if you try to ride with them jammed. There's no way to resolve the issue except for complete dis-assembly and meticulously cleaning out all the old plastic crud, which takes special tools, a lot of manual work, and time. It's imperative that any NOS and used KONIs you buy will need to be rebuilt or they most likely will be damaged. Be advised of this when considering buying any KONIs that have not been rebuilt."

and another post mentions this:

"The rest is the usual cleaning out of the dissolved washer gunge and replacement with a nylon washer. Not much else to go wrong except for bent rods from blocked transfer holes and then there is no point in a refurb. The 76 series in some ways is a better shock than the 7610. More adjustment range but more difficult to make that adjustment."

The best i can figure out is that it is part number 515 in the attached images which I referred to in my earlier post..

I hope that makes a bit more sense..just wondering if i can make my own and install it or just not worry about that part all together

rosewood

PS: Another thought I had Nils...is it possible to shorten the shaft by cutting new/extending the threads where the top mount screws on and then cutting say 10mm off so its only longer by 15mm over stock? I guess this may require new/shorter springs or they will be under too much preload.

NobleHops · « **Reply #11 on:** July 21, 2018, 08:03:53 PM »

Yes on all counts, that would work, with the caveats you identify.

rosewood · « **Reply #12 on:** July 22, 2018, 05:43:20 AM »

I also found a ebay listing from rhaagusa he is selling some old restored 76f 1374's. He mentions in his listing that the plastic washer is removed so i am guessing he doesn't replace them. Also has a picture of the gummed up internals. I now know what this part looks like. Mine were no wear near that bad inside so I'm going to assume it was never there..

I'm still struggling to get the piston off the piston rod, it wont turn at all. will try make a shaft clamp and see if that helps tomorrow. otherwise I'm just going to ultrasonic clean everything and blow out with some parts cleaner and compressed air.

For anyone attempting to restore these or buy an old pair think twice or leave it to an expert, not the easiest things to work on..

rosewood

danyo · « **Reply #13 on:** July 22, 2018, 07:46:59 AM »

If you are talking about unscrewing that 12mm head bolt it's a left hand bolt. I didn't know that and broke one. I'll contact Nils if he can get me replacement.

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NobleHops · « **Reply #14 on:** July 22, 2018, 08:47:38 AM »

Quote from: danyo on July 22, 2018, 07:46:59 AM

If you are talking about unscrewing that 12mm head bolt it's a left hand bolt. I didn't know that and broke one. I'll contact Nils if he can get me replacement.

Sent from my SM-N900T using Tapatalk

Measure it and photograph it Danyo - I might have an old pair with a workable part, but I might not.

danyo · « **Reply #15 on:** July 22, 2018, 10:10:50 AM »

Sorry for thread hijack but maybe sombody else will benefit. Those are dimensions of the special bolt, and the broken one. That bolt is drilled through so very weak. I did not put much force to break it.
Nils I ordered yesterday seal kit/ oil from your store. I assume that kit works for any 7610 shocks. I have two sets 1302 and 1296. Would like to rebuild one if will end up with success, will order another seal kit. I also have NOS 76 series shocks but one of them is very stiff indicating passage blockage. Future project.

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NobleHops · « **Reply #16 on:** July 22, 2018, 01:07:14 PM »

We don't have an order from you, it's possible you placed it elsewhere. Would not be the first time that happened :-).

Our website address is:

www.ikonshocksusa.com

danyo · « **Reply #17 on:** July 22, 2018, 03:11:46 PM »

Damn, was sure I'm ordering from you. Yes it's different website address. I will need another kit soon so I'll make sure not to make that mistake.

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rosewood · « **Reply #18 on:** July 22, 2018, 04:25:12 PM »

What model shock are you working on danyo??

the head of my bolt is 11mm or 7/16ths and it is definitely not left handed as I have managed to remove them (this was also documented in an older post), one was really stuck good and had to use the battery impact driver..not sure why (may have been put together poorly) but I've damaged the thread slightly taking it out but i think I can clean up with a tap and die its a 1/4 - 28 UNF if that's of any use to anyone.

Quote from: danyo on July 22, 2018, 07:46:59 AM

If you are talking about unscrewing that 12mm head bolt it's a left hand bolt. I didn't know that and broke one. I'll contact Nils if he can get me replacement.

Sent from my SM-N900T using Tapatalk

danyo · « **Reply #19 on:** July 22, 2018, 04:36:56 PM »

^^^ so it must be different for aluminum body shocks or 7610 series. Yes it's almost 11mm, I have 2 sets ( 7610-1302 and 7610- 1296).opened now and mine are left handed. That should help for anybody trying to remove those screws in the future. If I would know that I wouldn't break mine

.

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rosewood · « **Reply #20 on:** July 23, 2018, 04:50:44 AM »

Right I finally got everything apart and fully cleaned up and ready to go back together....very intricate parts and assembly I can now appreciate the price tag of new ones. The only thing i didn't fully dissemble was the bottom valve (the swagged tabs holding those washers on the bush) the other side with the tiny screw came apart fine but had to grind the outside of an old 7mm socket to get access to the nut on the other side. Washers/shims all cleaned and all those tiny passages checked and cleared.

I also had to make a shaft clamp to get a good hold of the piston to unscrew from the shaft, was a bit anxious undoing them but they came off easily in the end, I heated everything up and hit it with pb blaster the night before, not sure if this was necessary though. Everything was a right handed thread. Will post some pics tomorrow so others can see what the are in for before attempting this.

Last question for everyone...what is the preferred or best oil to use. Fork oil? I have some 5 and 10W. I have read some others using ATF. Also the correct amount? I've read 65, 75 and 85mil in others posts. And what is the best procedure to reassemble everything including the oil?

rosewood

flatlander · « **Reply #21 on:** July 23, 2018, 11:48:41 AM »

here's what geoff from ikon told me re. fill hight:

Quote

Rule of thumb would be to fill the pressure tube & allow the out reserve tube to fill by 1/3

the oil they use is 5W. but weight designation is different per brand so maybe start with the 5W you have, see how it feels and experiment by mixing in a certain ration of the 10W until you get the behaviour you want.

seanbarney41 · « **Reply #22 on:** July 23, 2018, 02:00:29 PM »

rosewood, this is a good thread. Please be sure and share your impressions of the results.

rosewood · « **Reply #23 on:** July 23, 2018, 02:49:48 PM »

Ok here's some pics to share, not a proper re-build thread but I think good info that I was having trouble finding..will post images with a few notes as I worked through these shocks..

As they arrived and disassembly...

The clevis bushes were in bad shape and I noticed 1 spring retaining ring was missing on each shock..

I milled out the holes on the gland nut to 5mm and a little deeper, and made a pinned tool with 5mm dowels to get the gland nut off as my first attempt wasn't holding well enough. (not pictured) This worked alot better and they came off with a few knocks easily without and slippage..

rosewood · « **Reply #24 on:** July 23, 2018, 02:56:25 PM »

Ultrasonic cleaned

Everything layed out

I machined up some spring keepers as well..

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Author Topic: Re building old koni 76f 1296 shocks (Read 8834 times)