Better OIF Damper rod piston ring

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Shawn_Mc
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Better OIF Damper rod piston ring

Post by Shawn_Mc »

Besides Racetech, does someone offer a better, slicker option piston ring for the damper rods? I cant find it anywhere. Ive got a Gold Valve emulator coming for the fork, but I dont want to deal with those sticky OEM orings. Mine are brand new, but man, smooth, they arent.
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Barry Creary
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Re: Better OIF Damper rod piston ring

Post by Barry Creary »

I bought a type of ring like a fibre Piston ring I think made of carbon fibre ( it was a long time ago) from British spares in New Zealand and seems to work well
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Re: Better OIF Damper rod piston ring

Post by Shawn_Mc »

RaceTech makes a teflon one, and they're a 20 minute drive from where I am, but dropping $20 a piece for glorified orings..I cant do it. It's the principal of the thing.
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Re: Better OIF Damper rod piston ring

Post by minetymenace »

If you fit an emulator, won't that take care of the damping so you won't need the original valve and O-ring?

I recall a square cross section fibre ones, L&P Williams stock them here, but that is $33 for a pair of glorified O-Rings!
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kommando
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Re: Better OIF Damper rod piston ring

Post by kommando »

No you need the seal even using the emulator or the oil by passes the emulator around the outside. The emulator only fixes 1/2 the problem as they only provide compression damping and no rebound damping. You can get round this by turning one of the emulators upside down but then you get issues with flow rates due to each valve needing to provide double the damping. This lead me to go for the BMW SS1000RR solution I posted earlier which has large flow ports. Even with this solution I needed to seal the outside edge, I reused the PTFE seals but shortened to suit the smaller diameter I turned the main valve body down to. You need to be careful which stanchions you use, newer ones seem to ignore the requirement for the ID to have a good surface finish and the right size, even the best seal in the world will not work when the ID is as rough as sandpaper.
Last edited by minetymenace on Fri Mar 27, 2020 11:37 am, edited 2 times in total.
Reason: For some reason kommando's BMW solution is in parts for sale!!
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Re: Better OIF Damper rod piston ring

Post by minetymenace »

kommando wrote:You need to be careful which stanchions you use, newer ones seem to ignore the requirement for the ID to have a good surface finish and the right size, even the best seal in the world will not work when the D is as rough as sandpaper.
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Re: Better OIF Damper rod piston ring

Post by Shawn_Mc »

The stanchions I got were the heavy duty parts from the UK. I had to wash the cosmoline off/out of them and they were pretty good inside.

Those phonelic parts probably work pretty good, but at $33 American, then being shipped to the US...YIKES...Gotta be a better way.

I'll probably make a pair out of the pile of scrap teflon Ive got in the garage.
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Re: Better OIF Damper rod piston ring

Post by bbenxe »

kommando wrote: Fri Mar 27, 2020 10:12 am The emulator only fixes 1/2 the problem as they only provide compression damping and no rebound damping. You can get round this by turning one of the emulators upside down but then you get issues with flow rates due to each valve needing to provide double the damping.
Or you buy four emulators and stack them up! Two in one leg, and two upside down in the other!

I presume less damping required for rebound and you may only need one upside down so you can save 25% and just have 3...? Or would one emulator in compression using a spring with twice the rate achieve the same as two at half the rate? I believe it would. Cranking down the screw on one side wouldn't achieve much as this only controls the pre-load and 'blow-off' point of the valve rather than the rate once in motion. Racetech do include alternative stiffness springs but not presumably at twice the standard rate.

Some calculations required to ensure you don't over-spring the front end cutting your springs down by 2 inches on one side and 1 on the other though. At least we've got the spare time for it now.

I'm currently waiting on my post from the US containing two emulators and am now wishing I had asked for a third. I have also got the phenolic o-rings from LP Williams and can report they are a tasteful teal colour rather than brown pictured on their site if that sways you.
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Re: Better OIF Damper rod piston ring

Post by kommando »

I presume less damping required for rebound and you may only need one upside down so you can save 25% and just have 3...?
You need more rebound damping than compression damping. Compression damping is working with the spring, rebound has to work against the spring hence the different requirements.
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Re: Better OIF Damper rod piston ring

Post by jim-nz »

Hi I have three points to make on this subject. I comment based on research I have done in getting to a similar point as the original poster here.

One is that I tried to find an off the shelf solution to the o ring issue without luck. Eventually I bit the bullet and bought a set of ptfe seals from a British bike supplier for about 40nzd. I won't name the supplier. So to satisfy my curiosity I took them around to a local seal specialist to talk about them. They made me a second pair for 18nzd which would have been cheaper per unit if I had ordered them in quantity. The invoice came with dimensions and material type on it and they said if I bought those dimensions back again they could use them to make further replicas. I don't have them to hand right now but can get to them at a later date.

Two is that I am lead to believe that the emulators cover compression damping and the original rebound damping circuit covers the rebound damping. The rebound damping is then adjusted by fork oil viscosity. Once the rebound is set the emulator is adjusted. Sounds good to me but again I say I have no real experience I am just going off what is basically advertising material.

Thirdly my plan is to build a set of forks with the following features; Emulators, racetech springs and spacer under the top out springs to shorten the fork legs. The spacers will end up being somewhere between 25mm and 50mm depending on the required ride height. A question I have regards the two small holes which are near the top of the damper rods. I am worried that as one or both of these may end up being obscured by the spacer can I move them or possibly drill a single alternative hole or even eliminate them completely.

Cheers.
Jim.
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Re: Better OIF Damper rod piston ring

Post by minetymenace »

jim-nz wrote:I don't have them to hand right now but can get to them at a later date.
Putting this info on the forum is what the forum is all about, please publish this when you can.
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Re: Better OIF Damper rod piston ring

Post by Shawn_Mc »

jim-nz wrote: Thu Apr 02, 2020 7:45 am Hi I have three points to make on this subject. I comment based on research I have done in getting to a similar point as the original poster here.

One is that I tried to find an off the shelf solution to the o ring issue without luck. Eventually I bit the bullet and bought a set of ptfe seals from a British bike supplier for about 40nzd. I won't name the supplier. So to satisfy my curiosity I took them around to a local seal specialist to talk about them. They made me a second pair for 18nzd which would have been cheaper per unit if I had ordered them in quantity. The invoice came with dimensions and material type on it and they said if I bought those dimensions back again they could use them to make further replicas. I don't have them to hand right now but can get to them at a later date.

Two is that I am lead to believe that the emulators cover compression damping and the original rebound damping circuit covers the rebound damping. The rebound damping is then adjusted by fork oil viscosity. Once the rebound is set the emulator is adjusted. Sounds good to me but again I say I have no real experience I am just going off what is basically advertising material.

Thirdly my plan is to build a set of forks with the following features; Emulators, racetech springs and spacer under the top out springs to shorten the fork legs. The spacers will end up being somewhere between 25mm and 50mm depending on the required ride height. A question I have regards the two small holes which are near the top of the damper rods. I am worried that as one or both of these may end up being obscured by the spacer can I move them or possibly drill a single alternative hole or even eliminate them completely.



Cheers.
Jim.
Yes, you can. I've done this many times in the past. Although, it wont really matter.

The compression damping of this OEM BSA rod is that slot. The emulator requires you to drill 6ea 1/4" holes in the damper rod starting where that hole begins at the bottom of the rod. That eliminates that slot and allow the rod to flood up against the emulator valve. The rebound, at that point is then metered by the OEM BSA check valve at the bottom of the original piston and those two little holes. Adding one would quicken the rebound, but if your shortening the stroke, the spring will need to be stiffer, or if you cut the spring that's there, that will raise the effective rate of that spring and you'll need more rebound damping to control the front wheel.

I didn't want to wade into the multiple emulator scenarios being as new as I am to this board. But those scenarios wont work, for several different reasons.

What could work would be cutting the top off the damper rod entirely, adding a stem and using a Gold valve on that stem. You might need to drill the bushing beneath to flood the stanchion, but it'd work.

Ive been tuning modern day Motocross suspension for a very long time. The simplicity of this unit compared to a modern leaf spring, spring loaded cone valve or more standard twin chamber fork...It leaves you wondering really...Even an open cartridge fork looks like rocket science compared to this thing.
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kommando
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Re: Better OIF Damper rod piston ring

Post by kommando »

Buying some PTFE washers from

https://www.ebay.co.uk/itm/Bespoke-Cust ... 2749.l2649

These are to fit some Koni 76 series dampers where the iron sealing rings have broken. You specify the ID and OD and there are listings for different thicknesses.

Will add more when they arrive.
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Re: Better OIF Damper rod piston ring

Post by Shawn_Mc »

kommando wrote: Fri Apr 03, 2020 9:57 am Buying some PTFE washers from

https://www.ebay.co.uk/itm/Bespoke-Cust ... 2749.l2649

These are to fit some Koni 76 series dampers where the iron sealing rings have broken. You specify the ID and OD and there are listings for different thicknesses.

Will add more when they arrive.
Are you getting 1000 of those? :shock:
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Re: Better OIF Damper rod piston ring

Post by kommando »

No I ordered 3 for 2 pistons as I expect to break one testing for fit, total bill was £3.66 for all 3.

From the listing

Pack Qty 1 washer

Unfortunately, Ebay does not allow single items to be listed at less than 99p. So the prices can look expensive when you purchase a few. Therefore we are happy to offer a 30% discount when ordering 3 or more washers.
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Re: Better OIF Damper rod piston ring

Post by jim-nz »

Can anyone comment on the importance of the location of the two little holes. particularly in relation to whether they are above or below the stanchion end plug.

As stock at full extension the upper hole is inside the end plug and the lower is approximately 21mm below. If i run a 30mm lowering spacer under the top out spring the top hole is 21mm above the cap and the lower hole is inside the end plug and if i run a 50mm lowering spacer both the holes are above the end plug and the top hole will be partially obscured by the spacer.

Should i move one or both of the holes or perhaps replace them with one of an equivalent size?

My forks are stock except for emulators and 0.7kg springs.

Between 30-50 mm is the range of lowering i expect to be working in but i will not be sure what the final figure will be until i have tested and tuned the bike.

The bike is to be a road racer.

Cheers.
Jim.
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Re: Better OIF Damper rod piston ring

Post by Shawn_Mc »

Here's how the damping rods work. This drawing is fairly generic, but pretty much, everything is there and applies.


https://www.racetech.com/page/title/Emu ... hey%20Work
Current Bikes
1971 BSA B25 Victor Trail
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