Unofficial Royal Enfield Community Forum
General Discussion => Tech Tips => Topic started by: AgentX on September 08, 2012, 04:04:55 pm
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The following is pasted verbatim from my post on Ace's page; thought it might be of interest. Apologies for a lack of pics on my end, but the instruction sheet with the product has a good set of diagrams. (Edit: I just attached it to this post)
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Long time coming, but I finally installed the YSS cartridge valve emulators.
Executive summary--FANTASTIC! But you may need to do a little more work than just pop them in. Still a hell of a lot easier than a front-end swap.
Background:
I've seen reference to them as a Racetech clone but I have no personal idea, and don't know how much the Racetechs cost. These were $135, plus $10 for cutting
me some spacers. Believe they're made overseas. (Thailand, I think I once read?)
My fork is the old-school Bullet fork from the 1977 model year, with the screw-down oil seals. Can't speak for all bikes with all forks, obviously, but most of the Bullet forks seem to share the same basic configuration and operation.
I took measurements from a disassembled fork and Klaus at YSS tech support in NJ told me the 29mm would be a perfect fit. (AMENDMENT: The 29mm valves will not fit in the disc fork I just tried to transfer them into! Looks like 28mm or less will be necessary; next size down seems to be 26.5mm.)
Installation:
Basically, the procedure is to drill extra holes in the pumping rod ("hollow stud" or "spring stud" in the fork leg in most Bullet technical manuals) to allow oil to move freely; the cartridge emulator then provides all your damping via a speed-sensitive shim stack. On the Bullet, you drill out the existing bottom hole to 8mm (or 5/16") and then add three more 8mm holes on top of it.
The emulator itself is a small cylinder with an adjuster screw coming out the top. It sits on top of the pumping rod and under the spring, trapped by light spring tension at rest. Because of the nut on top of the pumping rod, you need to add a cylindrical spacer to give the emulator a place to sit. (Some other makes' rods have a cupped shape on top, so they don't need this.)
Klaus provided me PVC spacers, but they ended up being 1) too thick-walled, and covered up the existing rebound valving holes 2) too short, according to Klaus, when he saw how the rebound system operated; he said the oil needed more space to flow. So I got thinner steel ones machined...17mm high, about 1.5mm-thick
walled. They fit perfectly.
So, the valve was around 14mm tall IIRC, and the spacer was 17. Obviously, this height shoved under the spring was going to add an intolerable amount of preload to the spring. I simply had the springs cut to correspond and ground flat again, taking the spacer/emulator stack height off the top portion of the coil. This portion is static; the coils are touching one another and don't add anything to the operation of the suspension, so it's no-loss.
In reassembly, I used 200ml of 20wt Motul fork oil. 20wt is all I can find locally so I gave it a shot.
Initial Evaluation:
When I got the front end buttoned back up, I was a bit concerned. It felt like a rock at first. But you need to remember suspension is not designed to feel good sitting still. (A common problem with mountain bike suspension...they under-spring and under-damp because they know most punters will just buy whatever feels squishy on the showroom floor!)
I was a bit cautious for about 30 seconds on the test ride before I was blasting over speed bumps at a pretty shocking speed [Enfield-relatively speaking...] The speed sensitivity of the valving is obvious once you're moving. Took the rough choppy stuff and big humps just fine at speed. I picked my way down some ledges and steps, and the bike took them nicely...soft landing with good
progression mid-stroke.
The valves were set with 2.5 turns preload on the shim stack adjuster screw(2 being the stock recommendation for lighter riders...I am 160 lbs.) Oil weight is the only way to control rebound and the 20wt was suitably fast.
Overall, a rider on smooth pavement might like a bit more cranking on the adjuster screw, or maybe a higher oil height for greater progression, but for India's chopped-up roads this setting felt great for a start. The front of my bike feels better than the Hagons on the back now.
Unfortunately, you need to open up the fork to change settings, but even as it is, it's a massive improvement, so I will likely ride it like this until my new fork bushings show up. Then I'll add a turn of preload and see how it does.
I'll re-post if there are any future problems or revelations.
Website for the product is: http://www.yssusa.com/products_yss_pdforkvalve.html
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This is fantastic news! Thanks for sharing AgentX ! I'm very interested cuz I'm not happy at all with the shocks on my bike. Have you noticed if the the heavy diving when breaking hard has lessened after the up grade?
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Yes, there's less dive now. I never had a lot of it before, but my fork (it turns out) had some elastomer top-out bumpers installed, which decreased shock height and increased preload...this may have helped me in that regard, even prior to the installation.
You can tune the valve, so you can stiffen the damping if that's your preference.
The valve doesn't have separate high speed and low speed compression damping adjustments, however, so you can't really tune out brake dive specifically without making the fork overall less compliant. Generally, I'd guess that only top-end super-modern bikes have separate high and low speed compression circuits.
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OK, time to resurrect another old thread! There seems to be maybe two members here that have any experience with installing emulators on these bikes. Searched and searched for any info on specific part# or what other make/models for these emulators from YSS. Can't seem to find any mention other than the diameter is 29
mm, for 35mm forks. Also read somewhere about ones from MikesXS : https://www.mikesxs.net/product/27-1086.html (https://www.mikesxs.net/product/27-1086.html) So one would assume emulators for 1977-84 Yamaha XS650's will fit. But a YSS part# and knowing the specific make/models they fit (as there is no mention of R-E) would help for others future reference. ;)
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YSS sells them by diameter. There's nothing make/model-specific about them.
As noted in my post, the 29mm fit my first drum brake fork and the 26.5mm fit the disc fork. That is the only spec you need to know to order them from YSS.
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YSS sells them by diameter. There's nothing make/model-specific about them.
As noted in my post, the 29mm fit my first drum brake fork and the 26.5mm fit the disc fork. That is the only spec you need to know to order them from YSS.
Got it. I forgot to mention Racetech as the other option. Those 29mm emulators fit other bikes though. THAT is what I want to know. Some may buy YSS, others Racetech, maybe some new unknown off brands, some may buy them direct, online, on Ebay, or at a swap meet. Always good to know what other bikes they fit. :)
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I have looked into these before but never pulled the trigger. But this thread being brought back up got my curiosity brewing again. One reason I never pulled the trigger on these is because it seemed like a big PITA to install and set up. But I've been reading all the tech support for these at RaceTech for the last 30 minutes and it actually seems really simple to do. Especially considering that I have a whole other bike with another pair of forks that I can build off of the bike and then just swap out the legs. I even have a brand new pair of fork springs from H's that I never installed because I didn't feel like making spacers at the time. And actually, Metal Supermarket is literally just around the corner from work and they cut everything to spec for your needs. So I bet I could just take one of the fork assemblies down there and have them cut me a few different spacers at different lengths for $10-$20.
For those who are still trying to wrap your head around this mod, here is the RaceTech fitment guide with illustrations that make it much easier to visualize what is going on.
http://www.racetech.com/download/IP_FEGV_FIT_web.pdf
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AgentX - I do have a question for you. Does the emulator sit on top of the fork spring perch on top of the damping rod? Or does the emulator replace the spring perch?
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And actually, Metal Supermarket is literally just around the corner from work and they cut everything to spec for your needs.
:o
You effing guys and your living in civilization... spoilt, I tell you! ;)
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AgentX - I do have a question for you. Does the emulator sit on top of the fork spring perch on top of the damping rod? Or does the emulator replace the spring perch?
It sits just as in the Racetech .pdf you attached. Since the Enfield damping rod is flat on top rather than cupped, you need to use a short tubular spacer under the emulator for it to sit in.
Springs need to be shortened to correspond to the added height of the spacer/emulator combo, unless, I suppose, you happen to need a massive amount of preload added.
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Do you think I will be ok with just the spacer on top of the damping tube? My replacement fork springs were about 2.5" shorter than the originals anyway which is why I never installed them.
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Apologies if this double-posts, but I thought I'd entered a response from my mobile and now I don't see it.
Best I see it, you could use the shorter springs by:
1) using a long spacer under the emulator; don't think this would cause issues with the emulator unless somehow it put the emulator above the oil level in the fork
2) using a shorter spacer under the emulator and another on top of the spring to take up any resulting slack
3) using a spring or spring/spacer combo underneath the damper rod as a lengthened top-out spring to shorten the overall fork length, which might be desirable depending on geometry concerns.
Overall, unless you're running into coil bind with the shorter springs, you should be able to space it out to work.
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Just received a response from MikeXS about the emulators they carry. They are 23.8mm diameter and 14mm tall. While they are smaller than the YSS mentioned above, they may still work with custom fab'd adapters. From whats been mentioned on various other vintage bike forums many have used them on larger forks than whats on the Enfield, with good results, and at $57 for a set seem worthy of considering. I'll be pulling the forks soon and verifying the dimensions to see if they are the same as what Agent posted, and what it will take to make 'em work. (unless somebody already has and would post!) Here's a link to a good thread by someone who dissected them basically: http://www.xs500forum.com/index.php?topic=240.0 (http://www.xs500forum.com/index.php?topic=240.0)
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OK, pulled a fork, disassembled and took measurements. This is on a 2001 500
Spring Free Length= 543mm/ 21.375"
" Outside Diameter= 28mm
" Inside Diameter= 18.5mm
Spring Stud Rebound Valve (picture #2): Diameter (springs sits on top of)= 28.5mm
Inner Raised Tube Diameter= 18mm
Fork Tube Inner Diameter= 29+mm
Manual and various other sources calls for a 521mm/ 20.5" free length spring with a 1" diameter (based on various sources). It appears someone prior to me fitted a longer spring w/ a heavier rate (I suspect this bike in its past life pulled a sidecar)
Regardless, the spring stud and fork tube dimensions should be consistent. The 29mm YSS and 29mm Race Tech FEGV S3501 emulators will fit the later Enfields, and doing as Agent has mentioned/done should work no problems. But the MikesXS 23.8mm emulators will work also, as well as the various sized YSS/Race Tech emulators that are available (23.8mm/26.5mm) and the fork spring will rest on top of these sufficiently, only the required spacer would have to be stepped inside for the emulator to sit in and the outside diameter of the spacer could be up to approximately 29mm to match the spring stud rebound valve. Here's some pics of the components, the last picture shows measuring the length of the stud/valve in order to determine (subtracting the distance of the spring below the fork tube end) how much preload (in stock form) will be put on the spring when it is screwed into fork tube bottom.
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Got the MikesXS emulators, nice quality as expected, made adapters from gray 1/2" plumbing "couplers" from Lowes, which are 28mm diameter, have pipe stops (ledges) in the inside, perfect for the emulator to sit on, cut off 4mm from each end (down from 39mm to 31mm) one sides hole enlarged to a tick over 23.8mm for emulator to fit in, the other hole ends inner edge is chamfered to clear rebound valve head ports. All minimum inside clearances with emulator, spring, adapter and valve head are good. Ready to install, emulators cost $63.39 shipped, and couplers were about .60 cents for both. Less than $65 and minimal time to make the adapters. Here are the measurements:
Adapter to fit MikesXS emulators (23.8mm):
length= 31mm (4mm off each end )
diameter=28mm
emulator hole (one side only) diameter= 23.8+mm
hole depth to step= 14mm
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Have you assembled the forks yet and had a chance to ride?
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Have you assembled the forks yet and had a chance to ride?
Not yet, hoping later today. Have to cut down the springs to compensate for the adapter, yet mine don't have any dead coils where I can just cut and grind it flat, I'll have to cut and then torch the coil to bend it then grind a flat so the whole spring diameter make contact. Screw driver inserted where I want the first bend, spring clamped to apply pressure and then propane torched to set the bend. Repeated this process further up the coil closer to where the cut was made.
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Emulators installed. Using Race Techs instructions they recommend to drill 1/4" holes in damper rods under 17mm so that's what I did. Mine had two holes, I ended up drilling 4 more holes for a total of 6 1/4" holes and chamfered the holes with a bevel cutter and small round file. Polished the damper shaft per Race Tech, cut the spring down, stuck a screw driver in between the coils where I wanted the bend to start, then used a vise grip (for clamping sheet metal) to get between the coils and clamped it beyond the screw driver , and used a propane torch (didn't have much faith but it actually worked) to heat the coil near the screw driver and was able to "set" the bend. Worked better than expected. Also replaced the seals, but removed the top seals wire in hopes of reducing the excessive stiction somewhat. 225cc of Mobil 1 synthetic trans fluid added (will need to adjust most likely) to ensure the level is above the adapter/emulator. Road test tomorrow if weather holds out.
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Nice work! Never thought of polishing damper rods.
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Nice work! Never thought of polishing damper rods.
Me neither, a waste of time I'm most sure but Race Tech mentioned polishing I think it was Triumph dampers and I thought what the heck! :o
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Have you assembled the forks yet and had a chance to ride?
All buttoned up, set the emulator preload at 2-1/2 turns and took for a spin. Bike weight is 350lbs, 210lb rider, Mobil 1 synthetic ATF, unknown fork springs (static and rider sag perfect though) At lower speeds it is much firmer with much less brake dive, nothing jarring but I could stand a little more plushness. At higher speeds through the twisties and with some bumpy pavement thrown in the front end feels planted, smooth, especially through esses, no chatter or oscillations detected over pavement undulations. Will back off the emulator preload, maybe try a lighter emulator spring, up to drilling an extra hole in the valve plate per Race Tech tuning manual:
http://www.racetech.com/page/title/Emulator%20Tuning%20Guide (http://www.racetech.com/page/title/Emulator%20Tuning%20Guide)
to see if I can gain a little plushness at lower speeds and over smaller bumps. I've already made a tool to drop down from the top of the forks to adjust the emulator preload allen bolt, and now working on a two piece tool to slide up through the bottom through the damper to reach the jam nut on the emulator, whilst holding the emulator body to keep it from turning when adjuting and locking the nut down so I wont have to pull everything apart to adjust. Fingers crossed.
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All buttoned up, set the emulator preload at 2-1/2 turns and took for a spin. Bike weight is 350lbs, 210lb rider, Mobil 1 synthetic ATF, unknown fork springs (static and rider sag perfect though) At lower speeds it is much firmer with much less brake dive, nothing jarring but I could stand a little more plushness. At higher speeds through the twisties and with some bumpy pavement thrown in the front end feels planted, smooth, especially through esses, no chatter or oscillations detected over pavement undulations. Will back off the emulator preload, maybe try a lighter emulator spring, up to drilling an extra hole in the valve plate per Race Tech tuning manual:
http://www.racetech.com/page/title/Emulator%20Tuning%20Guide (http://www.racetech.com/page/title/Emulator%20Tuning%20Guide)
to see if I can gain a little plushness at lower speeds and over smaller bumps. I've already made a tool to drop down from the top of the forks to adjust the emulator preload allen bolt, and now working on a two piece tool to slide up through the bottom through the damper to reach the jam nut on the emulator, whilst holding the emulator body to keep it from turning when adjuting and locking the nut down so I wont have to pull everything apart to adjust. Fingers crossed.
Great pictures and details on this project !
If you can change fork oil without taking them off the bike, changing to different grade of fork oil could adjust damping. There are many weights of fork oils available from 2.5W,5W, 10W up to 30W with viscosity ranging from 15 cSt to 100 cSt. I see that you prefer ATF of Mobil whose viscosity is about 36 cSt, close 32 cSt of 10W fork oil (Bel-Ray). Going up or down will make the fork firm or soft.
The tools you are making to access emulator from top and bottom will be amazing. Do you have a picture of the tools ?
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Pics soon, the tool for inserting down through the top of the fork is basically a long t-handle with a centering sleeve and a small allen (hex head) pressed in the end to engage the emulator bolt, the tool for inserting up through the damper (spring stud) is also a t-handle wih either a blade tip or hex tipthat will engage a modified jam nut. Pretty confident iit'll work, and not be too complicated. The whole idea is to be able to adjust the emulator preload without yanking it all apart and make a set of tools that are easily replicated. 8)
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Alrighty then.....tools are finished! And I can proclaim: SUCCESS!
Cartridge emulators installed in the Bullet can be adjusted without having to remove them. I have made three simple tools and modified the jam nut so all one has to do after the emulators are installed and the front end is assembled is to:
1) Remove the top fork caps in the casquette, remove the spring stud caps on the bottom of the forks, let the fluid drain into a container (to be reused) insert the preload t-handle tool down through the fork to engage the hex (allen) bolt that adjusts the preload of the emulator spring, insert the emulator lock tube up into the spring stud (damper rod) and engages the emulator body "splines", then insert the jam nut t-handle and engage the modified jam nut.
2) Holding the preload t-handle stationary (a helper is best used), and then holding the emulator lock tube stationary, simply loosen the jam nut a few turns with the jam nut t-handle.
3) Now, still holding the emulator lock tube stationary, make the desired preload adjustment with the preload t-handle, then hold it stationary again, along with the emulator lock tube, and tighten the jam nut with the jam nut t-handle.
Install the bottom crush washer and cap, refill the fork, install the cap, and test ride. Repeat the process as needed to dial in the desired damping. No need to tear the whole front end apart to make the adjustment, which from the research I've done, is required on any bike that these are used on. No so with the Enfield. It can be adjusted, and quite easily with the design of the spring stud.
Keep in mind these tools are for the MikesXS emulators that are 23.8 diameter. Not sure what size bolt and jam nut come on the YSS or Race Tech. Total cost of the tool supplies is less than $15, and not much labor. Most of the time involved was doing the "figuring out how" in my head. 3 foot 5/16" steel rod from Lowes (hardware store) the allen I had extras of, and the brass tube is from an ebay hobby/train supply outlet. After grinding the t-handle fork I hardened and tempered it. This is one way it can be done.Ffor your viewing pleasure here are some pictures.
This is the emulator lock tool and jam nut t-handle tool inserted into the spring stud (damper rod)
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The jam nut t-handle
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Emulator lock tool engaged into the emulator
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Preload t-handle engaged in the emulator allen bolt
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Laid out
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The tools
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The modified jam nut and jam nut t-handle tip
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Nice work! Did you have to modify the jam nut because a socket will not fit up thru there onto the nut?
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Nice work! Did you have to modify the jam nut because a socket will not fit up thru there onto the nut?
Exactly. The spring sud hole diameter is 9mm, the jam nut takes a 7mm socket.It might be possible to turn in a lathe or grind it down one of those cheap 1/4" drive sockets that you see for a few bucks in clearance bins. All I did is flipped the nut so you thread it on "nylon" first, , used a dremwl with cutoff wheel to grind sharp edged slots. Like Peter Brady said of his volcano: "It Works!"
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That's what I thought looking at the pics, you basically made your own spline drive. My boss has a small lathe at work and I know I have an extra 7mm, so I'll see if I can turn down the socket far enough to fit inside the damper tube. If that works, how much tension do you think is on that nut, 8-12#? I'm thinking in regards as to how thin I can actually make the wall of the socket. You say the ID is 9mm, a 7mm nut is 8.1mm corner to corner, which means the wall can only be about .25mm thick to work. I wonder if the socket will fail before it holds anything.
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That's what I thought looking at the pics, you basically made your own spline drive. My boss has a small lathe at work and I know I have an extra 7mm, so I'll see if I can turn down the socket far enough to fit inside the damper tube. If that works, how much tension do you think is on that nut, 8-12#? I'm thinking in regards as to how thin I can actually make the wall of the socket. You say the ID is 9mm, a 7mm nut is 8.1mm corner to corner, which means the wall can only be about .25mm thick to work. I wonder if the socket will fail before it holds anything.
The torque on the jam nut to snug it is really minimal, I made a few different tips with those prongs, 2 prongs at first and cranked it till they twisted off. The nut was tight enough to not worry, others I tried tightening a few nuts and then used a box wrench to undo etc. With the nylon piece on that nut it holds pretty damn tight, and all you really need to do is snug the nut to ensure the bolt doesn't back off. One could also somehow pin the emulator to the adapter to the rebound valve so it doesn't rotate when adjusting and then there would be no need for the tube and you'd gain additional diameter and have to turn down a socket a little less. I think there would be sufficient material on the socket for it to still be strong enough to snug the nut.
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Just an update, I ended up drilling a second low speed damping bleed hole on the valve plate as suggested by the Racetech tuning guide
and have the emulator spring preload now set at 2 turns. With about 220cc of atf fluid I am pretty happy with the results. A touch more supple at slower speeds and slightly less firm at speed than after the initial installation where I had one bleed hole and 2 1/2 turns of preload. Ideally I would go with a slightly softer emulator spring and adjust the preload to where it was in the middle of its adjustment range, about 3-4 turns of preload so I could firm it up more or soften it more. But as is I will leave it and play with fork oil levels for the time being. Overall, a highly recommended mod IMO.