emulators on a 79

Larry Zimmer
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Re: emulators on a 79

Post by Larry Zimmer »

Best way I can try to explain 'point C' is: When you have all the bits in place ready to close things, the cap should need to be compressed against the spring by some amount before you can engage the threads to screw it into the fork tube. That distance is the spring preload. Among the various bits that go into the tube, there should be some type of spacer sitting on top between the spring and the cap. That spacer is what would be adjusted either by cutting it to shorten it; or, getting a longer piece. Honestly, I don't know if the original '79 tubes have a spacer. If not, you may need to 'create' one. A piece of PVC pipe will work.

As for which spring to use, I'd say depending upon what type of riding you do, I suggest either the middle one or the stiff one for you. I don't remember which color is which. I believe RaceTech identifies them.

P.S. Good to hear the seal removal went well.
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wyly
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Re: emulators on a 79

Post by wyly »

I found this video but I don't know if this guy knows what he's doing...it doesn't seem to match what I read (or I'm just not understanding it on the race tech website...

if someone would watch the video and let me know... please :-)

https://www.youtube.com/watch?v=fXsZqGGUvH0
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Re: emulators on a 79

Post by NobleHops »

Reread what Larry said. Its simpler than you think. With that stack setup as instructed, everything sticking above the top of the fork tube, including the cap up to the edge that contacts the top of the fork tube equals the preload. I don't recall what they suggest but IIRC it's around 15mm. Adjust the spacer length till you get that amount, remove the springs, set the fluid height, replace the springs and cap it off. You're home free if you're this close.
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Re: emulators on a 79

Post by wyly »

am I using the original springs for measurement? then cutting the spacer to make up for the shorter spring from race tech?
and if that is correct do I do the measurement with the new emulator in place or the oem setup?
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Re: emulators on a 79

Post by Larry Zimmer »

This might make it clearer, Wyly. After you have the emulators installed, put all the other pieces (washers, etc. and the RaceTech springs into the tubes. Extend the tubes full length. Be certain you have the washer on top of the spring. Now, measure from the top of the spring (actually the top of the washer that is on top of the spring) to the top of the fork tube. Be certain the fork tube is fully extended while you measure. Make your spacer 15mm to 19 mm longer than that measurement. (5/8 to 3/4 inch) Then, put the cap over the spacer, PUSH, and screw it together.

P.S. I watched the video. From my chair, I didn't see him put any preload onto the springs. Most of his other info was good. Just not his preloading. And, he didn't think enough to adjust his camera, or work position, to show the top of the tube when he was doing what he called preload.
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Re: emulators on a 79

Post by wyly »

Larry from that answer am I right to assume I don't need a top washer as my Racetech instructions call for?

racetech instructions call for a washer on top of the spring and another on top of the spacer or under the cap, the diagram shows it tight to the cap...

but the washers inside diameter is too small to fit over the nipple on the bottom side of the cap...no mention of what to do then, leave it as in picture (that seems very very wrong), enlarge the hole, or find another washer...or if understand you correctly no washer on top of spacer.

now if ignore the RT instructions and follow your method I measure 5.5" from washer to top of tube ...the spacer supplied by race tech is only 4 7/8"... I'll need to buy more spacer what type of material is acceptable for a spacer? electrical conduit? 5.5" + 3/4"...new spacer 6.25"?

7196



paid a machine shop $50 more than I intended to spend on drilling holes but there weren't any used drill press available for less than $200...but the machinist was a bike nut who I swapped bike stories with so now I've got a new buddy who I can bring my work to...
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Re: emulators on a 79

Post by Larry Zimmer »

Wyly,
That spacer tube looks to be PVC pipe. Or similar material. Should not need the washer with that. What is the dimension from the bottom of the cap flange to the bottom of the threads where they would contact the spacer? If it is between 15mm and 19mm, I would suggest that you only need a spacer to come to the top of the tube -- that is, 5.5inches. What you want to accomplish is to compress the spring by a nominal 17mm after the cap has been screwed into the tube. If you do need to get a longer spacer, try to use one piece of PVC of the appropriate length. Should be able to get it at many hardware stores/Home Depot, etc. Should be essentially same stuff, ID and OD, as the RaceTech spacer. If necessary, some 1 inch steel water pipe might work. With that, you will want to fit a washer on top of the spacer under the cap. Otherwise, the steel pipe will not be kind to the aluminium cap when you screw it together.

Anyone else have any good experience to give Wyly, do join in.
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Re: emulators on a 79

Post by wyly »

If I'm measuring correctly, from the underside of the cap/flange to the bottom/thread it's 18mm...
I have some 3/4 PVC conduit that's ok to slip over that nipple but it's OD seems a bit large, it fits but not by much... I'll go to Home depot in the morning and see if I can find something smaller the ID needs to be at least 9/16 or 15mm to fit over that nipple...
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Re: emulators on a 79

Post by Larry Zimmer »

If were me, Wyly, I'd use that 3/4" stuff you have. Assuming it goes into the tube without any force, should be good. It doesn't move inside the fork. I assume it is PVC water pipe with a wall thickness approx 1/8"+. That's what I used in my Suzy with 35mm tubes. That 'nipple' on the cap will fit nicely inside it. Cut the length so that the spacer is flush to a mm or so longer at the top of the tube when fully extended. You can 'tinker' with the length of the spacer after doing some riding to tweek the preload.
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Re: emulators on a 79

Post by wyly »

Larry Zimmer wrote:If were me, Wyly, I'd use that 3/4" stuff you have. Assuming it goes into the tube without any force, should be good. It doesn't move inside the fork. I assume it is PVC water pipe with a wall thickness approx 1/8"+. That's what I used in my Suzy with 35mm tubes. That 'nipple' on the cap will fit nicely inside it. Cut the length so that the spacer is flush to a mm or so longer at the top of the tube when fully extended. You can 'tinker' with the length of the spacer after doing some riding to tweek the preload.
I'd already gone to HD and bought 10' of 1/2" pvc electrical conduit before I read your post... it's exactly the same dimensions as race tech's spacer, it fits nicely over the nipple will which will hold it in place, if it doesn't work I can switch to the 3/4" ...only $4 for the conduit, 9" left so I can experiment with different lengths if I need to...got the spacers cut, sanded and cleaned ready to install...I only need to adjust the emulators and put in the new seals before I re-install the forks...
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Re: emulators on a 79

Post by wyly »

reading my emulator instructions I see there is an option to drill another two bleed holes for low speeds for a total of four, something I can do later if I need too...has anyone done this?... race tech implies it's best for vintage bikes...

set the emulators to 4 turns in on the blue #40...
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Re: emulators on a 79

Post by wyly »

forks on, oiled...just need to torque everything up and some nice weather in the next month for a test ride. :D
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Re: emulators on a 79

Post by Larry Zimmer »

wyly wrote:reading my emulator instructions I see there is an option to drill another two bleed holes for low speeds for a total of four, something I can do later if I need too...has anyone done this?... race tech implies it's best for vintage bikes...

set the emulators to 4 turns in on the blue #40...
As you said, Wyly, "can do later". I'd ride it as it is -- see how it feels/rides/handles. Now ---- for some sunshine, clear roads and warm air.
Larry Zimmer
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