One more time - fork springs

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Mark W
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One more time - fork springs

Post by Mark W »

OK, I've finally got everything together for reassembly. Thanks to Vince for putting up with my lack of knowledge and my forgetfulness.

I've put the clips on the bottom of the spring and inserted the spring into the fork. Without the spacer washers, I have about 3 mm of space between the damping rod nut and the top of the fork cap. I am assuming that I need to make my 1" PVC spacer this length + whatever amount of preload I want on the springs (I'm going with 5 mm to start as that seems to be a common answer for initial preload length).

I've read Eric Gorr's book on replainc fork oil and there seems to be more than just pouring in oil and then measuring the correct amount fro the top. Is there anything to do after pouring in the oil and prior to measuiring the amount of oil - ie. do I need to pump the damping rod a few times to release trapped air bubbles or do I need to let it sit for awhile after addig the oil.

This project should be finished by the end of the day.

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Post by KDXer »

You measure between the top of the spring and the bottom of the fork cap screwed all the way down.

Yes you need to pump it up to get the oil right in everywhere.

Hope it helps some.
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Post by Indawoods »

Pump that rod several times, let it sit a bit and pump it again.
You need to get the oil all through the system and get all the air out, this is the only way you can get an accurate measurement.

Remember... When you are putting the cap on the tube... turn the tube instead of the cap, this will prevent that clicking sound that you get if you turn the cap instead.

Also... after you cut the PVC, make sure the edges are cleaned up, you don't want any of that floating around in you oil blocking orifices.
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Post by Mark W »

OK Vince it isn't April 1 so you must be serious on the turn the forks instead of the cap. Why does turing the cap instead of the fork make a clicking sound. Enquiring minds want to know....

thanks

Mark
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Post by Indawoods »

It's really a mystery... My theory is, it puts bind on the springs and unseats them from the bottom clips or seat. The clicking has been widely reported by people changing out their springs and after tearing them back down, they could not find anything wrong. But, reassembly with turning the tubes instead, the problem goes away. Go figure.... :?

And...you don't turn the entire forks... just the top tube or else you have the same effect as turning the cap.
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Post by KDXer »

Sounds funny but he's right. Yeah you hold the cap and twist the shiny bit up onto the cap.
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Post by KDXGarage »

I helped wsjkawasaki with his forks the past couple of days. I finally got to see what you all were talking about on the various parts. I noticed that there is no spring guide, so maybe that helps to cause any binding, along with the cap, spacer seat, spacer, spring seat and other spring seat. With all those parts spinning during reassembly and it not having a spring guide, it is not surprising about the spring scraping the inside of the inner fork tube. We did the "spin the inner tube into the cap" trick as well. Thanks for the advice gents.

On the fork oil, pump the rod a bunch and let it set. Measure the oil level before putting in the springs.

You may want to get your spacer length measurements correct before you worry about the oil. It proved to be helpful to get those set, then take them off, pour in the oil and pump/wait/check oil level, THEN put the spring (with bottom spring seat cc! :grin: ) and other parts back in.

As best we could, :lol: we calculated a 2 13/16" spacer would create about 10mm of preload. HEY! I just did the actual math, and if my previous reading of 38mm of preload stock is correct, then we were less than 1mm away! :supz: I wish we had a calculator when we were working on it!!
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Post by canyncarvr »

Sounds right.

You're taking the spacer locating washers into account? Those flanges are about 3mm.

And, yes...with the cap all the way on. That does NOT mean the jam nut has to be run back up the rod...it can just sit where it is while you're doing your figuring.

Of course...don't forget to run that jam nut back up against the cap when you're done.

You're running XR springs, right? Thus the small preload spacer?

All my personal worthless opinion for your application...but you'll like a 3mm preload better'n 5mm. Those two silly little mms made a big difference in my forks.

Don't forget to set your clickers. Set'm as soft as you can and not be bottoming the frontend...much. Maybe from time to time...:wink:

The OEM valving is less responsive to the clickers than an aftermarket valve setup is.

Get yourself a set of pressure bleeders. You'll like them a whole lot!!

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Post by KDXGarage »

You are not suggesting to leave the cap bottomed out on the rod, are you? I just bottomed them out, then backed them off a touch.
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Post by Indawoods »

All done Mark? :razz:
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Post by Mark W »

I alomost got done but then was called in to do some more entertaining for the in-laws and other assorted guests.

I got the spacer made - that was a pain to cut straight. I ended up inserting an aluminum rod about the same diameter as the ID of the PVC. I cut 4 mm spacers and they are about as straight as I think I can get them.

I poured in the manual recomeended amount of oil - 530 ml and found that it wasn't enough so I puored in some more. I still have to get the right oil level but that will have to wait until tomorrow after Easer dinner and after watching James Stewart return to the ring.

I do have one problem. My springs were slonger than 530mm. Long enough than when I put on the fork caps with the old spacer washers, the cap is tight against the springs - maybe 1 mm of free space. So, I cut 4mm spacers and now I have to turn one of those spacer washers the other way. Putting the two of them between the new PVC spacer would have required a 7-8 mm spacer so that the ends of these old spacer washers would not touch. What I did was the following:

The washer on the bottom still is facing into the new PVC spacer (facing the same way it came out of the stock set-up. On top of this I put the 4 mm PVC spacer. On top of this I put the spacer washer but put it in so that the indenture is going up into the fork cap. I don't think this will be a problem. Comments?

So, hopefull tomorrow the bike will be together but you never know.

Mark
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Post by Colorado Mike »

I wonder why all these springs are different lengths. I just put in some XR400 springs .38 Kg/mm , and they were about 513 mm long (luckily both of them). I cut my PVC spacers to 1 1/8 " long, which gave me very little preload, something like 3mm. Hopefully I'll have a plush ride but a little firmer than with the stockers.
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Post by IdahoCharley »

My XR 400 springs were 533 mm long. Reportable OEM out of a 00 or 01 XR 400.
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Post by canyncarvr »

Hold the phone.

Don't run that washer upside down. I take that to mean the protruding part (thin, sharp edge) is going to contact the cap? I wouldn't like that.

Either remove one of the washers or machine (file, grind, cut) the 'nipples' of them so they can fit facing each other in the spacer.

Which, BTW is a side effect of schedule40 PVC in this case...I don't worry about it directly contacting the cap. I wouldn't do that with metal, though.

re: Bottom the cap?

Yep. It was bottomed when I took it apart. It kind'a tends to do that while dealing with the rod nut getting jammed at the end of the threads anyway. If you choose to NOT bottom it out, just take the difference into your preload measurements.

Uh....you listening Mark? :wink:

You could back your cap off the rod the amount of space you need to put that other washer in.

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Post by KDXGarage »

Thanks for the info.

The light bulb just came on! I JUST figured out why the 1995 and up damper rods are drilled and have a bleed hole. It is for the air screw. My USD forks have the air bleed screw away from the center, out towards the side). I was wondering for a few days why they were different. It makes sense now.

Don't back it off too much, though! I just backed it off enough to get the parts to quit touching each other.
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Post by IdahoCharley »

MarkW - I also ran the spacer washer into the fork cap.

The raised radius portion will center itself around the center portion of the cap where the rebound rod attaches; I don't believe there will be a problem. The lower spacer washer I turned into the PVC spacer. 4mm spacers would be tough to cut - I cut my spacers then squared them up with a disc sander. The disc sander was stationary and I just carefully held the spacer against the sander then rotated it 90 degrees and reapplied to sander until it was the correct thickness and square. :supz:
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Post by canyncarvr »

IC: You've paid more attention to it than I have, then. I don't recall the cap having a raised radius portion that will center the cap. I'm not saying I recall there isn't such...but that I have no recollection at all as to much of what it looks like.

Still, the very small area of the washer edge will be pounding into the cap...centered or not.

Your call, certainly. I wouldn't do it.

re: 4mm spacers

Yeah. Fun, 'eh? Using a mitre box (powered or otherwise) or a table saw worked pretty good. Still had to file a nubbin off.

There's still the 'back the cap off the rod threads' idea. That's good. The cap is threaded ONto the rod a good bit. Not a big deal to lose a couple mm.

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Post by KDXGarage »

"There's still the 'back the cap off the rod threads' idea. That's good. The cap is threaded ONto the rod a good bit. Not a big deal to lose a couple mm."

I have read of a couple of recent year YZ's that had trouble with the rod and cap coming apart because it may not have been down on the rod enough. That made me think to keep it as far down as possible without bottoming out. I just threaded the nut up to that point, took the spacer measurements from there, then disassembled / reassembled it.

By the way, the FRP springs had the rate ground into one end of each spring. I thought that was cool. Seeing 40 on one and 42 on the other was not! :roll:
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Post by Mark W »

I guess I can't see a difference between putting the top washer either into the fork cap or pointing it down into the PVC. Either way the washer is the same diameter and with the spring taught due to the preload, it isn't as if the top washer is going to be moving up or down.

Once again, didn't get to it tonight. Washer broke and had to install a new one. Broomball in 1/2 hour. Do I hold the record for longest time required to change out fork springs? I think I am well over 2 weeks now. Must deserve some kind of prize.

Getting nice enough up here to seriously think about riding the bike. I think we went over 60 today. Couple of places should be good to go.

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Post by Indawoods »

Still haven't gotten a check from Fredette for my KDX frontend. :mad: I need to get my carb off to Ron and Jeff is holding it up! (how many people can say that?)

It got to 60 today and supposed to be 72 tomorrow... talk about getting the itch!!!!
Conditions woulda been perfect today and better tomorrow.... I may have to just drive up to Beecher and look Jeff up so I can get this show on the road. :lol:

Mark...screw Broomball? :roll: Get those forks done so I can hear how nice they feel! :razz:
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