Changing Springs (Gen I) Question

Just went through this today on BigOgre's bike (an '04 1st gen). He had a Yamaha shop install Race Tech Springs (1.0kg/mm) when they were also replacing the oil seals. After they did the work he immediately began to notice clicking metallic noises when the forks were even slightly compressed, worse when on the real roads, that appeared to be coming from the forks. At CFR a couple of us listened to them and agreed the sound seemed to be coming from inside the fork legs. We made plans then to dig into them later.
Today we (finally) had a chance to pull off the fork legs and found most of the parts seen in the above quoted post. He had no washers underneath the springs, but had the funny torpedo shaped black delrin spacer thingee on the damper shaft with the spring over it. The bronze stepped washer was on the top of the spring with a steel washer over that.

One problem that we immediately found was that the shop had installed the stock length top spacers back into the forks which put about 50mm of preload on the new Race Tech springs. This was made apparent when the lock nut shot across my garage when we released the tension.

I'm pretty sure that what making the noise was that the black delrin torpedo spacers, which are free to slide up and down the damper shaft, probably worked their way up the shaft and then the spring was allowed to work off to one side on the bottom, where it sits on top of the (flat) cartridge top. Once the spring is off center the black spacer would no longer be able to drop down anymore (as far) to help in maintaining the spring centering. Seems like a bad design to me.

To fix the problem we decided to put the brass lipped washer on the bottom of the spring, to hold the spring centered and also protect the top of the cartridge. Then we installed the springs with a pair of GP Suspension spring buffers (I had on hand waiting to go into my own forks) on the top of the springs to perform the same centering duties up there. They look like this:

It's the black thingee in the picture above.

By installing these spring buffers it holds the spring concentrically centered on the damper shaft, so the spring cannot work its way off center and rub on the inside of the fork legs. But, also being captured at the top of the spring stack, it means that the damper shaft does not ride up and down inside of that soft spacer and potentially wear it.

The above damper adds 10mm to the spring stack-up dimension, so you do need to account for that when you measure and cut your top spacers. Before the change, using only the Race Tech supplied parts, we had a 99mm space between the installed spring stack-up and the lock-nut underneath the fork cap (with the cap installed and the nut locked up). After installing the GP buffers that space decreased to ~ 89 mm. We ended up cutting those spacers a lot.

Some new fork oil and these components re-installed, we made some sag measurements on the bike and got ~25mm of static sag (just the bike weight) and 35mm of dynamic sag (rider weight on the bike). My experience says that this will still be on the sporty/stiff side of the suspension compromise. These are the sags that I have been running on my bike for the past several years and I might want to go a bit softer sprung for dealing with real world roads. But it's bound to be **** ton better than the way that they were installed previously.

I wish we had done sag measurement before, but I'm guessing we had zero static sag and just a little dynamic sag with all of that preload. I'll wait to hear from Mike (BigOgre) on what the results were, but I'm guessing he will be very pleased.

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RaYzerman19 said:

No you can leave the forks intact, cartridge stays in . I'll assume you've dumped the old oil....... Just be sure the diameter of the new springs is same as the old on the end that goes down....... oops just noticed you have Gen 1...... which means the "washer" on top of the cartridge should be big enough for the spring. On the upper end, depending on what kit you are trying to install, they may have supplied you washers or maybe not, if you need one. Next, you calculate length of spacer needed and cut your spacers. Now you take the springs out, add oil to the required level, etc.

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RaYzerman19 said:

I will dig up an instruction sheet from RaceTech..... it's all the same idea for spacer length and preload. Your plastic guides likely go in the top of the springs, with OEM flat washer on top of that, then the spacers..... you will have to cut them off. Back out the preload on the fork caps so the surface is flush with the bottom of the cap, and measure to that surface..... Essentially, you want 15mm of preload, meaning you have to compress the springs 15mm to get the fork caps threaded back on....... anyway, stay tuned.

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https://www.traxxion.com/Fork-Spring-Installation-Instructions/
I dug up the RaceTech instructions for my V-Strom, but those forks don’t have cartridges…….. maybe use Traxxions…..

The Delrin thing is to keep the springs centered so they don’t (a) get off the brass nut/washer on the top of the cartridge (which I think is big enough for the diameter of the springs anyway), (

keep the springs centered inside the tube, can be top or bottom. You put it where you think it will do the most good. Sometimes they give you a flanged washer, which will do the same thing. NOTE, your originals had nothing, and the earlier spring kits had nothing……. They relied on the ID of the tube to keep things in there, and there was a small end to the spring which could never fall off the brass nut/washer on the cartridge….. anyway, just sayin’, whatever looks good to you based on the springs you have. I think RaceTech’s go on the bottom also.

So, assuming it goes on the bottom, Delrin damper inside the spring, temporarily install onto the cartridge. Measure thickness of top washer (OEM) that sits on top of the spring. Extend fork tube, measure top lip of fork tube to top of spring. Deduct thickness of top washer. This is your first number.

On fork cap, back out preload adjuster so the bottom of it is flush with the bottom of the fork cap (if you wind it out all the way, it will be up inside the fork cap somewhat). Measure fork cap, bottom surface to bottom of top flange that becomes the fork tube cap. Subtract this number from the first number. Add 15mm because we want 15mm of preload when you finally assemble the forks (You will have to push down on the fork cap to get it to start threading in…….). Now, your final number is the length of the spacer you need. Mark with a tube cutter, then carefully hack saw it off….. or maybe you can use the tube cutter (I never have). File off any burrs.

Now, test fit. With everything together, top cap screwed on, raise fork tube and there should be a 15mm gap to the bottom of the fork cap or near enough. You can always compensate with a washer if something isn’t quite right, but don’t worry about being perfect to 1 mm or two either…..

If all OK, disassemble, pull spring and leave the delrin thing in the fork (so we don’t have to guess how much volume it takes up). Fill with oil, OEM spec says 98-100 mm below the top of the (collapsed) fork tube with springs out. Perhaps make that a little more (RaceTech says 110). Just means a little more air cushion, nothing you’ll notice much…… OK, put it all together, you’re done.

On the bike, check your sag, adjust preload to suit….. or, just screw in the preload until 3 bars are showing and go ride. Set rebound to 6-8 clicks out, compression same. Unless you already know what your dialed in previous settings were…… maybe back out one click more since you have better springs now.

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