Race Tech Springs confusion / questions

[ReidMcT]

I bought Race Tech fork springs for my 2016 RC390. I am confused about how much to shim them.

The only instructions in the package said to see the Rectech website, which I did. That site said to set ’Preload’ to 10mm. I am not sure how to put that into practice on the RC390. I presume it is done with shims/spacer tubes, but I don’t know if they are saying to install only 10mm of spacers in total, or what. I don’t think that could be right, since the new springs are 30mm shorter than the stock springs. Maybe they want enough spacers installed so that the cap compresses the spring by 10 mm when installed; but that seems rather clunky to figure out.

Other items I found in the package you sent were some washers totaling 12mm in thickness (6mm per leg), plus a lengthy piece of metal tubing.

When I disassembled the forks, I found that each of the stock forks had three nylon shims on top of the springs, two black ones sandwiching one white on, and totaling 12mm.
Do I leave these the in place and add more spacers?
Thrown them away?
Put a 40mm slice of the tube atop each spring (30mm to make up the difference in length from stock, plus 10mm for the recommended preload)?
Something else entirely?

Help!

One other thing: RaceTech uses a mm measure for fork oil height, instead of the volume method in the KTM service manual. Do they both accomplish the same level?

Thanks!

 

[m3hl]

Put a 40mm slice of the tube atop each spring (30mm to make up the difference in length from stock, plus 10mm for the recommended preload)?
Something else entirely?

Help!

One other thing: RaceTech uses a mm measure for fork oil height, instead of the volume method in the KTM service manual. Do they both accomplish the same level?

This is basically what I did. I remember that i am running more that 10mm of preload though. Not the max amount but pretty high up there. My memory is hazy but the goal was to match the total lengths of all spaces and spring.

for oil, factory is 450ML (I did not use oil height). I hear it will bottom out, so I am running 410ML. So far so good. Hopefully someone will correct me if im wrong. I'll try to dig up my thread.

 

[ReidMcT]

This is basically what I did....

Thanks very much for the guidance. I feel much more confident now. Matt from Formula390 also emailed me similar guidance. Thanks again!

 

[John390]

I actually came on here to ask about doing fork spring and oil changes.

Please, if anyone can put up some good directions with pictures that would be great!!

I don't want to frig it up.

 

[ReidMcT]

This is basically what I did. I remember that i am running more that 10mm of preload though. Not the max amount but pretty high up there. My memory is hazy but the goal was to match the total lengths of all spaces and spring.

for oil, factory is 450ML (I did not use oil height). I hear it will bottom out, so I am running 410ML. So far so good. Hopefully someone will correct me if im wrong. I'll try to dig up my thread.

Now that I am clear on the measurements, I will endeavor to take some photos and write up the steps this weekend. Although it is an unusual design, it is not difficult to work on... Providing you have the right tools, notably a soft jaws vise, pin spanner (6 mm for mine), and heat gun.

 

[m3hl]

I had to make a special tool to get the cap off to access the spring. it is a PAIN. Basically glued on with loc-tite. Use lots of heat. More than you would expect.

 

[CDN Duke]

Now that I am clear on the measurements, I will endeavor to take some photos and write up the steps this weekend. Although it is an unusual design, it is not difficult to work on... Providing you have the right tools, notably a soft jaws vise, pin spanner (6 mm for mine), and heat gun.

There's a write up here :

https://r.tapatalk.com/shareLink?ur...3&share_tid=583&share_fid=157361&share_type=t