I got an email from my contact at MTC today, he thought it was important enough to mention this to help avoid confusion:
MTC wrote:Our latest shipment of springs are not black, we were told that this was a process that our supplier no longer provides as it adds nothing to the function of the spring. This is an across the board change, other springs we order from them had a brownish/blackish tint are now all silver. In fact when we first received this last shipment they were just plain silver. We sent them back and asked them to put a blue stripe on them, so they would at least have that on them. Rest assured they are the same rate/pressure springs we’ve been shipping for the past few years, just from a new batch. It’s been almost 3 years since a kit left here with the red springs, so I doubt anyone has an old one lying around on their shelves. There is nothing different about the springs other than the color or lack thereof.
So from here on out the springs are no longer black with a blue stripe - they are either silver or silver with a blue stripe. There is no other change to the springs themselves. I'm mentioning this just to avoid any confusion.
As some of you may know I've been working with MTC Engineering on testing and improving their clutch packs for the VTX off and on for a couple of years now. A handful of guys from the VTXOA did some excellent troubleshooting the clutch on this bike:
And thanks to their time and effort I was able to provide MTC with some great feedback outside of just what I'd been finding on my own. Well I spoke with MTC today and they told me that they are now shipping these clutches with the new "blue" springs. For those that don't know I've been testing these springs in a few other people's bikes to get real world feedback and results in an attempt to improve the existing clutch setup. Now all the work has come to fruition and a the new springs will ship in all MTC clutch packs for the bike from now on. If you're ordering and want the blues make sure you're getting new product and not something that's been sitting on the shelf.
Per MTC - they are shipping these with shims so that riders with high-performance needs (mostly guys running NOS or other engine mods that need additional pressure on the clutch pack) can shim if they feel it's necessary. Since the blue springs are a little taller than the reds they don't recommend shimming over .150" or else you may experience coil binding.
So thanks to all those out there who helped diagnose the clutch deficiencies so far, those guys as well as the testing I've been doing myself and with other riders has made this change possible.
After a lot more measuring, testing, etc - and a big thanks to Verbatim for all his hard work - currently the best setup IMO is the new MTC blue springs with .075" shims on each. You can read some of Verbatim's work in the first thread linked above (if you can wade through the bullsh!t). Verbatim's testing produced a lot of great info, and it will continue once riding season is over and winter gives him time to be curious again.
For those not wanting to wade through pages of information, the extremely condensed and abbreviated version is -basically- like this...
Stock springs average 72.3 lbs/spring
MTC blue springs w/ .075" shims average 82.5 lbs/spring
Average clutch pack disengagement with stock springs is .064"
Average clutch pack disengagement with MTC blue springs w/ .075" shims is .063"
So you get approximately 60 extra pounds of pressure and sacrifice only .001" of clutch pack disengagement.
Again, this is a very abbreviated version and doesn't give the full details and measurements, but it gives the idea for those who are "sort of" interested.
Hopefully we'll have more data come next winter, but for the time being I feel comfortable enough with what data we have that I use and recommend the .075" shim pack until we have more data.