I will share what I have tested and what I have found using the RTX/LTX models as a testing reference.
1. 8JP belt with stock clutches will be limited to approximately 93-95 mph.
2. 8DN belt with stock clutches will be limited to approximately 103-105 mph.
3. 8DN/8JP belt with secondary setup properly will allow you approximately 113-115 mph.
4. 8DN belt with both primary and secondary setup to match the belt properly will allow you approximately 120-121 mph.
The stock secondary setup with the 8JP belt will stop your belt approximately 3/8" to 1/2" below the top of the primary clutch due to two reasons, the stock secondary will stop shifting at that point and this stops the belt from going any higher in the primary as well.
Now if you install an 8DN belt you can get the belt to approximately 5/16" from the top of the primary and gain some top speed in the correct conditions.
Stock secondary clutch travel is approximately 0.870" and after setting up the secondary properly you can achieve just slightly over 1" of travel (1.008").
Stock primary clutch travel is approximately 1.104" of travel and after setting up the primary properly you can achieve 1.317" of travel and get the belt all the way to the top of the primary clutch, leaving no clutch face surface unused, in the correct conditions.
This is an informational post from Ulmer Racing, call us if you have questions, I do not want to offend or argue with anyone, as it will not help anyone in the end, and there is 100 different ways to alter clutching via the clutch arms, springs, helix, etc, but when the belt is limiting the shift ratio, changing those items will only do so much.
We will offer primary & secondary machining/setup process for those that are interested. You can purchase a clutch kit to match it or if you already have a Ulmer Racing clutch kit I will modify it to work properly as well. If you want to continue to use your own clutching, but want the clutches machined properly with some advice on how to setup your helix/spring I can do that as well.
Phone: 605-387-2833
Email:
Srxspec@Gwtc.net