CVT test run

[thebuggyman1]

Tuning the CVT clutches seems to be more of an art form than science.
When I built the Bigfoot http://www.6x6world.com/forums/max-a...-tall-tub.html I ordered clutches from Recreatives, hoping to get a matched set and not need to tune. I also mounted the 40 horse Kohler on the original motor plate with rubber mounts. I knew there was a lot of movement in the mounts, so I added a couple extra stabilizing springs to help out. The problem I had was the clutch upshift seemed to happen too fast. When I would start out Everything seemed to engage properly, but the machine would take a giant leap forward in speed making trail riding tough...it really wanted to run over the person in front of me.Over the Christmas break I pulled the motor and replaced the rubber mounts with solid ones. That change really improved how the clutches worked.Now I feel I just need a slight amount of fine tuning. My thought is the engagement is a touch too high...like 1900-2000 rpms, but the normal driving range is correct at 2500-3500 rpms.I'm looking for opinions here, so please let me know what you think.

[micmac]

Jim,

What kind of solid mounts did you use? How much increase in vibration did you notice if any?

[thebuggyman1]

The original rubber mounts were 1" tall. so I replaced them with a piece of 1" square tube layed on top of the frame rail. 3/8" holes drilled through it (them, X2) and nuts welded to the underside of the frame. I adjust the motor by sliding it on the motor mount plate, not by the original slots in the motor plate.
Vibration is not an issue...if it were out of balance that bad, it would shake itself apart at high rpms.

[Noel Woods]

I noticed there was no engine shudder, I believe there is a calibration issue between the two clutch assemblies. Otherwise engagement wouldn't come at such high rpm.

[Bazooo guy]

Did you have it on blocks for the video or were you driving on level ground.
I dont think the clutches react the same if the wheels are spinning free.
My understanding is the secondary spring determines the shift point and the primary
determines the engagement point based on rpm.

[thebuggyman1]

I was driving around the yard. It's mostly flat ground, but at about 4 1/2 minutes in I stopped at the base of a small hill (dirt pile). That is where I was able to get a realistic engagement RPM. On flat ground it rolls too easy...like with a good breeze. I tried to keep the machine at normal driving speeds. One thing I did fail to mention is belt tension.
I have 1" to 1 1/8" of deflection, perhaps I should loosen it a little.
What little info I could find on the powerbloc clutches ...... the spring in the primary determines the engagement RPM, the weights determine the upshift. The secondary is more downshift. Of course there is interaction between all three.

[2gnospam]

Sorry I can't help with the clutch tuning, but would want to know where did you get that tach. Been looking for a low cost one compatible with a Vanguard twin.

Thanks