First Terra-Jet Project, for a Newbie

[ARGOJIM]

I hate doing things twice, but in this case there was no option. The original exhaust I made:
[ATTACH=CONFIG]18071[/ATTACH]

After slicing and dicing:
[ATTACH=CONFIG]18070[/ATTACH]

And back in place:
[ATTACH=CONFIG]18069[/ATTACH]

Thanks Grandma!

Didn't get a chance to try it out last night, hopefully I may get it out for a road test today.

That does look a better fit.

[Goach2]

Took the TJ out for it's first road-test last night. Everything seems to be working right, but it has no guts! Reverse seems right, Low gear is really low and High is a crawl. I adjusted the transmission back as far as I could get it, but there's still enough play that the belts can touch in between the clutches if I squeeze them, without much effort. Now I'm thinking an even shorter belt is required? Some people are saying wider too, but this belt HP2014 is the width that Comet specifies for it's clutches.

Anyone can to wade in on this? Thanks!

[dirtdobber]

Belt tension is definitely the first place to start. You should only have approximately 1 inch of deflection in the belt. With it being so loose, you are not able to enjoy the full benefit of the higher speed ratios the clutch system will produce - so you are stuck in low gear so to speak.

Your belt width is right (google search indicates your belt number has a top width of 1.19). Tighten the belt or get a shorter belt and you will be amazed at the difference.

[Goach2]

Thanks DD, placed an order for one 2" shorter. Hope that does it. Others have suggested going up 3/16 in width as well. Guess we'll see. May open up a used belt store, if this continues...

[dirtdobber]

Be careful going wider. If you get too wide the belt will always grip the pulley sheaves and thus never allow the transmission to quit spinning. This may not matter for your transmission (I'm not familiar) but it does for t-20 transmissions.

Roy at Quality Drive Systems in California is extremely knowledgeable and helpful. (626) 293-5770 Give him a call and he can help you size the proper belt.

Sorry, I didn't mean to attach a pic. Please ignore.

[Goach2]

New HP2015 belt in place. Little wider than the previous too. Wondering if the guy sold me the wrong one last time. This one is 2" shorter, how do I measure deflection without the secondary clutch opening up?

https://photos.app.goo.gl/XUpi3CQe5YdQfvrP7

[dirtdobber]

The deflection is measured with the engine off and clutches relaxed. The theory is this - you want just enough deflection, or slack, in the belt so that when the engine is at idle, the belt is not driving the transmission. This allows you to change gears without grinding (on the T20 - I don't know about your transmission). In your picture, it looks like your clutches may be mismatched. Your drive clutch appears to be a Comet 780. I cant' tell what your driven is, but typically the belt rides along the outer circumference of the pulley. Your belt appears to be running pretty deep. This robs you of low end torque.

[Goach2]

Dirtdobber,

I'm interested to know what causes mismatched clutches? I know this is the most common setup for these machines, but perhaps there is room for improvement? The belt does sit low right now, but it's not tight to the axle on the primary clutch, there is room to allow it to come up. Could it be that the belt needs to break in a bit to allow it to be a little more pliable? There is also room to adjust the tension in and out, I just have no idea how to go about setting it right... any suggestions? Thanks

[dirtdobber]

Mismatched simply means clutches designed to run with different belt widths. I'm no expert, but there are quite a few different CVT clutches on the market and they vary in terms of utility. Some heavy duty (snowmobile, John Deere Gators, etc.), some light duty (go carts). It is possible your driven clutch is intended to be paired with a different drive clutch, but I don't know for sure.

If there is something you need to do for the belt to get into its "resting" position, then do it. Resting position means where the belt would rest in the pulleys after running and shutting down the machine. If you need to tighten some bolts, spin the pulleys, or do whatever then do so. At rest, the belt should ride such that the driven clutch is completely closed (sheaves are closest together) and the drive clutch is fully open (sheaves fartherest apart). If you can't accomplish this with the belt you have, then something is wrong. Either wrong size belt or wrong driven clutch.

Here is a video of my machine. https://www.youtube.com/watch?v=dmkUjcR-opE

This is how it should all fit together on a Comet 780 clutch system. Pause the video as needed to see how the belt rides in the driven pulley. In this video, my belt is just a tad tight because it still spins the transmission at idle, but it will stop with just a bump of the steering laterals with no belt squeal.

[Goach2]

Great video, thanks. I see how it should sit now. If this new belt was a little 'tighter' to the primary it would sit higher on the secondary. Perhaps it needs a little break-in time, but regardless, I know what it should look like and how it will behave. Just curious what size belt you're using?

[dirtdobber]

Looking back at post no. 59, it looks like your belt is riding pretty high in the driven clutch, as it should. Break in time shouldn't matter. The spring pressure in the driven clutch should force the belt to return to the outside (or largest) circumference. It needs to spin in order to do this, though. When the engine increases RPM, centrifugal force closes the drive clutch and forces the belt to follow a larger circumference. At the same time, the belt is forced deeper into the driven clutch, with the driven spring providing the resistance to keep the sheaves in solid contact with the belt. As you reduce RPMs, the drive clutch "backs off" the belt and the spring on the driven clutch forces the sheaves together to avoid slack in the belt and forces it to a larger circumference. If the belt is so tight that it won't allow this to happen, then the belt is too short. BUT, if the driven clutch is designed for a wider belt than what you have, the belt isn't going to run in its intended position.

I don't know the outside circumference of my belt, but it is 1-3/16 top width.

[Goach2]

Post 59 had a belt that was longer and I had it adjusted out pretty much as far as I could and there was still a lot of slack inside of the primary. I'm going to try and make a few adjustments with this one that is 2" shorter to see if I can get it to where it needs to be.

Any chance you have a shot of the slack around the primary at rest?

[dirtdobber]

I'll snap a pic this evening.

[dirtdobber]

Here yo go.
20200408_054653.jpg20200408_054706.jpg20200408_054713.jpg20200408_054743.jpg

[Goach2]

Great pics, very helpful thanks. Played with it again last night, even put the longer belt back on. Nothing seems to stop the secondary from moving at all, however, there is a brake for the secondary itself. I wonder if this is meant to allow for some movement, if it can be stopped without too much effort by your foot? Does your setup have a brake?