Help with Clutch on EZGO electric to gas swap

[Danger Nooney]

Hello All,

Long time listener, first time caller.

I have a 2007 EZGO ST 2+2. It started life as a 36v cart. It was in bad shape, so I gutted it and built a custom engine mount similar to the VC engine mount. I finally got the cart running two weeks ago and it is geared way too low, so I bought a used 8:1 gear set that I installed this weekend. Vast improvement and now it has some powerband. However, I can't seem to keep the chain on it. My 40 series torque converter has the driven pulley installed on the FNR gear box. I have the idle around 1650 rpm but it spins the driven pulley too much at idle for me to shift into forward or reverse without it grinding. I think I need a better clutch setup to get rid of the herky-jerky operation of my gear box which seems to sling the chain. I sling the chain off when I take my foot off the gas and it engine brakes. It is 50 chain and it is very short. Is there a clutch that I can get that would keep my driven pulley stationary at idle speed and allow me to "coast" so to speak when letting off the gas. I feels like it needs some slack somewhere so it doesn't jolt the chain and gear box so hard. My setup is below. The photo of the clutch was taken before I swapped out my spring and let it float on the shaft.

• HF Predator 459 cc un-governed (upgraded valve springs on the way)
• Blast LED 8-18 hp FNR gear box 12 tooth sprocket, forward ratio of 1:2, and reverse ratio of 1:2:6 (according to their website)
• Blackhorse Racing (comet clone) 40 series TAV with medium weights in the driver pulley for 2,200 rpm engagement
• Driven pulley is mounted to spin CCW and has the reverse wound yellow spring with the pulley floating on the shaft
• 23” tires inflated to 20 psi
• Stock electric EZGO ST 36v rear differential with ¾” jackshaft coupled to the rear end with a 10 tooth sprocket, spinning CCW
• Working on fabricating a chain tensioner to see if that helps

Thanks,

Josh

 

[BrownStainRacing]

How is the driven moving at idle???
Is belt too short???

Is chain twisted or kinked???

Throwing chains is usally an alignment issue or flex issue.

Them big blocks will twist, bend steel and aluminum.

 

[Snaker]

Couple things:

Some trans are non-synchronized.
They need to be completely stopped to shift.
I had riding lawn mowers like that and a cart.
Some CVT's creep when not loaded.
The trans in neutral presents a no-load and can't stop the CVT from creeping.
Solutions:
Make sure the CVT center to center distance is perfect.
Proper belt dimensions length and width.
Pulleys maintained
I added a spring loaded switch on the ignition kill circuit to fix my cart problem
I put pressure on the shifter while bumping the kill switch
It cuts the ignition just enough to allow a smooth shift while not completely stalling the engine

The photo looks like your driven pulley movable sheave is riding on the wrong side of the ramp for that setup

 

[BaconBitRacing]

How is the driven moving at idle???
Is belt too short???

Is chain twisted or kinked???

Throwing chains is usally an alignment issue or flex issue.

Them big blocks will twist, bend steel and aluminum.

That engine mount looks a little “suspect” could be causing issues…
Polished TC is going to be best for you and belt life. We have some TC Wizards here so that shouldn’t be too hard to get sorted.

 

[ezcome-ezgo]

I think the whole cradle needs more support to prevent flex, which is probably happening and is your enemy. To begin with, see if you can connect the top of the engine to the top of the diff housing with a rod or channel. Here is a poor illustration:

 

[Danger Nooney]

What do you think is suspect about the engine mount? I thought I did a decent job, haha. Chain is not twisted or kinked. I am using a 203789 belt which is supposed to be for 11" center of pulley to center of pulley, which is my exact measurement. I used the Comet chart to determine my belt length. Everything appears to be aligned. I wish I could get the chain tighter, but I am working on a tensioner. It is just such a short chain that there is hardly any room. The driven just spins slowly at idle. Please elaborate on the driven pulley moveable sheave being on the wrong side of the ramp. Since I had to mount the spring side outboard, I installed a reverse wound spring so that I could spin it CCW.

I see what you mean about neutral being a no-load situation and it is creeping. I like the kill switch idea. How does a regular gas powered golf cart compensate for the load situation in "neutral" without grinding gears when shifting? I have never investigated one of those.

 

[Danger Nooney]

Ezcome-Ezgo, good idea. I can do that using the bolt holes for the old electric motor.

 

[BaconBitRacing]

What do you think is suspect about the engine mount? I thought I did a decent job, haha. Chain is not twisted or kinked. I am using a 203789 belt which is supposed to be for 11" center of pulley to center of pulley, which is my exact measurement. I used the Comet chart to determine my belt length. Everything appears to be aligned. I wish I could get the chain tighter, but I am working on a tensioner. It is just such a short chain that there is hardly any room. The driven just spins slowly at idle. Please elaborate on the driven pulley moveable sheave being on the wrong side of the ramp. Since I had to mount the spring side outboard, I installed a reverse wound spring so that I could spin it CCW.

I see what you mean about neutral being a no-load situation and it is creeping. I like the kill switch idea. How does a regular gas powered golf cart compensate for the load situation in "neutral" without grinding gears when shifting? I have never investigated one of those.

You did a great job, very pretty. From the angle I can’t see the steel thickness. What was the gage? If you want to make sure it’s not a problem, triangulate some angle iron on the bottom.

 

[Danger Nooney]

It’s 1 1/2” x 1 1/2” at a 1/4” thick. However, the gear box mounting is a lot less than that. I am probably getting some flex. It jolts pretty hard when I can get it into gear. Maybe I could make a support across the top that would tie the top of the engine to the top of the gear box and then tie it in to the diff.

I saw a plethora of clutches on Comet’s website but the descriptions were vague as to what each one did. Is there a CVT that has adjustability without completely disassembling the pulleys. That would be helpful to dial it in. I have no idea if I put the proper amount of preload on my reverse wound yellow spring in the driven pulley.

 

[BrownStainRacing]

With 2200 rpm stall (engagement) and an idle of only 1625, you should be able to turn the driven by hand in neutral with the engine running while belt is installed.
Or, put it in gear and push it around while engine is running.

I jus can't get in my head, why theres load on the belt at idle?????

Something is up with the belt or engagement is off.

 

[Snaker]

What do you think is suspect about the engine mount? I thought I did a decent job, haha. Chain is not twisted or kinked. I am using a 203789 belt which is supposed to be for 11" center of pulley to center of pulley, which is my exact measurement. I used the Comet chart to determine my belt length. Everything appears to be aligned. I wish I could get the chain tighter, but I am working on a tensioner. It is just such a short chain that there is hardly any room. The driven just spins slowly at idle. Please elaborate on the driven pulley moveable sheave being on the wrong side of the ramp. Since I had to mount the spring side outboard, I installed a reverse wound spring so that I could spin it CCW.

I see what you mean about neutral being a no-load situation and it is creeping. I like the kill switch idea. How does a regular gas powered golf cart compensate for the load situation in "neutral" without grinding gears when shifting? I have never investigated one of those.

That movable sheave is Torque Sensing, Its all about the angle, ie ramps
The movable sheave should twist against the belt rotation during upshift and twist with the belt rotation on downshift
The spring wind must be that it winds tighter as the movable sheave upshifts (opens)
A better photo of that would give more confirmation.

 

[Snaker]

With 2200 rpm stall (engagement) and an idle of only 1625, you should be able to turn the driven by hand in neutral with the engine running while belt is installed.
Or, put it in gear and push it around while engine is running.

I jus can't get in my head, why theres load on the belt at idle?????

Something is up with the belt or engagement is off.

The clutch function of these CVT's consists of the drive sheaves squeezing the belt when engaged or separating from the belt on disengagement.
At disengagement, a side gap between the belt and the sheaves should be present.
I have never seen a spec from Comet on that gap, a similar design from Polaris calls for a .020" side gap at disengagement.
Creep can be caused if that side gap isn't present

Creep can also be caused by simply having a stiff belt riding on a spinning boss.
You have the drive pulley spinning inside the belt and even if the belt has slack, it can be dragged around the pulley if it doesn't have enough resistance to hold it back.

Creep can happen with centrifugal clutches as well.

 

[Danger Nooney]

That movable sheave is Torque Sensing, Its all about the angle, ie ramps
The movable sheave should twist against the belt rotation during upshift and twist with the belt rotation on downshift
The spring wind must be that it winds tighter as the movable sheave upshifts (opens)
A better photo of that would give more confirmation.

I will get better photos for you this evening.

 

[Danger Nooney]

I should probably clarify that the chain didn’t jump off. I broke it at master link. Master link pieces have not been found, haha. Photos attached of my setup. Without the engine running I pulled on the belt. It spins the driven pulley, without any slippage. It’s like it is wedged in there. I included a photo showing how deep it is in the sheaves. No play at all. I had play on the driver pulley and a little bit of side gap. The 40 series I bought was a comet clone and I used a comet belt thinking it would work. Thoughts?

 

[Snaker]

Well, the driven pulley movable sheave looks oriented properly in these photo's.

 

[Danger Nooney]

Well, the driven pulley movable sheave looks oriented properly in these photo's.

Why do you think it would be so tight on the driven pulley? Is it possible the sheaves are too close together from something I did when I swapped to the reverse wound spring?

 

[Denny]

With your driven being mounted like that you WILL have to turn your drive clutch around for proper belt alignment!!! That’s right unbolt the drive clutch from the engine and turn it around. That will give you the proper slack if you have everything set up properly.

 

[Danger Nooney]

Ok, I will give that a shot.

With your driven being mounted like that you WILL have to turn your drive clutch around for proper belt alignment!!! That’s right unbolt the drive clutch from the engine and turn it around. That will give you the proper slack if you have everything set up properly.

Ok, I will give that a shot.

 

[Danger Nooney]

So I went and examined an 1190 clutch that a friend has on a V-twin buggy and it operates in the same fashion on the driven belt as mine does. When I pulled on the belt it spun the driven pulley, just like mine. His buggy isn’t running so I couldn’t witness it in action but I would think that if I can pull the belt by hand and spin the pulley with no slippage that it would be the same if it was running. I am having such a hard time understanding how this pulley would be static or able to be moved by hand when the motor is running. The sheaves have the belt sandwiched with no side gap. Same as my friends 1190 clutch on the V-twin. Am I missing something?

 

[Danger Nooney]

I wanted to follow up with everyone and let you know what happened. As Denny suggested I swapped the driver pulley around for proper belt alignment. I left my driven clutch floating. I messed around with the mounting of the engine and reduced the distance between the two pulleys to about 10 3/4" instead of 11". I still get creep, but it is much better. I guess my belt was just stiff. I can at least shift in and out of gear without all the noise now. Thanks for everyone's advice. I think I will swap to a 780 clutch one day instead of this knockoff from Amazon.