40 series Torque converter belt to tight

[Chainlink]

Hello everyone,
I’m new to the site and need some assistance. I have a knock off 40 series torque converter and my belt is way to tight and It takes off when I start the engine. The belt is a 203785A and my center to center measurement is 8 9/16. Besides it being a cheap eBay TC I’m not sure why the belt is so tight. Thanks in advance.

 

[Karttekk]

Scroll to Comet 40 and 44 Series belts

Comet Torque Converter Belts | Go Kart Drive Belts

Go Kart Belts and Mini Bike Belts. American Comet Torque Converter Belts, Go Kart Drive Belt Catalog: Genuine Comet 30 Series Belts, CAT99 Belts, 20 Series Belts, Comet 40 Series Belts, 44 Magnum and 500 Series Belts. Comet Torque Converter Belt Charts.

www.gokartsupply.com

 

[Karttekk]

Comet belts are your best bets

 

[madprofessor]

It doesn't seem very likely that a TC mounted on a factory backplate is going to come with the wrong belt, but of course it's possible. After all, even the right belt will never be as good as a genuine Comet. Here's a link that explains all you need to know about TC's and their belts. Read all the text at the beginning of the page, and scroll down to the bottom and read all of the text down there, all good stuff. You'll pass belt size charts along the way for 30, 20, 40 and 44 series, etc., check out the 40 series chart after reading how they measure for belts. Just 2 measurements, driven pulley diameter and center-to-center of both shafts.
Comet Drive Belts | Comet Torque Converter Belts | Go Kart Belts (gokartsupply.com)
Another possibility for you is that everything on the TC is correct, and you're just idling too high. Turn it down until it dies, to see how low you can go.

 

[Chainlink]

Thank you karttekk and madprofessor! I’ll check it out.

 

[Snaker]

Hello everyone,
I’m new to the site and need some assistance. I have a knock off 40 series torque converter and my belt is way to tight and It takes off when I start the engine. The belt is a 203785A and my center to center measurement is 8 9/16. Besides it being a cheap eBay TC I’m not sure why the belt is so tight. Thanks in advance.

Assuming the engine would be spinning CCW as seen from the left side, the driven movable sheave is on the wrong side of the ramp.
It should twist against the direction of belt during upshift.
And that would make the spring be the wrong wind as well (it tightens as the sheave twists open)

 

[redflash]

You have the driver pulley on backwards....the clutch part should be on the outside.....that will do it !

Da Flash

 

[Denny]

If he has a 40 series the driver is on correctly in this instance.

 

[madprofessor]

It's correct as OEM supplied. The 40 series has a V-belt and V-pulleys. Both driver and driven as set up will move the belt away from the engine as they shift together. Driver will squeeze the belt away from engine, and driven will inhale the belt away from the engine also.
Belt will remain as close to straight alignment as it's going to get during the shifts. Flip either pulley over and the belt will go catty-wompus sideways during the shifts.

 

[panchothedog]

FWIW I have 4karts and all 30 series torque converter and with 5 grandkids I have changed my share of belts. I have had several occasions when the new belt so tight that the engine won't even start. Too much tension or drag on the engine output shaft. I put a floor jack under to get the rear wheels off the ground, start the engine and tickle the gas for 3or 4 minutes, then rev it pretty good while holding on the brake. It cures the problem. I have read somewhere that the belts DON'T stretch. WELL I say they loosen up. Call it what you want.

 

[Denny]

Again I say measure for correct belt legnth and driven pulley diameter and buy a Genuine Comet belt.

 

[madprofessor]

Again I say measure for correct belt legnth and driven pulley diameter and buy a Genuine Comet belt.

Ditto. Ditto. Did I mention ditto? Ditto.

 

[Snaker]

You have the driver pulley on backwards....the clutch part should be on the outside.....that will do it !

Da Flash

That is becoming a legit fix, although some say that setup won't fit on their particular engine? Its a good thing to have the fixed sheaves on opposite sides of the belt.

 

[Chainlink]

Sorry folks, it’s been a long week. I appreciate everyone’s input on this. My pulleys wouldn’t align in any other way and I read before on the forum that I could put my driver on inboard and and keep my driven outboard. The belt is the correct size according to center to center measurement and driven diameter. The belt loosens and tightens if I start to push and pull the cart back and forth (not started) kinda weird. I’ll try buying a comet belt in the meantime.

 

[madprofessor]

Here we go again with the Gokart Supply webpage that tells it like it is. Starting at the top of the page, there are black and white drawings in an overhead view of TC pulleys properly set up.
The first 2 overheads you see are of asymmetric series 30 and 99 TC's, and the moveable sheaves of both pulleys on each are on the same side.
The next 4 drawings of symmetrical (V-belts) series 20, 88, 40 and 44, and 500 all show the moveable sheaves on each to be facing opposite of each other. Like your 40 series.

Comet Torque Converter Belts | Go Kart Drive Belts

Go Kart Belts and Mini Bike Belts. American Comet Torque Converter Belts, Go Kart Drive Belt Catalog: Genuine Comet 30 Series Belts, CAT99 Belts, 20 Series Belts, Comet 40 Series Belts, 44 Magnum and 500 Series Belts. Comet Torque Converter Belt Charts.

www.gokartsupply.com

 

[Chainlink]

Hello folks,
Still having some trouble with my kart engaging at idle. Belt size is correct and I have my driven with red springs outboard with driver inboard. Idle is good, but just in case I set it really low and the kart still moves forward and you can’t stop it. I’ve read some drivers come with a brass ring but mine does not. Not sure if that would cause an issue? I can rotate the driver with my hand and instead of just turning freely without the belt turning... it moves the belt? Even though it’s the correct belt size should I order a size bigger?
Thanks

 

[Denny]

The brass ring is not always on the larger ones. To me it sounds like the belt still may be too tight. By how much I don’t know though. I wish I was there. Put it up on blocks with the tires safely off the ground and start the engine. Does it look like the primary starts to squeeze the belt? A lot or a little?

 

[Snaker]

Assuming the engine would be spinning CCW as seen from the left side, the driven movable sheave is on the wrong side of the ramp.
It should twist against the direction of belt during upshift.
And that would make the spring be the wrong wind as well (it tightens as the sheave twists open)

***

 

[Chainlink]

Thanks again for all input. I bought this torque converter off eBay and I just found the same one on Amazon and figured I’d read the reviews on it and everyone who bought that particular kit is having the same issue of belt engagement at idle. The sheaves stick out to far. Going to buy another one and see if that fixes the problem. I’ll let y’all know.

 

[Denny]

I think snaker is on to something there. Remove the nut on the driven and snap ring if equipped and move the point on the cam to just the other side of the wear block and try it.