TC Identification and Orientation

[smax]

Hi,
Bought a used kart for my boy and just starting to learn about what's on it. The torque converter belt blew (took out the cover and battery too) so I guess the first thing I'm learning about is torque converters. The pullies are symmetric, it's a predator 420, so I'm guessing it's a 40-series, maybe a clone (not sure how to tell other than there are no markings for Comet). I measured things and got the following: driver 5-1/2" OD, driven 7-3/4" OD, Center distance is 8-3/16". Seems to line up with a 40 series with 40D driven and a 203784 belt.
Assuming I'm on the right track so far, I'm wondering will any 40-series cover fit the backplate?
Also the orientation of the pulleys seems reverse of what I've been seeing in other threads. The driver is oriented with the clutch toward the engine and the driven has the spring/cam side away from the backplate. The jackshaft sprocket is between the driven and backplate, which seems right. I've attached a photo.

 

[panchothedog]

The orientation of your clutches is fine. Your driven already has the reverse wound spring which is necessary to keep the cams on the front side of the stops, which I can see from your picture. The driver is reversed to help with alignment and works fine às is. As for the belt you are close, and maybe correct. Haven't looked at a chart in a while. Your distance of 8 3/16" is standard centers for a 40 series plate system. No one measures the diameter of the driver because the center is the same on all of them. The driven is more than likely considered an 8" . Was there a listing for a 7 3/4? Cause I could be wrong. Also, Welcome to the forum. Lots of good helpful members on this site.

 

[Denny]

Also buy a Genuine Comet belt! The chineseum belts are much cheaper but made of boiled yak grease and hair fibers. They do not last nearly as long as the Genuine Comet. You will want to clean all the old belt from the clutch faces too!
Comet belts are more expensive but well worth it! It’s a good thing the cover got destroyed!

 

[Denny]

With no cover the belt has a better chance of cooling. Which means longer life!

 

[panchothedog]

The belt might cool better with no cover, but it could also slap you really hard if it were to break at speed. As far as I know all plate style covers for the 40 series are the same. They are also a little thicker than the 30 series covers.

 

[smax]

Going for a more premium belt and a cover. The "dismount" of the previous belt tore through the cover and destroyed the battery so anything I can put between it and the human is going on. I could see fabbing a sort of half cover or even semi-open cage out of metal in the future.
We're taking the opportunity to service the pulley assemblies. So far the driver looks pretty clean, not a lot of dust or residue but could use some dry lubricant.
I think the weights/rollers are the heavies (solid all the way across) and no idea what springs. Probably going to leave the internals as is for now unless there's a strong reason to change. I'm guessing this decision involves gear ratios and tire sizes?
The thing I'm considering replacing are the brass? bushings that the drum rides on. There is a little play between them and the shaft and I'm wondering if its allowing binding and causing the abrupt engagement/banging on take-off.
Is there supposed to be a little slop in these?

Thanks

 

[panchothedog]

Are you referring to the bushing on the driver clutch, the one the belt rides on ?
If so then yes, it's inner diameter is larger than the outer diameter of the driver clutch and it is narrower than the space between the two sheaves when fully open ( relaxed ) . Sorta sloppy so the kart doesn't creep and the belt doesn't wear at idle.

 

[smax]

Are you referring to the bushing on the driver clutch, the one the belt rides on ?
If so then yes, it's inner diameter is larger than the outer diameter of the driver clutch and it is narrower than the space between the two sheaves when fully open ( relaxed ) . Sorta sloppy so the kart doesn't creep and the belt doesn't wear at idle.

I meant the two "bearings" or bushing or washer-like rings that the moving sheave rides on. I think they are brass or maybe bronze. They work as bearings except they are solid (I call such things bushings, maybe that's wrong). Anyway, I've cleaned, polished and lubricated, reassembled and going to try it out, see if engagement is any smoother.

 

[smax]

Update:
Got every thing back together, thanks for the hand holding. There was/is a small issue of the moving side of the driver clutch not retracting all the way at idle occasionally. This was causing the belt to engage even at idle, making starting impossible and generating extra heat when it happened after a successful start. Because it appeared to be a very small distance from fully retracted and I was feeling lazy and the old belt measured about 0.1" narrower than the new, I opted to modify the belt by sanding off a little smidge on both sides. This seems to have worked a charm and honestly the belt still measures right around 0.87" so maybe I just took off a "sticky" layer.
Overall the acceleration seems to be much smoother, where previously there was a "bang" or jerk sometimes it now feels smooth.

I wonder what is causing the clutch to stick just before full retraction, maybe just wear on the tracks and wheels/weights (they had asymmetric wear patterns) causing binding? Or maybe the springs aren't strong enough to pull them all the way back every time (not my preferred theory)?

Anyway, this thing now rips scary fast, enough that the next project might be to put a governor back on.

Thanks for the help.

 

[panchothedog]

Glad to hear it is working better. Great idea sanding the belt. I agree with you on the springs. New ones are cheap, the stronger ones better. Have some fun with that thing and your son.