40 Series TC problems

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colinreay

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Hey everyone, hope you're having a great day!

I'm in desperate need of some guidance for the problems I'm having with my 40 series torque converter.

Quick info:

Engine: Predator 420cc (governor removed)
Transmission: 40 series driver and driven with custom 1/2" aluminum backplate (axle distance based on belt chart, 203785)
Drive: Chain drive to solid rear axle

*I just took apart the driver pulley, applied graphite, and cleaned and polished the sheaves with a brass wire brush*

I'm using this setup on an old cushman golf cart which is quite hefty. The problem I am experiencing is the torque converter belt becoming stuck in the driven pulley. Despite looking, I haven't been able to find anyone else who has experienced the same problem.

I suspect that the vehicle's heavy weight is causing the driver pulley sheave to move inward with throttle, in turn moving the driven sheave outward, which causes the whole torque converter to bog down and finally become stuck. Additionally, while the axle-axle distance is set up correctly (at least according to comet's belt chart), the engine constantly stalls on startup and needs throttle to be applied to stay alive. The belt leaves black rubber residue on the driver pulley's sheaves that I remove with brake cleaner.


Furthermore, sometimes the cart starts to creep on startup. This leads me to believe that the idle is too high, and that I may need to swap out the cam rollers and springs. What're your guys' thoughts? I think that the heavy weight of the cart is working to the detriment of the torque converter, which can't handle that kind of stress.

Thanks, and have a great day! I will post photos when it becomes light out for more clarification.
 

itsid

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belt size charts are one thing.. a clone belt might not match comet's charts (while still showing the correct number)
soo measure the belt's OC to verify correct length.

Check the weight rollerss are inside their tracks and the tracks are properly dry-lubed
make sure the driven is preloaded in the correct direction
post a picture of your setup for us to confirm)

A terrible gear ratio can cause terrible misbehaviour..we don't know your ratio, so we can't tell yet.

If ou're still having problems after all of that is confirmed to be in perfect order...
loose the sh177y backplate, and flip the driven unit the right way around (inboard)
then you will not have issues like that.

Problem was discussed extensively over and over..
running a series 40 outboard isn't a good idea in the first place,
especially not if the driven isn't floating (7/8" inboard)
some claimed flipping the driver inboard would work.. but I never seen it being done (other than a seller mocking it up that way)

So get rid of the backplate and replace it with a proper jackshaft, then set up the series 40 as it was intended to be set up by Comet!
(inboard with red spring... or outboard with yellow and the driven floating 7/8" inboard)
that's the only two ways the belt will run straight at all times.

'sid
 

colinreay

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Thank you so much for the response!

Here's the setup as it stands now. The camera's perspective makes the slight angle between engine and frame seem far more severe than it really is, but I plan to straighten it out with new motor mounts. I bought the belt directly from gopowersports and it's a TZBRT. I'll measure the belt's OC to confirm sizing.







I'll start designing a new mount for the driven pulley's jackshaft. That way I'll be able to mount the driven pulley inwards (which I assume is the correct orientation). I am 100% on board with making any changes you suggest if it may solve my issues.
 

colinreay

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You need to rig up a stabilizer bearing for that jackshaft.....

Gotcha! Based on your feedback and itsid's, I'm going to fab up an independent mount for the jackshaft, supported on both sides with the driven in the middle. Hopefully this combined with running the driven inboard will alleviate my problems! (Or at least make it driveable :))
 
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