Murray Kilowatt With Predator 420cc--Torque Converter Question

[OneTimeUser]

Hi All,

First post here and pretty new to carts.

I bought a thoroughly abused Murray Kilowatt cart with a Predator 420 on it. It was very poorly set up. It had a series 30 torque convertor (the kind with a back plate) and the axle sprocket welded on to the left "drivers" side of the axle.

I'm trying to get back to the original drive train set up but using a series 40 TC to handle the larger engine. The original drive train set up had the drive TC pulley on the crankshaft, the driven TC pulley on a jack shaft mounted directly to the cart's frame, and the final drive axle sprocket on the right "passenger" side of the cart. This set up did not include a TC back plate.

This drive train configuration was how the cart came when new--but with a smaller engine and a series 30 TC.

Anyway, I've got this mostly all figured out except for: I don't understand the proper orientation for the series 40 TC. The Predator 420 crankshaft turns CCW when viewed from the side where the TC mounts.

I have room to mount the driver TC pulley inboard or outboard, but only enough room to mount the driven TC pulley outboard. Both will be spinning CCW when installed (regardless of inboard/outboard orientation of either).

I don't understand if this set up (both TC driver pulley and driven pulley spinning CCW with the driven mounted outboard) requires a regular spring or "reverse wound" spring.

I'd appreciate anyone helping me understand how to which spring is needed. Be gentle, please, I'm of average intellect, but I'm a bit dyslectic and the CC/ CCW and left/right things are very difficult for me.

 

[Whitetrashrocker]

Look at the ramps on the driven pulley.
There's a movable side, the inner one of the assembly. Attached to the sheaves, where the belt rides.
The other ramp is fixed with the body and other sheave, the outer one.
The ramps of the movable inner side should be "trailing" the fixed side in the proper rotation.
That should tell which direction the spring is wound.
40s come sprung to be run spring inboard.

Clear as mud?

 

[Whitetrashrocker]

For example.

This is the wrong direction.
See the inboard ramps are "leading" the outer ramps.



Now this is proper.
Notice the ramps are "Trailing" in this pic.
The driver if you notice is flipped to align the belt.

 

[OneTimeUser]

Thanks for the help. If I get it right, I can run my driven pulley outboard if I run my driver pulley with the "big" part inboard AND, have the whole thing rotate CCW with the red spring.

Did I get it?

 

[Whitetrashrocker]

Lets see a pic of your set up.

Being the 40 series uses a Symmetrical Belt the units can run either way.

(Unlike a 30 series which uses an Asymetrical Belt has to be set up one way.)

As long as your belt is lined up straight either way will work.
Your individual application will dictate how your orientation will be. Some setups will only work with a reverse wound spring.

 

[OneTimeUser]

WTR,

Thanks for the help. I'll send pictures tomorrow.

 

[CartMan007]

Lets see a pic of your set up.

Being the 40 series uses a Symmetrical Belt the units can run either way.

(Unlike a 30 series which uses an Asymetrical Belt has to be set up one way.)

As long as your belt is lined up straight either way will work.
Your individual application will dictate how your orientation will be. Some setups will only work with a reverse wound spring.

Thank you. This solved a very confusing point for me. There are so many youtube videos talking about the right and wrong direction for the driver, but I hardly hear the explanation attributed to asymmetrical belts they just say "this is right" and "this is wrong"

 

[OneTimeUser]

WTR,

Here are a couple of pictures. This is the way I'd like to run the pulleys: inboard for the driver and outboard for the driven. Everything fits best this way. Main question is about the spring. Red or green? Stock or reverse? I think I may have it figured out but would appreciate a more learned opinion. Again, thanks for the help. BTW, the driven pulley is being held on with a stick, not a real jackshaft.

 

[Whitetrashrocker]

Yes the way you have things oriented will work.
Line up the red side as they dont move.
The yellow sides move.
Blue represents the torque applied to the shafts. The closer to the bearing the better. But then you will need the reverse wound spring or the other one from what you have now.

Your belt length will be easy. Measure the driven pulley. 6" and 7" i think are the 2 models. Then a center to center measurement. Then look at the comet chart for the belt part number.

 

[OneTimeUser]

WTR,

Thanks a ton. You have solved a vexing problem for this old dyslexic. I have the reverse spring on order. Attached is a picture of my other little kart that I got a few months ago. It has been so much fun that I bought the larger Kilowatt. It is a real mess an is up on blocks. It's gonna take a while to fix and figure out all the bad work done to it. The guy(s) who owned it prior are even worse welders than I am and I've done a bunch of cutting and grinding on it so far.

I'm a motorcycle guy really but have moved to karts 'cause I'm too old to fall down these days.

Finally, do you know of a way to date Murray Karts? I'd kinda like to know if this thing is older than my wife.

Happy trails...

 

[OneTimeUser]

Whoops, forgot the picture. Pre and post roll cage padding.

 

[Denny]

Qtr that is a 40 series and one must face one way and the other the other. Or the belt will be out of alignment once the clutches start moving. OTU you need to flip one of those clutches.

 

[OneTimeUser]

Qtr that is a 40 series and one must face one way and the other the other. Or the belt will be out of alignment once the clutches start moving. OTU you need to flip one of those clutches.

Deny, I don't understand. Will you elaborate please? Thanks.

 

[Denny]

For the clutches to properly stay in alignment and not chew up belts one needs to be turned around. I would turn the top one (primary).

 

[Hellion]

Finally, do you know of a way to date Murray Karts? I'd kinda like to know if this thing is older than my wife.

Wow, you must have a trophy wife, eh? Most of the Murray Karts seem to have been made in the mid to late 1990s and early 2000s. There's no real way to date them as they don't have a VIN with a date code embedded in it. An original receipt is probably the only way.

Murray filed Chapter 11 bankruptcy protection in December, 2004. Murray was purchased by the Briggs and Stratton Corporation as of February 11, 2005. Briggs and Stratton has "determined that it will not manufacture, sell, or distribute [go-karts], nor will it provide any service parts, warranty coverage, or technical support for these products." Further, it has been reported that Briggs & Stratton destroyed all replacement parts for the Murray go-karts. Therefore, parts are very limited for Murray karts.

Murray still exists and makes lawnmowers but the go kart division is gone.

I think JimD has said that the entirety of the American fun kart industry went tits-up in about 2005. Couldn't stand up to the lawsuits due to injured (or gulp, dead) children. I like to think that with our helicopter parenting, things might be different in 2026.

 

[OneTimeUser]

Hellion,

Thanks for that answer. Made my day.

I do have a trophy wife, but her VIN indicates she was made in 1961. I'm a '55 model myself--back when cars still had fins (sort of).

 

[OneTimeUser]

Denny,

Turns out (no pun intended) that I have to put the driven pulley with the spring facing outboard (facing away from the engine). If understand this correctly, that means I need a reverse yellow spring. Is that correct? Thanks in advance for the help.

 

[Whitetrashrocker]

So you flipped the driver unit around? Now the driven needs to be flipped for alignment. Yes you will need the other spring.
Look where your rubber buttons are in relation to the rotation. They should trail the other ramps.

 

[OneTimeUser]

I have to flip the driven for things to fit. The driver will fit best with the fixed sheave towards the engine. If I've got this right, if the fixed sheaves are on the same plane an outboard driven with reverse (yellow spring) will work properly. Do I gots this right?

 

[Whitetrashrocker]

Post a pic.

The fixed sheaves on the same side make for easy alignment of the belt.
If you flip them, fixed with movable, then you will need to be real accurate to split the difference with the belt. It will work being Symmetrical but it will be a little crooked at each end of travel.

Look at how the rubber buttons on your driven are oriented.
The movable sheave has to rotate opposite to the spin direction to open.