Torque Converter not opening up when wheels are on the ground.

[DuckSoup]

Wanted to run this past you guys and get some thoughts on this.

So my GoKart project is done, well I thought it was at least. :-D
I've put some work into getting the engine running again, replacing the axle, added hydraulic brakes, new sprocket, and a new Torque Converter.
I was taking it out on a run yesterday and I wanted a shot of the TC in action, but to my surprise, it's not actually opening up when I'm running full throttle.

Some specs on this, it's running a predator 212, a 12 tooth clutch sprocket, and a 60 tooth axle sprocket. 14in rear wheels and I think the total weight with me on it is around 220-240 lb's. It has a 30 series Torque Converter that I picked up from GoPower sports. (This one: https://www.gopowersports.com/gopowersports-30-series-torque-converter-kit/)

Going off app.kartcalc.net, it should be giving me approximately....

Lowest Ratio: 15.5:1
Highest Ratio: 5.6:1
Final Ratio: 5:1
Max Wheel Torque: 141 ft lbf
Min Wheel Torque: 50.43 ft lbf
Acceleration: 17.50 ft/s
Top Speed: 26 mph


When I have the wheels off the ground, the TC opens up, but when driving it around, it doesn't. I'm wondering if my engine just isn't producing it's maximum amount of power. The next thing I was going to try was replacing the engine oil since what came with it was from the previous owner. (Stupid me, I should have done this already)
Anything else that I may be missing here?

Here's a video of it in action at full throttle. Just to note, the section where the wheels are off the ground, that was before I installed the new axle and brakes.

 

[JimD]

To me it looks like your belt is way to loose. When you start it should be almost snug at the bottom of the driver pulley. If you can squeeze a business card under the belt on the driver it is perfect. I believe if you take the outer sheeve off on the driver unit (engine) and look at the belt you probably can get your finger between the belt and the oilite bushing. You want instant response when you hit the gas and I don't think you are getting it right now. just my 2 cents.

 

[DuckSoup]

Thanks for the feedback. I definitely can't get my finger between the belt but something I noticed was that the engine isn't maintaining that full power.

Also, if the belt was too loose, what's the fix for that? The whole thing shipped as a kit so I don't know that I can adjust tension.

 

[Master Hack]

They make different size belts. Unless you bought a genuine comet TC the belt will only last a few minutes. There is a specific brand belt you have to buy (unless ya like changing belts) but ya rarely hear it mentioned. Denny will remember cuz he gets paid commission on dem things.
By the way there is no such thing as done.
You’ll find out soon enough.
I thought mine was done 4 years ago!

 

[Edwin Spangler]

The driver not closing looks to be the issue. The belt is fine but just to be sure, whats the numbers on it? If the problem was a loose belt, the driver would close all the way and you would see slipping.

I would open that driver and see if theres anything going on but it sounds like the engine is limited...

Ill get a picture of my belt tension so you can compare.

 

[Edwin Spangler]

They make different size belts. Unless you bought a genuine comet TC the belt will only last a few minutes. There is a specific brand belt you have to buy (unless ya like changing belts) but ya rarely hear it mentioned. Denny will remember cuz he gets paid commission on dem things.
By the way there is no such thing as done.
You’ll find out soon enough.
I thought mine was done 4 years ago!

Those GPS belts arent bad... Theyre not as good as the good ones but theyre better than the floppy rubber ones.

Best belt manufacturers are-

Comet
Rotary
GPS (even though I dont support them)
Gates

 

[JimD]

Several checks you can do for starters. Drive around for 5 minutes WITHOUT TOUCHING THE BRAKE, just coast to a stop. Now get out and feel the brake disk, it should be cold because you haven't used the brake but if it is hot to the touch your brake alignment would need adjustment. Just a simple trick to pin point reasons you aren't getting ful speed.

Now back to the t/c. I would like you to just take a picture of the driver unit on the engine without the cover and floating sheeve on it so i can see how the belt is on the unit. This gives me a better feel for how loose it is. Next comes out the old tape measure. I want to know the center to center distance on the two shafts --the crankshaft and the driven shaft. Measurement # 2 -- I want the diameter of the driven unit --it is either going to be 6" or 7".

I watched your video a couple more times and when you had it on the stand I could see the floating sheave in the driver come out to move the belt upward on the driver but when you went for your ride I never saw it come out. You might when you take it off for the picture make sure it slides freely on the four lobe piece and that what gets lubed with a dry moly lube, never oil that because that will foul it up and capture belt crap and dirt preventing the floating sheave from moving towards the engine. This site loves pictures so take several.

 

[Master Hack]

We all be good with the 5:1 final drive? With a 212? 6:1 as recommended a kazillion times doesn't apply here? I'm askin, not being a smart azz for a change.

 

[DuckSoup]

Thanks guys for all the feedback. Let me make sure I got everything here that was asked.

So quick note, after one of my buddies noticed the engine not performing super well, I took the carb back apart and gave it another really good cleaning. Here's a video of my 2nd test run. The engine performs much better now, but I'm still not getting the TC to open up.

Took some pictures. The distance between the two shafts is right about 7 inches.
The belt type is also shown in the pictures.
That brass fitting does slide fairly easily as well.

Also for this test run I adjusted the brakes way down so that with the pedal fully down, it was barely engaging the disc, just to rule out and possible brake issue. (You will notice them wobble a bit in the video)

It's like it's so close and wants to open up but the engine just isn't quite there.

 

[panchothedog]

I'm with Jim. I think they shipped you the next size bigger belt by accident. Do you have the belt oriented properly? Almost looks like you have the flat side out. Maybe just the picture. Flat side needs to be in on the engine side. About 7 inches really isn't close enough. Go on the belt chart at GPS, and I believe most of the size measurements are in increments of either 1/16" or 1/8" at the most. Very little difference in center to center measurement is cause for a different belt. With the driver disassembled, inner sheeve on the engine and the belt on the driven it should be somewhat difficult to get the belt on the driver. If it slips right on easily, it's definitely too big.

 

[Edwin Spangler]

Guys...

Hows that driven look to ya??? Isnt the cam supposed to be following?

 

[Edwin Spangler]

I'm with Jim. I think they shipped you the next size bigger belt by accident

Unless the belt is incorrectly labeled, its the right one. 725...

 

[JimD]

No Ed, cam is on the correct side for an outboard mount. I am still saying the belt is to loose. Always liked the arrows indicating you are mounting the belt correctly but even Comet's supplier goof up one time and put the arrow on the wrong side. People make mistakes which is another reason we went with a symmetric system it was idiot proof and ran much cooler.

I will assume Ducksoup looked at the belt closely and put the flat side towards the engine. I went to GO Power Sports to read up about the belt an all it said was it was their replacement for their t/c. The above pictures were good by the way so we thank you. To quote our buddy Denny who needs more points to get his next check for recommending the real belts by Comet. I would get the 7" Comet belt #884-70 which fits a 6. 9375 to 7.000 center to center (You can always take out the bronze bushing if it is too tight.)

Also push back in one of the wear ramps in your picture #2 you are about to loose it which are "spares" for when you get too much wear on the only side the ramp will ever touch.