Torque converter on Predator 420cc

[karl]

After putting rear end on stands and watching clutches misalign and plate flex I realized the one inescapable fact...fab work.

Wait a minute............

No comment?

 

[GoKartNarc]

I ordered the one that is on there now from Go Power Sports. It's the 40 series and says it works with 8hp-18hp. Should I go a size up to the 5/8"?

 

[karl]

I ordered the one that is on there now from Go Power Sports. It's the 40 series and says it works with 8hp-18hp. Should I go a size up to the 5/8"?

The idea of using the smaller shaft, is that the bearings have more meat, and hold up better, it may help.

I have constructed a diagram your viewing pleasure , to explain your problem.

This is why flipping the engine driver helps, the direction the sheave moves is the issue.

Since the sheave slides the wrong way, it needs to move on the shaft. That is why the backplate is flawed.

You can return/resell the setup, and make a traditional jackshaft.

 

[Joe-405]

I ordered the one that is on there now from Go Power Sports. It's the 40 series and says it works with 8hp-18hp. Should I go a size up to the 5/8"?

That would be a size down sir. If you have the 3/4” driven.

what I was saying is all the ones I’ve seen all have the traditional 5/8” shaft. And yes as Karl said more meat on the internal rollers for the bearings is also what I was referring to.

 

[65ShelbyClone]

Ok I figured as much. The 3/4 jackshaft bearings are junk. If you switch to the 5/8” stuff it will solve your issue. I have the same problem.

I switched to these bearings and packed them tight with red Lucas grease and it helped but they are still a issue...............

Needle bearings are supposed to be used on a hardened and ground shaft or used with a hardened shaft liner.

 

[GoKartNarc]

OK so I replaced the broken bearing. I rode it yesterday and everything seems to be working well. The bearing isn't loose or wobbly. I did a little research and ordered speed bearings. I haven't received them yet, but when I do I will use them and hopefully solve the problem.

 

[Nicks_go_karts]

Wait a minute............ why is your driven a 3/4 one if you got your kit from gopowersports ? The one I bought which didn’t have a single issue on my mini Dragbike was 5/8. I just looked on the website and it still comes with the 5/8 version.

did you special order yours differently ?

Hi everyone,
So I have a 420cc on a Manco Dingo frame. I bought the torque converter from Go Power Sports. The problem is with the bearing for the jack shaft closest to the torque converter. The original bearing had disintegrated and fell apart cause something was rubbing, but I fixed that already. So I ordered new bearings specifically for go- karts and a new jack shaft for the torque converter. I installed the new bearings and shaft and then took it out for a ride, probably about 15 minutes worth and when I got back to my garage I noticed the bearing closest to the torque converter had disintegrated again. Not sure why this is happening. Everything seems to be lined up properly in the back. Chain isn't too tight or loose. Any suggestions.

Thanx,

GoKartNarc

Hello, I’m Nick, I’m 14, and I rebuilt a year dog 3203 and put a stage 1 predator 420 in it with a GPS 40 series TC in it. Its great, has plenty of torque, and does about 40.
I just made this account because Im having the same issue and I have no clue what would be the best way to solve it.

Ive had it on the stock TC and stock 60T rear sprocket and it’s been doing well, I did run into the issue where the driver clutch locks up, and I upgraded the springs and sprayed some graphite lube. I haven’t had that issue lately, but now the bearing(s) gave in.
Just like Joe described, the one closest to the TC practically disintegrated, and I assumed it was because the chain was too tight or I was running it too hard.
I replaced both bearings with the oem gps bearings, same result.
Replaced both again with different bearings (same exact size), same issue.
I did this multiple times, adjusting chain tension, making sure the jackshaft nuts weren’t too tight (my dad thought that was the issue) but even with all of that checked, it would only last anywhere from half and hour to multiple hours before eventually giving out again. (jackshaft wobbling and smoking, chain falls off)

I have an instagram account (_go_kart_kid) where I post videos and updates. ive been able to reach out to people with a similar setup, and one guy with a 3202 suggested that it could be because of the gearing (10:60) I have with the torque that’s causing it. He suggested going with a 54T sprocket in the rear, and keeping the front the stock 10T.
I liked the stock gearing, because I had plenty of torque and a good top speed.
I’m not the greatest at fabrication, so I’d appreciate a solution that might not include welding.
still figuring out if it has to do with the chain tension, the torque, the gearing, maybe the bearings, or perhaps the TC itself.
I‘m honestly not sure how to fix this issue, but its been a serious pain in the a**.
so far the plan is to definitely add new jackshaft nuts (mine are very worn) new bearings (already got them) and a new chain.

also, (at least from my experience, and what I’ve seen all over yt) the gps 40 series tc comes with the 3/4 jackshaft.
also, A few questions.
would changing to the thinner 5/8 shaft but beefier bearings strengthen the jackshaft setup?
would changing the gearing from 10:60 (good torque, 40 top speed) to 12:54 (less torque, higher ts) reduce the amount of stress on the bearings?
I like the stock 10:60 setup, bit if reducing the torque is necessary, then so be it.

I’d greatly appreciate any help I can get, and I’d be happy to answer any questions.
thanks for your time.

 

[Snaker]

ID 3/4" × OD 1-3/8"
They didn't specifically say they were the bearings for the jack shaft though. I did a little research and is it possible that I need the high speed bearings? You can see how the new belt is rubbing a bit. The torque converter plate is from Go Power Sports. I have two different torque converter drivers, not sure which one is on there now. That could be another problem.

A couple things:
1. The driven movable sheave is on the wrong sides of the ramps
Should always twist against the belt on upshifting (opening)
Should always go with the belt on downshifting (closing)
2. The spring looks right but would be wrong if the fixed is positioned properly
All that changes if you flip the driven pulley
3. Is it me or is the drive pully fixed sheave flat (30 series)

 

[madprofessor]

Not convinced everybody's of the same mind on the basics here. First things first, check out the link below, read all of the info text at the start of the page, then scroll down all the way to the bottom and read that even bigger info text section. Read everything, then................
Scroll back to the top and start looking at the simple black & white drawings of TC setups for the various size belts all the way down the length of the page, there's 6 of them. The first 2 are of the asymmetric type (30 series & CAT99 series) TC's with the pulleys all being flat on one side. The other 4 are the symmetrical V-belt type, including the 40 series with its 7/8" wide belt.
See how asymmetrics have the spring on the same (outboard) side of their pulleys? That's because the flat side of their pulleys (and flat side of their belts) must always be on the same side so that their BELTS NEVER MOVE toward inboard or outboard as speed increases. See how symmetrics like the 40 series have the spring of the driver (outboard) also, but have the spring of the driven on the opposite (inboard) side? That's because the driver MOVES THE BELT towards the motor (inboard) as speed increases, and the driven will move the belt evenly that way (inboard) also ONLY when it's mounted opposite of the way the driver's mounted.
The built-in jackshaft for the driven on the 40 series TC's that come complete with a backplate and the driver's and the driven's springs on the same side usually isn't long enough to allow flipping the driven opposite of the driver's mounting, hence the belt always moves in/out of alignment. Some folks manage to flip the driver around on the motor shaft, but it barely stays on there far enough.
The only cure I know of for that which actually works right is to throw out the backplate and mount a separate jackshaft to the kart frame with framed bearings (I use only cast iron pillow block bearings, see pictures below of them on a 30 series setup.)
Comet Drive Belts | Comet Torque Converter Belts | Go Kart Belts (gokartsupply.com)

 

[Denny]

And your gear ratio is fine. It will not cause the problems you are having.