GP 40 series driver getting stuck?

[Jean Luc Picard]

Hi all, it seems as though my new go power sports 40 series driver has an issue. When I'm driving the kart for a while and go to accelerate then come to a stop the driver sticks partially open riding the belt making the engine shut down.

I removed the driver and disassembled it to find one of the rollers have derailed in the slots and twisted sideways not allowing the sheath to close fully when coming to a stop. Sometimes if I slow down steady, I can hear it make a clunk when I fully come to a stop and it doesn't get stuck?

This has happened now three times, I've tried aligning the pulleys different ways, I aligned them with the belt perfectly straight then aligned them as go power sports recommended which is aligning both back plates. All to no avail, any help would be greatly appreciated fellows.

 

[8t6bronco]

Have you called Go Power Sports?

 

[itsid]

that's why the driven should float 7/8" when mounted outboard...

the crooked belt can (in some occasions) tilt the moveable sheave just enough to cause
issues with the rollers.

'sid

 

[KartFab]

i have had that happen with the genuine 40 series in the inboard position too. Its usually when im doing crazy donuts, flying around like a lunatic and whatnot and i have to disassemble, and line everything up again. both the 30 and 40 series units always have issues. ive hardly ever had any issues with the driven units.

On an interesting side note, the little springs that stick in the rollers (not the actualy springs but the clips the springs attach to) free float on the lighter rollers that i got, but the heavy rollers dont have those little spring clips free floating, they are actually wedged in. Just a thought.

 

[gman3850]

Rpm probly has a some effect to this as well. They are only rated to I think 5k rpm

 

[itsid]

a binding pin should cause the roller to wear unevenly, not?

If so, it should be easy to ream the roller bore to allow the pin to rotate freely.

a locked roller (unevenly worn) might indeed loose it's track more easily of course;
still that crooked belt on the moveable sheave...
surely does not help to keep everything aligned

'sid

 

[Jean Luc Picard]

@8t6bronko yes I contacted them and am awaiting there response.

@gman3850 I doubt it, I'm only hitting about 4500 rpm.

@KartFab exactly what's happening to me bud. But I also noticed that it mainly happens when it gets hot, which leads me to believe the main spring is getting soft and not returning the sheave. I have seen this a lot in scooter cvt's where the contra spring heats up and acceleration suffers greatly.

@itsid so your telling me that the gp 40 series has an inherent flaw as in the rear driven should float? Is there anything I could do itsid?

Thanks for all of thoughts guy's, I really appreciate it.

 

[itsid]

@itsid so your telling me that the gp 40 series has an inherent flaw as in the rear driven should float? Is there anything I could do itsid?

No, the series 40 should be mounted inboard, then nothing has to float.
it's build so that the two moveable sheaves open in the same direction so the belt shift caused by the driver will be compensated by the openening of the driven.

Now, if mounted outboard this will NOT happen of course, instead the driver moves the belt in the exact opposite direction as the driven would be able to compensate, soooo belt misalignment adds up.
to a total of 7/8"

THAT amount needs to be compensated for, the driver must not float,
so the driven is the only part that could.
Well on an ordinary jackshaft that is....
on the GPS backplate there's just not enough room to have a floating driven..
So yeah, there's an inherent flaw IYAM.. but it's not in the Comet series 40

the backplate is a compromise and it might be worth taking in very few occasions (mini bikes with not enough room is the only I can think of)
since one thing will wear prematurely, best case the belt, worse rollers or moveable sheave of the driver...

'sid

 

[Jean Luc Picard]

Thanks for all of the help itsid, gopowersports is sending a replacement front drive so I will give that a try and see how it goes.

I have the driver (clutch) pushed out away from the motor and the driven in toward the plate as from the factory. From what I'm gathering this is how this particular setup is supposed to be. I may have to take some pictures for you, so you can get a better understanding of what I'm saying.

 

[Bbqjoe]

Just don't line them up like this!!!!

 

[Jean Luc Picard]

@Bbqjoe idk about that, that's a pretty aggressive bend for the belt isn't it? I could try it but I'm not sure the belt could bend that much.

Below I will try and post some pics of my setup so you can give me some feedback on if it's gtg or not.

 

[Jean Luc Picard]

picture

@Bbqjoe idk about that, that's a pretty aggressive bend for the belt isn't it? I could try it but I'm not sure the belt could bend that much.

Below I will try and post some pics of my setup so you can give me some feedback on if it's gtg or not.

Here is a picture.

 

[Bbqjoe]

Looks like too many washers behind the driver.

 

[itsid]

*sigh* Joe, would you at least try to NOT confuse people with your "funny images" .. ?

IDK what GPS recommends tbh,
maybe you want to ask them for their recommendation of belt alignment.
to me that looks to be 'too gentle' of a crooked belt in idle tbh.
Again, that belt moves roughly 7/8" and at speed it should really run straight...

the driver is pushing the belt towards the engine (up in your pic) , the driven away from it (downwards in your pic)
So yeah.. imho that driver should sit out farther out a bit IYAM
(personally I'd target half an inch of offset for starters)

I really do not like that backplate at all.... nor how GPS markets it.
(savings on the retail price... my 455 *cough* they MAKE that thing!)

Anyways, I cannot be of huuge help here, since normally I'd say what Joe just said
(which is indeed the WRONG answer for YOUR question though )
align them at idle and they'll stay aligned all the time.
unfortunately that's simply false with this backplate;
thus you need a crooked belt at one point in time; I'd dial towards low speed.
(a huge pain in the behind to set up with the notoriously short shafts of predator engines)

yeah well... what can I say..
make a shaft extension (inner spacer, just cut some length of keyed 1" shaft, center drill it, get a longer bolt and put it in your driver with the key spanning the crankshaft and your extension)

Also: make a proper spacer for the back, washers won't do!
(they tend to rub the outer race of the crankshaft bearing which is BAAAAD!)
so at least make sure the first washers are not touching anything but the inner race and the next washer

'sid

 

[Jean Luc Picard]

That's what I thought joe, But everywhere I look says to align both back parts of the pulleys? Exactly what needs to happen here? Should I center the belt in between both pulleys or should the front driver be slightly off center towards the wheel or a lot off center towards the wheel.

On a side note, I do notice that sometimes when I'm accelerating it sounds like it won't up shift to a higher gear (top speed) almost like the belts slipping or it's not shifting all of the way, yet when I had my brother on it with me to take a look at it, he said it was shifting fine. All the way up on front and all of the way down on the rear, even when it makes that noise?

Thanks for all of the help joe.

---------- Post added at 09:08 PM ---------- Previous post was at 08:51 PM ----------

Yeah I see what your saying sid, the clutch sheave is pushing towards the engine and the driven sheave away from the engine, therefore at higher rpm's they should be aligned. But remember, if I make the belt too crooked on idle, I will have the clutch inner sheave riding the belt, making the kart want to leach forward on idle.

The washers only ride on the crankshaft up to the step up, trust me, I keep an eye on things like that seeing I rebuild mx bikes which are much more complex. I agree with the washers though, I was thinking of making some one inch spacers out of bar stock on the lathe.

I do believe if I extend the clutch anymore on the shaft I could run into the idle issue seeing it's starting to tug a bit now.

Thanks again sid for all of the help, your knowledge on this particular situation is priceless to me.

 

[Bbqjoe]

Aww H3ll. I said don't align it like this!

Anyways, I'm apologizing if I gave the wrong info.
I thought they were all about the same when it comes to the belt being straight.

 

[itsid]

And you would have been correct Joe.. but this is the GPS backplate... it cannot have or keep the belt running straight at all times
So it's better to have it misaligned when it's under less load IMHO...


Jean Luc, I know about the dilemma you're having or I could imagine it to be precise,
IMHO that setup with the backplate is more hassle than installing a series 40 properly,
it doesn't "ease" anything...

GTC (a TC manuafacturer) announced to develop a series 40 backplate a few years ago, but they gave up for those very reasons.. it's simply not going to work properly.
they even took the announcement down...

Anyways, go as far as you can without a leaching kart, if your kart came with a hand brake that could buy you some extra thousands of an inch

and then just hope for the best I guess.

I'm sorry that I cannot provide you with a really good solution,
IMHO the best thing would be to get rid of the GPS system, get a proper jackshaft and install the series 40 as it supposed to be installed (inboard, fixed on seperate jackshaft)
frankly.. I might even ask GPS for a refund tbh.
But that is just me (since as I said I'm not particularly a fan of that product )

I keep my fingers crossed for you though, that it was a flaw in the first driver you got
and that the new one will work reliably from now on and you can keep the setup you have.

'sid

 

[Jean Luc Picard]

Yeah, I think I will fabricate something up and utilize the the parts from the gps 40 series driven to make it work.

I do believe I can make the driven float by making a motor mount plate and welding some brackets to that for the 5/8" bearings for an extended 5/8" jack shaft. Of course this is all just in my head, in reality I have to take a look and see what can be done.

Thanks again sid.

 

[itsid]

keep in mind that you can also just install a correctly wound spring again and mount it inboard instead, no need to have it float that way

'sid

 

[Jean Luc Picard]

Ahh I see. I did not even think about that. Well that's the route I will be taking then. Thanks for all of the help sid. Like I said, your info is priceless.