My 250cc charger no longer shifts into forward gear. Moves back but not forward. I think something came apart or broke inside the gearbox, since the gear shifter bar is actuating the way it should. I have started to remove the gearbox. I have the shafts/wheels and the bolts mounting it to the frame off. The only thing holding it on is the shaft coming from the motor. I have tried to pry it off with a couple of large screwdrivers and it won't budge. Any ideas? I ordered a new gearbox off ebay that looked just like it. It now looks as if it won't fit as it has a different connection at the engine and slightly different design (better) where the shafts go into the gearbox. My spindles actually go into the gearbox into the oil seal. It has always leaked. The new gearbox keeps the shafts outside. The oil seal is around what comes out of the gearbox which doesn't shift around all the time while riding. Much better design. Any ideas how I could modify this to work on my kart? Please help.

Dude, you’re a live! Us Challenger 6250 Dbl owners have to stick together you know. I feel like we are the only two people in the world that own this particular buggy.

As for the gearbox, I am pretty certain there is a driveshaft that comes out of the gearbox and connects to the bell-clutch in the CVT. So in order to remove the gearbox you will probably need to open up the cvt and remove the Bell-clutch.

So you are saying the whole shaft comes out? Completely different than the replacement gearbox I received. Does your gearbox leak oil? Have you changed your oil seals? Or should I say, how many times?

I just checked and the bell clutch shaft does not line up with the shaft that leaves the motor and enters the gearbox. I can't see how removing the bell clutch will help in is getting the gearbox loose. Ever take this off?

This shows part #19 or the output axel on my Dazon 250 and I would think the GY6 would be similer.This is a right side view and the gearbox will be connected to the output axel.I don't know if this will help you in any way but I will say I hope in some way it does. mancoman

The replacement gearbox I received was for your 250cc kart. It has a female splined coupling coming out of the gearbox that would fit on the drive axle shown in the diagram you sent. Unfortunately, it looks like the drive shaft goes right into the gearbox on the challenger 250cc that I have. Doesn't make any sense to me, as how are you supposed to get it apart? Anyone have any experience with the coolster based 2 seater go kart with shaft drive that can help me?????

You need to take it to a buggy-auto mech or motorcycle mech that knows how to help you.Seems you can't do it.I could not either!But I will have to mine has a bad fluid leak-but I can rig it with keep filling it full of gear oil. mancoman

I know that on GY6 engines the output shaft isn't the same shaft the clutch and pulley are on. The clutch shaft actually goes to a final gear reduction before it outputs to the other side. You do have to go in from the CVT side to get to these parts. I would hit someone up for a exploded engine/transmission diagram before I ever to it to a shop. I know this is about a 250CC but I'm sure it has the final gear reduction also.

Plus the external gear box you are talking about sounds like a external reverse gearbox. Which is not really the transmission gearing just the reverse gear.

After I looked at some pictures I'm sure that the external part is just the reverse gearbox not the actual transmission.

I've found a artical about installing a new external gear box and it says you have to pull apart the CVT side of the gear box to remove the output shaft.

PLEASE BE WARNED I'M A NOVICE. YOU MIGHT WANT TO WAIT TILL THE TURKEY BAY BAS H IS OVER AND GET BETTER HELP FROM BIGE OR SOMEONE.

But here are the instructions that I found. Wrenching on these things is half the fun.

Directions:
1. Remove muffler.
2. Remove (8) 8mm bolts holding CVT cover to crankcase. Carefully remove CVT cover; Go slowly, as the gasket can be easily be destroyed. It is best to carefully slide a flat blade screwdriver between the cover and gasket material to separate them. We have replacement gaskets in stock if yours is destroyed.
3. With the cover off, you can see the variator (unit with fins), driven clutch pulley (unit with 6 holes), and belt. Remove the variator and clutch nuts. They are both 19mm. The minimal force needed to remove these nuts is 40ft/lbs -- It is best to use an air impact wrench. If an air impact wrench is not available, use a large strap wrench to hold the unit steady while loosening bolt.
WARNING: DO NOT hold the cooling plate in place by jamming items through the fins; this will most certainly result in broken fins and other damage to the cooling plate.
4. Remove belt, variator, and clutch pulley.
5. Drain gearbox oil at this time. With the oil drained, remove the (6) 8mm bolts on the Final Gear Case Cover. To remove the Final Gear Case Cover, very carefully tap it away from the crank case with a hammer. This will take patience, as the gear case gasket is easy to destroy. When you have enough clearance between the crankcase and cover, very slowly slide a screwdriver between the cover and gasket and then pull cover away. We have replacement gaskets in stock if yours is destroyed.
6. You should now see the final gear case internals. Pull out the output shaft (The shaft positioned closest to the rear of the buggy) and gear. The counter shaft may fall out, but just sit that aside.
7. If the new output shaft you received in the kit does not have a C-Clip, remove the clip from the original output shaft and install onto new shaft. Place the final gear onto the new output shaft supplied with the kit, and place the new output shaft into the crankcase.

I'm not sure where the GY6 engine came into this discussion. I am talking about my 250cc kart and it does have a haft drive gearbox. I found that on this unit the drive axle goes all the way through the gearbox and is held (why I could not get it off) by a snap ring at the end of the axle. This is hidden in a little comparment hidden underneath the gear shifter actuator bar asembly. I now have it off and apart and all the gears are torn apart. I need to find a gearbox for this. The daxon 250cc will not fit for a number of reasons, biggest is the drive axle configuration. Anyone know where I can find a gearbox for the Coolster Challenger 6250dbl?

I am sorry about your pain. So far my Coolster Dbl has been great! No leaks, brakes work great, even the emergency brakes works, if it is adjusted correctly. I have been tracking down a rather annoying idle issue, but I think I may have it licked. I all started when I fiddled around with the valves, so I need to adjust them correctly.

As for your gearbox that following web site is the “official “ parts source for our buggies. But like so many other internet dealers, none of the part are ever in stock: http://www.coolster.com/catalog/index.p ... 5&opvid=25

Don’t we have the same gearbox as the Roketa’s? I think the gearbox on the Coolster Dbl looks identical to the gearbox on the Roketa Titan. http://gokartsusa.com/images/view.aspx? ... 60&index=8


I realize this is expensive, but I am thinking if I could find it here you should be able to find it elsewhere: http://www.monstermarketplace.com/Autom ... a1105.html