Jarret

Ok, my cousin has a Ofna Ultra GT LX Pro and we noticed that it has a stripped differential. At least we are pretty sure that is what it is and we just wanted to make sure that is what it is.

Here is what we saw.

We started up the motor and got it to idle and tried to drive it around. When the throttle was applied the buggy would hardly move and only the brakes would work. We then noticed the drive shaft going from the transmission to the rear differential spinning like the buggy was at full throttle.

So does this mean that the rear differential gears are stripped out? Is it only one of the gears inside or would we have to take it apart and look to see which ones are stripped out and replace those?

Or would it be better to just spend the $40 and get a whole new differential.

Nitroaddict

confused. At idle the drive axle is spinning? if so, then u have a clutch problem too.

Please advise.

Jarret

Yes, when the buggy is at idle the drive axle coming from the transmission going to the rear differential is spinning.

The spur gear, clutch bell, and gear in front of clutch bell spin as fast as the drive axle.

Nitroaddict

well. before we go any further - if any drive shaft, or the main spur gear is spinning at idle, as is the clutch bell, then there is something wrong with the clutch. Is the idle really high? or is it normal? if the idle is very high, turn it down with the idle set screw adjustment on the carb, and see if it stops. If not, then remove the engine and take off the bell housing, see if there is anything wrong.

Jarret

The idle seemed a little high but not enough to make a noticeable difference.

So if after we turn the idle down, and it does stop spinning, do we have to fix anything?

And if we do take the clutch apart, what should I look for?

Nitroaddict

the clutch engages via centrifugal force. So if the RPMs are too high at idle, that will cause it to engage. Turning down the idle will stop this from happening. However, this only happens if the idle is VERY high, so i doubt this is your problem.

Take the clutch apart, and look for clutch shoes that show signs of wear, or are broken/damaged. Also, remove them and inspect the springs. If the springs have broken, or wore out, they wont hold the shoes in place, and even at idle, the RPM's will cause it to engage.

This will not fix the rear drive axle problem, most likely. But it is part one of the problem. Lets get this fixed first.

Jarret

Ok, I will tell my cousin that is part of the problem.

The only thing I can't understand is why there is a problem in the first place.

The buggy still hasn't even gotten through the total break-in process, but I guess things happen.

Nitroaddict

The GT LX is not known as one of the premier buggies. If you are going to sell a buggy at 299.00, when every other good buggy is 500-1200, some things are going to have to be of less quality to allow a price that low.

Jarret

Well you get what you pay for, right?


Anyhow, thanks for the help, and will post more later on after dissambeling the clutch.

scale only 4 me

My Feedback: (158)

If the buggy is new it's most likely a set screw to one of the rear out drive hubs, this happens with the RTRs allot.

Any time you get a new nitro power car or truck, you need to take it apart and make sure all the metal to metal connections have Loctite, or similar thread locker.

I bet the problem is minor, take it apart before you start spending any money.

scooz13

My Feedback: (-1)

i had the same problem once. check all the set screws that hold the dog bokes into the the cup things.if they are not locktited they will come lose and the engine will rev up and the car wont move. you really need to make shure to use a lot of locktit because the do come loose. thats what i would do b4 taking apart the whole car.

MassiveMods

i am having the same problem , ill rev the engine but it dosent wanna go anywhere. i mean itll put around but met with any gradient it stops. if its the clutch then how do i adjust it to grip more?

Jarret

Thanks for the info guys.

The car is about a year old, so it isn't completely brand new and has been run a couple of times on a track.

I'll check the screws when I go over there later today.