[JMT]

Ok, I know this has nothing to do with headphones but I am trying to help my son. He has taken the plunge into a nitro powered remote controlled car. It is called a Nitro Rush made by HPI Racing. He bought it with his Christmas money and recently has had problem with it. It will not accelerate into the higher speeds. The motor seems to be running ok, but the speed simply isn't there. We have changed fuel, changed the clutch, changed the glow plugs countless times, adjusted the brake linkage to the servo, but it still refuses to accelerate past moderate speeds.

I am hoping there may be some RC fanatics within the headphone asylum we have here that can provide some guidance. I have searched through HPI's website forum, but there doesn't seem to be a troublshooting forum.

HELP...and thanks.

 

[becomethemould]

there has been alot of talk about rc cars in www.overclockers.com.au so one of the members made up a forum at www.dotr.net im sure those guys could help yas

 

[setmenu]

Hi JMT
It could be a number of things but for starters:
Have you checked the drive train for binding and fouling against bodywork?
When you push the car it rolls OK?
Does the engine rev high but the car accelerate slowly to a low
top speed?
Is the engine run in? they can be tight from new.
Correct clutch adjustment is important.
If every thing seems free to roll you can do a simple[crude] jeting/
clutch check by starting the engine holding the car down on a grippy surface[firmly compressing suspension to prevent wheel spin] hold on tight and open the throttle slowly to full,assuming you have a normal centrifugal clutch an ok jetted motor will rev sounding loaded and laboured but still keep runing until it gains no more revs.do this only for BRIEF bursts you do not want to burn the clutch out.[do not let the wheels spin if pos]
If the motor dies at low rpm check the jetting there, if at higher it starts to stall check main jet setting.
If the engine just revs freely you clutch is the culprit.
This technique used to help me roughly set things up but remember open the throttle smoothly and allow cooling
between tests, do this too much and clutches wear!
If any of the above makes no sense feel free to PM me with further questions.
I am not an expert but have indulged in both IC and electric cars.
Good luck

 

[JMT]

Quote:

Does the engine rev high but the car accelerate slowly to a low

Thanks guys. setmenu, that is exactly what happens. I believe he broke the motor in correctly, he followed the manual and the exhaust is a nice bluish white color. The drivetrain does not seem to bind anywhere. My son did mention that he heard a sound when it first occured, he described it as "like sand." Disassembling the transmission is a major undertaking (at least for me and him), so we only want to do that as a last resort. Is it possible for the gears in the tranny to slip?

 

[setmenu]

JMT
It is possible for gears to slip if they are secured onto a shaft
with a pinch screw and it loosens,but this problem would get
worse very quickly as things wore.
Is this car all gears and shafts in the transmision?[also 4wd?]
Still most likely somethings come a drift it will only get worse.
Was this a ready to run car with no building required?
If yes and it is an assembly fault.
It is the manufacturers FAULT!

Hope you get it fixed,they a great when working well

 

[JMT]

Yes, he bought it ready to run. It's a 2WD, but from the looks of the illustration in the OM, the tranny has gears and shafts everywhere. For the short amount of time that it worked, it was very cool.....and quick! That is what is disappointing, it only goes about half the speed it's capable of at full throttle. I guess the tranny will have to undergo some surgery.

 

[setmenu]

May I suggest if the fault lies with the manufacturer that it be
returned/replaced/repaired by them?
If it needs new parts that could cost$$ not fair if it was not your
fault.
If it is not practical to do the above,the gearboxes are pretty
simple just pay attention to the manual, any way the things
get damaged bits wear etc you have to strip them in the end
so enjoy it.. you mey get hooked I even designed and built my
own palm sized electric racer in the end[you don't have to go that
far]

So have fun