Tmaxx 3.3 keeps stalling

[Nitro hobby]

I am new to this site... I have a traxxas tmaxx 3.3 and I have put about a gallon of fuel through it... The other day when I was running it I applied the brakes and it died right out of the blue. My slipper clutch pads did go out a while back so I upgraded to aluminum ones and I'm wondering if I got them too tight and ruined the engine clutch. Usually it stalls if I hit the brakes, sometimes it idles rather rough...so I'm not sure what to do...any help?

 

[Certified Mike]

First of all, welcome to RCNT!

Now down to business... It sounds to me as if your issue is likely a pretty easy, quick fix. The 'engine clutch' is exactly where I would start looking. Make sure you haven't just worn them out. Although a single gallon of fuel does seem to be awful fast to blow thru clutch shoes, depending on how they were set, if there were any contaminants that got into the bell, even rust on the bell could drastically reduce the lifespan of them. Also, make sure everything is set correctly. The bearings should be right and spin free and smooth. Be sure that your springs are in good shape as well.
There are other things to consider here also. Be sure your brakes aren't hanging up or dragging at all. You do need to be sure that your slipper is set correctly. Have you changed any of the gearing, running stock sized tires, any other modifications?
How are you using the truck? Are you racing it? What do you surfaces do you run on primarily? There are a number of aftermarket clutchbells and set ups that are designed to disipate heat and handle the abuse of higher stress on the driveline.
Yes, a simple fix is likely but many things to consider before you get to the actual fix.
Look for the actual problem and let us know. Also, let us know about all the other info. There are a LOT of tmaxx owners here who can get you set up right.
Good luck!!!

 

[hamz9561]

The other thing to check is that the carb isn't closing all the way down when you apply the brakes. With the engine off and the air filter removed, make sure that you 1-2mm of throttle opening when the brakes are applied.

 

[cbaker65]

I am new to this site... I have a traxxas tmaxx 3.3 and I have put about a gallon of fuel through it... The other day when I was running it I applied the brakes and it died right out of the blue. My slipper clutch pads did go out a while back so I upgraded to aluminum ones and I'm wondering if I got them too tight and ruined the engine clutch. Usually it stalls if I hit the brakes, sometimes it idles rather rough...so I'm not sure what to do...any help?

You can check your idle gap first ,make sure that the carb is not closing off when you apply the brakes!
It may just be that simple!
Check it first before you blame the clutch springs!..

 

[Nitro hobby]

Thanks for the suggestions... I'll check the carb out on it but I really think it's the engine clutch that is my problem because when I set it on a stand it's the wheels off the ground and turn it on and let it idle then stop the wheels with my hand it kills it every time....

 

[Certified Mike]

The idle is Def a good place to check. Sorry, my assumtions got ahead of me on this one!

It's not a bad thing to check, it's easy. Use an Allen wrench or feeler gauge. You want it set to approx 1mm. Before you go about setting needles etc, the VERY FIRST place you adjust js gonna be the idle anyways. Let us know how you make out!

 

[Nitro hobby]

Well I adjusted the idle speed up and now it won't stall when I hit the brakes but I'm still bewildered because I cannot start it without lifting it off the ground or running along side it with the starter engaged... so evidently something else is wrong... the starter always try's to turn the wheels when I'm trying to start it. What doesn't make sense to me is if the engine clutch is froze up why does it not stall all the time when the wheels stop even if the idle speed it turned up???

 

[cbaker65]

Well I adjusted the idle speed up and now it won't stall when I hit the brakes but I'm still bewildered because I cannot start it without lifting it off the ground or running along side it with the starter engaged... so evidently something else is wrong... the starter always try's to turn the wheels when I'm trying to start it. What doesn't make sense to me is if the engine clutch is froze up why does it not stall all the time when the wheels stop even if the idle speed it turned up???

Your right ,actually ,if it does want to take off when you try to start it ,it definitely sounds like the clutch!

The clutch spring or springs are worn an broke or a fried clutch bell bearing!...
We always suggest to always check the easiest stuff first!...

 

[Certified Mike]

For sure! K.I.S.S. is the way to go! I would pop the clutch off and have an actual look at what you've got going on in there. Its not a terrible job to do. This eliminates all guessing and really is your next step to diagnose this imo.

 

[Scalded-dog]

So most of us internet rc mechanics think that your clutch is engaged when it shouldnt be. The next question is whats causing it.

Your clutch could be jacked up. Does clutch bell spin freely by hand when not meshed to spur gear? It should sound and spin sorta like a skateboard wheel. If it does not then you have a definite clutch problem.

If inside of clutch bell is debris free and not deeply grooved its fine. If shoes aren't worn down to nubs they are fine. If springs are not broken and keep shoes pulled in and its hard to move the shoe by hand.. they are probably fine. Look at user manual and see if clutch is assembled correctly.

The part about you being a noob (no offence intended) and you burning out clutch shoes so quickly has me suspecting that your car may be idling wayy to high and causing clutch to be engaged to some extent even when it should not be. Does car sound like angry bee hive when at idle or more like a loping harley? Does the carb have an idle gap about the width of a paper clip when closed? Does your linkage and trim setting allow carb to close to this "normal" idle gap? An incorrect carb tune can cause phantom mechanical issues in nitro cars. (I fought with one last week) Incorrect carb needle setting can be masked by cranking up the idle speed screw. And cranking up the idle speed screw too far can overwork your clutch. Etc.

Think of a real car truck or motorcycle with a manual transmission. If you do not disengage the clutch when you brake to a stop the engine dies. Theoretically you could keep on the brakes... rev up the engine quite a bit.. and it might keep running. But you would burn out the clutch in short order. A centrifical clutch like on a nitro rc disengages (when properly assembled) by decreasing engine speed (rpm).