Some wheels were too big to fit into the cut out. The kyosho one fits perfectly. The Tekno, Reds or losi flywheel will fit. 34mm flywheels.

This is almost always the result of bad starter box aligment. You need to move the wheel over
(Not all boxes allow for this) so the highest point is in the chassis. What happens is the high
side of the wheel hits first and to allow the wheel more travel they gring on the chassis.

Not always the case actually. Some bump box wheels are simply too big to actually fit into the cut out. Which is why i had to change starter boxes as the one i originally bought, the wheel was too big to fit into the cut out.

Hey guys. Have a NB48.4. What do I need to convert to EB? Motor mount? Chassis? Thanks

So my flywheel nut came loose.

But the flywheel didn't come loose and needed, as usual, a flywheel puller to get it off.

Once off I noticed that inside of the flywheel that presses down on the collet was scored.




Is this ok to carry on with? As I say, the flywheel was tight on, just the nut was loose. Clutch bell was tight too.

Those scores imply that the collet slipped and spun inside of the flywheel. I think it will be fine so long as the nut is tight.

So went out last weekend and the same thing happened. Flywheel not loose. Need the puller to remove. But when I take the bell and bearings off I notice the nut has come loose.

I'll have to use more locktite on than I'm using I guess. Thing with loctite is it makes it harder to put on off the nut and will likely forces me to zip tie the head through the exhaust to stop the pinion rotating.

How often are you taking the flywheel on and off?

You shouldn’t need Loctite on your clutch nut. I’d replace the collet and clutch nut and see if that solves the problem.

I clean up the shoes and bell every race weekend. Im not taking the flywheel off typically, unless I'm going to properly clean and remove metal bits hanging off the shoes.

I'll go with a tad more loctite before I consider using my fresh collet, flywheel and nut. I've only put a gallon through it.

​​​​​Feel like I'm missing something obvious.

You said your clutch nut came loose previously. So, you have a loose nut on the end of a crankshaft that's spinning 30K+ RPM. Even though your flywheel stayed on you saw what the tiny bit of looseness from the clutch nut not being tight did to the inside of the flywheel. I doubt that crankshaft spinning inside the loose clutch nut did it any favors. That's my reason for suggesting you try another clutch nut and see if that fixes it. Cause one of these days when that nut works loose the flywheel IS going to come off and you're going to be WOT on an engine that suddenly has no load on it. Might not end well.

that's a good point! To be clear I'm fully listening to you.

I'm currently running 1 of 2 old engines donated to me by someone as the track. Still have some compression. But if it goes pop I don't care.

The nut, both times seems to have just backed off a little. I wonder if I have too little or two much bell play? Could it be expanding, compressing against the nut and then undoing?

I'm be sure to use a new flywheel collet and nut when I install my shiny new Blok.

Do you recommend scruffing up the collet and flywheel to remove some of the anodised coating of the flywheel to get better friction? It's a 2.0 flywheel by the way.

Clutch bell shimming shouldn't affect whether your clutch nut stays night. That shimming is mostly to keep the clutch bell off the flywheel and make sure the shoes are grabbing 100% of the bell. Shimming between the crankcase and flywheel I suppose could keep the clutch nut from grabbing enough threads to stay tight. Not likely though. Take a look at the threads on the clutch nut and crank and look for damage. More likely to be the clutch nut than the crank. Try another nut, if that doesn't work then maybe try another flywheel or try the other engine and see if it happens with that one also. So many things that can go wrong, both the joy and the pain of nitro. Keep with it, nothing like it when you get it right. Will put a big stupid grin on your face.

I've swopped engines this morning ready for next weekend. The other loaner.

Of course I'd put more locktite on the nut and getting it off was a nightmare as engine would turn over. Used zip ties which cut right through. Ended up putting the head of a zip tie in the sleeve, letting it stop the piston move up to get the nut off. I'll have to properly strip it down to make sure no plastics bit s are about.

So I'll see how I get on with the new engine. I have channel lock pliers and as hard as I could tightened the nut. So we will see next weekend.

I have it like this..

Rear engine bearing-2mm shim - 2mm shim (needed for proper mesh alignment) - collet - flywheel - nut - 0.1mm shim - bearing - bell - bearing 0.2shim - end screw (jt bearing clutch screw)

I havent put the smaller washer on the screw at the end..as it just adds more length. Not sure it's really needed?



I see