Annoying niggle with my DB17.

So I built a DB17, as I alluded too in another thread. Truck is awesome, bulletproof through and through with HD gears, GCM, Innovative RC etc. mods and lst shocks and the install is great looking. Ground down the motor mount so I can run a wider range of gearing to offset the big joes, everything runs real nice and lukewarm on 6s with 17/44 and I've had no breakages or wear on anything. However every run has been cut short by one thing, a whuring sound and a lack of movement as the pinion gear works itself loose and slides off the shaft. Tried blue, red and green threadlock and am out of ideas, no matter what I do it just backs the grubscrew out and stops. Sometimes with sparks if running at night as the pinion bounces off the spur. I'm scared of using superglue on it incase I wedge the pinion irretrievably on a $150 motor. To be honest I was very surprised when red threadlock failed.

Anyway this is the truck:

[ZippyBasher]

Try a new Pinion gear or at least new set screw. I use no locktite and never had 4mm set screw pinion come off... Or try to mark where the pinion set screw sits when meshed right and make a small divit (sp?) on the motor shaft so it sits in a little hole and will be less likely to move...

And what body is that?

[suicideneil]

A pinion puller will remove even the most stubborn pinion, so I think some CA glue would be one option- I like to apply a little blue threadloc ( tamiya stuff )to the actual motor shaft & then to the setscrew. Make sure you give it long enough to dry fully, and that should do the trick.

I've never had a pinion come loose on me before, I must be lucky..

Try a new Pinion gear or at least new set screw. I use no locktite and never had 4mm set screw pinion come off... Or try to mark where the pinion set screw sits when meshed right and make a small divit (sp?) on the motor shaft so it sits in a little hole and will be less likely to move...

And what body is that?

This is the third different pinion/grubscrew I have tried, all have the same issue. Body shell is an Alan Woodall fibreglass XL, it is so strong I can stand on it. Heavy though. May try the 'divit' idea, gotta be worth a shot.

A pinion puller will remove even the most stubborn pinion, so I think some CA glue would be one option- I like to apply a little blue threadloc ( tamiya stuff )to the actual motor shaft & then to the setscrew. Make sure you give it long enough to dry fully, and that should do the trick.

I've never had a pinion come loose on me before, I must be lucky..

Hmmm. Maybe i'll hit up some CA then. I have tried smearing everything in threadlock then leaving it over night to dry, no dice.

another thing is, sounds dumb but use a good hex driver you can really torque on. i used blue loctite, and torqued it as tight as i could and its held great.

[_paralyzed_]

having the point of the setscrew match the angle of the notch in your shaft helps too.

Like, if there is a flat spot on the shaft you want the bottom of the setscrew to be flat. If you do drill a divot on the shaft, angle the bottom of the setscrew to match the angle of the divot. The more mating surface area the better.

Superglue is too brittle when dried.

Green loctite is actually "sleeve loc" and is meant to glue the pinion to the shaft without a setscrew, and not meant to be used as "thread loc".

Red loctite usually requires 350+ degrees to seperate (usually) so use it carefully.

As mentioned by neil a puller will remove any pinion without damage to the motor, and is just a handy tool to have.

Good lucks! Nice looking truck!

Thanks for the replies guys, I'll have another go with the red loc I think, then if it does not work i'll see about getting a more suitable mounting for the pinion on the shaft.

I too have never had a problem like this with the pinion so keen to unwind itself. It's getting annoying because the truck is ballistic and it really is stopping me enjoying it.

[brian015]

The only time I had trouble with a pinion coming off was when there was an alignment issue between rotor and spur gear (such as from a bent or misaligned motor mount).

[Big House]

What kind of wheels are those. I got a truggy project they would look nice on.

[nitrostarter]

The tires in pic 1,2, and 3 are Proline Big Joes mounted on Proline Tech5 wheels.

The tires in pic 4 are stock hpi.

[Jahay]

yep i run the same chassis and experienced this prob a few times...

I just use a load of blue loc tite on the motor shaft and slide the pinion on... then blue loc tite for the screw and let it set over night and all done...

I have used red but required a heat gun to get it off... No Biggie!

Get some vids of that bad boy running!

what sort of temps are you getting? considerng you are running one of the heaviest setups... LST Shocks and FibreGlass shell with Big Joes and how much does it all weigh?