Worn out pinion grub screw - RC-Monster Forums

**Worn out pinion grub screw -** 05.31.2009, 10:29 AM

Tried to change my pinion today but turn out the hex thread is worn out. It's too near the motor mount for me to use my dremel to cut a slot so I'm pretty much stuck. Help?

Question: The PINION grub screw is 3mm. If I drill a hole say, 2mm into the center, would a 3mm screw extractor be usable? It's the smallest size I can find. I don't think I should drill a 3mm hole instead, right?

maxair45 · 05.31.2009, 10:41 AM

Grabit(sp?) might work here. I've never personally used one but from what I hear they are awsome. I had this happen before to me. I was at the track(in a hurry)so I hacked it out by putting an old L wrench in there, filling with glue stripped out spot with glue, spraying some accelerator, and unscrewing very cautiousally. I was able to use the pinion with a new set screw and even the L wrench lived for another day.

Hope this helps

JThiessen · 05.31.2009, 10:44 AM

I'd also cut off the end on your hex - they get worn a bit, so cutting it off gives a fresh good end. If that doesnt work, maybe there might be room to get a hacksaw in there to cut your groove.

05.31.2009, 11:48 AM

Forgot to mention that my itchy hands had added loctite before I screwed it in the other time....Man...I think I'm screwed. Unless the loctite does not hold well, at least the screw extractor method may work.

E-Revonut · 05.31.2009, 12:00 PM

I see no reason you couldn't use a dremel to cut a slot parallel with the motor. You may have to take the whole center diff/transmission assembly out of the vehicle to do it though. Also try a butane torch style lighter and heat the set screw up a bit. The heat helps to soften the loktite.

rchippie · 05.31.2009, 01:38 PM

Take a soldering iron . Lay it on the set screw for a minute or two . That will help loosen up the set screw . Then as JT said take a allen wrench with a fresh end & give it a try that may help. Also you may be able to pry it off the shaft , if the allen wrench does'nt work . I have pry 'ed pinions off before .

05.31.2009, 02:32 PM

Quote:

Originally Posted by E-Revonut

I see no reason you couldn't use a dremel to cut a slot parallel with the motor. You may have to take the whole center diff/transmission assembly out of the vehicle to do it though. Also try a butane torch style lighter and heat the set screw up a bit. The heat helps to soften the loktite.

even if I take the assembly out of the vehicle, my dremel will still not be able to reach the position of the grub screw. However, I do thank all those who've replied and I'll try the methods out. Thanks. :)

BP-Revo · 05.31.2009, 02:17 PM

Depends whether you want to sacrifice the pinion or not, but you can drill out the set screw so much that it becomes structurally weak and just slide the pinion off the shaft.

lincpimp · 05.31.2009, 02:20 PM

You can also find a pinion puller, or rig up your own with a slightly modded battery terminal puller available at the local auto parts store... Or just cut the pinion in half parallel to the shaft, stick a flat blade screwdriver into the slot and it will spread it enough to get it off.