Six Gear differential spring & nut backing off

[EM1-TC3]

Good morning, I have a six gear trans that I rebuilt but I wasn't able to use the original part number for the diff spring and nut, instead I used the Associated 6587 Stealth Torque Control Spring & Locknut. I just can't justify the eBay prices for the original parts right now. My issue is after a few runs the nut starts to back off more and more til it slips. Do I need to use the correct nut & spring or is there a trick to keeping it on?

I've removed it completely off once to go to a bigger spur (one time use?) and the motor is a 3500kv with the throttle end point backed well below half until my 2230kv arrives.

Thanks,
- Brian Dumass

[Y'ernat Al]

The 6628 spring you need will be $2.00 in september. You can message any of those ebay sellers charging $12.00 right now and let them know they are going to be stuck with thier spring unless they lower thier price for you?

You can try turning the 5-40 nut you have from the 6587 kit backwards so all the nylon is engaged? Or use some locktite until september? That spring isn't correct but I suppose that if you get the diff to behave (spin one wheel and see that the other wheel spins freely and firmly in reverse - then hold both wheels firmly and try with great difficulty to spin the spur) other springs would (sort of) work?

[EM1-TC3]

The 6628 spring you need will be $2.00 in september. You can message any of those ebay sellers charging $12.00 right now and let them know they are going to be stuck with thier spring unless they lower thier price for you?

You can try turning the 5-40 nut you have from the 6587 kit backwards so all the nylon is engaged? Or use some locktite until september? That spring isn't correct but I suppose that if you get the diff to behave (spin one wheel and see that the other wheel spins freely and firmly in reverse - then hold both wheels firmly and try with great difficulty to spin the spur) other springs would (sort of) work?

Oh, wow, so the spring is wrong too Thought maybe it was an updated part # or something

Alright I'll try a dab of blue Loctite, once it's initially on it works flawlessly, it just has to be retightened every 7-10 minutes. I appreciate the help!!


-Brian

[GoMachV]

The way the 6 gear diff works is unlike the newer diffs like the stealth. On the stealth the screw and hub need to be separate and the spring and nut can loosen if there is a problem in the thrust. The 6 gear diff has flat spots on the upper shaft and the outer hub splines to the flats. The spring should never spin and thus the locknut should not unscrew. The only way I can imagine it unscrewing is a weak nut (sounds like yours is new) or the flats are worn or the outer diff hub is worn and spinning on the flats.

[Y'ernat Al]

The way the 6 gear diff works is unlike the newer diffs like the stealth. On the stealth the screw and hub need to be separate and the spring and nut can loosen if there is a problem in the thrust. The 6 gear diff has flat spots on the upper shaft and the outer hub splines to the flats. The spring should never spin and thus the locknut should not unscrew. The only way I can imagine it unscrewing is a weak nut (sounds like yours is new) or the flats are worn or the outer diff hub is worn and spinning on the flats.

Yep, and there be just enough play in the flat spots that a loose nut can ratchet itself off as you hit the throttle/brake/hit the throttle.

Another thing you need to check is to make sure the threads on the shaft are perfect (and someome didn't try to put a 4-40 nut on there and bugger them up enough that even a new 5-40 doesn't properly grab).

[GoMachV]

Yep, and there be just enough play in the flat spots that a loose nut can ratchet itself off as you hit the throttle/brake/hit the throttle.

Very good point- it may be a loose but not stripped fit causing that.

[EM1-TC3]

Thank you so much Brian and MachV, I for now just put a dab of blue thread lock on it and it ran for 30 minutes today til the pack emptied with no issue. I will probably start replacing parts as they become available again as the buggy was abused by me 20 some odd years ago, I remember running a trinity 9T Kevin Kevin motor in it with a run time of approx 2 minutes

thanks for pointing me in the right direction guys,
-Brian