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View Full Version : The perfect gear mesh (MR)?


Skv012a
2009.05.05, 01:05 AM
Using my PN 90 MM as the test case I noticed that if you loosen the motor and its holder enough to allow some free movement, you get an active perfect gear mesh. Also if you tighten the motor to its holder, but dont screw the holder all the way. The only thing is that i can see losing plenty of screws this way and there's no way to tighten the bolts w/ nuts instead.

Thoughts guys? If the motor screws don't fall out, there shouldn't be any moments where the motor would completely disconnect.

bermbuster
2009.05.05, 09:00 PM
Using my PN 90 MM as the test case I noticed that if you loosen the motor and its holder enough to allow some free movement, you get an active perfect gear mesh. Also if you tighten the motor to its holder, but dont screw the holder all the way. The only thing is that i can see losing plenty of screws this way and there's no way to tighten the bolts w/ nuts instead.

Thoughts guys? If the motor screws don't fall out, there shouldn't be any moments where the motor would completely disconnect.

the free motion is going to cause wear. The screw/motor threads. The pinion/spur. You are also putting extra load on your motor bearings/bushings. Really the worse thing that can happen is the assembly gets too loose during a race and it causes you a dnf.....

EMU
2009.05.05, 09:10 PM
I agree with Berm.

Its not a good idea to run with your motor loose. I had a mount that did not use the screw holes. And the motor had a little play in it. Over time, my pinion, spur and motor bushing all showed much more wear than normal. Although, this car was very fast with a stock Kyosho motor... and won many 015 spec motor races :p

With the PN 94LCG mount, I have had the adapter come loose on me, causing a DNF when I was leading the field by more than a lap. There wasnt enough time to adjust the mesh and tighten it before the race finished, so I finished 5th. I allways use threadlock on the screws as well, I guess uit was time to clean and re-lock...

Skv012a
2009.05.05, 10:37 PM
I see. I'd still like to at least try the idea if there was a way to secure the motor and the mount while allowing a lil freeplay. I guess I'll just have to go with the usual.

benmlee
2009.05.06, 02:19 AM
I agree with Berm.

Its not a good idea to run with your motor loose. I had a mount that did not use the screw holes. And the motor had a little play in it. Over time, my pinion, spur and motor bushing all showed much more wear than normal. Although, this car was very fast with a stock Kyosho motor... and won many 015 spec motor races :p

With the PN 94LCG mount, I have had the adapter come loose on me, causing a DNF when I was leading the field by more than a lap. There wasnt enough time to adjust the mesh and tighten it before the race finished, so I finished 5th. I allways use threadlock on the screws as well, I guess uit was time to clean and re-lock...


Use hex head stainless steel screws instead of the black ones supplied by the mount. Stainless steel hex screws for some reasons don't come loose like the black ones.

benmlee
2009.05.06, 02:22 AM
I see. I'd still like to at least try the idea if there was a way to secure the motor and the mount while allowing a lil freeplay. I guess I'll just have to go with the usual.

Meshing gears have a force that push them apart. Since the motor is on a slot, it would just keep sliding back away from the diff gear until it disengages. Maybe I am missing something here.

Skv012a
2009.05.06, 03:15 AM
Fact is that it slides away, but due to motor's weight the mesh ends up being just perfect. I did this holding it right side up and observed what happened to the whole thing as I played with throttle.

So you guys are saying that titanium screws don't need locktite at all? I HAVE noticed that all of them on my mount hold up pretty good, but I haven't had the chance to test that theory on-track yet.

color01
2009.05.06, 01:26 PM
Question... are you running some freakishly huge pinion that doesn't let you tighten the motor mount all the way? Otherwise the motor mount should be allowed to do its function, that is, hold the motor STILL in the right place.

Even if you allow the motor's weight to bring the mesh down when you're bench-testing the car, under load that motor's weight is not going to compare to the inertia of the car and the forces that the spur teeth will exert back on the car -- the motor will just stay up there in its "bad gear mesh" position and chew up your gears. Life works differently under load. ;)

Skv012a
2009.05.06, 03:26 PM
Thanks for input guys. I think I'll just adapt this tech from the experiment: using loose motor holder while giving it gas to find the perfect mesh and then tighten it at that point.

benmlee
2009.05.06, 04:00 PM
Fact is that it slides away, but due to motor's weight the mesh ends up being just perfect. I did this holding it right side up and observed what happened to the whole thing as I played with throttle.

So you guys are saying that titanium screws don't need locktite at all? I HAVE noticed that all of them on my mount hold up pretty good, but I haven't had the chance to test that theory on-track yet.

Don't know about Ti screws, but stainless steel ones sold by PN don't need locktite. They rarely loosen.
If you want the pinion to be held by the weight of the motor, the right way to do it is to use a bushing that the screw clamp up to. Make the length of the bushing just longer than the thickness of the motor mount. Then you have to enlarge the hole in the motor mount so bushing can slide up and down. Might want to test out the idea with some locktite first. The bounce of the car on a rough track might disengage the motor.

MantisMMA
2009.05.06, 04:52 PM
Use hex head stainless steel screws instead of the black ones supplied by the mount. Stainless steel hex screws for some reasons don't come loose like the black ones.

stainless is softer than the stock screws, another reason why i dont believe in using SS kingpins!

Skv012a
2009.05.06, 05:35 PM
So titanium FTW?

MantisMMA
2009.05.06, 06:35 PM
ss for the motor mt would be the best because they dont back out as easily as the OM steel ones do

Skv012a
2009.05.06, 06:57 PM
I got that, they feel very solid so I suppose time will tell. If my car gets iffy after 1 qualifier, I'll lock 'em.