CA P90 gear issues

[Dynamo]

i have a CA P90TR that im modding with a HUTU (http://www.airsoftcanada.com/showthread.php?t=132727) thats is having some gear alignment issues.

when the owner of the gun dropped it off, he was complaining about its really low rate of fire. he is currently running the P90 on 11.1v Lipos and the rate of fire is in the 600-650 rpm range (really slow for the battery being used)

after taking a look inside the gearbox i noticed that the P90 has an M130 spring (likely for importation). the thing is, even after replacing the M130 with an M110 the rpm has hardly changed. i figured that i should check the shimming of the gears, and thats where i found a rather frustrating problem. the sector and spur gear are binding together. they bind just before the sector engages the piston, and run smooth before that. thinking that maybe he has bad gears i swapped them out with another set.. still binds in the same spot.. i try another set again, and again, and even try different combos from the three gear sets.. nothing, they all bind the same way.

so now im thinking there might be an issue with the bearings, but they work fine in a V2 and V3 gearbox with all three gear sets as well as the CA gears... so it would seem that the hole spacing of the CA gearbox may be off.. but if it were it wouldn't bind just in one spot..

so this is where i am right now.. i have a P90 gearbox that seems to not like any brand of gears.. any thoughts on what could be done to get the gears running smooth again short of replacing the gearbox?

this is where it starts to bind, and it continues until the tappet plate pin reaches the 2 o'clock position. with the gearbox closed i can not rotate past this point by hand.

[Dynamo]

im thinking about maybe putting the gears on my lathe and reducing the diameter of the two gears by a few thousandths. i'll wait to get the owners input first.

[Kos-Mos]

Try an other bearing set.

In the P90, it's easy to bend/break them if the hole is not perfect (it never was in my 4 P90s).

Especially if they are bearings and not bushings.
Also make sure you can insert and remove the bearings with your fingers, but still require a little force.

[Dynamo]

i have tried metal and nylon bushings, still binds. i checked the spacing with a caliper and got .540 on the P90 gearbox. on the other two V2 and V3 gearbox i got .550 and .553.

.01 -.013 is quite a difference.

[Dynamo]

i might just recommend that the owner get http://www.airsoftparts.ca/store2/in...oducts_id=1067. considering the amount of time i would need to spend modifying this gearbox, it would end up being cheaper for him.

[Styrak]

Does shimming the top gear up more help?

[Dynamo]

shimming makes no difference. the holes are simply too close together. my only options so far are to clamp the shells onto my mill and elongate the holes along the axis at which is lines up with the next hole by .013, but then i might run into issues with the sector gear lining up with the piston. or replace the gearbox shells.

[lurkingknight]

I'm having this exact same issue with a TM p90 gearbox with the TM bushings, 2 sets of gears that work fine in an E1 box with bushings will bind in the same spot. Shimming fixes nothing.

Could it be possible for the gearbox shell to have twisted somehow?

[Styrak]

Originally Posted by lurkingknight

I'm having this exact same issue with a TM p90 gearbox with the TM bushings, 2 sets of gears that work fine in an E1 box with bushings will bind in the same spot. Shimming fixes nothing.

Could it be possible for the gearbox shell to have twisted somehow?

I think Echo1 P90's take standard V2/V3 gears and TM P90's take V6 gears, no?

[Kos-Mos]

Originally Posted by Styrak

I think Echo1 P90's take standard V2/V3 gears and TM P90's take V6 gears, no?

Find me some V6 gears online and we will see...

V2/V3/V6 all use the same gears.

It is quite possible that the mechbox is tweaked.

Cheapest way would be to get the new mechbox shell especially since it's only 55$.

[Dynamo]

i talked it over with the owner and he is going to get the whole gearbox replaced by his dealer.

as for the gearbox shell being twisted or tweaked, it was perfectly flat and not at all warped. i think that .013 inch difference between the sector and spur gear holes of this gearbox over the others is the issue.
guess he was just unlucky to get one off spec. once he gets the replacement i'll update this thread.