Piston Replacement

[dfrear]

May have to bare with me here, certainly no gearbox expert!

Been trying to fit a new piston today, and after removing one of the teeth to match the old piston I've got it as far as the piston coming back, then stopping. The piston doesnt seem to travel forward again until the next cycle.

At first, it was travelling back then with the next pull of the trigger, travelling forward. This was also causing quite a lot of friction as the wires to the motor were getting rather hot as if the motor couldnt spin freely.

I've tried adding a bit of spacing to get the AOE correct, it appears to be correct but the gearbox is now simply locking the piston back and thats that. No more, just that ominous "click" as the gearbox is locked up everytime I attempt to fire.

One thing I did note is that the tappet plate is pretty damn hard to push back and it looks as though the post on the sector gear "may" be going underneath the tappet plate - although its difficult to tell as that could easily occur as I open up the gearbox and the piston snaps forward!

If anyone has any ideas I'd be grateful, tried everything I can think of!

Daniel.

[Montesa77]

Re: Piston Replacement

Have you tried it without the AoE adjustments? I presume you took of the 2nd tooth(the first small one after the big one).

[dfrear]

Re: Piston Replacement

Yea tried without and it goes back and stays there but without locking the gearbox. Yep second
tooth

[Montesa77]

Re: Piston Replacement

Think pic's are needed in this case. Could you get a few of the piston, runner rails ect.

Have you tryed running it up with out the piston? Could cut out some issues.l

[dfrear]

Re: Piston Replacement

Didnt think of that lol. Ill give that a go later. Will get pics too although there's nothing interesting

[Montesa77]

Re: Piston Replacement

To the untrained eye that is. You have charged the battery, haven't you?

[dfrear]

Re: Piston Replacement

Yea, may try another battery to be sure though.ill check later on or tomorrow morning. (Have to pop out) cheers for the help!

[dfrear]

Re: Piston Replacement

OK, took the piston/spring/spring guide out and tried without. Now I get quite a nasty grinding noise, took a video of this as its a bit difficult to describe:

http://www.youtube.com/watch?v=v5jBAVH6doM

My first thought was that this has something to do with the shimming or the tappet plate. Could be way off though!

[dfrear]

Re: Piston Replacement

Also, this is a V2 gearbox. Should probably mention that

Righto, I've stripped her down again - cleaned it up after the other piston was obliterated and left bits of plastic all over, done a full reshim and popped it all back together. Note: it no longer makes the lovely grinding noise after a reshim.

Better, but still having problems with the piston staying back fully or half. See this video:

http://www.youtube.com/watch?v=ZVZIf_3-Y6I

[screwdriver]

Re: Piston Replacement

that is totally normal the piston can rest in any position after firing ,but single shotting can normall get it to stop fully foward

[dfrear]

Re: Piston Replacement

I see, so in your eyes that's looking OK now? Before the re-shim and clean it was actually locking backwards. Appears to have sorted itself now.

Going to re-grease it all and give it another clean up before it all goes back into the body.

[guard-sniper87]

Re: Piston Replacement

Still over shimmed

take gear box apart

Only do shims nothing else
put gearbox together then pull trigger see if the gears spin full cycle with no unuasal noise or grinding

It should only be a faint whir as they spin

If anything else shim job
maybe buy new ones

[dfrear]

Re: Piston Replacement

Yea ordered some new shims, I'll crack her open again and reshim when they come. Thanks for the help guys.