Bearing piston head help needed

[grimreefer]

I don't think I'm installing this thing right. The polycarbonate head is binding against the piston when I tighten the screw. Should the piston head end up free-spinning? If so, how do I accomplish this? Am I missing something?

I have it installed like this: piston head, piston, washer, bearings, washer, plastic bit, screw.

It seems like there should be bearings on either side of the piston in order to work properly.

[TriChrome]

You're installing it correctly. The piston head isn't supposed to spin, it's supposed to be very tight on the end of the piston. The bearings are inside the piston so the spring can rotate freely (which is especially good for PDI springs since they like to twist as they compress).

Also, don't forget to use blue locktite on the piston head or it can come loose and wreak havoc on your gearbox.

[Crunchmeister]

Originally Posted by TriChrome

You're installing it correctly. The piston head isn't supposed to spin, it's supposed to be very tight on the end of the piston. The bearings are inside the piston so the spring can rotate freely (which is especially good for PDI springs since they like to twist as they compress).

Also, don't forget to use blue locktite on the piston head or it can come loose and wreak havoc on your gearbox.

+1. Piston head should have no play at all. The bearings are for the inside of the head for the spring.

[BORDENSNIPER]

bearings are for the inside of the piston head so that the spring can twist freely, hence relaving pressure on the internals.

make sure the piston head is sitting tightly and in the center, u are on the right track.

[grimreefer]

Thanks guys.

[m102404]

Don't over tighten it...you risk fracturing the "plastic bit" after several shots of the piston slamming forward.

Grease the thrust bearing...not too much...don't get grease or oil on the threads of the screw. 1 good drop of blue (med strength) loctite is enough.

Grease the oring of the piston.

If the washers are really tight in the piston body, either use a different piston or smaller washers, or file the washers down (mount a screw in a drill and use a mill file on them while it spins...you don't need to do both washers). If the rear most washer isn't turning freely...it's not doing what it's supposed to.

Best of luck,

Tys

[grimreefer]

Originally Posted by m102404

Don't over tighten it...you risk fracturing the "plastic bit" after several shots of the piston slamming forward.

Damn. Why couldn't you have said that about an hour earlier? :P Oh well...I didn't really crank it in there or anything....it's certainly tight though.

[dpvu]

I don't find thread lock necessary and it complicates things later if you want to swap parts or if something (like the piston) breaks. I've never had a piston head come off on me. Just tighten it well (but once it's in don't push it too much harder).

[HaZarD SFD]

I havent used lock tight at all on any of my pistons.. I did screw them in pretty tight after one did flip around on me.. But in an ICS its a quick fix..

[TriChrome]

Originally Posted by m102404

Don't over tighten it...you risk fracturing the "plastic bit" after several shots of the piston slamming forward.

As long as the piston head is a quality part (Prometheus, Systema, etc.) you should be fine. I put mine on there as tight as I can... too tight usually causes the screw head to start to strip a little but but I've never broken the plastic bit at least

Originally Posted by HaZarD SFD

I havent used lock tight at all on any of my pistons.. I did screw them in pretty tight after one did flip around on me.. But in an ICS its a quick fix..

A couple of my customers who used to do the same found out the hard way that a little dab of locktite can save them lots of money (the worst fix was when the piston head came off, cracked and scored the metal of the cylinder somehow, and when the piston came back forward again stripped the piston, and the big battery then stripped the motor's pinion gear from trying to pull the locked gears; about $70 worth of replacement parts).

In a pinch, since most people don't stock locktite, the smallest dab of superglue --I'm talking about an extremely small amount-- can do the trick. But be careful you only get it on the metal screw and the metal screw hole as superglue can eat away at some plastics.

[m102404]

I'd wholeheartedly agree with your comments about using quality parts! Unfortunately there's some not so great stuff out there. I've seen the results of 3 cracked/shattered (one shattered like tempered safety glass...kind of cool unless it happens to be your own mechbox... ) plastic bits (really don't know what to call that piece). 2 I highly suspect were over tightened, the other I cannot say for sure. Two of them happened to be from Guarder FTK...

I loctite every piston head to it's screw. It's silly to risk it coming loose for such as minimal/simple thing.

But since the original poster didn't specify what brand he was using and everyone tends to have a different sense of "how tight is tight"...I thought it best to err on the side of caution. Certainly tighten it down...just don't go Hulk on it.