Old Version ICS MP5 SD question - TM compatible?

[Flatlander]

My teamate gave me his ICS MP5 SD to upgrade and I was expecting the new split mechbox design with metal bushings, etc. Anyways, what I found was what appears to be a standard V2 mechbox, nylon bushings, turbo 2000 motor, etc - the old version. Did a bit of searching and I couldn't conclusively determine if this is completely TM compatible for upgrade parts (it appears to be on first inspection). So can anyone clarify this for me? Thanks.

[Mud Gunner]

Ask Fixerdude, he'll likely know

[mcguyver]

Parts that are NOT compatible:

Selector plate
Bushings
Gears
Tappet plate

If you manage to ram in some aftermarket bushings, you can change the gears. But it will be a very tight fit to get them in, almost to the point of having to use a press. I would stick with the ICS gears and use ICS bushings.

[Flatlander]

Mac, what's different in the ICS gears? Are the shaft diameters larger/smaller? I measured the bushing diameters with a digital caliper and they were 5.99mm (keep in mind the quality/accuracy of the caliper is questionable - Crappy Tire special FTW!)

I recently used an ICS gear in with a G&P mechbox/gears as one of them broke and he had some spare ICS parts kicking around from another broken gun and everything is working fine.

[gvanzeggelaar]

i have an older version with a turbo 2000 motor and all the parts you mentioned fit fine in mine. I have not replaced the gears but from what I understand the mechbox is a tm clone.

[Flatlander]

I broke open that G&P I talked about before (low FPS problem - most likely spring) to compare.

Axle Diam (G&P) = 3.01mm
Axle Diam (ICS) = 2.98mm

The tappet plates are virtually identical in measurements except that the 'tail' that attaches to the cam on the sector gear has a slightly different profile.

I can't check the bushing compatibility as the G&P is a 7mm and the ICS is a 6mm box.

EDIT: Looking at pics of selector plates online (G&P and Systema) they appear to be the same also. Also found a review on Arnies stating it was fully compatable with the other MP5's (he states's his is a version 3 with a turbo 2000 - I have no idea how to tell what 'version' it is).

[mcguyver]

Selector is different. The points that control the "yaw" bar (or semi-auto cutoff for the rest of us) are different than Marui. Using an aftermarket selector plate will give you lack of proper fire control, and the points won't jive.

As you noted, ICS has smaller axle diameter, so aftermarket gears will not fit in ICS bushings. And, ICS uses bushings with a smaller OD than everyone else, so you have a hell of a time getting them in the ICS mechbox shell.

Tappet is totally different. Look at the extra sliver of material of the arm of the ICS tappet. The tappet guide is wider on the ICS mechbox to accomodate this. Aftermarket tappets "may" work, but they will not stay true in the guide. This can cause the tappet to twist and break.