Upgrading your SJM 430 E2 or V2.5 with E3/V3 parts

[Nexus665]

SJM 430 Upgrade Photo Review Part One - tail system

Hi,

took a bit longer than I thought - the weather was too nice, had to fly instead of work on a photo review (hence the new avatar picture )

Here goes - there are a few caveats/gotchas to be kept in mind when you do an upgrade from an E2 or V2.5 (depending on where your model's from) model.

1) The tail pinion has to be modified so the flange bearing does not block, otherwise the pinion will connect the inner and outer shell of the bearing (easily noticeable when you try to rotate the tail shaft by hand)

Why? The beautifully machined new 1-piece aluminum housing is slightly narrower than the old tail housing (inside diameter). This necessitates a different pinion orientation, or rather, makes the tail belt run off-center; the "fat" part of the pinion sits flush against one of the flange bearings. As noted above, without modification this will block the bearing and damage it quickly in use; it'll become hot and seize at the most inappropriate moment, Murphy says

Solution: using a milling machine or - if you have nothing else, like I did - an electric drill and a file, machine away half a millimeter of the surface from the outside so a ring on the inside remains and sticks out and only touches the inner ring of the bearing. I mounted the pinion on a spare tail shaft and then in the electric drill, worked nicely. You'll see exactly what I mean when you look at the last photo - you can see the small step on the pinion next to the bearing. Alternatively, you can machine off 0,5mm on the whole surface and use a 0,5mm washer that has 4mm inner and 5mm outer diameter.

2) You'll need to drill new holes (closer together and a bit further forward or back) for the belt tensioning rollers because the new aluminium tail boom has less diameter (15,6mm vs. 18mm on the old system I believe), otherwise the tail belt can and probably will chafe on the inside of the tail boom, with potential disastrous consequences. You'll also need upgraded, wider belt tensioning rollers to use the new upgrade belts with 4,5mm width vs. 3mm for the standard version - a must if you have an upgraded motor and an aggressive flying style. Drill the holes only after unmounting the main chassis plate - the CF dust is very bad for all bearings and moving parts, don't want to get any of that in there. It's a bit of a bother, but it's worth it for peace of mind.

3) The aluminum standoff for the u-shaped tail pitch assembly isn't machined 100% perfect (unless Scott has more info here); as it is, the tail pitch assembly would be canted at a 5° angle or so to the tail housing and bind/flex while moving the tail pitch slider. Not good - solution: use a flat pair of pliers, some small wood blocks so you don't scratch it, mount one side in a press and bend the other carefully with the pliers (wood blocks between pliers and piece as well - would be a shame to scratch it ) until the angle is correct (see photos below).

I'm certain these small issues will be dealt with shortly by SJM - the pinion and the standoff (or the holes in the tail housings, but I guess the standoffs will be cheaper to re-machine ) should be easy fixes.

Before modification (note that all pictures include the longer tail shaft HS5003A as well as Vario ball links - much longer than SJM ones, and necessary for using the longer tail shaft to its full extent; they also include a self-made CF tail rod, much preferrable IMO, and therefore no tail rod guides are used):




Necessary parts for upgrade (not pictured: wider belt tensioning rollers)

Tail boom, 15,6mm fixing set (consists of 2x tail servo, 2x tail rod guide, 2x tail boom fixing clamp, 1x gyro board standoff, 1x tail strut centerpiece), new 1-piece aluminium tail housing (the upgrade kit includes all necessary fixings and even a new tail fin was in there), wider belt



The new tail housing in detail (excuse the dirty fingers, rebuilding helis is dirty work when they've been flying )







It's possible that there is some machining residue inside the aluminium tail boom - remove it before you mount it, so the metal shavings don't end up damaging your tail belt and mechanics.




Angled tail assembly standoff


Standoff after modification



Mounted on the new tail boom including new tail fin and retention mechanism (very nice to have, I'll get to why later)


Mounted on the heli




View from top (note the position of the tail belt - the pinion has to be mounted in this orientation, or the indentation on the tail shaft will not align with the set screw hole in the pinion. My humble opinion: a new design for the tail pinion would be great - use one with a couple more teeth and adjust the front pulley as well...pretty please? With cherries on top, even!



It looks very nice, even more of an eyecatcher on the flying field than before - especially in the sunshine, it glitters beautifully in flight.

The new system also works to suppress resonant vibrations much better than the old one - though it still cannot fully eliminate them. So, keep on balancing your main and tail blades, SJM 430 pilots! Your bird will reward you with great flight stability and longevity.

I mentioned that the new fixing mechanism for the aluminium tail casing is smart and good to have - here's why: before, the tail casing was bolted to the boom, so you could only adjust the angle of the tail shaft by rotating the whole tail boom. Now, you can make it a lot easier on yourself and only get the belt tension right; after tightening the fixing bolts for the tail boom at the front, you can always loosen the bolts holding the tail casing and just rotate it while leaving all the rest in place. Very useful and much less of a hassle to adjust. You can even adjust the belt tightness - albeit only in a very limited range - this way without opening anything up front - those are pretty inaccessible bolts anyway, and they tend to strip easily. Very nice in my book.

One more thing: because the new tail boom is polished aluminium, the surface is very smooth. This can make it difficult to fix it in place. Solution: just use fine grained sanding paper and lightly treat just the (invisible) places where the tail housing and the two fixing clamps at the front sit, fine.

That's it for part one - next are the new centerpiece and blade holders/flybar center.

Regards,
Simon.

P.S.: Some more pictures from Sunday - tell me that doesn't look beautiful (the scenery, too ).





(yes, it's still alive )