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Old Aug 16, 2010, 12:11 AM
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kosch's Avatar
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Motor mount screws

Does anyone know what type of screws are used for your usual 300-400 size motor? I'm looking to order some from RTL fasteners but don't know what they are.

Thanks!

Bryan
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Old Aug 16, 2010, 06:23 AM
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Quote:
Originally Posted by kosch View Post
Does anyone know what type of screws are used for your usual 300-400 size motor? I'm looking to order some from RTL fasteners but don't know what they are.

Thanks!

Bryan
Take the screws to a good hardware store and ask the clerk what size they are.
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Old Aug 16, 2010, 06:50 AM
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Quote:
Originally Posted by kosch View Post
Does anyone know what type of screws are used for your usual 300-400 size motor? I'm looking to order some from RTL fasteners but don't know what they are.

Thanks!

Bryan
You need a 2.5mm bolt (works in my Speed 400 6volt). About 6-8mm long should be a good length. That width also works in my 3mm prop savers.
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Old Aug 16, 2010, 07:24 AM
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In real 400s (Mabuchi brushed motors) they're actually threaded 2.6mm but as whitecrest says you can usually get away with 2.5mm and they're rather easier to find than the very rare 2.6mm (though you can sometimes find those as spares for Kyosho R/C cars).

Of course there's no guarantee than any other manufacturer, particularly of the brushless 300/400 equivalents if that's what you meant, uses the same sizes. In fact I that know that some use 3mm.

Steve
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Old Aug 16, 2010, 08:25 AM
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My prop-savers and mounts are M3 threaded ..... as are my 370 brushed motors.
Occasionally you will come across am M2 ... but not often.

I recently had a motor come loose in it's mount where you have the two grub screws tightened down onto the motor rear barrel. they worked loose and I am not so fiond of loctite on such as then it's difficult in cramped fixed cowling to undo. So I replaced with machine hex headed bolts ... long enough so that head does not come inside outer mount diameter and foul the mount to airframe screws. I can now use a 3mm allen key instead of the flimsy 2mm key to make sure all is tight.

As another says - take article to hardware store and let guy sort ... and try to get Black hardened screws ... expensive but worth it for thread stability.
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Old Aug 16, 2010, 08:29 AM
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Originally Posted by slipstick View Post
In real 400s (Mabuchi brushed motors) they're actually threaded 2.6mm...

Steve
After closer examination, this appears to be true on my Speed 400. The 2.6mm would be a perfect fit. I'd go with those if available, however, the 2.5mm bolt threads smoothly without crossing, and they are available at RTL.
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Old Aug 16, 2010, 01:46 PM
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Great, thanks everyone! I'll get some 2.5mm.

It's interesting that they use an oddball size. Kind of funny though, on all my Suppo motors I've always felt like the screws were a tad too small, maybe they are actually using 2.5mm in a 2.6mm hole.

Thanks!

Bryan
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