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Thread: PS4002FK slight change in spec?

  1. #1
    Join Date
    Sep 2014
    Location
    Auckland, New Zealand
    Posts
    292

    PS4002FK slight change in spec?

    At a recent race, I spoke with one of our suppliers who had just installed a new motor into his car, and was concerned the motor had very little 'cog' compared to the previous motors over the years. I wondered whether he had just accidentally installed the standard 4002 Euro Sealed version, but on inspection it wasn't.

    At the same time I grabbed a few new ones from him, and subsequently also got some from Pro-Slot HQ.

    All these new one seem the same, much less cog.

    I emailed John at Pro-Slot, he advised me that the magnets had the same Gauss and should perform exactly the same. Certainly the one that was tried by my supplier at the event didn't lack in power.

    Being curious by nature, I carefully took the seal off one and stripped it down to try and find the difference.





    The Arm seems the same - same diameter and stack
    Magnets seem slightly smoother on the inside face but otherwise meter fine, at close to 1200 Gauss (in the can), which compared to three older (used cans) is about 50-100 Gauss higher (so John is spot on there).
    The magnets also seems to be the same PolyNeo material - I can scrape some off an edge with a blade so they are not ceramic

    The magnet gap seems the same and magnets are well glued in now (with what seems to be cyanoacrylate)



    I was also pleased to note the Comm had very, very good concentricity.



    So I am buggered to tell any difference!! But maybe, they'll be an improvement on the previous batches especially with low downforce F1 cars and similar
    listen, study, spy, try, research, invent

  2. #2
    Join Date
    Sep 2014
    Location
    Auckland, New Zealand
    Posts
    292
    Since writing the above I have spoken to a few racers and some of them have also noticed the lack of cog.
    It has also been pointed out to me that there are differences in both the poly-Neo material and its alignment when formed.
    So maybe its a minor change to the magnet material that has contributed to this.
    Anyway, the general consensus is the lesser cog motors are a little softer in delivery and hence down on ultimate performance.

    I'm interested in anyone elses views or experience with this motor lately...
    listen, study, spy, try, research, invent

  3. #3
    Join Date
    Jul 2011
    Posts
    441
    Less cogg on these motors will increase performance. Maybe an excuse for you guys to stop using such huge pinions.

  4. #4
    Join Date
    Jul 2011
    Posts
    441
    Pull and measure the mags tips again. You might find them to be a tad larger then earlier versions. Larger tips reduce cog.

  5. #5
    Join Date
    Feb 2005
    Location
    Chesapeake, Va.
    Posts
    798
    I found that ceramic magnets that match closer or equal in strength also have less cog. Maybe they're attempting, in a crude way, to match the magnets creating a balanced magnetic field. The magnets may be stronger but because the magnetic effect is equal on both sides of the can it has lessened the cog. Just a thought that sounds plausible.
    I've done so much with so little for so long it seems like I can do anything with nothing at all.

  6. #6
    Join Date
    May 2002
    Location
    Kirkland
    Posts
    500
    what is COG ???

  7. #7
    Join Date
    Feb 2005
    Location
    Chesapeake, Va.
    Posts
    798
    That's COG, and it's the thump you feel when rotating the armature. Some motors have a lot like the PS4002FK motors (Neo magnets) some have very little to none. Just because a motor doesn't have a thump doesn't mean it's a bad motor. Many of my GP 12 motors have Cahozza T-5 magnets (very strong) and have little to no thump at all but they manage mid 2 sec. laps on most Gerding Kings.
    I've done so much with so little for so long it seems like I can do anything with nothing at all.

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