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  1. #1
    RC poster
    Join Date
    May 2016
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    2

    Corona DS-238MG questions after fitting

    Hi! New member and new Summit VXL owner here. Many people have said that the Corona DS-238MG servo is pretty much a direct drop in, so I would like to know if anyone here has noticed the points difference I mention below, and done anything about them? Thanks!

    I have just bought and fitted a Corona, which H-King is stocking here in the UK (and in the US). I had to temporarily dismantle the servo and take off the bottom plate to move the wires out of the way so it would slide in the gap - watch out here because the top of the servo can come off and the gears can fall out - I found this out the hard way haha.

    After fitting I have found physical differences from the stock Traxxas 2080 servo that don't seem to have been mentioned here yet,these make a difference to the steering geometry.

    First is that the Corona's spindle is in a different position. It is higher up from the mounting tabs, and long-ways it is closer to the edge of the servo., second is that the spindle is smaller diameter than that of the 2080, but seems to have bigger (and presumably less) teeth.

    So, the differences made to the steering are:

    - The stock horn does not fit snugly on the spindle, there is a small amount of play. This *seems* to be OK in operation if you make sure it's screwed down hard but I'm not 100% confident about it.

    - The altered positioning of the spindle (and subsequently the horn) means the geometry is off. The stock horn appears to be too short and the result is you don't get the full steering range, especially in one direction (don't remember if it was left or right). Also, when the servo and steering assembly are centered in preparation to mount the horn, I found that the horn's inadequate length meant it had to be screwed down at an angle, angled pointing slightly toward the front of the summit, not perpendicular to the servo body as you would want.

    I tried to remedy the range problem by using a longer horn that came with the Corona. I had to drill out the hole in it slightly so the stock ball screw fitted in OK. The horn still has to be screwed down pointing slightly forward, but it seems to have improved the range of movement. The opposite problem now exists that there is too much movement in the other direction, which means the servo strains in that direction at full lock as the horn hits the chassis (the chassis, not the servo guard). I cannot adjust the end point to fix this because the controller that came with my Summit is the very basic TQ 6516 (aka 6517 & 3047) which annoyingly doesn't appear have end-point adjustment.

  2. #2
    RC Champion
    Join Date
    May 2002
    Location
    Midvale Utah
    Posts
    1,768
    Sounds like that servo isn't going to work. I haven't seen that one recommended before. A true drop in servo is the savox 0250mg servo. It has the same dimensions, and fits the stock servo horn, plus it's waterproof. The only other direct drop in I know of is the bluebird 390

    If yoi want to try to make yours work, Your radio should have steering dual rates, which simply adjusts both endpoints at once.
    Dacaur

  3. #3
    RC poster
    Join Date
    May 2016
    Posts
    2
    Thanks for the tips, I may buy one of those servos you mention later. There have been a few threads here and at other sites recommending the Corona for the 1/16 vxls, but none mentioned my issues so I was curious why not. Maybe the corona design has changed recently. Also my TQ 6516 has no obvious dual rate setting and there's no manual or instuctions for it anywhere, with my documentation or online. Would love to be told how if anyone out there knows! The controller is extremely basic with just one knob for trim.

    Having said all this I took my summit out just now and in practice the corona worked very well after trim adjustment, so if I can find out if dual rate change is possible I'll be happy with it for now.

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