Will a record weight harm the motor in a direct drive turntable?

I own an AT618A that I purchased in Tokyo on one of our visits.  (Sometimes I just buy stuff I don't really need only because I am there and it costs less.) It weighs 600g, or more than a pound. I use it only on my SP10 Mk3, which has a 21 lb platter, on the basis that the record weight is only about 5% of the platter weight for which the bearing was designed and therefore should not hurt the bearing. But I certainly would not say the 618A is too heavy for a TT81, etc. I use a 250g weight on my TT101. The AT618A really does seem to get more out of the SP10 Mk3 than the SOTA reflex clamp, for example. That is a purely subjective off the cuff judgement. I do like it.

I just weighed the screw-on clamp from one of the SMEs, 355g (12.5oz). A tiny fraction of the weight of the platter (which I can't weigh: it swamps kitchen scales, bathroom scales are inaccurate and I no longer own a set of baby scales!)

Hello Aggie88,

I’ve been using an Audio-technica AT 618 weight on my vintage Denon DP 51F since I purchased that TT new in 1982. The AT 618 weighs 600g/(21 ozs).  I did contact Denon to ask if the AT 618 weight would be detrimental to that TT performance/life.  The tech that I spoke with indicated it would not be an issue and added that it would be an effective addition to the DP 51F.  She added that weights under 700 grams would be fine.  That addition occurred in 82, about 4 months after I had purchased that TT. BTW my Vintage Denon is still spinning vinyl flawlessly. Only change was when I replaced the TT’s rca interconnects about 15 years ago.  There are various TT weights on the market now.  I haven’t had a need to shop for one in since 82.  Hope that this post is helpful. 
Enjoy the music. 

Ps. Out of curiosity I checked to see if the AT618 was still available.  Low and behind Audio-technica continues to make them as the “AT618a” currently.  Just search the audio-technica website for AT618a. 

Thanks everyone for the info.  It’s especially good to hear the comments from the Denon technician.  I’ve owned quite a few turntables over the years (Sony linear tracking, Ariston, Thorens, Music Hall, Fluance, etc) but the Denon DP-59L is my favorite.  I purchased it about 6 years ago recapped and restored from a guy in Dallas who sources the TT’s through a friend in Japan.