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I was using a mild BL in my Zerda but it was still too much for the all belt transmission so I decided to go back to a brushed setup and chose a Goolrc 17t motor with the same pinion/pulley a 20 tooth one , after 5 min running it was so hot it desoldered the negative wire , so I went down to an 18t pinion/pulley , after 5 min it was up to 169C so I went down to a 16t pinion the lowest that came with the car and try'd again and after 5min I still had 155C . The belt tension is not over tight , infact I still had a little slip on the last run oh I'm running 2s lipo by the way .
Now the question is this , is a 17t motor just too much in the Zerda , too heavy ? Too much transmission drag with the dual belt drive ? Or do I have a duff motor ? , the motor is brand new .

It's the lipo's. 2s is like running a 7 cell 8.4v pack with way more juice in the tank. How quickly does the motor heat up? Brushed motor on turbo essentially with longer runtime and it will definitely "Bring The Heat".

I am not an electrics wizard like some around here, so I may not be all that right. But it's gotta have something to do with it.

It took 4-5 min to get that hot , I'm still supprised it was so quick ! I have a 21t brushed in another 2wd an Ayk Sidewinder and I can run that on lipo for 15-20 min without excess heat and that's on 2s lipo as well but it's quite slow by comparison .

brushed motor heat management is like voodoo... so many factors involved. Quality of the brushes, tension of the springs, how well the arm is balanced (if any), comm diameter, comm surface, where is the arm centered, how well aligned (or not) the bearings/bushings, etc... BL took a lot of that out of the equation. It could very well just be because that GoolRC motor is a P.O.S. To be honest, since BL took over, the quality of the available brushed mills have gone done tremendously. This plus lipo as explained by @@TRX-1-3 above could explain it.

Yeah the lipo has much more energy stored so it will act like a 7 cell pack that doesn't give up. Gearing down was helping so it's likely that you just can't get a low enough ratio to keep from cooking the 17t. When nicd was king, races lasted 4 minutes so you checking at 4-5 minutes would be just about where the nicds dumped anyway.

I'm not familiar with the cars drivetrain but if it has a lot of drag that will also cause heat. Lots of load on the motor

Check the motor timing and possibly reduce it back to something like 5 degrees or so.

Thanks guys , I'll look for a 19 or 21 turn motor , I have a 21 I could try out and if that stays cool then maybe try a 19 . I'm tempted to get a really mild BL system ,17t maybe but the Zerda has a plastic loop in the gear casing that goes around the rear end of the motor so the wiring has to be on the end of the motor not the side like most BL motors , oh well !
Thanks for the help .

I had just seen this a couple days ago, and thought they would be perfect for cars that won’t accept a traditional brushless style motor. Tamiya TBLM series

I've also see these cool motor/esc combos that might work for certain chassis quite nicely.

https://www.horizonhobby.com/DYNS1450?KPID=DYNS1450&CAWELAID=320011980000240340&CAGPSPN=pla&CAAGID=37619207031&CATCI=pla-382564219633&gclid=CjwKCAjwhLHaBRAGEiwAHCgG3qo9rhIOXJd-hfYsbWq0BKCw8f3LMc7zp9-tuUbPlNKPCfuJ6vmHyRoC9WkQAvD_BwE

I think they are just a bit longer so might avoid guards and such.

Both look like possible answers , I'd lean toward the Tamiya motor on price and clearance for the wires , the combined motor/ESC would need careful measuring to be sure it would fit . It will have to wait now for anyway untill the holidays are over as most of my spare cash will go on entertaining the kids .
Thanks again .

I just found a pair of 7.2v NiMH battery's that I forgot I had they are for a pair of Heng Long 1/16 Tiger Tanks , just switched the plugs over to deans and I'm cycling them now YAY problem solved for now .