Success, my 1985ish RC10 runs on backyard grass! I wanted to post an update in case any other fathers of a certain age wanted to get their childhood RC10 in a condition to race their son's traxxas in their backyard.
In summary I have spent far more money on trying to get this to run than I really should have. I have really enjoyed the process and all the helpful threads on this forum. In that spirit, below are all the things I bought to get it to run and not overheat the motor and the esc. I may follow this post up with a few other bits and pieces that I have bought depending on how they work out.
Must have changes.
1.) Wheels from JC Racing available here -
https://www.jcracingproducts.co.uk/wheels/rc10
2.) Schumacher full spikes -
https://www.amainhobbies.com/schumacher-full-spike-1-10-buggy-front-tires-2-soft-scht652/p362286?v=170794 and
https://www.amainhobbies.com/schumacher-full-spike-2.2-1-10-buggy-rear-tires-2-yellow-schu6596/p362309?v=170804
3.) The tires have the schumacher hard foam interiors
https://www.amainhobbies.com/schumacher-sst-foam-tire-insert-24-25-hard-2-schu6627/p866457 . I have no idea whether hard was a good idea but convinced myself that I may get a few extra millimeters of that all important clearance.
4.) 9T 36 Pitch pinion gear (long grass, short gears) -
https://www.amainhobbies.com/robinson-racing-absolute-32p-hardened-pinion-gear-9t-rrp1709/p454468?v=186486 - Even with the brushless on 11T (which I also bought) the motor would seem to get a little too hot, so I have stuck with 9T which seems fine (30 mins no problems). Also, at this ratio in a straight line race on grass my son's traxxas stampede and the rc10 are neck and neck so that's also nice, makes for some close races.
5.) A 17.5T brushless motor with ESC - I got this one -
https://www.amainhobbies.com/hobbywing-xr10-justock-sensored-brushless-esc-sd-g2.1-motor-combo-17.5t-hwa38020241/p784984 - I was really worried as to whether a brushless would cripple the 6 gear and the really nice thing about this one is that it has the ability to set the punch level (which is how much acceleration is applied). I have it set to the lowest punch setting and all seems well.
Nice to have changes.
1.) I read a lot of threads talking about how delicate the six gear is with brushless. Some of the threads advised outdrive bearings and so I got this set
https://www.ebay.com/itm/254610360277. I took apart the six gear and rebuilt it replacing some of the bearings and adding the outdrive bearings. Maybe this helps, honestly it's not clear that it's necessary.
2.) Andy's front arms - I got a set printed from shapeways here
https://www.shapeways.com/product/W39S32F6Q/reproduction-of-andys-rc10-front-arm. With the suspension cranked they seem to give me a little more height in the front than the standard arms (at least that's what I tell myself to justify the $20)
3.) I did crank the suspension a fair bit. I still have some droop but it def. helps.
That's pretty much all the changes related to getting it to run on grass although, as you can see from the pics, I did get a new detonator body. It was the only body I could find and the original one was a mess. If anyone can point me at a place to get reproduction original bodies and stickers I would maybe invest a few more dollars!
Here's how the car and truck stack up now. The races are really close, although if I was honest, I think my son is slightly ahead.
Thanks for all the help !
Rob