dilemma
 

been working on my latest mid 2wd buggy, an update of my previous homemade job. the old car weighed in at 1366g and needed weight at the back to bring the balance rearward, added 150g around rear gearbox to get close to 60/40. the new car, without body as i havent even thought about what the body will look like, gives 60.1/39.9 weight distribution, and balance side to side within 5 grams. all up weight is 1299 grams so i need to add 175g to just get up to the weight limit. big question is where do i put it!!! three options really, front and rear, front rear and centre, or as much central as possible. have to say though its going to be fun finding somewhere to put that much weight!

you want all that weight right where the car balances on a pin and as low as possible. Using tungsten would be best ;) I would suggest a heavier main chassis but you and all that weight in the center to make it agile, which is why mid motor is popular, its not so much the weight bias.

If your using heavy metals I suggest you get some osmium as its the densest metal in the world :)

somehow i think i will be sticking to lead and brass....lol heavier chassis isnt an option because its a carbon tub, was thinking of a brass plate under the battery/electronics and a lead centre weight, although was wondering what the overall effect would be of weights front and back

the further forward/backward it is, the more swingy it will be, no good. Further out will increase roll

Love to know how you got it that light in the first place!

easily, didnt even try!! mind you things like the frsky receiver help because they are only a couple of grams! will take a couple of photo's in the next day or two and put them up. so far i have cast a 60gram lead centre weight, also have another 20g under the slipper adjuster in the middle of the car, 30g under the servo further forward and 20g under the gearbox. have also cast another 30g to sit behind the gearbox to see what effect that has. ideally a brass plate under the motor/battery area would probably be better but i havent got any sheet brass. front to back is now 63/37 so has moved backward slightly but that should still be fine for most conditions and i can easily move it around by playing with the weights anyway

It's also brittle and damm expensive :woot:

well heres a couple of pics. new car next to the old, new one is a bit longer, thinner and motor and battery a bit further back. weight distribution is much better, the old one needed a lot of weight at the rear to get near to the magic 60/40. also gone back to a pretty much standard b4 front end instead of the tc3 rack. rear end has changed quite a lot, its now more easily adjustable and contains a lot less parts overall, tc3 gearbox instead of b44 brings the spur further back and allows braces to be to the side of the gearbox rather than over.http://myweb.tiscali.co.uk/dodgydiy/p1010156.jpghttp://myweb.tiscali.co.uk/dodgydiy/p1010157.jpghttp://myweb.tiscali.co.uk/dodgydiy/p1010159.jpghttp://myweb.tiscali.co.uk/dodgydiy/p1010160.jpg

the old car was quite a safe, easy car to drive, but propably lot that quick overall, exceeded its drivers abilities though..... the new car is a lot more responsive and seems to generate more grip overall, just need a bit of time on track to try and find a good setup, and also to design and make a bodyshell for it.

http://myweb.tiscali.co.uk/dodgydiy/p1010156.jpg

https://imagizer.imageshack.us/v2/72...904/6jmtGd.jpg
https://imagizer.imageshack.us/v2/12...910/At9o70.jpghttps://imagizer.imageshack.us/v2/72...913/VrMWFJ.jpghttps://imagizer.imageshack.us/v2/12...540/kjjzFY.jpg

Wow .. and I thought all the variations for mid motor had been done !! :lol:

Excellent work .. :thumbsup:

Looks a similar shape to the Schumacher KF so a KF body might fit ...

If you need more rear weight, how about making up some weighted slipper plates to counter the spin of the motor and to improve the balance ?? Phosphor bronze would work well ...

going to find a bit of brass sheet to add some more inboard weight, and remove the lead weight at the back when i get round to it. dont really want to counter the rotation of the motor, as in this position the torque generated by the motor puts downward pressure on the centre of the chassis, when i was experimenting with the first car at first the motor was on the other side, and moving it over to where it is now did make the car accelerate a bit better, also far less change in steering on and off throttle so a bit more consistent too. hopefully will get to do a bit of a back to back comparison between the new and the old one on wednesday night, weather permitting anyway

ran both cars tonight, the new car is a definite improvement. it seems to have a lot more grip overall, certainly has a lot more steering and needs far less tyre on the front than the old version. it carries a lot more speed in the corner too and just feels a bit safer. couple of other racers from the club had a quick go and both found it very easy to drive, so a positive result on the first outing!!