Australian Slot Car Racers Association

can anyone help with setting up the mesh of the gears on a flexi car. how do you know how much backlash there should be.

I use doubled up tally ho paper.

thanks for that. do you double the paper and let it roll between the gears and make sure it runs through with a bit of pressure

The paper idea works ok with a bit of practice.

Another way that also takes a bit of practice, and if you don't happen to have any tallyho paper.

Set the side clearance in the axle and lock the gear and wheel/s, so the axle spins freely with excesive side play.

Hold the motor in position and engage the pinion with the spur gear, then rotate the wheels in the normal forward direction and find the tightest point of mesh. Most gears are not perfect and will sit on the axle at a slight angle which makes the gear run slightly out of round.

Once you have found the tightest position, adjust the motor for clearance so that you can feel a slight back and forth movement in the spur, but the movement is hard to see. A bit hard to explain, but you can actually feel the backlash more than you can see it.

In my simple terms, set it so that you can just feel the movement, but can't see it.

Once you get to that point, screw or solder the motor in.
Check the clearance to make sure nothing has moved, and away you go.

There is a further step with plastic gears that you can go to, to get an even better mesh, but takes even more practice, and most would say it's not worth the effort.

awsome thanks for that will check ours because i think ours is too loose.

another way is to loosen the back gear and axel, and move it about 1/16" out from the chassis. You can then push the pinion hard into the spur and solder.