Stock Motor Gearing for TC3

[burgie]

I have a TC3 that my son runs. On Sunday, I geared it with a BRM Stock motor with initially a 23 pinion on the kit spur. It came of scalding hot. I then geared it how I used to run it at Macc, which was a 25 pinion on the kit spur. It still came off scalding hot. What gearing would you suggest as a starting point?

We run on rubber tyres, so I don't believe tyre diameter will play as bigger part as with foams.

The car doesn't bind, it was meshed properly, and without a pinion on, runs very very freely. (I like cleaning cars, it is never dirty!)

[Kevin G]

This is difficult this one. I am sure you have read the other posts about hot MVP stock motors it seems a common problem.

I am drawing several opinions from what I have read..

From what I can see is the bigger the pinion the slower the RPM of the motor and this can be a contributor to hot motors, as there is not enough natural airflow from the rotation of the motor. A over spinning motor, will also cause over heating.

Devil and deep blue sea syndrome. My initial thoughts would be try smaller pinions. This is to be my approach.

Here are some questions for you

1 Do you have a heat sink
2 Does it block the vents

I cant wait to get mine and start playing with the thing to work out why and if it can be stopped without extreme measures like 5v fans

[gaz_d]

It would depend on the size of the track and the layout, large open track then gearing around 5.8 to 6 indoors, short twisty tracks then drop down below 7.5.
I ran mine on 7.6 on a 30 x 16m track that was tight and twisty and it was very fast and come off at 54 degrees C after a 6 1/2 minute practice.

Oh and rubber tyres do affect motors too, gearing changes with diameter, majority of rubber tyres between 63.5 and 65 mm, and yes .5mm does make a difference. It just a case of finding that sweet spot for the gearing.

[TC3]

hi chris

my lad run 72 24 on a monster stock okay at bury so i would have thought a pinion acouple of teeth bigger on abrm would be okay.
does the motor need skimming and new brushes. brm brushes are ok and file a little of the trailing edge might help it run a little cooler.
olso oil the bushings regular

cheers n wilson

[burgie]

thanks nigel - no the motor doesn't need skimming. I skim it every week, usually during the course of a meeting. Well, it more of a polish really, and the brushes are replaced very regularly. The trailing edge? is that the left hand side as you are looking doen the brush hood towards the can?

[rc_jammer]

BRM's will get hot indoors, its in their nature along with Orions and Peak's.

I have been helping some of the boys down my way with BRM's and we have hit a bit of a sweet spot with the motor of 72/24 on a olympiad size track. (not sure how big but its fairly big)

The trailing edge is a must to do as indoors it does reduce heat significantly enough. If you look down the brush hood at the com then it is the left hand side. Only needs about 1mm taken off.

[burgie]

thanks for that - i will give that gearing a try.

[Andy M]

I was running 72/24 at Olympiad today and sealed my best result so far, car was really quick.

Think Olympiad is about 16mx30m by the way