TuxRacer

Hey guys,

I have been racing a couple of times at a carpet track here in Texas. When I bring my car off the track my motor is extremley hot. What should I do to figure how to lower the motor temp.

Do I need to increase pinion size or lower? What are some general suggestions?


Thanks,

JWATT

First, check gear ratio. Do this by listening to your car on the straightaway. If it does not reach full rpm at 3/4 of it's length, you are probably over (too large) geared. If it reaches full rpm before 3/4, you are under (too small) geared. Check with other racer's as to what gear they are running with the same type motor. You could also put a small (1" sq.) fan on it, aimed at the motor brush hoods. Reedy makes a motor heatsink that has a fan bolted to it. Don't try and remedy an over or under geared situation by a fan. Find the right gear first.

You might want to check the drag in the driveline. With the motor pinion away from the spur gear, see how your car "free spins" buy spinning the wheels. There may be something here causing the overheat, even if the gear ratio is right. Show the "free spin" to other racers, and they will tell you if it is OK.

Hope this helps!

John Watt

TuxRacer

Yeah, that helps.

It gives me something to go on. I am pretty sure my drivetrane is free of any hang ups, but I will take a closer look.
I will take your advice on pinion sizes. I suspect it might be too small a pinion gear. I reach top speed pretty quick.

What is a normal temp for the motor to be at when it comes off the track?


Thanks,

JWATT

Hard to give a sense of feel for heat, but it should not be so hot that you can't touch it for a second or two. How are the brushes? If they are discolored it is a sign of overheat. Also, next time at the track, ask someone about the motor temp. Easier to evaluate if the person advising you about temp. is the one touching it.

onnetz

I always run outside and motor heat varies dramatically depending on the weather. Would popping the motor in the fridge before a run on hot days help?, or would I get moisture on it like a pop can?

JWATT

Get gear ratio, driveline issues correct. Buy a fan if you want. But I would not recommend chilling it for the issues you mentioned. Motor manufacturers make them to run, and produce heat, and survive both. It is up to us to make sure we are not asking them to do more than they were designed for.

Hope this helps.

John

onnetz

thanks.....
I got a good heatsink for now and that did make a difference.
It's just that on some days it will be barely warm after three paks and others its hot to the touch after one. I geared it to the manual but it seems like on cool days I could go up one or two teeth and on hot days have to go the other way..
makes it hard to find a happy medium.

JWATT

Gear the motor to the track, not the ambient temp., and all will be good!

mafiaracers

iTrader: (22)

I race stock truck and buggy. In these classes, its all about freeing up the drivetrain. If I take the pinion gear off my motor and spin the tires, it feels like they spin forever. Also, gearing for the main straight is the best way to find a ratio. I've found and been told by the owners of AXIOM and BIRDMAN that as long as you're not getting soft before the end of the race, don't worry too much about the heat.

If anything, polish the bushings and shafts of your motor and that will make a huge difference.

popsracer

There is an old "Trick" of putting an Ice Cube on the Can about 1/2 hour before a race.
Never tried it myself, but have read several claims of the Motor staying considerably cooler after a run. Something it think about.

Sleighty

Just a few things to think about:
Firstly do not gear your car for the straight! gear it so that its revving hard out of the corners. Of course ask people with the same car as yourself and preferably in the same class so that you can get a good idea of a gear ratio.

Secondly, dont get the Reedy fan and take off any heat sinks as niether of these work to be honest, the fan might work to an extent but your much better off getting a Ride Air Duct. These force fresh air into the motor instead of the fan which just re-circulates warm air back into the motor

As for the 'Ice Cube Trick' i tried a few times and it does without a doubt work! Use upto 2 ice cubes on the motor and it will be super cold for your run and will also run much better!

JWATT

Using a infrared temp guage I have verified that my fan makes 40-60 degrees cooler temps. 160 deg without, 110 degrees with, after 5 min runs. Indoor track.

Do you have a site for the Ride Air Duct? Have not seen or heard of it.

JDXray

iTrader: (3)

Think it is worth it?

http://cgi.ebay.com/ws/eBayISAPI.dll...192967804&rd=1

Hebiki

iTrader: (26)

i didnt get to read all the posts.. but i raced last tuesday and my gear mesh was waaaaay too tight and when i pulled my car off, the motor was extremely hot. after loosening the mesh up a bit, the motor ran a lot cooler.

Lonestar

iTrader: (14)

depends if it obstructs the motor's vents...