R/C Tech Forums

Go Back   R/C Tech Forums > General Forums > Electric On-Road

Reply
 
Thread Tools Search this Thread
Old 05-13-2004, 07:40 AM   #1
Tech Initiate
 
Join Date: Nov 2003
Location: Texas
Posts: 22
Default Motor heat

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,
TuxRacer is offline   Reply With Quote
Old 05-13-2004, 07:53 AM   #2
Tech Regular
 
Join Date: Nov 2003
Location: Driver's Stand- Tulsa, OK
Posts: 280
Default

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
JWATT is offline   Reply With Quote
Old 05-13-2004, 08:27 AM   #3
Tech Initiate
 
Join Date: Nov 2003
Location: Texas
Posts: 22
Default thanks

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,
TuxRacer is offline   Reply With Quote
Old 05-13-2004, 08:35 AM   #4
Tech Regular
 
Join Date: Nov 2003
Location: Driver's Stand- Tulsa, OK
Posts: 280
Default

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.
JWATT is offline   Reply With Quote
Old 05-13-2004, 08:45 AM   #5
Tech Master
 
onnetz's Avatar
 
Join Date: Apr 2004
Posts: 1,727
Default

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?
onnetz is offline   Reply With Quote
Old 05-13-2004, 08:52 AM   #6
Tech Regular
 
Join Date: Nov 2003
Location: Driver's Stand- Tulsa, OK
Posts: 280
Default

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
JWATT is offline   Reply With Quote
Old 05-13-2004, 08:57 AM   #7
Tech Master
 
onnetz's Avatar
 
Join Date: Apr 2004
Posts: 1,727
Default

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.
onnetz is offline   Reply With Quote
Old 05-13-2004, 09:07 AM   #8
Tech Regular
 
Join Date: Nov 2003
Location: Driver's Stand- Tulsa, OK
Posts: 280
Default

Gear the motor to the track, not the ambient temp., and all will be good!
JWATT is offline   Reply With Quote
Old 05-13-2004, 09:13 AM   #9
Tech Elite
 
mafiaracers's Avatar
 
Join Date: Mar 2004
Location: West Linn, Oregon
Posts: 3,759
Trader Rating: 22 (100%+)
Send a message via AIM to mafiaracers Send a message via MSN to mafiaracers
Default

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.
mafiaracers is offline   Reply With Quote
Old 05-13-2004, 09:26 AM   #10
Tech Elite
 
popsracer's Avatar
 
Join Date: Oct 2002
Location: "Hot, Sunny Southern California"
Posts: 3,120
Default

Quote:
Originally posted by 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?
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.
popsracer is offline   Reply With Quote
Old 05-13-2004, 11:04 AM   #11
Tech Addict
 
Sleighty's Avatar
 
Join Date: May 2003
Posts: 568
Default

Quote:
Originally posted by 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
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!

__________________
A1-RC.com
Team Scream
Xray
Sleighty is offline   Reply With Quote
Old 05-13-2004, 12:59 PM   #12
Tech Regular
 
Join Date: Nov 2003
Location: Driver's Stand- Tulsa, OK
Posts: 280
Default

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.
JWATT is offline   Reply With Quote
Old 05-13-2004, 01:04 PM   #13
Tech Elite
 
JDXray's Avatar
 
Join Date: Mar 2004
Location: Long Island, New York
Posts: 2,802
Trader Rating: 3 (100%+)
Send a message via AIM to JDXray
Default think?

Think it is worth it?

http://cgi.ebay.com/ws/eBayISAPI.dll...192967804&rd=1
JDXray is offline   Reply With Quote
Old 05-13-2004, 01:07 PM   #14
Tech Lord
 
Hebiki's Avatar
 
Join Date: Aug 2003
Location: Chino, CA
Posts: 12,919
Trader Rating: 26 (100%+)
Default Motor Temp

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.
__________________
Hebiki Design Works
Custom R/C Vinyl Graphics & Apparel: Your gear, your way!
Web Design - Web Development - Logo Design - Graphic Design
www.facebook.com/HebikiDesignWorks
Hebiki is offline   Reply With Quote
Old 05-13-2004, 01:22 PM   #15
Tech Elite
 
Lonestar's Avatar
 
Join Date: Oct 2001
Location: Switzerland
Posts: 2,367
Trader Rating: 13 (100%+)
Default Re: think?

Quote:
Originally posted by JDXray
Think it is worth it?

http://cgi.ebay.com/ws/eBayISAPI.dll...192967804&rd=1
depends if it obstructs the motor's vents...
__________________
When the flag drops, the BS stops.

The train stops at the train station. The bus stops at the bus station. In my office I have a workstation.
Lonestar is offline   Reply With Quote
Reply

Similar Threads
Thread Thread Starter Forum Replies Last Post
Brushless motor heat sinks w/fan... P2 Electric On-Road 1 05-08-2008 05:25 AM
When and how to pre heat a motor..... Mpowerz Nitro Off-Road 10 01-14-2008 09:42 PM
Motor Heat Sinks - Good or Bad? Eggyolkeo Electric On-Road 2 08-14-2007 03:09 AM
Motor Heat Sink Question Drift_Buggy Electric On-Road 1 02-05-2007 01:35 AM
Stock Motor Gearing/Heat LOSI123 Electric On-Road 35 01-12-2007 11:01 PM



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off



All times are GMT -7. It is currently 08:18 PM.


We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
Powered By: vBulletin v3.9.2.1
Privacy Policy | Terms of Use | Advertise Content © 2001-2011 RCTech.net