R/C Tech Forums

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

Reply
 
Thread Tools Search this Thread
Old 07-13-2008, 02:02 PM   #16
Tech Addict
 
Join Date: Apr 2007
Location: las vegas, nv
Posts: 554
Trader Rating: 30 (100%+)
Default

Thanks for info I appreciate it. So will a bigger or smaller spur have a cooler running motor?
chuckharrisjr is offline   Reply With Quote
Old 07-13-2008, 02:12 PM   #17
Suspended
 
Join Date: Jun 2008
Posts: 592
Trader Rating: 1 (100%+)
Default

Quote:
Originally Posted by chuckharrisjr View Post
Thanks for info I appreciate it. So will a bigger or smaller spur have a cooler running motor?
Not really, though getting up to speed quicker helps the motor run easier as there is less strain on it.
rocket-mtrsprts is offline   Reply With Quote
Old 07-13-2008, 02:21 PM   #18
Tech Addict
 
Join Date: Apr 2007
Location: las vegas, nv
Posts: 554
Trader Rating: 30 (100%+)
Default

Gotcha thanks again....
chuckharrisjr is offline   Reply With Quote
Old 07-13-2008, 04:59 PM   #19
Tech Elite
 
Join Date: May 2003
Location: Northern & Central Illinois
Posts: 4,337
Trader Rating: 1 (100%+)
Default

Quote:
Originally Posted by rocket-mtrsprts View Post
Larger spur = quicker initial acceleration
same final gear ratio = same top speed
I'm sorry, but I can't follow your logic.

Are you saying that a larger spur gear and larger pinion will give quicker initial acceleration than a smaller spur and smaller pinion with the same FDR but spinning up less mass? I would think that the larger mass would be slower to spool up.
AreCee is offline   Reply With Quote
Old 07-13-2008, 07:38 PM   #20
Tech Master
 
BadSign's Avatar
 
Join Date: Feb 2002
Location: Franklin, IN
Posts: 1,158
Trader Rating: 15 (100%+)
Default

When my off-road track switched from 27T to 13.5, we all geared about 6-7 teeth higher (48 pitch) on the pinion. I think that's 8 or 9 teeth on 64P
__________________
This is the day the Lord has made, I will rejoice and be glad in it- Psalms 118:24

World Champion Turn Marshall
BadSign is offline   Reply With Quote
Old 07-13-2008, 07:39 PM   #21
Tech Master
 
BadSign's Avatar
 
Join Date: Feb 2002
Location: Franklin, IN
Posts: 1,158
Trader Rating: 15 (100%+)
Default

Quote:
Originally Posted by AreCee View Post
I'm sorry, but I can't follow your logic.

Are you saying that a larger spur gear and larger pinion will give quicker initial acceleration than a smaller spur and smaller pinion with the same FDR but spinning up less mass? I would think that the larger mass would be slower to spool up.
heavier gears place more load on the motor, which raises amp draw and increases torque from a dead start.
__________________
This is the day the Lord has made, I will rejoice and be glad in it- Psalms 118:24

World Champion Turn Marshall
BadSign is offline   Reply With Quote
Old 07-13-2008, 08:59 PM   #22
Tech Elite
 
Join Date: May 2003
Location: Northern & Central Illinois
Posts: 4,337
Trader Rating: 1 (100%+)
Default

Quote:
Originally Posted by BadSign View Post
heavier gears place more load on the motor, which raises amp draw and increases torque from a dead start.
So if heavier gears give you more torque then why do we buy lightened gears with holes in them and pinions machined from aluminum. We should be using solid steel spur gears and steel pinions in 64P for mod motors. Right!

I guess all those physics classes must have confused me.
AreCee is offline   Reply With Quote
Old 07-14-2008, 12:07 AM   #23
Tech Master
 
BadSign's Avatar
 
Join Date: Feb 2002
Location: Franklin, IN
Posts: 1,158
Trader Rating: 15 (100%+)
Default

Quote:
Originally Posted by AreCee View Post
So if heavier gears give you more torque then why do we buy lightened gears with holes in them and pinions machined from aluminum. We should be using solid steel spur gears and steel pinions in 64P for mod motors. Right!

I guess all those physics classes must have confused me.
Place more load on a motor and it creates more power. Just look at any dyno sheet.

Too much load, though and we all know what happens- the power to weight ratio goes downhill, and the power curve doesn't improve enough to make up for the additional rotating mass. It's the law of diminishing returns.

It's really a nit-picky thing. All my pinions are aluminum, but steel is just fine.
__________________
This is the day the Lord has made, I will rejoice and be glad in it- Psalms 118:24

World Champion Turn Marshall
BadSign is offline   Reply With Quote
Old 07-14-2008, 08:54 AM   #24
Suspended
 
Join Date: Jun 2008
Posts: 592
Trader Rating: 1 (100%+)
Default

Quote:
Originally Posted by AreCee View Post
I'm sorry, but I can't follow your logic.

Are you saying that a larger spur gear and larger pinion will give quicker initial acceleration than a smaller spur and smaller pinion with the same FDR but spinning up less mass? I would think that the larger mass would be slower to spool up.
When you're talking about gear size versus spinning up mass I guess you're forgetting the most important part of the scenario -- and that being the relationship between the size of the spur gear relative to the rear tire.
rocket-mtrsprts is offline   Reply With Quote
Old 07-14-2008, 09:18 AM   #25
Tech Champion
 
John Tag's Avatar
 
Join Date: May 2004
Location: Huntersville, NC
Posts: 8,925
Trader Rating: 42 (100%+)
Default

Quote:
Originally Posted by BadSign View Post
heavier gears place more load on the motor, which raises amp draw and increases torque from a dead start.
Heavier gear were used in PAST for larger Oval racing to keep RPM range up and motor rotion up. Light wt gears are choice now days for all racing. Lighter always spool up faster. Put a brick on your motor shaft see how long it takes to turn over..
__________________
www.express-motorsports.net for all your motor needs
Multi time National Champions,Reedy Champs,Vegas Champs,Birds, Champs,[email protected]

Team Associated-Express Motorsports-Trinity-Reflex Racing-A Main Hobbies-ProtekRC
John Tag is offline   Reply With Quote
Old 07-14-2008, 12:37 PM   #26
Tech Master
 
BadSign's Avatar
 
Join Date: Feb 2002
Location: Franklin, IN
Posts: 1,158
Trader Rating: 15 (100%+)
Default

Quote:
Originally Posted by John Tag View Post
Heavier gear were used in PAST for larger Oval racing to keep RPM range up and motor rotion up. Light wt gears are choice now days for all racing. Lighter always spool up faster. Put a brick on your motor shaft see how long it takes to turn over..
That's why I said it's a real nit-picky thing. I guess my words should have been "too small to make a noticable difference"
__________________
This is the day the Lord has made, I will rejoice and be glad in it- Psalms 118:24

World Champion Turn Marshall
BadSign is offline   Reply With Quote
Old 07-14-2008, 12:46 PM   #27
Tech Elite
 
Join Date: May 2003
Location: Northern & Central Illinois
Posts: 4,337
Trader Rating: 1 (100%+)
Default

Quote:
Originally Posted by BadSign View Post
That's why I said it's a real nit-picky thing. I guess my words should have been "too small to make a noticable difference"
We've had similar arguments regarding bicycle gearing before. Finally someone put a power meter on his bike and we tested the different big ring/cog vs small ring/cog that gave the same ratio. The results were that the power was equal in both combinations.

I will assume that other than an infinately small difference of mass that you would never notice any difference using different sized gears as long as the final drive ratio or rollout is equal.
AreCee is offline   Reply With Quote
Old 07-15-2008, 04:28 AM   #28
Tech Regular
 
Join Date: Jul 2002
Location: England
Posts: 417
Send a message via MSN to Bigger Brother
Default

I can't believe some of the small numbers you are talking about running....... :O A few weeks back at one of our regional champs, I had one of the fastest cars down the straight in 13.5, using a Novak SS with the standard (sintered) rotor, timing slightly above 0, geared at around 5-5.1. Speedo was an LRP TC Spec with punch on one from the highest setting. Motor was temping around 130-140 F.

Although it was on a really small track - something like a 30m straight, so maybe thats why I was geared so differently from the numbers you're talking about??
__________________
Oli Meggitt | London, UK
.:. Essex Winter Series .:. CML Racing .:. ToniSport .:. Zen Racing .:. Moorespeed RC .:. OTM Racing .:. RC Racing TV .:. RIDE R/C Scoreboards
Bigger Brother is offline   Reply With Quote
Old 07-15-2008, 05:13 AM   #29
Tech Elite
 
Join Date: May 2003
Location: Northern & Central Illinois
Posts: 4,337
Trader Rating: 1 (100%+)
Default

Our tracks are similar in size 100' x 40' (30x12m) and using an FDR of 4.5 my motor temps at 155-160F or 68-71C after a 5 minute qual. with the ambient temp around 80F or 27C.
AreCee is offline   Reply With Quote
Old 07-15-2008, 05:19 PM   #30
Super Moderator
 
Grizzbob's Avatar
 
Join Date: Feb 2002
Location: Sand Springs, OK
Posts: 3,063
Trader Rating: 2 (100%+)
Default

Quote:
Originally Posted by Bigger Brother View Post
I can't believe some of the small numbers you are talking about running....... :O A few weeks back at one of our regional champs, I had one of the fastest cars down the straight in 13.5, using a Novak SS with the standard (sintered) rotor, timing slightly above 0, geared at around 5-5.1. Speedo was an LRP TC Spec with punch on one from the highest setting. Motor was temping around 130-140 F.

Although it was on a really small track - something like a 30m straight, so maybe thats why I was geared so differently from the numbers you're talking about??
Yes, the track that the original poster & I were talking about is fairly big, has a long back straight & a VERY high-speed sweeper right after(at least it's that way every time I've raced there). But while I would gear my cars at about 4.6FDR there, here at home, I gear it at more like 5.1FDR, because of the smaller track we have here(near Tulsa, OK) to get in the ballpark.....
__________________
Bob Seay
Tamiya TRF417, TA05v.2, TRF211XM, M-05ver.2R, XRAY X12, Associated B5m Factory Lite

Go Pokes!!!
Grizzbob is offline   Reply With Quote
Reply

Similar Threads
Thread Thread Starter Forum Replies Last Post
Gearing lickashotblaow Electric On-Road 0 07-29-2007 05:47 PM
NeeD Help with gearing please daver1 Electric On-Road 4 07-20-2007 09:12 AM
Gearing for TT-01 tl-01-jhb Rookie Zone 0 11-10-2004 05:35 AM
Need help gearing a TC3 fasda1 Electric On-Road 10 11-06-2004 11:51 AM
Gearing??? mike m Monster Trucks 3 01-24-2004 07:54 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 03:22 AM.


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