R/C Tech Forums

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

Reply
 
Thread Tools Search this Thread
Old 05-20-2008, 05:54 PM   #4801
Tech Champion
 
Nova F1 Racer's Avatar
R/C Tech Charter Subscriber
 
Join Date: Mar 2003
Location: Peoples Republic of Northern Virginia
Posts: 5,682
Trader Rating: 3 (100%+)
Default

Quote:
Originally Posted by KHoff7 View Post
smaller spur = taller gearing
bigger pinion = taller gearing
taller gearing = more speed and less acceleration

at 301 you will want very tall gearing compared to most local tracks (For us).
I'd go with Karl's idea for 301....
__________________
This is DICK!!! And you're NOT!
RC Tech member #11
Aussie Rules Footy, Brisbane LIONS!!
[url]http://www.pitter-pat.com/[/url] for pet care needs in Northern Virginia
Nova F1 Racer is offline   Reply With Quote
Old 05-20-2008, 07:11 PM   #4802
Tech Elite
 
chris moore's Avatar
 
Join Date: Mar 2004
Location: Phx AZ
Posts: 3,755
Trader Rating: 87 (99%+)
Default

Quote:
Originally Posted by KHoff7 View Post
smaller spur = taller gearing
bigger pinion = taller gearing
taller gearing = more speed and less acceleration
Well said and because brushless has so much torque you really need to gear tall.

Quote:
Originally Posted by nemix View Post
well looks like i need to swap out my spur as well. what brand spur gears fit well in the db12?
I really like the PRS and thay have spurs down to 76.
chris moore is offline   Reply With Quote
Old 05-20-2008, 07:19 PM   #4803
Tech Elite
 
KHoff7's Avatar
 
Join Date: Jan 2007
Posts: 3,166
Trader Rating: 4 (100%+)
Default

Quote:
Originally Posted by chris moore View Post
Well said and because brushless has so much torque you really need to gear tall.



I really like the PRS and thay have spurs down to 76.
Its a combo of track size and brushless.
__________________
Awesomatix USA / Middle River Hobbies / Sweep / Psycho Cells Racing
Karl Hoffmeister
KHoff7 is offline   Reply With Quote
Old 05-20-2008, 07:27 PM   #4804
Tech Champion
 
Join Date: Nov 2001
Location: Hawaii, USA
Posts: 7,177
Default

Ok I am making the switch to 13.5 BL in this next race. I need a ball park gearing for the following 60'x60' track:
Attached Thumbnails
BMI's DB12R-keiji-tgp.jpg  
InspGadgt is offline   Reply With Quote
Old 05-20-2008, 10:36 PM   #4805
Tech Fanatic
 
Join Date: Jun 2005
Posts: 900
Default

Quote:
Originally Posted by nemix View Post
is there an advantage to a smaller spur and larger pinion combo?
Not really. The face width we use (the width of the gears) is much larger than really needed, and gives a high safety factor. Broadly speaking, the larger the pinion and the smaller the spur gear, the more teeth are in engagement, and the stronger the combination. The smaller the pinion gets, the less teeth in egnagement and the more likely it is that you could strip the spur on a bumpy track, or if you set it up wrong.

Given the choice of a small pinion and a small spur, or a large pinion and a large spur, go for the latter every time.

Quote:
Originally Posted by Kropy View Post
PRS, Kimbrough, RW, Robinson
...of which I would highly recommend Kimbrough and RW for long life and the best gear forms. HTH
SlowerOne is offline   Reply With Quote
Old 05-20-2008, 10:49 PM   #4806
Tech Champion
 
Join Date: Nov 2001
Location: Hawaii, USA
Posts: 7,177
Default

Running a smaller spur gives you more room in the pod for gearing adjustment and moves the motor closer to the rear axle.
InspGadgt is offline   Reply With Quote
Old 05-21-2008, 06:13 AM   #4807
Tech Champion
 
Scottrik's Avatar
 
Join Date: Sep 2004
Location: Billings, MT
Posts: 6,194
Trader Rating: 243 (100%+)
Default

Quote:
Originally Posted by InspGadgt View Post
Running a smaller spur gives you more room in the pod for gearing adjustment and moves the motor closer to the rear axle.
More room for adjustment, no doubt. I would argue, however, that "like for like" the motor stays pretty close to the same position relative to the axle as to compensate for the smaller spur you are installing a similarly larger pinion to get the same rollout. Overall, since we're finding what had been heretofore considered ENORMOUS rollouts to be the new reality for bl racing I'd say the motor is finding its way further from the axle if anything.

Of course some engineer-type (or Michael) may come on and blow me out of the water on this one...
__________________
Congressmen should wear uniforms like NASCAR drivers so we can identify their corporate sponsors.

THE REVOLUTION WILL NOT BE TELEVISED -Gil Scott-Heron (1949-2011)
Scottrik is offline   Reply With Quote
Old 05-21-2008, 07:00 AM   #4808
Tech Champion
 
hanulec's Avatar
R/C Tech Elite Subscriber
 
Join Date: Sep 2007
Location: @ the post office
Posts: 8,417
Trader Rating: 27 (100%+)
Default

17.5T brushless 1/12th is fun. I have 3 axles with different spur gear sizes 76, 78, & 80T in order to match rollout as tire sizes change.
__________________
FJ / ROAR #2-122945 / MaxRotation FPV Drone Racing / Shop@ Awesomatix USA / Wild Turbo Fan / Mon-Tech Racing / RocheRC USA / Side Piece /
LRP / John's BSR Tires / TeamEAM / TQ Wire / R1 / Team Scream / PCR / MIX
RacerLog wiki Awesomatix A700 / 2wd offroad 4 life
hanulec is offline   Reply With Quote
Old 05-21-2008, 09:46 AM   #4809
Tech Addict
 
Join Date: Mar 2007
Posts: 684
Trader Rating: 24 (96%+)
Default

ok so lots of information to digest here... luckily i have a day to practice on friday before the race.

So here is what i'm looking at - running 10.5 brushless on a large track.

Set up test 1

current 64p 88tooth spur is on the car now

pick up 38 - 42 tooth pinions to test with on the 88 spur

Set up test 2

Pick up a 78 tooth spur

pick up 49 - 52 pinions to test with on the 78 spur

I dont mind buying extra stuff to add to my pit because i dont have many gears yet at all, and i will be running cars at other tracks with other motors in the future, i.e. 17.5 stock etc.

whatcha think?

thanks for your help guys!
__________________
AE TC5
DB12R
DB10R
Losi 8T
Kyosho RB5
http://www.kolorsbykropy.net
nemix is offline   Reply With Quote
Old 05-21-2008, 10:19 AM   #4810
Regional Moderator
 
CarbonJoe's Avatar
 
Join Date: Jul 2006
Posts: 2,660
Default

For what it's worth, with a 17.5 on a medium size carpet track, I am currently running 51/78 with 1.75 inch rear tires. On a large outdoor track, I'd probably buy pinions up to 55 or 56.
__________________
*** The Gate - Celebrating 7 years at the same location ***
The difference between genius and stupidity is that genius has its limits. - Albert Einstein
Understeer is when you hit the wall with the front of the car and oversteer is when you hit the wall with the rear of the car
CarbonJoe is offline   Reply With Quote
Old 05-21-2008, 11:50 AM   #4811
Tech Champion
 
Join Date: Nov 2001
Location: Hawaii, USA
Posts: 7,177
Default

Quote:
Originally Posted by Scottrik View Post
More room for adjustment, no doubt. I would argue, however, that "like for like" the motor stays pretty close to the same position relative to the axle as to compensate for the smaller spur you are installing a similarly larger pinion to get the same rollout. Overall, since we're finding what had been heretofore considered ENORMOUS rollouts to be the new reality for bl racing I'd say the motor is finding its way further from the axle if anything.

Of course some engineer-type (or Michael) may come on and blow me out of the water on this one...
To keep the same gear ratio or roll out when going to a smaller spur you need to go to a smaller pinion as well which will move the motor back toward the axle. If your running say a 100 spur with a 25 pinion to keep the same roll out with an 88 spur you'd have to run a 22 pinion given the same sized tires in both. But if your comparing brushed to brushless then yeah the motor might stay in relatively the same place because they run such different roll outs.
InspGadgt is offline   Reply With Quote
Old 05-22-2008, 06:25 AM   #4812
Tech Fanatic
 
darnold's Avatar
 
Join Date: Feb 2002
Location: Bolingbrook, IL
Posts: 936
Trader Rating: 2 (100%+)
Default

I weighed the standard Associated front end with bearings and CRC brace but sans the ride height stand-offs Satruday and it was 1.4oz.

I will take off the CRC front end and weight accordingly (bearings and brace but sans the ride height stand-offs) and post by next Monday. My guess is that the CRC front end will be half and ounce heavier but this is just a guess.
__________________
Team Top Racing USA,Team MaClan ESC, Pro One Tires, Hot Race Tires

Last edited by darnold; 05-23-2008 at 08:54 PM.
darnold is offline   Reply With Quote
Old 05-22-2008, 09:33 AM   #4813
Tech Adept
 
Join Date: Jan 2007
Location: Switzerland
Posts: 131
Default

Asso and CRC Frontend have nearly the same weight. I weighted them a long time ago (when i built my GenX) and the i think the difference was just 2gr
Der Dicke is offline   Reply With Quote
Old 05-23-2008, 03:18 AM   #4814
Tech Lord
 
protc3's Avatar
 
Join Date: Jun 2003
Location: Spring Hill,Florida
Posts: 10,829
Trader Rating: 13 (100%+)
Default

SE cars should be ready real soon. We are waiting on parts to come back from anodize. Everything else is complete
__________________
Jason Breiner
BMI Racing
Team Associated
J Concepts
protc3 is offline   Reply With Quote
Old 05-23-2008, 06:32 AM   #4815
Tech Addict
 
t4mania's Avatar
 
Join Date: Jan 2006
Location: Virginia
Posts: 541
Trader Rating: 5 (100%+)
Default

Jason, any plans on doing an SE car for the DB10R. Sounds like a cool idea for the DB12 but I already have one.
__________________
SC10 4X4 Short Course
SC10 FT 2WD Short Course; FT B4.1 +8mm Buggy
FT T4 Dirt Oval
Silva Concepts R50 Oval
Custom Works Dominator; FT TC3 Trans Am
t4mania is offline   Reply With Quote
Reply

Similar Threads
Thread Thread Starter Forum Replies Last Post
NEW IN BOX BMI DB12R bigb11 R/C Items: For Sale/Trade 47 10-09-2008 04:36 PM
-BMI DB12R- joey R/C Items: For Sale/Trade 11 05-18-2008 09:25 PM
BMI DB12R wallstreet R/C Items: For Sale/Trade 17 02-15-2008 05:04 PM
BMI DB12R D-Bizzle R/C Items: For Sale/Trade 2 12-21-2007 03:48 PM
WTB BMI DB12R chris moore R/C Items: Wanted to Buy 8 06-29-2007 06:25 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 03:47 PM.


Powered By: vBulletin v3.9.2.1
Privacy Policy | Terms of Use | Advertise Content © 2001-2011 RCTech.net