R/C Tech Forums

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

Like Tree1Likes
Closed Thread
 
Thread Tools Search this Thread
Old 11-13-2008, 06:59 PM   #3226
Tech Fanatic
 
414MPH's Avatar
 
Join Date: Aug 2006
Location: SE Wisconsin
Posts: 987
Trader Rating: 8 (100%+)
Default

Quote:
Originally Posted by liljohn1064 View Post
Can you ballpark the pinion and what pitch?

I got an equation directly from RRP that works for figuring out the diameter of any gear.



Without a distance from center to center you have no starting point, but that can be found. If you have a pinion of any pitch that's fits, It can be worked backwards.

I'm guessing it's a 48 pitch spur?

(77 + 2) / 48 = 1.65 inches diameter. The radius is 1/2 the diameter, .825 Inches.

Now, center the motor, slide any old pinion on that and makes contact with the spur and that you know the pitch of, metric will not work. The teeth will not mesh if they mismatch, so don't turn the gearing. All that's needed is the pinion tooth number.

For arguments sake, the pinion number we need to have will put us at 1 1/8 inch.

Again, (77 + 2) / 48 = 1.65 inches diameter. The radius is 1/2 the diameter, .825 Inches.

.825 (the spur radius) + Pinion Radius = 1 1/8 inches (1.125).
So the pinion radius is 1.125 inch - .825 = .3
we need to reverse the equation above. First thing is to double the radius for the diameter, .6 inches.
Now we have (P+2)/48 = .6, this becomes P = (48 x .6) -2. P = which points to roughly a 27 tooth pinion.

Run the equation again for the pinion and add the 2 final numbers together. You now have the distance from the center of the spur to center of the pinion. Now we need the internal gear ratio of the car. I know my TC3 is a 2.5, my e4js is a 2.0588.

As an example my e4js:

(Spur / Pinion) X <the internal ratio of your car> = FDR
(88 / 52) X 2.0588 = 3.484


Now to work it all backwards so the FDR meets the pinion to spur center to center distance. You'll have distance, the FDR and the internal ratio of your car. So lets change the example and keep calculating until we meet the magic distance number. This first one is for a Spur that is too large which is where most of us start from with these insane FDR numbers. This all trial and error on paper, but with this you buy a couple spurs and gears ONCE.

The distance number we need to achieve is still 1.125 inches.

(110 / P) x 2.0588 = between 3.4 and 3.5 P = 65 Sweet! (NOT)

Spur (110 + 2) / 64 = 1.75 inches diameter
1.75 / 2 = .875 inches
Pinion (65 + 2) / 64 = 1.05 inches diameter
1.05 / 2 = .525 inches

.857 + .525 = 1.4 inches or about 3/16 of an inch too big.

So decrease the spur size to calculate the new pinion.

lets try a 104 spur.

(110 / P) x 2.0588 = between 3.4 and 3.5 P = 61

Spur (104 + 2) / 64 = 1.66 inches diameter
1.66 / 2 = .83 inches radius
Pinion (61 + 2) / 64 = .984 inches diameter
.984 / 2 = .492 inches radius

.83 + .492 = 1.322 inches or about 1/18 of an inch too big. Closer though.

Keep going until you can be less then .075 of an inch up or down from your magic distance number. This will allow you to slide the motor around as needed to adjust for good gear mesh.

I found using this method that 94s are the largest spur to consider and 88s the smallest. My pinion collection goes from 40 to 52. I can hit anything from a 3.484 to a 4.838 as needed. I went overboard, I know.

Now to make anyone who has bothered to put up with me this long rest a little easier. I have a spread sheet that shows all of this. It can be adapted to any car, it includes rollout in millimeters and inches based on the FDR and Tire diameter. Not only that, the formulas are built into it. If you put in a spur, a pinion and your car's ratio, it spits everything else out for that row.

PM me your car's internal ratio, or the car make and model, with a valid email addy and I'll send it off.

Spur Pinion Center Ratio FDR
to
Center
88 40 1.031 2.20 4.529
88 41 1.039 2.15 4.419
88 42 1.047 2.10 4.314
88 43 1.055 2.05 4.213
88 44 1.063 2.00 4.118
88 45 1.070 1.96 4.026
88 46 1.078 1.91 3.939
88 47 1.086 1.87 3.855
88 48 1.094 1.83 3.774
88 49 1.102 1.80 3.697
88 50 1.109 1.76 3.623
88 51 1.117 1.73 3.552
88 52 1.125 1.69 3.484

John, you gave me a headache...way too complicated...lol

You don't need center distance, just tooth count. Try this meathod.....

Many USVTA racers are finding it difficult to get their gearing options near the 4.2 FDR and getting the sellected spur pinion to fit.

It is actually very simple to figure what spur pinion you need to run and what will fit in your particular chassis.

With the exsisting spur mounted in your chassis and an assortment of pinions, determine the biggest and smallest pinion that will mesh in your chassis due to motor adjustment limits.

Example, I run a Tamiya 414M. I had a 120 tooth spur in the car. The largest pinion that would mesh was a 38 tooth, and the smallest was a 31 due to motor adjustment limits.

If you add the spur tooth count with the pinion count you find the min and max tooth combination that will fit your chassis.

For the 414, it is 120 + 31 = 151 tooth min
& 120 + 38 = 158 tooth max cobination.

Simple soo far... NOW,

If I want to see what available spur will get me close to the lipo/21.5 FDR of 4.2, and knowing my internal secondary ratio of 2.1333 (thats a 32 tooth diff pulley divided by the 15 tooth center pulley or 32/15 = 2.1333)
I simply divide to target by the internal ratio...
or
4.2 / 2.1333 and get 1.968

Now I have to see what spurs are available and I see the LHS has 112,108,104,100 and etc. spurs in stock.

Now, without buying a spur to see if it will fit in the car and can simply run a few numbers......

Will a 120 get me to the 4.2 FDR on my chassis? Lets see.

Just divide the spur tooth count by the 1.968 I solved for earlier...

120 spur / 1.968 target ratio = 60.97, or a 60 pinion.

Now add 120 spur + 60 pinion and get 180 total. This will not fit the 158 max to 151 min established earlier. The spur is too big!

Lets try the 104 spur...

Divide the spur tooth count by the 1.968 I solved for earlier...

104 spur / 1.968 target ratio = 52.845, or a 52 pinion.

Now add 104 spur + 52 pinion and get 156 total. This will fit the 158 max to 151 min established earlier. This combination will work and give me some room to use a smaller pinion to adjust my FDR for different tracks as I can go down in pinion size to a 47 tooth and know I can achieve propper gear mesh.

Sorry to be long winded, but I think this helps in determining what size gears will fit before you buy a bunch of gears that won't fit your chassis.

PM me with questions if you like.

Marty (The FATHER of organized Vintage Trans-AM)
http://www.rctech.net/forum/wisconsi...ing-class.html
414MPH is offline  
Old 11-14-2008, 12:40 AM   #3227
Tech Champion
 
liljohn1064's Avatar
 
Join Date: Sep 2008
Location: Deerfield, WI
Posts: 5,582
Trader Rating: 17 (100%+)
Default

Quote:
Originally Posted by 414MPH View Post
John, you gave me a headache...way too complicated...lol

You don't need center distance, just tooth count. Try this meathod.....

Many USVTA racers are finding it difficult to get their gearing options near the 4.2 FDR and getting the sellected spur pinion to fit.

It is actually very simple to figure what spur pinion you need to run and what will fit in your particular chassis.

With the exsisting spur mounted in your chassis and an assortment of pinions, determine the biggest and smallest pinion that will mesh in your chassis due to motor adjustment limits.

Example, I run a Tamiya 414M. I had a 120 tooth spur in the car. The largest pinion that would mesh was a 38 tooth, and the smallest was a 31 due to motor adjustment limits.

If you add the spur tooth count with the pinion count you find the min and max tooth combination that will fit your chassis.

For the 414, it is 120 + 31 = 151 tooth min
& 120 + 38 = 158 tooth max cobination.

Simple soo far... NOW,

If I want to see what available spur will get me close to the lipo/21.5 FDR of 4.2, and knowing my internal secondary ratio of 2.1333 (thats a 32 tooth diff pulley divided by the 15 tooth center pulley or 32/15 = 2.1333)
I simply divide to target by the internal ratio...
or
4.2 / 2.1333 and get 1.968

Now I have to see what spurs are available and I see the LHS has 112,108,104,100 and etc. spurs in stock.

Now, without buying a spur to see if it will fit in the car and can simply run a few numbers......

Will a 120 get me to the 4.2 FDR on my chassis? Lets see.

Just divide the spur tooth count by the 1.968 I solved for earlier...

120 spur / 1.968 target ratio = 60.97, or a 60 pinion.

Now add 120 spur + 60 pinion and get 180 total. This will not fit the 158 max to 151 min established earlier. The spur is too big!

Lets try the 104 spur...

Divide the spur tooth count by the 1.968 I solved for earlier...

104 spur / 1.968 target ratio = 52.845, or a 52 pinion.

Now add 104 spur + 52 pinion and get 156 total. This will fit the 158 max to 151 min established earlier. This combination will work and give me some room to use a smaller pinion to adjust my FDR for different tracks as I can go down in pinion size to a 47 tooth and know I can achieve propper gear mesh.

Sorry to be long winded, but I think this helps in determining what size gears will fit before you buy a bunch of gears that won't fit your chassis.

PM me with questions if you like.

Marty (The FATHER of organized Vintage Trans-AM)
http://www.rctech.net/forum/wisconsi...ing-class.html
Marty,

I like it! Mine came out of necessity. I was really in no man's land. My car didn't even come with a pinion recommendation! Your's is from the book of wisdom. Its so much easier to understand and use. To get your's to work consistantly only requires you get a pinion and spur of the same pitch to fit and take it from there. Much easier.

John
__________________
John Higgins former student of The Ian Ruggles Negative Reinforcement Driving School. The "Team Principal".
liljohn1064 is offline  
Old 11-14-2008, 05:53 AM   #3228
Tech Addict
 
KE4PJO's Avatar
 
Join Date: Feb 2002
Location: Columbia,Tn.
Posts: 642
Default

Quote:
Originally Posted by TeamGoodwrench View Post
I think there are going to be quite a few of the older chassis parked when the 27T motor gets dropped -- some of the older chassis (like my old Yokomo MR-4TC just don't have the motor adjustment to get the big gears on if you need to get into the 4.2 to 5.0 FDR with the 21.5 motor.
That's not the case, a 88, 90 or a 92 tooth spur gear will get you close. (64P)

Last edited by KE4PJO; 11-14-2008 at 10:03 AM.
KE4PJO is offline  
Old 11-14-2008, 10:34 AM   #3229
Tech Adept
 
GMacRCMan's Avatar
 
Join Date: Mar 2002
Location: Fargo, ND
Posts: 130
Trader Rating: 1 (100%+)
Default

Hey guys, I am looking to resurrect an old FT TC3 that I ran for years in foam form.

Anyone have a way to get Mike Collins setup from the gate?

I read all about motor this and battery that, but being that I never ran rubber, what I really could use is a good starting point for my CAR setup.

Excited about trying this class out.

Ian




Cain..... you better get your BL Lipo gear goin'.. .cause I am coming after you at Pingree with my antique gear....
GMacRCMan is offline  
Old 11-14-2008, 10:54 AM   #3230
Tech Master
 
bigemike's Avatar
 
Join Date: Aug 2002
Location: hamilton, oh
Posts: 1,750
Trader Rating: 35 (100%+)
Send a message via Yahoo to bigemike
Default

Ian,

Here is a good starting point for you tc3

I attached a pdf with a baseline, should be a great starting point for your tc3

On another note, i saw in another thread, that novak is coming out with a 21.5 havok speedo combo with a great price point. It will be a nice setup for anyone wanting to go lipo / brushless
Attached Files
File Type: pdf tc3 vta.pdf (354.4 KB, 175 views)
bigemike is offline  
Old 11-14-2008, 11:40 AM   #3231
Tech Fanatic
 
scootr117's Avatar
 
Join Date: Jun 2006
Location: On a Stage or Stand somewhere
Posts: 939
Default

Quote:
Originally Posted by GMacRCMan View Post
Hey guys, I am looking to resurrect an old FT TC3 that I ran for years in foam form.

Anyone have a way to get Mike Collins setup from the gate?

I read all about motor this and battery that, but being that I never ran rubber, what I really could use is a good starting point for my CAR setup.

Excited about trying this class out.

Ian













Cain..... you better get your BL Lipo gear goin'.. .cause I am coming after you at Pingree with my antique gear....
Here is the site/forum he watches....post and oldmancollins shall reply..........http://www.thehobbyshoponline.com
__________________
Scooter EXperimental
RK Designs
CD SuperPro Motors
Mike Pulfer is my HERO....
scootr117 is offline  
Old 11-14-2008, 11:51 AM   #3232
Tech Adept
 
GMacRCMan's Avatar
 
Join Date: Mar 2002
Location: Fargo, ND
Posts: 130
Trader Rating: 1 (100%+)
Default

Bigmike - Thanks. I was afraid that your setup was going to say "one-way". I guess I am probably going to have to get one.

Scootr117 - Thanks. I will try to get some info from him and see if his setup requires a one way. Hate to have to buy one of those things if I can get away without it.
GMacRCMan is offline  
Old 11-14-2008, 12:16 PM   #3233
Tech Elite
 
Trips's Avatar
 
Join Date: Aug 2001
Location: 360 Speedway
Posts: 2,251
Trader Rating: 16 (100%+)
Default

Couple of questions for Doug...

First, a few years back at one of the Reedy Races they outlawed oneways and the reaction post race was that it made for some of the closest most fun racing that guys could remember (according to post-race driver interviews)

Any thought on keeping oneways and spools out of Vintage TA? I have a oneway in my Losi at the moment, so it when I set it up for VTA it will have the oneway, but I thought I'[d ask anyway...

Second... the rules state any 4WD touring chassis is allowed... now I'm wondering if the "spirit of the rules" is that the cars must run as 4WD, in other words would it be illegal to remove the front belt and run the car rear-driven? Just thinking it might be beneficial to reduce drag, but it might make the car very hard to drive... Just thought I'd ask before even trying it out...

Thanks, looking forward to my first VTA race... probably some stupid questions from a guy who hasn't even run the class yet...
__________________
MARSHAL!!
Trips is offline  
Old 11-14-2008, 12:23 PM   #3234
Tech Elite
 
Trips's Avatar
 
Join Date: Aug 2001
Location: 360 Speedway
Posts: 2,251
Trader Rating: 16 (100%+)
Default

Just wanted to add... I'm all for the ideals behind this class, I especially like the "Spirit of the rules" clause in the rules... I'm not trying to re-engineer things or get an unfair advantage... I am behind the idea of fair, close racing, and I REALLY like what I've seen of VTA so far. I intend to follow the letter and spirit of the rules completely, the previous post was just asking for clarification.

Thanks
__________________
MARSHAL!!
Trips is offline  
Old 11-14-2008, 12:38 PM   #3235
Tech Master
 
bigemike's Avatar
 
Join Date: Aug 2002
Location: hamilton, oh
Posts: 1,750
Trader Rating: 35 (100%+)
Send a message via Yahoo to bigemike
Default

Quote:
Originally Posted by GMacRCMan View Post
Bigmike - Thanks. I was afraid that your setup was going to say "one-way". I guess I am probably going to have to get one.

Scootr117 - Thanks. I will try to get some info from him and see if his setup requires a one way. Hate to have to buy one of those things if I can get away without it.
You can use a diff with that setup, that is a really good baseline carpet setup for the car. you can also try spool if you like. You will have to adjust any setup you get for the track, so try that and make changes, if you aren't sure what to change let an experianced racer turn a few laps with your car

also look in the for sale forums for a one way, they pop up for $20-$30 all the time. Also ebay has one from chine for under $30 but I am not sure of the quality. One way makes about .2 sec a lap difference probably, not huge, so until you get within a lap or so of the leaders, I wouldn't make it a priority. Work on your driving and setup until you get close then start buying go fast trinkets when you can feel those subtle setup changes.
bigemike is offline  
Old 11-14-2008, 01:10 PM   #3236
Tech Champion
 
snoopyrc's Avatar
 
Join Date: Oct 2006
Location: Tunnel Hill GA
Posts: 5,046
Trader Rating: 2 (100%+)
Default

Not tested and true but I would expect that on carpet you might have an advantage with the loss of friction in the drive train. On asphalt you will likely not fare as well as the 4WD TC's and either way I think running on RWD would be illegal unless your belt breaks during the middle of a race.
Of course its all rubber tires so IDK.
__________________
www.battlefieldraceway.com Racing videos at http://www.youtube.com/snoopyrc
snoopyrc is offline  
Old 11-14-2008, 03:50 PM   #3237
Tech Master
 
Join Date: Nov 2003
Posts: 1,850
Trader Rating: 5 (100%+)
Default

The reason they banned one-ways back in the day was because there were so many wrecks and people getting punted due to not being able to get on the brakes to avoid hitting someone. In VTA, a front one-way is not always better anyway. On my local track the long back straight ends with a tight 180 turn. My car sets up for and goes around that turn much better and more consistently with a front diff compared to a one-way. Its smoother and more consistent in most of the other turns with a front diff as well. If you have a front one-way, try both setups and see which feels better. If you don't have one, I wouldn't go out and spend the cash on one until you've gotten every last possible hundreth of a second a lap out of the car, and have nothing else to try.
__________________
Serpent SRX8 electric
Serpent Cobra 811TE-E
Serpent S120LTR 17.5 1/12th and S100LTR Pro-10
Serpent S411 Eryx 4.0 USGT
Team Serpent America and Desoto Racing
Stealth_RT is offline  
Old 11-15-2008, 05:24 PM   #3238
Tech Elite
 
reenmachine's Avatar
 
Join Date: May 2008
Location: Studio City, CA
Posts: 2,539
Trader Rating: 26 (100%+)
Default

Quote:
Originally Posted by TwoTone View Post
Shady tree degree = take motor mount, remove all material inbetween the holes- slotted motor mount.

No math involved- priceless.
Great for some situations, but TB-02 has a plastic motor mount and if you remove the material between the holes the motor just doesn't mount securely anymore. The nice thing about not being slotted is that once you get the gears figured out, there's no way for the position to slip and screw up your mesh, strip gears, etc.
__________________
Pete Waydo
2010 Big Fat Turkey Race Mini Cooper AAA Main Champion
*** currently in stasis ***
reenmachine is offline  
Old 11-15-2008, 05:42 PM   #3239
Tech Master
 
TwoTone's Avatar
 
Join Date: Jun 2008
Location: Maryland
Posts: 1,002
Trader Rating: 12 (100%+)
Default

Quote:
Originally Posted by reenmachine View Post
Great for some situations, but TB-02 has a plastic motor mount and if you remove the material between the holes the motor just doesn't mount securely anymore. The nice thing about not being slotted is that once you get the gears figured out, there's no way for the position to slip and screw up your mesh, strip gears, etc.
Just messing with you. We have something in common, while we didn't do it to the level you do, I used to work at a shop restoring old Mustangs called Mustang Magic. I've had two 69's, one Grande and a Conv. My wife was a customer when I met her, she had a 66 Conv.
TwoTone is offline  
Old 11-15-2008, 05:44 PM   #3240
Tech Elite
 
reenmachine's Avatar
 
Join Date: May 2008
Location: Studio City, CA
Posts: 2,539
Trader Rating: 26 (100%+)
Default

Quote:
Originally Posted by TwoTone View Post
Just messing with you. We have something in common, while we didn't do it to the level you do, I used to work at a shop restoring old Mustangs called Mustang Magic. I've had two 69's, one Grande and a Conv. My wife was a customer when I met her, she had a 66 Conv.
Cool...and congrats on the pick-up...Mustangs work great that way! lol

My best friend had a '69 Grande in high school and we spent many a night out in the driveway thrashing on that thing. Brings back a lot of memories!
__________________
Pete Waydo
2010 Big Fat Turkey Race Mini Cooper AAA Main Champion
*** currently in stasis ***
reenmachine is offline  
Closed Thread

Similar Threads
Thread Thread Starter Forum Replies Last Post
Georgia Vintage Trans Am Racing shadow102 Georgia Racing 725 02-24-2012 09:56 AM
Vintage Trans Am Scottrik Electric On-Road 47 02-24-2012 08:21 AM
Vintage Trans-Am TC hlpressley R/C Items: Wanted to Buy 5 10-23-2008 04:00 PM
Thursday Vintage Trans Am racing at Victory in Green Bay Brian F Wisconsin & Illinois Racing 13 05-10-2008 08:37 AM



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 09:32 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