# Novak GTB/SS 13.5 Pro Gearing Help - TC3



## jdob (May 5, 2007)

First post here - looking for some help if possible!

I am going to use the Novak GTB/SS 13.5 Pro Combo in my old TC3. My TC3 has 48 Pitch Gears and comes with a 72 Tooth Spur Gear Standard. 

Associated says to use a 28 Tooth Pinion for a Stock 27 Turn Brushed Motor.

Novak says to use 2-3 tooth higher pinion than you would use with a Stock 27 Turn Motor. So that would mean I need a 30 or 31 Tooth Pinion. Does that sound right? That just seems like a HUGE pinion! The 28 Tooth just barely fits with room for adjustment - I almost feel like I am going to have to use a smaller Spur?

Using the Stock 72 Tooth Spur and the 30 or 31 Tooth Pinion my TC3 would have a Final Drive Ratio of 6.0 or 5.81. Does this seem alright? I don't really know anything about using tire diameter to determine rollout - so I can't get into that.

I guess what I want to know is - Can I use my GTB/SS 13.5 Pro Combo in my TC3 with it's 72 Tooth Spur Gear and the 28 or 26 Tooth Pinion that I currently have without doing any DAMAGE? 

Any info is greatly appreciated - Thanks!


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## OvalTrucker (Dec 14, 2003)

You will not damage your car with that gearing.

I don't know much about TC gearing but I'm sure you will be okay with your 72 tooth spur and the 28 or 26 tooth pinions you have. Especially if you are just playing around in your driveway or something. If you are racing, you should ask what the other drivers are running for a rollout and you can make changes from there. I think if you want to go faster, you could get a smaller spur gear and you can still use the pinions you already have to go faster. 

Here's how you figure rollout;

Measure your tire diameter with a caliper. Multiply that number by 3.14. Multiply that number by your spur [72 tooth]. Divide the final number by your pinion.

Simply put; Tire Diameter X 3.14 X Spur / Pinion = ROLLOUT


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## kevinm (Jan 16, 2002)

I ran my TC4FT today with pinions from 30-32 with a 72 tooth spur (with approximately 2.5" tires). I've gone as high as a 34 pinion, but that felt over geared. Try a 32 tooth. (You may have to grind away some of the plastic in the chassis to allow the motor cam to rotate far enough to fit a pinion this big. Or go to a smaller spur.) You certainly won't damage anything geared 28:72 (assuming you don't HIT anything :jest: ), but it probably won't be very fast. The 13.5 motor has a lot of torque, but turns a lot less RPMs than the current crop of brushed stock motors. Assuming you don't unhook the little blue wire, the system will protect itself if you gear too high.


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## kevinm (Jan 16, 2002)

OvalTrucker said:


> Here's how you figure rollout;
> 
> Measure your tire diameter with a caliper. Multiply that number by 3.14. Multiply that number by your spur [72 tooth]. Divide the final number by your pinion.
> 
> Simply put; Tire Diameter X 3.14 X Spur / Pinion = ROLLOUT


I think you meant: Tire Diameter X 3.14 X Pinion / Spur = ROLLOUT, and that's not counting the transmission ratio (2.5 for a TC3). The entire formula is:

Rollout (in./rev) = Tire Dia. x 3.14 x Pinion / Spur / Transmission Ratio

I ended the day at a rollout of 1.38


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## OvalTrucker (Dec 14, 2003)

Oh. Yeah. What he said!


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## Stratus54 (Jul 16, 2005)

At the Novak in the rubber tire 13.5 class we ran FDR in the high 4's.
I think I ran a 36 or 37 tooth pinion on my TC4


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## kevinm (Jan 16, 2002)

If you'd rather not mess with a calculator, use this chart:


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## jdob (May 5, 2007)

Thanks for all of the input guys! I ran today with the 72 Spur and 28 Pinion and everything was good to go - I will try to go a little bigger next time with a 30 or 31, any bigger than that and I think I will have to either convert to 64 pitch or warm up the dremel! Thanks again for the info!


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## viper1 (Aug 14, 2005)

*gearing calculator sites:*

mm's:
http://www.actmcrc.org.au/technical.htm

inches:
http://www.thercshack.com/index.asp?PageAction=Custom&ID=10


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## BullFrog (Sep 24, 2002)

gear it to 5.0-4.50 and it should be okay. Just check the temperture and keep it under 175 degrees.I run rubber tires outdoors with an RDX.


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## kevinm (Jan 16, 2002)

viper1 said:


> http://www.actmcrc.org.au/technical.htm
> 
> you ready for Saturday at H.T.U. Kevin?
> going to be a warm one! :tongue:


Interesting website. The only problem is that it wants tire size to be measured in M&Ms. I can't seem to get the darn things stacked more than 3 high before they fall off. Maybe if I glued them together..... :freak: 

They're predicting temperatures in the high 80's, so I predict that we'll see more "thermals" this weekend. I'll probably regret leaving the same pinion on the motor after switching to a smaller spur gear. Oh well, that's what qualifiers and practice runs are for.


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## sportpak (Dec 23, 2005)

Those 13.5 Pro motors will pull a mountain of gear and not even break a sweat. Run you final drive in the low 5s and you'll be safe. Final drive spur/pinion X int ratio. In your example 72/31 x 2.5 = 5.80 final drive This would be way on the safe side and off the pace. If you can't fit 35 or 36 pinion, then you'll need to drop down in spur size. Changing pitch won't help much because ultimately you still need to change the overall diameters of the gears.


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## DLS II (May 31, 2007)

I don't want to hijack this thread but does anyone know the KV of the Novak 17.5(3417)? Or for that matter gearing it in a TC? Thanks, Don


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## kevinm (Jan 16, 2002)

I swapped out the bonded rotor for a sintered one in my 13.5 motor, didn't change the gear, and it came off the track 40° cooler than the previous weekend. Most of the racers in the 13.5 touring car class at Lazer are running with a final drive ratio between 4.0 and 4.5, but this is with an approx. 160' straightaway, so "your mileage may vary".
Since the 17.5 is (as far as I know) only in limited release to oval racers, I've got no clue on it. Never seen one, but the official number for the 18.5 is 2700, with the 13.5 at 3300?????? Doesn't seem right... And why put one in a Touring car???


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## DLS II (May 31, 2007)

OK I thought the 17.5 was being released as a " limited class" motor. It's on the Novak site at the same price as the 13.5. They say in the writeup as a slower than 27 degree stock or for longer run times. Don


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## kevinm (Jan 16, 2002)

Well, it took me quite a few mouse clicks to find it, but the 17.5 is listed in the "shop Novak" section. It's main purpose in life is for the 4-cell oval racers who were looking for a brushless motor that would run on a 2-cell (7.4V) LiPo battery like a stock brushed motor on 4 NiMh cells.


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## NovakTwo (Feb 8, 2006)

kevinm said:


> Well, it took me quite a few mouse clicks to find it, but the 17.5 is listed in the "shop Novak" section. It's main purpose in life is for the 4-cell oval racers who were looking for a brushless motor that would run on a 2-cell (7.4V) LiPo battery like a stock brushed motor on 4 NiMh cells.


Here is a direct link to the Shopatron page:

Novak Electronics SS17.5 Pro Brushless Motor

No one at Novak has yet measured the Kv for the 17.5T motor, but it would be slightly higher than the 18.5T Crawler motor which is 2700 Kv.

Also, no gearing advice for TC--doubt that anyone considered installing it in a TC.


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## DLS II (May 31, 2007)

OK, thanks. Don


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## AEman69 (Nov 21, 2007)

Well it is also based on your track. If you can hit your top speed i would go smaller lol .


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## AEman69 (Nov 21, 2007)

Well it is also based on your track. If you can hit your top speed i would go smaller lol . :woohoo:


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## jlfx car audio (Nov 11, 2007)

well our track as said to do a 17.5 in the stock tc carpet oval class so i am also interested in knowing something about it


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