Tech Help, Nitro TC3

1 I have a question about the two speed gear set up. The big gear spins freely in one direction and does not go in the other; however, the smaller gear spins in both, and there is a gap. Is this right?

Yes, the 2-speed has a one way bearing in it and that will stop it from spinning in one direction, and the clutch bell gears will spin both ways until the clutch shoes engage. There is a gap between the 2-speed gears of about 1/8th of an inch.

2 The shock tower #2250 keeps coming loose from the diff cover #2368 during the race.

On the shock tower there are 3 screws. One is on the gear side of the case and one is in the middle of the shock tower in the back. Remove those two screws and replace them with ones that are 4-40 x 1/2" (#6925). That will give you more bite into the diff case. The ones that come in the kit are 4-40 x 3/8.

3 What would be a good pinion and spur gear combination so it would be faster off the line other than the stock 22/26 with 54/50?
The bigger the final drive number is the faster acceleration you will get.
To figure out gear ratios:

Spur (2-speed gear) divided by clutch bell gear x trans ratio (2.5) = final drive.
The bigger the number the faster it will take off, the lower the number the more top end it will have.
Ex: 50 divided by 20 x 2.5 = 6.25 (fastest acceleration)
50 divided by 21 x 2.5 = 5.95 (next)
50 divided by 22 x 2.5 = 5.68 (next)

4 What difference would it make by putting the rear shock tower on the front?

It stands the shocks more upright and makes them feel softer.

5 I found a small hole in the top cover at the bottom of a screw hole that is not used by the shock tower and is therefore open to the atmosphere.

You can cover the hole.

6 Can you please advise me on how to choose the best possible servos?

Speed and torque for the steering, and for the throttle, you might look for more on the speed side than the torque for the quick throttle responses.
Some are running the Hitec 645mg in both areas, others are running Airtronics servos #941757, just to give you some ideas of what they are running. (May 2002).

7 What is the internal gear ratio of the NTC3?

The diffs are 2.5 ratio.

8 What are the recommended uses for the one-way and solid axle?
One-way:

Gives more on-power steering with on power 2 wheel braking capability as the one way free spins off power.

Solid Axle:
1. When used in the front, it works like a one way in front while on power, but has 4-wheel braking. It’s used for slippery conditions or for tight tracks with short, straight stretches.
2. Used in the rear, on very high bite tracks it gives excellent acceleration with very good on-power steering, but it is less stable coming out of the turn.
Note:
Using either the one way or solid axle will put more stress on the drive line and makes it easier to damage those parts.

9 What engine works in the NTC3?

Any .12 or .15 non-big block engine, with either slide or rotary carb will work in the kits. The engine has to be either a short crank style or SG crank style.

10 Conversion notes:

If you get a pull start kit--
Side exhaust manifold and pipe are included.
... If you want to use a rear exhaust non pull start engine, you'll need:
#2341 non pull engine mounts ($6.00 pr)
#2322 non pull flywheel ($8.00).

If you get a non pull start kit--
Rear exhaust manifold and pipe are included.
... If you want to use side exhaust pull start engine, you'll need:
#2343 side exhaust manifold ($13.50)
#7730 side exhaust pipe ($21.00).

11 I have a NTC3 with a Trinity Picco XP12s. Stock flywheel collet and included Picco collet do not work. Motor has SG crank.

You will need to contact Trinity/Picco for a collet and flywheel. Their engine crank size is different from most all others in the industry.

13 Will the NTC3 ball suspension work for the TC3?

No.

14 Does the Rally Conversion for the Electric TC3 fit the Nitro TC3?

No.

15 I understand the NTC3 uses different diffs then the TC3. Can we use the parts from the TC3 for a temporary fix?

We suggest using the standard parts in order to be able to adjust the tightness of the diff action. If you use the TC3 parts, the diff will wear out in less then 30 minutes and will not be adjustable.

16 Is there a heavy sway bar available for the rear? I found the need for harder springs in the rear (white) to keep the car settled through the very fast sweeper.

White is probably way too stiff and could be causing part of your problem. Try one rate lower for the entire chassis. Buds Racing makes a .078 sway bar for the rear. We have yet to find a general need for this sway bar but it may help you.

17 Is Associated going to bring out some form of power clutch, as the kit clutch even with harder springs doesn't seem to work very well.

By drilling a 1.5mm hole through each of the clutch shoes (side to side), you will lighten the shoes and simulate a stiffer spring.

18 What's the #7721 tank insert for?

The tank insert is used to decrease the tank volume from 78cc to 75cc, which is required under IFMAR rules in Europe. They accept a fixed insert.

19 I am running the tallest gearing you supply, yet I can't match the top end of many of the other cars.

Try shortening your manifold by 6 to 7mm. That will help to increase your top end performance. You may also be running the engine too rich; monitor the head temperature and lean as needed.

20 How do I convert a pull start to a non-pull start?
If you keep it as a side exhaust you only need to replace the engine mounts and fly wheel.

Engine mount #1710 and flywheel #2322.
But if you are changing engines to a rear exhaust you will also need a new header and muffler.
#2350 header and pipe #2353.

21 What combo of pinion and spur gears can be used in the 2 speed to have the right gear mesh?

21/25 with 54/50
22/26 with 54/50 (stock in kit)
23/27 with 54/50
20/26 with 54/48
21/27 with 54/48

There are more pinion/spur gear combinations with the right mesh. They are:
20/22 with 52/50
21/23 with 52/50
22/24 with 52/50
23/25 with 52/50
24/26 with 52/50
25/27with 52/50
But these have less difference in speed and acceleration than the others earlier posted. This kind of combination could be very useful in small and tight tracks, where you usually run your car with single speed gearbox instead of a two-speed gearbox.

22 Since the engine is reversed on the chassis, when I turn my starter box wheel sideways, do I have to reverse the polarity as well? e.g. If it was an old Mugen prime 12, I would turn the starter wheel 90 degrees, so what exactly do I do with my new NTC3?

You will need for the bump wheel to turn from left to right when activated.

23 Could you tell me the internal dimensions of the "Nitro TC3 Single Speed 26T clutch bell" where the clutch shoes go, both depth and width? Also the size bearing it takes and if it's 32pitch or not?

Width is 1.11" and depth is 3.72." Bearings: 5x10x4 and 5x9x3 flanged. The gears are 32 pitch.

24 What size are the tires and wheels on the NTC3?

The tires and wheels are 24 mm.

25 What NTC3 RTR upgrades are recommended to handle the power of an .18 engine that I am planning to install?

Since we recommend only up to .15 size engines, we can’t advise you on this.

26 Why isn't the industry-standard Centax-style clutch standard on the NTC3, especially the FT version?

At the time the Ft NTC3 was planned, our race team preferred the conventional style clutch design that as of 2004-5 is sold in the FT kit. Since then, many aspects of 1:10 nitro racing has changed, including much more powerful engines. Until recently, many of the Centax-style clutches were much too heavy for a typical .12-size racing engine. They were actually .21-size engine clutch parts used on .12 engines, which provided easy adjustments, but lower on-track performance. Now there are some scaled-down version of these clutches available and this has given us a good reason to consider this for the future. Cliff

27 I'm having a tough time finding instructions on how to remove the NTC3 carb restrictor.

1. Remove tie wraps from around air filter boot.
2. Remove air filter boot.
3. Remove carb restrictor by using a small flat blade screwdriver (put the blade between the metal of the carb and the base of the restrictor and pop it out).
4. Once you have it out you MUST to reset your idle first and THEN reset you low-end needle.

28 What is the difference between torque and RPM when it comes to pipe selection?

Torque equals more acceleration and RPM equals more top end power.

29 Does the NTC3 factory aluminum screw kit replace every screw on the car, or just the undercarriage ones?

It does not include every screw. Only certain screws are designed to be replaced by the aluminum screws. screw_locations

30 What is caster and how do I control it?

Changing your castor blocks on the car changes caster. More castor tends to give more steering entering corners and less coming off the corner. The exact opposite will be true for less castor.

31 I'm having a problem with my front one way diff. It is causing either my left or right back wheel to spin out on any corner under braking.

When you brake using a one-way diff you will spin out. The front wheels will continue to spin while the rears lock up. You are going to have to learn how to roll the car through the corners. If you find that you need brakes then a one-way should not be used on that particular track.

32 NTC3 #2031 ver.2: Revelation Raceway is such a high bite track with no wheel spin, and the stock engine clutch shoes seem to burn and glaze over. Is there an upgrade to the engine clutch shoes material?

Try the heavier clutch springs #2307. they are stiffer and are more suited for the stock engine.

33 What can I do to get my NTC3 transmission to shift into second gear... It shift from first but not into second...the engine just revs.

Back the two speed adjustment screws out farther, ¼ of a turn at a time. Also check and remove any grease or oil from the inside of the clutch bell.

34 What are the benefits of converting the .15 to non-pullstart using the AE parts listed?

If you convert to non-pull start AND get the non-pull start engine mounts, you'll gain an important racing advantage: your engine will be lower and weigh less.

35 What more can I do to my car to get the most out of it? My tuning skills are improving.

We produced a tuning guide eBook and video CD-ROM on how to tune the NTC3. All our recommendations are compiled there. Check them out here: tuning_guides.htm

36 At idle the car spits a lot of gas out of the pipe compared 2 other cars.

The excess fuel spitting out of the pipe is normal. You will need to lean the high-speed needle out. Please follow the directions in the manual for the proper procedure on setting your carburetor.

37 When it spins out or does donuts it stalls out.

Check that your clutch shoes are not sticking to the clutch bell and that the springs are in good condition with plenty of tension.

38 How many turns out should my 2 speed adjustment screws be? What is a good starting point?

NTC3 manual, page 6: "tighten the screws gently until they are fully compressed. Now, turn each screw 3 1/2 turns counter clockwise. Adjust both screws equally."

39 I put a OS cvrx 18 on my car. now it just spins out when i jump on the throttle.

It sounds like it probably has too much power. You need to learn how to roll on the throttle and not pull it all at once.

40 Is the part that opens and closes when given gas inside the carb supposed to slide from side to side?

It should not slide from side to side. The idle adjustment screw is backed out too far. Please screw the idle screw in so that the screw is properly seated in the groove that is on the barrel.

41 What would be needed to convert the old 2 speed transmission to the Sure Shift transmission?

You will need part number #2290 and 2292.

42 Is there is a trick to installing and removing those roll pins?

A pair of needle nose pliers seems to work best.

43 When I run my car it shift fine but when you stop or slow way down it goes into neutral or some thing wont grab a gear again till RPMs come way down

Check to make sure that both two-speed adjustment screws are adjusted exactly the same. Also, it sounds as if your idle is slightly too high. Lower the idle slightly (adjust needles accordingly) and please try again.

44 Does NTC3 have a slipper clutch?

No it does not.

45 Can #31123, Factory Team VCS2 Shock Upgrade Kit, be used on the NTC3?

Yes, the NTC3 uses VCS shocks.

46 What can I do to reach a higher top speed and get more acceleration without changing the engine?

You can't get more top end speed and more acceleration at the same time. Pick one. Make the change by swapping clutch bells. For more top end and less acceleration, get a clutch bell with more teeth. For more acceleration and less top end, get a clutch bell with fewer teeth.

47 On the version II rear suspension, what is the lower shock hole on the lower a-arm used for? No reference in the manual

It is there because the arms can be used on the right or left side. So if you flip the arm for the other side the bottom hole now is the top hole.

48 I was sitting here studying the 2 speed set up and I am curious as to how this actually works. if both gears are on the bell crank they would turn the same speed all the time. can you please give a description of operation that I could understand? Thanks

OK real briefly: the gears (pinions) on the clutch bell spin at the same speed but the gears (spurs) on the two-speed shaft spin at different speeds. The first gear drives the shaft while the second gear will spin faster on a regular ball bearing independent of the shaft. Then when the two speed kicks in the shaft is driven by the second gear and the first gear is able to spin slower due to its one-way bearing.

49 I'm having a hard time looking for the right size wrench for the lock nuts for FTNTC3, they are much bigger than the standard size, any idea?

The wrench size that you are looking for is 11/32", or our green nut driver.

50 I was wondering what differences exist between the NTC3 V1 and V2 and what assemblies I would need to get to fully upgrade my V1 to a V2.

The part number for the suspension upgrade is #2319. The upgrade changes the rear suspension for easier set up, improved handling, and improved durability.

51 Can I upgrade the NTC3 with the .12 engine and single speed transmission to two speed?

Yes, you can. The part number is #2285, NTC3 Two Speed Kit. article

52 What's the difference between a slide carburetor and a rotary carburetor? How do you convert between the two on the NTC3 RTR?

The slide carb is more responsive. You can use either on your car by simply rearranging the linkage.

53 I want to know what gear ratio for speed? Do you gear the NTC3 low or high?

This page from our #2382 Tuning Guide: NTC3 should help: ntc3_gearing

54 The Traxxas TRX 2.5R and TRX 3.3 with multi-shaft cranks do fit in the NTC3.
I have been running the 2.5R in club pull start races for a year now without problems.
I would not recommend the TRX 3.3, because it destroyed the two speed and the front diff in less than a tank.

Thanks for the info!

55 Will the LRP Z18S Pro fit in the NTC3?

Yes.

56 Why is that my NTC3's rear tires wear faster than the front tires?

Because the balance of the car is not optimal. Your front tires have more grip than the rears. The front tires stay in contact with the ground wearing at a slow rate while the rear tires are sliding back and fourth along the ground which wears them out quicker. Try using a harder front oil/spring combination or go to a slightly harder compound front tire.

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