Nitro 4-Tec conversion

[lincpimp]

So I acquired a Nitro 4-Tec for a guy who had tried to convert it...

All I can say is that it is not pretty. Needs belts, he mangled most of the uper deck parts trying to make room for the battery, and his wiring must be seen to be believed...

So I tore most of it apart, replaced the steering servo, and had a look at what I could do. The car came with a mm/5700 combo, and he was running it with a maxamps 6300, 3s lipo, 9 2100 cells in a 3s3p config. With the stock gearing of 1st gear 15/45, and 2nd gear 19/41, it was good for over 100mph on paper... It could not pull the gearing, and stay cool, needless to say.

You have to admire someone who takes a 5" fan and mounts it to the body to keep temps down. The only cool thing he did was have the local machinist make some adapters to screww the stock pinions on, and mount directly to the cc 5700 1/8 shaft. Pitty that I will not be using that adapter.

I did some measurement, and found that the tekno motor mount will fit great with only minor mods to the chassis. I am talking about this mount. This will give me room to run the electric clutch adapter and use the stock 4 tec clutch bell and 2 speed. I am going to run the clutch, mainly due to the very high gearing. No tranny reduction to speak of. It has a 1.7 diff ratio, and the mentioned 1st and 2nd primary gearing. So the spool up the clutch offers will allow the vehicle to start better than it currently does. Hoping it will keep some of the heat down...

Now the maxamps lipo has a bad cell, so I plan to make a 6300 2s lipo. That will give me a little over 42k rpm with the 5700kv motor. Gearing is high but I hope it will work!

I will use the mech brakes, so no reverse. I just plan to drift and so some speed runs with the car, so that is ok with me.

Heres both ratios plugged into BG's calc:

1st

Differential Ratio: 1.7
Transmission Ratio: 1
Other Ratio: 1
Spur Tooth Count: 45
Pinion Tooth Count: 15
Total Voltage: 7.4
Motor KV: 5700
Tire Diameter (inches): 2.5
Tire Ballooning (inches): 0
Motor Current Draw: 0
Motor coil Ω: 0
Spur/Pinion Ratio: 3 : 1
Total Ratio: 5.1 : 1
Tire Circumference (inches): 7.85 inches (199.49 mm)
Total Motor Speed: 42180 RPM
Vehicle Speed: 61.51 mph (98.81 km/h)
Estimated Adjusted Speed: 56 mph (91 km/h) - 8% loss


2nd

Differential Ratio: 1.7
Transmission Ratio: 1
Other Ratio: 1
Spur Tooth Count: 41
Pinion Tooth Count: 19
Total Voltage: 7.4
Motor KV: 5700
Tire Diameter (inches): 2.5
Tire Ballooning (inches): 0
Motor Current Draw: 0
Motor coil Ω: 0
Spur/Pinion Ratio: 2.16 : 1
Total Ratio: 3.66842 : 1
Tire Circumference (inches): 7.85 inches (199.49 mm)
Total Motor Speed: 42180 RPM
Vehicle Speed: 85.52 mph (137.37 km/h)
Estimated Adjusted Speed: 75 mph (121 km/h) - 12% loss

I should have all the parts together at the end of the week. I got a ton of spares from this guy for a great price, so no comlaints from me.

[lincpimp]

1st question for you guys: any point running an external bec on the MM with only 2s lipo? From what I have read, the Bec inside of the MM will not put out much heat on 2s. I will be running 2 servos, a 2070 for steering, and a 2055 on brakes. Not sure if that will over tax the internal bec.

I would think it would be more cost effective to just run an electric tc. there is only about a million. + its not like the 4tec is known for the most durable racing platform.

[TDC57]

sounds like a great project lincpimp.. those 4 tec are really COOL.. post some pictures of it when your able..

have a great one

Shaun.

[lincpimp]

Originally Posted by dubkatz

I would think it would be more cost effective to just run an electric tc. there is only about a million. + its not like the 4tec is known for the most durable racing platform.

Good point, I have a TC3 and a couple of tt-1 tamiyas. I am only fooling with the 4-tec because I got it with a bunch of stuff. Plus the fact it has a 2 speed and high gearing make it easy to do, and I have almost all of the parts.

To make a long story short, a guy that used to frequent the lhs went to jail and recently got out. He needed to sell his r/c stuff for family purposes, so I helped him out and bought it.

Originally Posted by TDC57

sounds like a great project lincpimp.. those 4 tec are really COOL.. post some pictures of it when your able..

have a great one

Shaun.

Thanks Shaun, I will take some pics tomorrow and post them up. I will also try to document the build a bit better than usual, as there do not appear to be too many 4-tec conversions.

[TexasSP]

I am looking forward to seeing this simply because as you said not many are done.

Originally Posted by dubkatz

I would think it would be more cost effective to just run an electric tc. there is only about a million. + its not like the 4tec is known for the most durable racing platform.

That is just not the lincpimp way to follow what everyone else does. Also, as he will not be racing I don't see any real problems. It should be a fairly sturdy platform and a lot of fun when completed.

Great project linc, can't wait to see pics!

[bl-is-future]

them 4tecs are fast in nitro form so bl should be insane if done right. Cant wait to see this one done.

[lincpimp]

Originally Posted by TexasSP

I am looking forward to seeing this simply because as you said not many are done.

That is just not the lincpimp way to follow what everyone else does. Also, as he will not be racing I don't see any real problems. It should be a fairly sturdy platform and a lot of fun when completed.

Great project linc, can't wait to see pics!

Thanks Texas, I have wanted to do one for a while, but always had an electric tc to play with so I never really got around to it. The 4-tec seems very simple and sturdy. plus I have a ton of spares. I like the al chassis, but not too fond of the belt drive. It will be on road only so it should be fine.

Originally Posted by bl-is-future

them 4tecs are fast in nitro form so bl should be insane if done right. Cant wait to see this one done.

Yep, the 4-tec gearing and 2 speed should allow for some serious speed. I have had issues with the electric tc trying to find small spurs and large pinions. That will not be an issue with this one. It is geared stock to do around 70mph with a nitro engine that can maybe do 35k rpm. I am aiming for about 42k rpm with the cc motor.

[BL_RV0]

Can't wait to see pics! Hope that CC motor doesn't have heating problems. I had a 5700 in a Rustler that I only ran onroad, lowered suspension, buggy foams.... The motor got to 295* on 3s with 20/86 gearing.

[lincpimp]

Originally Posted by BL_RV0

Can't wait to see pics! Hope that CC motor doesn't have heating problems. I had a 5700 in a Rustler that I only ran onroad, lowered suspension, buggy foams.... The motor got to 295* on 3s with 20/86 gearing.

We shall see, if it does run too hot, I have a l can size aveox motor that is 2500kv. I can run it on 4s lipo. That motor should have plenty of power. Hopefully the motor mount and the al chassis will act as a good heatsink to draw the heat away...

[brushlessboy16]

Originally Posted by lincpimp

We shall see, if it does run too hot, I have a l can size aveox motor that is 2500kv. I can run it on 4s lipo. That motor should have plenty of power. Hopefully the motor mount and the al chassis will act as a good heatsink to draw the heat away...

It should, one thing though the whole car sounds the signal tone of the MM, with my outrunner and mount bolted righ to the chassis the motor vibrates the whole car so they whole car talks

[brushlessboy16]

lookin good!

[lincpimp]

Originally Posted by brushlessboy16

lookin good!

Thanks, it will look alot better when I get rid of the butchered parts...

[brushlessboy16]

well yeah...
lol always

[TexasSP]

Minus the hack job conversion I think it will look nice. A couple of years ago I looked at doing one because I had a chance to get a 4tec for cheap. I actually designed my own chassis but in the end did not buy it. I think it's a great platform simply because it's so rugged.