Nitro 4-Tec conversion
 

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.

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.

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.

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.

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.

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!

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

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.

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.

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. :surprised:

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:lol:

Time for some pics. Here is the car mocked up with the parts I currently have. I have ordered most of the rest of the parts, and will hit up the lhs when they open tomorrow and see what they have.

http://i206.photobucket.com/albums/b...p/DSCF2283.jpg

http://i206.photobucket.com/albums/b...p/DSCF2284.jpg

http://i206.photobucket.com/albums/b...p/DSCF2285.jpg

http://i206.photobucket.com/albums/b...p/DSCF2286.jpg

lookin good!

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

well yeah...
lol always

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.

That 2 speed setup looks trick, when / what speeds does it kick in at, or is that your 3rd channel (?)..

Looking forward to see it run..

Good luck (not that you need it)..

It is an auto shifter, has a one way braing on the first gear, and a rpm based clutch on the second speed. Std traxass 2 speed in design, just outside of the case!

Thanks, I need all the luck I can get!!!

Got the motor mount today from impakt. The CC motor will not work as it has small screws that hold the endbells on, and they stick out the sides, effectively making the motor larger than 36mm in diameter. I tried a few feigao and hacker motors and they fit fine, will try out my 2500kv aveox and see how it does. If it fits I will run it on 4s lipo, instead of 2s with the cc 5700. Still need to mock up the chassis, and build the clutch.

http://i206.photobucket.com/albums/b...p/DSCF2300.jpg

http://i206.photobucket.com/albums/b...p/DSCF2299.jpg

http://i206.photobucket.com/albums/b...p/DSCF2298.jpg

http://i206.photobucket.com/albums/b...p/DSCF2297.jpg

looking good!

Those mounts look very nice, I definitely want to keep them in mind for the future.

Thanks!

Bad News
 

So I mocked the car up with the tekno mount, and it does not allow enough clearance between the side of the mount and the brake disk. Need to be able to move it over about 1/4 inch to get the gears to mesh.

Also, it raises the motor too high, making the clutch contact with the plastic "bridge" that is attached to the front tranny bulk. So it looks like I will be making my own mount, and using the 5700 motor after all. The tekno mount is nice, and I am sure that i will find another use for it.

I still intend to use the tekno clutch adapter and the stock clutch assembly. My motor mount must allow the motor to sit directly on the chassis, for clearance of the clutch. I will most likely use an l bracket mount that has the center of the base removed so that the motor can sit as low as possible. I will tap it to accept the stock nitro mount screws, and adjust it via the slots on the chassis.

Most likely will not get to that till the weekend, and I am still waiting on some parts from tower.

Man that sucks, i was hoping to see this thing run by this week. Anywho, keep up the good work. I'm sure you will figure everything out.

Yeah, me too. I have the mount design in my head, and just need to free up some time to make it and test it. It is very simple, you will most likely laugh when you see it...

I would make the battery tray, but I always do that last, after I have everything else mounted, and sometimes I even wait till I have tested the setup. You may notice that some of my vehicle have cool ziptie battery mounts:party:

Yeah too bad you couldn't use the Tekno mount. I'm gonna keep an eye on this thread because I've wanted to build a 4-Tec for a while. I'm just a fan of belt-driven things; less noise, better efficiency.

I am the opposite, and will most likely sell the car when I am finished the conversion... (note that I did not say that I like "shafts":whistle:)

If rolling resistance is anything to go by, my tamiya tt-01 has almost no drag, especially compared to this belt car. Not really a problem, as brushless has plenty of power. I am changing all of the belts, and checking all of the bearings, so it will be better than when I got it. He did have the mesh set too tight, and the primary gears had seen better days, tghat may have accounted for the drag...

Does anyone know if soaking the belts in wd-40 is a good idea before installing them? I read to do that in a mag a while ago...

You could try using light-weight shock oil on the belts, silicone is very slippery stuff. If you're replacing the bearings you may want to consider ceramics. Especially if you're going to sell it afterwards, you can ask a bit more, since they're still an exotic commodity in RC. Then there's that rediculous performance increase as well...

NONONNONONONONo!!!! It softens the compound of the rubber.. that would be bad for the cogs..


using wd is an onld drag racing trick, throw some on the tires and go do your burn out, tires come out clean and sticky

Thanks, I will just throw them on as is. Does traxxas have any spec on how tight the belts should be? They must need to be setup with some sort of deflection when pushed...

my Rustler has ziptie battery mounts also...you do what you gotta do.....

between zip ties and duct tape you can fix the world. (at least for a little while)

Looks to be another sweet conversion linc. Good luck!

Thanks TD, I hope I have some time this weekend to fool with it...

Got all of the parts at hand now. I think my first plan is to assemble it and get the belts setup correclty, and check for any drivetrain drag. Than I can make the motor mount and install everything.

I am still debating if I should go with the clutch or not. I have a feeling I will give the clutch a try, if only to help the motor overcome the high gearing.

Going to try the 5700 on 2s first. Simplest wiring, and I have it all handy.

Just curious Pimplinc, does that Tekno motor mount attach into the adjustable engine mount slots? If so it would be great for any nitro conversion.

I does use m4 bolts, and the mount points are 32mm square. So it may fit some chassis...

parts car only 85 bux
http://www.rcuniverse.com/market/item.cfm?itemId=413192