E-Revo with Twin Force Tranny
 

Well, I blew up a diff in my twin force, so I decided to convert my Revo to brushless while I was waiting for parts. It took around 2-3 hours, and is not real pretty, as I was just seeing if it would work. It worked great, although I am pushing the slipper to the max. The hottest part of truck after a run is the slipper, at around 150. Everything else is cold, as it should be after playing in the snow.:lol:
http://homepage.mac.com/lonewolf039/...o/P1110019.jpg
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I am running the ESC in the Twin Force electrical box, and the temps are usually around 100-120 after a good run.
http://homepage.mac.com/lonewolf039/...o/P1150028.jpg
http://homepage.mac.com/lonewolf039/...o/P1150030.jpg
The battery packs are just zip tied on, I was in a hurry to get it going.:lol:
http://homepage.mac.com/lonewolf039/...o/P1150031.jpg
Stock Revo front drive shaft. Long axle shaft in the rear.
http://homepage.mac.com/lonewolf039/...o/P1150032.jpg

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Tucks up real nice.
http://homepage.mac.com/lonewolf039/...o/P1150034.jpg
I had to space the motor plate up 3/8 inch to get the outputs in the right place. I used some delrin I had kicking around.
http://homepage.mac.com/lonewolf039/...o/P1150036.jpg
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Motor plate and chain drive.
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I am using Revo shafts on my Twin, so the outputs bolted right up.
http://homepage.mac.com/lonewolf039/...o/P1150049.jpg
I enlarged the front part of the frame 1/8 inch on each side to fit the tranny.
http://homepage.mac.com/lonewolf039/...o/P1150050.jpg
The tranny out of the truck. You can see the delrin blocks that everything bolts to.
http://homepage.mac.com/lonewolf039/...o/P1150055.jpg
http://homepage.mac.com/lonewolf039/...o/P1150057.jpg

Overall, I am quit happy with it. It is a little slower than a stock Revo, but a better motor will fix that in a hurry. With the two NiMH packs, all up weight is 10.5 pounds, so a good Lipo pack will also bring that down.

so what are the advantages of doing this?

it looks pretty cool and differnt though

No advantage, the main thing was I had all the parts laying there, and wanted to see if it would work. The Twin Force tranny is quite beefy and simple, it just needs a better slipper.

Looks like a revo slipper could be installed in place of the stock slipper. That should be able to hold up to the power. Is the shaft 5mm in diameter?

The advantage??????? No gears, no second speed, no one way bearing.... just a slipper and a chain:oh: So for me, this system should be wayyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy more solid than the stock revo trany.

I'll gine a chance to my stock revo trany, and if i break it, i put this twin force setup in mine!!!!!!!!!

Oupsss! could you tell me if the twin force slipper gear is 32 pitch or MOD1???
Look like to be 32 pitch:whistle:

Ya, it's 32 pitch, but if converted to a revo slipper, you could use the mod 1 revo gears. If not the revo slipper, you could use an MGT spur gear with the stock slipper, they are mod 1. You just have to slightly ream out the center to fit the stock 10x6 mm bushing.

The shaft is 6 mm, but could be machined down to 5 mm. The main problem is that the revo slipper would move the gear further away from the motor. The chain sprocket already takes up a fair bit of room. Look at this pic, you can see it between the motor and slipper. The revo slipper will take up some room too.
http://homepage.mac.com/lonewolf039/...o/P1150034.jpg

I have been looking hard at it tho. I really want to get a decent slipper for the Twin.

http://homepage.mac.com/lonewolf039/...o/P1150031.jpg

Is it just me, or is this the most compact and tidy layout you've ever seen. That electronics box is perfect, and makes everything so tidy. The tranny is perfectly place low down on the center-line of the chassis, yet doesnt hang out the bottom at all. As for battery trays, I would suggest some like Serum's. Its a shame the slipper is a bit week, but Im sure a fix can be invented for that; other than that its a brilliant piece of conversion work, well done!

Thanks, I like how it turned out. It is very compact. Serum's conversion was one of the ones I really like, and I was going to do the battery trays the same way, but now I am thinking of chopping up the stock chassis and tigging or bolting on some aluminum battery trays.

Well, I fixed the slipper. It all boils down to the fact that I was using a GT2 spur gear, and the slipper pads for the GT2 are pretty slippery. I tried a couple of different materials, and none seemed much better. I went back to the stock Kyosho spur gear and now the slipper is pretty much locked up. I had to back the tension off a fair bit to get any slip. So the moral of the story is that you need the right material for a monster truck slipper pad.:whistle: Now if I could just find some pad material the same as the Kyosho stuff, I can use the GT2 spurs, as they are really easy to get.

Also it looks like I might be able to use Savage X spur gears, once I get some Mod 1 pinions and a decent motor.

thats a nice conversion, as said very compact. I thought there was a one way on the front of the TF

The one way is built into the dogbone cup, so when I converted my twin to the revo shafts, I got rid of it.

I played around with a few gears and the Savage X spur will work, it's just a little big. I had a 49 tooth kicking around. A 46 tooth would work perfect.
http://homepage.mac.com/lonewolf039/...o/P1160022.JPG
http://homepage.mac.com/lonewolf039/...o/P1160023.JPG

Ok, I've got the slipper issue fixed, but now I think I have figured out why the performance is lacking. I ran my whattmeter for a run today, and my ib4200 batteries are way down in performance. When they were new 2 weeks ago, I was getting 72 amp peaks with a voltage of 6.26 volts per pack. Now i just got peaks of 54 amps, and the voltage dips down to 5.6 volts. Total mah was only 3400 until they dumped. They have been taking 4200-4300 mah on charge, so I thought they were doing good, but now I realize they are getting really weak already. I only have 25-30 cycles on these packs. I have a lot of small lipo packs for my 3d planes with over 100 cycles on them with very little performance drop. I got the nimh batts for winter bashing, thinking they would be more durable then lipo in the snow, but I guess I wasted $90 on them. I wonder if taking apart the stick packs and balancing them would help? Anyone know much about these ib4200 cells?:neutral:

how were you charging these?

at how many amps and all that?

I have that same spur in my MBX5T. I also have the steel 48T one. They all work very nice.

I've try to find Twin force parts on the web, but..............NOTHING.
Tower, A Main, flebay, nothing:oh:
I would like to have this twin force chain drive system, but as i can see, any hobby shop have the twin force parts in stock.

I have been charging them on my Triton2 at 4.2 amps using a y adapter to charge both batts at the same time. I am now trying to slow charge them at 1 amp, but the stupid Triton has a 90 minute timeout feature, so I have to keep resetting it.

Hopefully a slow charge will perk them up. If not, maybe individually charging them will help. They are both the same temp after charging at 4.2 amps, so I figured they were charging evenly. They have always been used in a pair, so they should be close.

Sorry, I forgot to mention that Kyosho parts are hard to get. The only place I have seen to order online is Kyosho America, but they only ship within the USA. Here is a link to the Mad/Twin force parts.http://www.shopkyosho.com/index/410....5411.25465.0.0

Are you using your packs hot off the charger? I never found IB4200s to be a stable cell, and 30-50 cycles is all I can ever seem to get out of sub-C anymore. I have started to really dislike anything but lipo lately. It is cheaper in the long run and there are less cells to go bad in a pack!

Yes, I run them hot off the charger. I have been reading up on these 1b4200 cells, and they sound really fragile. Sounds like you are only supposed to run them 1-2 times per day, and even then they are only good for a few races.

I got these so I wouldn't have any worries running in the snow for winter, but now I guess I should have got lipos. I have had really good luck with lipos in my 3d planes, and I run them as hard and often as I can.:lol:

Flightpower, here I come.

2 cycles a day is what I hear too. Anything above about 3700mah in a sub-C jacket is fragile IMO. The nice thing about lipo is that they can just make the cell taller for more mah. No worries about cramming too much in.

OK, I figured out how to reset the safety timer on the Triton charger to 720 minutes, and I did a 1/10 C slow charge last night. I repeaked the batterys at 4.2 amps just before heading out. Performance was the same, run time slightly longer, so the slow charge might have equalized the cells a bit, but didn't restore any voltage. At 1 minute into the run, I got 55.5 amps peak and 11.1 volts minimum, for 616 watts peak. I also got the same numbers at 5 minutes. At 8 minutes, voltage was down to 10.2 volts under load. At 9 minutes the batterys started to dump, 3600 mah used. At 10 minutes, end of run, the lowest voltage recorded was 7.6 volts, 3900 mah used. Performance was rather weak throughout the run.

I ran the numbers through the top speed calculator:

Differential Ratio: 2.8461538461538463
Transmission Ratio: 2.36
Other Ratio: 1
Spur Tooth Count: 54
Pinion Tooth Count: 15
Total Voltage: 11.1
Motor KV: 4400
Tire Diameter (inches): 5.8
Tire Ballooning (inches): 0
Motor Current Draw: 55
Motor coil Ω: 0.0073
Spur/Pinion Ratio: 3.6 : 1
Total Ratio: 24.18092 : 1
Tire Circumference (inches): 18.22 inches (462.82mm)
Total Motor Speed: 47073.4 RPM
Vehicle Speed: 33.59 MPH (53.96km/h)
Effective Speed Rate: 3.03mph/V (4.86kmh/V)
Effective KV Value: 4240.85
Motor Torque: 0.09 ft-lbs
Final Torque: 2.13 ft-lbs

Top speed of 33 mph looked about right. When the batterys were new, the voltage stayed up around 12.5-12.6 under a load of 70+ amps. The higher voltage in the speed calculator puts top speed at 37 mph, which was probably pretty close. Now they can barely put out 50 amps. If I had know how crappy the nimh batts were, I would never have even bothered with them. I really did not think I was abusing them. Oh well, live and learn. I am now charging them at 5 amps, so I'll see if a bit of torture will wake them up. I really don't care if they blow up now.:diablo:

Well, run 2 was a little better. At 1 minute the voltage was 12.82 volts at 54.38 amps. At 5 minutes, voltage was down to 11.84 volts at 55.48 amps. Pack dumped at 3700 mah. So the higher charge current did raise the voltage up for a bit, but these batterys are on their last legs.

Anyways, there haven't been any pics for a while, and I know we all like pictures, so here we go.:party:

http://homepage.mac.com/lonewolf039/...o/P1200027.JPG
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And my highly scientific measuring method:whistle: A whatts up meter in a baggie zip tied on.
http://homepage.mac.com/lonewolf039/...o/P1200049.JPG

I got the battery holders done tonight. Turned out not too bad. I wish the Revo didn't have that hump on one side of the chassis. It makes the one battery stick out 1/4 inch more than the other one. I've been thinking about cutting up a chassis and tigging in some holders that are nice and centered.

http://homepage.mac.com/lonewolf039/...o/P1210002.jpg
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http://homepage.mac.com/lonewolf039/...o/P1210008.jpg
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I see what you mean about the bump, but it does look like like you could 'cut and shut it' to make the trays more sysmetrical. I cant weld myself, the sparks scare me too much.... :oops:

holy clean wireing batman...looks gread dude makes me want some kyosho stuff

wow thats amazing... im pissed that i just ordered my tekno conversion now... wish i had spent the money on that instead. looks awsome. very compact

I actually put the twin force tranny back in the twin, I only wanted to see if it would work. Besides, the twin was broken, and my 3.3 pullstart kept freezing up, and then I boke my carb, so I took 2 broken trucks and made 1 good one.:lol:

Check here for the next phase of the Revo project.
http://www.rc-monster.com/forum/showthread.php?t=9722