T maxx hv conversion
 

Ok, here is my latest project (yeah, like I need another project!)

Have a ton of maxx parts and brushless stuff and want to go Hv with it. So here is my planned setup. Std t maxx chassis with a revo tranny, proline bellcrank steering, 4wd thru some hybrid bulks (maybe), and an interesting powerplant!

I have a feigao 20xl (835kv) and a pair of 2200mah 20c 5s lipos. So figuring 10s lipo thru the motor should get it spinning around 30k rpm. Gear it about 20/40 and leave the 2 speed intact in the revo tranny. Forward only so no reverse servo. Keep the mech brakes too. Thinking of using the great planes hv esc that recently came out with a pixstix adapter.

ESC: http://www3.towerhobbies.com/cgi-bin...?&I=LXRDH3&P=7

So, what do you guys think, worth a damn? Keep in mind I have everything except the esc and a few small parts (not much missing).

got my attention. sounds like a cheap build to complete too so bonas.

If you've got the parts laying around, then why not build it- use it as a test mule for all kinda of crazy setups.

My only issues will be battery mounts, but I think I have that figured out. I am thinking that a modded RCM revo mount will be used as the motor mount. Last time I did a brushless t maxx my mount was the part I did not like, so the revo mount should be better. I was going to use the 20xl in a xfactor based crawler, but I want to try some high voltage setups and I think this will be badass! I also have enought 20c 2100mah cells to do a 12s 2100mah batttery config, but that may be a bit much!:wink:

Hm. How about using this for an ESC?

https://www.unitedhobbies.com/UNITED...idProduct=4691

Not that you'd need 100A at 12S, but the price is right. :) Should be a pretty cool build. A 20XL with that kind of voltage should just give you oodles of runtime.

Man, oodles is the coolest word ever, except for maybe weasel. :)

Sleeb

Yeah, I was thinking of that one at first but then found the great planes one and figured that I would give it a try and let you guys know how it worked, just in case anyone else wanted one!


That is hilarious:yipi:

Weasel is a cool word, wonder how they came up with that word? 2 guys sitting in the woods, one says "hey what is that thing over there?" other guy "dunno looks like a rabbit?" , "thats not a rabbit!" "well, watch wanna call it then?" "How bout a weasel?" "Ok, dude that is a cool word, weasel!" "I know!" We can only guess that is how it came about.

What I wanna know is, Who was the first guy that seen a Calf getting Milk from the Mamma cow, and thought there MIGHT be something good to drink in there? :lol:

Good point, I think his brother thought that eating fish eggs (caviar) was a good idea. Probably something wrong with the whole family!

Update time!
 

Ok got some work done on the chassis today. I have decided to use my spare bombproof torpedo chassis braces. I mated them to a stock tmaxx chassis and made an extension for the rear. I used 6061 al plate and al u channel to make the extension/brace. It added 5.5cm to the length of the stock chassis. Transmission is a tmaxx 3.3 case with revo internals (thanks arct1k). I installed a wide ratio 2nd gear. Steering is a proline setup. Skids, bulks, and towers are all stock, had them laying around! Heres the pics:

http://i206.photobucket.com/albums/b...p/DSCF1778.jpg
http://i206.photobucket.com/albums/b...p/DSCF1779.jpg
http://i206.photobucket.com/albums/b...p/DSCF1780.jpg
http://i206.photobucket.com/albums/b...p/DSCF1781.jpg

Time to do the diffs! I am going to adapt a set of aftershock/lst diffs to the maxx bulkheads. Got the idea from another member here that used muggy diffs (same thing). Found a 1/2' pvc coupler that fits into the bulks well. It is tapered so that it will not be able to come out of the bulk. I need to enlarge the inside diameter to match the aftershock case, and cut the coupler to length so that it takes up the slack between the diff and bulk, as there is a small amount of play. I will also enlarge the inside of the front diff support (stock traxxas part) so that it fits the nose of the diff case. Heres a few pics, including the motor on mike's revo mount and my 2 5s batteries. Yes that is masking tape, I made the packs myself and prefer to use tape over shrink. I may clear shrink over this for even more protection.

http://i206.photobucket.com/albums/b...p/DSCF1782.jpg
http://i206.photobucket.com/albums/b...p/DSCF1783.jpg
http://i206.photobucket.com/albums/b...p/DSCF1784.jpg

Just finished installing the rear diff. Not really diffincult, just time consuming. The pics below should give you an idea of how it was done. Had to cut the pvc coupler to the correct lenght and press it into the bulk by hand. When you have the size correct, enlarge the inside diameter to fit the aftershock diff case. Also make sure that a revo driveshaft can fit thru the outside with some slack, as it will sit inside the pvc slightly. Then when it is in there trim the excess that sticks out flush with the bulk. You will have to cut the notch that is used for access to the driveshaft pin, but it is easy with a hobby knife. The front support has to be ground out on the inside to fit the nose of the aftershock diff case. And it will have to be notched to clear the diff case screws. Lots of test fitting involved, but I did it right the first time, with no redos.

http://i206.photobucket.com/albums/b...p/DSCF1785.jpg
http://i206.photobucket.com/albums/b...p/DSCF1788.jpg
http://i206.photobucket.com/albums/b...p/DSCF1787.jpg

hahaha sweet man! and I love the extended chassis braces!

Its all your fault. Now that my maxx has beefy diffs I can finish it up! I have about 4 other maxx trucks that may get the diff mod too!

Keep up the good work Linc! :yes:

I may be following in your footsteps on this one really soon.

What gear ratio are those diffs? If I recall correctly, they use the 43 tooth spur and are 1/8 size. :yes:

Will the spiral 43 tooth ring and 10 tooth pinion fit these?

Looks like a 8mm pinion shaft with 6mm output shafts. :yes:

Thanks Sike!

The diffs have 43/13 gears, and I see no reason why the hb truggy gears would not work. I have a spare hb diff somewhere I will try it out in the case (factory al cases cost 10 bucks each!).

The 6mm outputs are mike's output adapters. I will run the new emaxx driveshafts you are sending me! pinion is 8mm and I will run a set of mike's adapters to hook up revo sliders as center driveshafts.

The chassis will need to be clearanced so that the rear driveshaft will fit. I may be out of luck with the revo motor mount. I may have to make a different lower mount that will clear the driveshaft. I will take a pic of my proposed setup and we see what it looks like.

Yes would you Please check to see if they fit for me? I would really appreciate that. That's amazingly cheap on the cases. Did you get these from Ebay?

You know what this makes me wonder about don't ya? Could there be an affordable way to create a Direct Drive to Diff E maxx? :surprised:

Now that I have some motor winding "eduamacation" under my belt, I wonder if it would be possible to use a smaller diameter outrunner that would fit between the frame rails? There is only 45mm there to work with.

Smaller Diameter means less torque but higher kv when it comes to outrunners. but the Wye wind termination can be used to make up for that. :yes:

Lets see, I got the diffs complete unused on ebay for 20 each. Losi al diff cases are 10 bucks IIRC, brand new from horizon or the lhs. I do not think that the al cases are needed on a maxx, but we will see The diff case is a superior design to the maxx case anyway.

If I can find a machinist who works with plastic i may have some adapters made up, that way the diff would be a drop in, and with mikes input and output adapters a complete setup. The plastic adapters would not cost much to make, a lathe would most likely be the only tool needed. Maybe a mill to make the pinion support? They could be plastic or al, depending on what people want.

LOL I have the same idea trying to get a price on making the adapter out of aluminum, ill let you guys know if I do make a run of these for parts.

Oh and sikes the muggy diffs are 11/45

An aluminum Adapter would be a good idea.

I was thinking I seen a 46 tooth ring somewhere.

A 10/46 setup would be something good to work with.

Did a little work today, got the front diff installed and am looking forward to the mail tomorrow as it has the diff output shafts, adapters for the 8mm pinions to use revo shafts, and a set of driveshafts. If all goes well tomorrow evening I should have a complete roller. I am thinking of flipping the chassis over so that the batteries trays will fit flush, right now the chassis bends up slightly on the sides, and that is where the edge of the battery trays will be.

you ever thought about a planetary gear box on both ends?

http://img.diytrade.com/cdimg/85838/...1129176311.jpg

ive been trying to read up on some.

Thats an idea that hasne been discussed much, but is worth looking at. feigao sell strong planetary reduction gearboxes that are a direct fit for any normal sized motor with a 25mm mounting pattern.

***update***
 

Spent a few hours on the tmaxx today and basically have a roller now:yipi:

Anyway, I have flipped the chassis over for better battery tray mounting, extended the chassis cutouts to make room for the revo center driveshafts. I used the really short revo 2.5 center shaft as the front driveshaft, and used a stock length wheel driveshaft for the rear center. I also modded the aftershock diffs to accept the rcm diff output adapters (drop in fit with the diffs) and the 8mm rcm driveshaft yoke for the diff pinion (required a little grinding for a perfect fit). Then assembled the arms and revo bearing carriers, using revo driveshafts. I also installed a set of blue ofna 17mm hubs.

Next up is to fabricate a set of battery trays (easy) and a motor mount platform (not so easy). I would like to use the rcm revo motor mount, and I have one and have been very happy with its performance and design so far. The only issue is that it may contact the rear center driveshaft, so I need to raise the base of the motor mount, while still retaining a solid mount. I am thinking some sort of bridge actoss the rear chassis cutout, and attaching the revo mount to that. I do not want to add too much weight, so I may make a new lower portion of the revo mount to bridge tha gap.

Heres some pics:

http://i206.photobucket.com/albums/b...p/DSCF1817.jpg
http://i206.photobucket.com/albums/b...p/DSCF1818.jpg
http://i206.photobucket.com/albums/b...p/DSCF1819.jpg

Now for a QUESTION: Does anyone know what linkages to use for steering and rear toe rods, as the tmaxx ones I have are too short. Do I need to buy revo links?

You need T/E-Maxx 3.3 ones. Revo won't work I don't think.

Linc, This is going to be an Awesome Conversion! :yes:

Is that the modded 1/8th diffs I see peeking out from in between those bulkheads?

Yep, did some research and found the part#s that i need. Should be 5141 5143 5347 and 5355. That covers the two different length rods and the pivot ball/spacers.

Thanks Sike, just need to make up a motor mount and battery trays and it should be ready to roll. I will try to get the steering and brake servos hooked up tomorrow, and maybe the bumpers, etc. I just ordered all 8 shocks, 28 bucks inc s/h from fleabay! And I should have the esc and prog card next wed. This project may come together sooner than I planned!

And yes, those are the aftershock diffs hanging out in the stock maxx bulks. This drivetrain looks very solid! Hope it can hold up to the 20xl on 10s!

What kind of shocks did you get?

Just the stock grey 3.3 ones. I have had very good luck with the stock shocks on the maxx. I only bash, and my driving skill is good enough that I rarely ever break anything. If I do anything I may add the al shock caps that traxxas sells. That said I knocked the lower front arm of the crt.5 tonight, but I was driving blind in the dark!

I do believe we have some things in common. LOL

I got so anxious to play with my Revo the other night but it was dark.

I have a quantity of those 9 LED flashlights. You know the ones that take the 3 AAA cells?

I strapped two of those flashlights to the front bumper bracket and made headlights. :lol:

It worked. I was able to enjoy my run and have my fun for the day. Was probably freaking the neighbors out a little though. LOL

I have a few of those. We actually took on and strapped it to my mini lst (crap by the way) and slowly drove it around the vacant lot across the street. A bunch of people saw the light moving around and could not figure out what it was. I was hiding behind a bush, so they did not see me. Great fun, especially when one person went after it, good thing it was brushless, and good for 30mph, or he may have caught it!

Any Progress as of late?

I'm a little curious as to how well those diffs are going to hold up.

I am still waiting on the brake components (linkage, and pad parts) to finish that up. I had the parts for the yusa on road project show up, so I put my attention towards finishing that. I still need to make the motor mount for the tmaxx and the battery tray, but a sunday should take care of that. Work has also been kicking my butt as we are very busy, and it is raining. After looking at the diffs I am confident that they will hold up with no issues. The cas design is better than the emaxx in that if it tries to spread apart, the pinion to ring gear mesh will not alter. The case is split horizontally, not vertically like the emaxx cases.

Another Update
 

Ok, got a chance today to do some more work on the ol' tmaxx. I made a chassis plate to mount the rcm revo motor mount to. Used a piece of t6 6061 and drilled and tapped it. It mounts to the chassis with screws from underneath and the revo mount bolts to it from the top. It seems very sturdy so I am sure it will be ok. I also picked up a 3.3 tmaxx radio box. It mount in the stock location and just misses the brake pads, I guess the chassis is not symetrical and flipping it over made some difference. The radio box looks big enough to get my receiver and the cc bec in, which should tidy up the chassis alot.

http://i206.photobucket.com/albums/b...p/DSCF1825.jpg
http://i206.photobucket.com/albums/b...p/DSCF1826.jpg
http://i206.photobucket.com/albums/b...p/DSCF1828.jpg

This looks GREAT Linc! :yes:

Is that a 6XL?

Nope, it is a 20xl! I found it on ebay and paid 50 bucks, brand new. 834 kv, so it should run about 30k rpm on 10s lipo. I also got my Great Planes 60HV esc and prog card in. It looks well made and even comes with a deans connector already soldered on! The card gives some decent options, like timing and freq, plus cutoff voltage and motor reverse, which is handy caus e I like to hard wire and it can be a pain if you have to desolder two wires and swap them to ge the truck going the right way. I have given up on connectors for mtor to esc wiring, they just seem to cause alot of problems!

The 5mm connectors are pretty beefy. I've never had any issues with them.

That's a great looking setup. Very impressive on the motor. Are you planning on adding some cooling to it?

I want a 20XL also... I couldn't find them on ebay... you lucky guy...

I have only ever seen this one 20xl motor for sale.

I would personally like to see any of the xl motors above the 14xl. They look like a great alternative to the higher end motors. I have had great success with the lower kv l can motors on 5s and higher. I can only imagine how well the lower kv xl motors will work. It seems like their design and constuction shortcomings are amplified less by higher voltage. I am guessing they work better with less current running through them.

Sike, I will use a rc monster heatsink/clamp on the motor, I have a feeling that will do enough.

Oh, and about those connectors. I have decided to just hard wire my motors. I have plenty of motors and speed controllers so I just hardwire them up and they work better, or at least they do not develop problems later on. Had too many issues with the 4mm connectors, and the 5.5mm connectors are too big, and look funny, just my asthetic side talking there!

bumpy, hows this project coming along man?