gearheadwilly

Brushless TNX/Terra Crusher build

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A couple members asked me to post a build thread on this, I've never been a post stuff kinda guy (ever) but I strongly believe that these trucks are over looked and underrated by most in our hobby so if I can help to change that common misconception and mabey help put a few more of these monsters back on or off the road im down to try. The Terra Crusher and TNX are great platforms to build from. Always pretty cheap on eBay or Craigslist, always have transmission and or engine issues both of witch don't matter since your going electric with a modern, current model transmission that is tough as nails. Some will say parts are hard to find but I've built 3 of these trucks just this year alone. Stock replacement parts are available,  some through Tamiya some on eBay. Some upgrades are hard to find but with some digging I've managed to find everything I've needed to complete my projects. 

Start by removing all nitro associated components from your truck including the transmission you can reuse the driveshafts and roll bar. Leave the mechanical box but remove the throttle servo, linkages etc. Perfect time to throughly clean and inspect the entire truck. The parts I used with part numbers are listed below. You can use whatever parts you think will work best but this works great for me. 

Traxxas 3908 heavy duty brushless emaxx/erevo transmission  Traxxas 3908 motor mount kit with clutch,68t spur, cover etc        Duratrax dtxc6202 battery tray with velcro straps                            Integy dual fan heatsink combo c23139blue                                     Castle 3800kv 4 pole race motor with Castle SCT ESC 1/10 scale 540 size motor. I've found that crawling and short course pinion size 10t-12t on 3s lipo and around 16t-18t pinions for hauling the mail on 3s lipo power. Heat starts to become an issue at 18t on 3s but good fans and a smart trigger finger help that a bunch.

  You will also need some material to make these plates from, they are just flat pieces of whatever correct thickness material with holes strategically drilled in them. What could possibly go wrong....... Right?   

The plates pictured are big, blocky and ugly but very much functional, you could trim them down way smaller than these. Most of the recent ones I've made are a bit easier on the eye but these in the pics are my original "R&D" set. Lol

I made my transmission plates from scrap carbon fiber because that's what I had laying around. You could use plastic, wood, steel, aluminum, titanium, moon rock or platinum if you want to get fancy.  You'll have some trial and error with the Dremel making these pieces fit tight against the transmission. I used all factory Tamiya bolt holes for my plates to chassis mounting but I did relocate my rollbar rearward about an inch to clear the plates on the chassis. Use nylon lock nuts on everything. You'll need various pieces of hardware for mounting all this together I can measure what I've used (just dug through my old hardware bin until it worked) if anyone needs specific lengths.  I fitted and secured my plates to the completely assembled Traxxas transmission with motor, clutch and cover installed to be sure everything is going to have room to breathe when assembled and then installed the assembly checking fitment and alignment repeatedly before clamping the plates to the chassis very tight and flipping the truck over to drill the plate to chassis mounting holes from the bottom through the original tamiya transmission mounting holes. After drilling these holes install hardware and secure the transmission. The 3rd hole in each plate towards the outer edge of the chassis requires removal of the frame rails to drill from the bottom through the original hole in the chassis.  

You will have to enlarge  (just a little) the cross holes of the main shaft of the new transmission if you building a TNX or if your  upgrading from universal type Terra Crusher driveshafts to the TNX dogbone type driveshafts. The Terra Crusher universal type fit perfectly with absolutely zero modification.  For the battery tray I used 4 counter sink type screws with washers to let them mount pretty much flush but I still use a thin rubber pad (cut up bicycle inner tube) under my battery. I use cheap redcat 2.4g dsm TX&RX and the trucks will go further than I can safely see to drive. 

I cut rough rectangles of scrap carbon fiber 80mm by 42mm by 14mm thick for terra crusher universal type driveshafts, 8.5mm thick for TNX style dogbones driveshafts. Proper thickness on the plates is of the utmost importance. Especially on the terra crusher style shafts. NOTE that these trucks do have a small amount of adjustment for diff pinion angle on the bulkheads if you need it. At the thicknesses Ive given you should be able to use the factory diff pinion angle setting. I used some nuts as spacers under my much thinner TNX plates while testing to find the best thickness plates for the terra crusher style shafts, the titanium GPM upgraded driveshafts on eBay are pretty good but for my bashing style I prefer the TNX style shafts so I eventually switched all my trucks to those type. 

Alignment and centering of the transmission is critical, you'll notice I have 2 sets of plate to chassis mounting holes in this set of plates ones is for crusher style shafts the other set of holes is for tnx style shafts. For terra crusher type driveshafts you need to make sure neither driveshaft is bottomed out in their respective diff/pinion gear. Both shafts should have equal travel (centered) between the diffs. For TNX type cup/dogbone style you'll want the dogbones centered in their respective cups (all 4 of them) before drilling your plate to chassis mounting holes. I actually put a very small thin peice of rubber inside the cups before I install the dogbones to help keep the dogbone from sliding all the way forward or rearward. The bones still have a few mm of slide if done correctly. I think it will prolong Driveline component life, haven't had an issue yet. Depending on what shafts you use you might have to "clearance" the original tamiya transmission hole (not the mounting holes)  to give room to access the plate to trans mounting screws from the bottom nothing structural just making a little room. Dremel works great with a small sanding drum attachment. 

I put my esc in the mechanical box without the mech box cover at first and tested with it on and off made no real difference in esc heat so I run it with the cover on and my redcat receiver is in a balloon sealed with silicone. I used urethane conformal coating on the esc circuit board and receiver circuit board but better safe than sorry when your driving across a pond right? Zero issues with any electronics since coating them, works great. 

This truck has a futaba 805bb duel ball bearing steering servo for the small local dirt track. Much quicker steering. I run a zippy  6.6v LiFe receiver pack (not pictured) on this truck now. 

The last picture is just of my bone stock TNX to illustrate the difference between the shafts. Both the F.R.A.T transmission and the later model non-reverse TNX transmissions basically share a common transmission main shaft so only difference is the cross hole that secures the cup on the TNX transmission is a little bigger. Very carefully drill those holes to 3mm on your new traxxas transmission main shaft ONLY IF YOU ARE USING TNX  DOGBONE TYPE DRIVESHAFTS. 

Im sure I've missed something but hey it's my first thread ever.  I'll happily answer any questions or post any other pics you might need. I saved all the part numbers for these builds as well as the numbers from my all aluminum crusher with 5.2r dogbone axle conversion and TNX dogbone driveshaft conversion, zerol bevel diff gears and aluminum servo saver horn. Also for the pivot ball suspension conversion. Currently working on fine tuning one piece aluminum chassis plates for Crushers. Can't find any so I'm making a few. Some with original giant 1/4 scale steering servo mounts and some with the regular 10th steering servo scale like the TNX came with. 

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5 minutes ago, TwistedxSlayer said:

Great write up mate. Well done. I remeber converting my T-Maxx to brushless. Miss that truck some days.

Thanks. They are great bashers and when you get bored on land, bolt on jumbo kongs and float/drive across creeks and ponds. Also a blast at the local track when everyone is trying to guess what it is. Loads of fun all the way around. 

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What a great build post, I really enjoyed reading that, thanks for taking the time to  past this.

i will now be on the look out for a terra crusher at a good price somewhere. :)

this is time last week as a huge Rc fan, I never even knew the terra crusher existed and now I "need" one. ;)

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1 minute ago, AndyjcClod said:

What a great build post, I really enjoyed reading that, thanks for taking the time to  past this.

i will now be on the look out for a terra crusher at a good price somewhere. :)

this is time last week as a huge Rc fan, I never even knew the terra crusher existed and now I "need" one. ;)

Careful, that's how it's started for me. Somehow it led to me "needing" lots of them! Last I checked ebay had a red Terra Crusher for $100 usd plus shipping.  Decent shape, original body and the normal transmission issues if I remember correctly. I've seen them sell cheaper recently and parts lots go real cheap usually. 

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Excellent stuff, very inspirational, thanks ever so much for that. It'll breath new life into my Terra crushers, ironically my gearboxes and engines were ok last time they were used, I just dislike nitro so looks like I can confidently sell those bits knowing I can make use of the chassis which is great news because aside from messy nitro, the chassis' are awesome so I'm thrilled to know that they will get to turn their wheels in anger once again!! I feel quite excited even though it'll be a while before I get back around to them due to over expenditure on other things and lack of time this year!

This Wild Commando is ripe for it...

large.image.jpg.b090ac8bad72bdc3bd615fd4

 

 

Cheers :)

 

 

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7 minutes ago, Nitomor said:

Excellent stuff, very inspirational, thanks ever so much for that. It'll breath new life into my Terra crushers, ironically my gearboxes and engines were ok last time they were used, I just dislike nitro so looks like I can confidently sell those bits knowing I can make use of the chassis which is great news because aside from messy nitro, the chassis' are awesome so I'm thrilled to know that they will get to turn their wheels in anger once again!! I feel quite excited even though it'll be a while before I get back around to them due to over expenditure on other things and lack of time this year!

This Wild Commando is ripe for it...

large.image.jpg.b090ac8bad72bdc3bd615fd4

 

 

Cheers :)

 

 

Thanks. Enjoy them and give us updates periodically whenever you get time to work on them. I'm excited to see how someone else's interpretation works out. I've wanted a Wild Commando to work this Magic on for a long time, 350z Crusher would be fun too. You gotta collect the whole set.......right? Lol. 

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Considering I had not heard of this car until last week I think I have done quite well as I won a Terra Crusher on bay of E last night  :D

Another thing for the wife to moan to me about  :D but like I told her it keeps me out of trouble and at least its a clean hobby (well unless I accidentally drive through a Dog Torpedo)

But I am looking forwards to this project.

 

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