TRX-4 to 6x6 Conversion Guide

[JimInMiami]

I recently converted one of the TRX4’s in the stable to a 6x6. It was a fun project and I thought to detail it here as a sort’a guide for those thinking of dipping their toe in the 6x6 world.



First, a word of encouragement. Do it: 6x6 crawlers are great fun to drive and will allow you to tackle lines on your trail that most 4x4’s wouldn’t hope to do. It’s hard to beat the traction available from 6 wheels working in concert.



Transforming a TRX-4 to a 6x6 is also a fun project that is mainly bolt together with little if any fabricating required (depending on a couple of things - more on that latter). The TRX-4 and TRX-6 are compatible platforms from front bumper up to and including the middle axle.

Parts list for what’s required:
TRX-6 Chassis Rail Set #8829 or used TRX-4 rails.
Rear Suspension Mount Set #8830
One Axel Pinion #8279
One Bearing #5180A size 6x13x5
One Bearing #5116A size 5x11x4
Middle Axel Diff Cover #8846
Rear Axel Housing #8837
Rear Axle Diff Cover #8847
Rear Upper Links #8832
Rear Lower links #8831
Shock Tower set #8216 (from the Sport)
Two rear shocks #8260
Rear Drive Shaft #8850 (may required modification)
Two Rear Universal Joints #8849

A complete TRX-4 rear axel assembly (either locked or lockable can be used, see note below).

So to begin, there are a couple of decisions to be made:

1. Re-use the TRX-4 chassis rails (cheaper option) or buy new TRX-6 ones? If you decide to use your existing chassis rails, you will still need to find another set of TRX-4 rails and either braze or bolt on an extension. It’s easy and cheap to find TRX-4 chassis rails on eBay from folks who part out rigs as a business or from a hobbyist who’s upgraded their rigs to another chassis. I chose the easy way out and ordered a set of new TRX-6 chassis rails.

2. If you want the distance from front to middle axle to be same as the Sport’s (12.3”) or the Defender’s (12.8”). This matters, because if you are starting out with the Sport, as I was, you will need to use a longer “female” driveshaft half to connect the middle and rearmost axle. In this case, order the half shaft assembly part# 8250. I went with the short middle axle wheelbase as it gives a better “break-over” angle, and by separating the middle and rear axles a bit more, allows for the use of over-sized wheels and tires if desired.

Note regarding the rear axle: As mentioned in the parts list above, a complete rear axle assembly will of course also be needed. These can also be found on Ebay from folks parting out rigs for profit. It doesn’t matter if you get a locked or lockable one because the lockable can be permanently locked by inserting an appropriately sized washer where the “Carrier” part # 8281 goes in the differential.

Additionally, a new rear axle housing part #8837 will be required. This is just the plastic housing. Simply disassemble the new rear axle you purchased and transfer all its internals to the new housing. The new housing places the ring gear on the opposite side compared to the standard axle so that the rearmost wheels spin in the correct direction.

A few build notes:

It’s useful to refer to the exploded views on Traxxas’ website to see what-goes-where and also to the below pic. https://traxxas.com/explodedviews/TR...diate-Assembly



The inner fenders on the “real” TRX-6 perform double duty as shock mounts, but the holes on the TRX-6 chassis rails also accommodate the TRX-4 shock towers at the correct locations, so you can go with those and save some $$$.

For the rear shocks, use the softest springs available because the weight of the rig is now spread among TWO axles rather than one and you want the suspension to conform to the surface of the trail. See in the pic below how the middle axle shocks are nearly fully compressed, while the rear ones are fully extended? You want that so the tires stay planted to maximize traction. Had I used stiffer springs, the rear axle would be in the air and surface contact to the rear wheels lost.



I chose the Chevy C10 body from Proline, but just about any “cab” style body will fit. The front end was secured per the standard method using the stock TRX-4 body posts, while the back was attached using these Tamiya body mounts I had lying around.



I tend to build my rigs more for performance than for looks, so only decorated the rear with an oil drum and spare tire. Those wanting to max out the scale look should consider the flatbed option from IE RC
https://iercscaler.com/ols/products/trx6-flatbed-v1



So have at it, order the parts, tear down your TRX-4 and build everything back on the TRX-6 rails. Fear not, as all the TRX-4 components will mount back up on the TRX-6 chassis. While you’re at it, take a moment to disassemble the old transmission, diffs and portal housings and regrease everything.

[twade984]

Very nice write up, thanks for taking the time


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[JimInMiami]

Originally Posted by twade984

Very nice write up, thanks for taking the time

Sent from my iPhone using Tapatalk

My pleasure, just paying it forward, as I've gotten a ton of useful info from this site!

[smog]

Nicely done Jim! Roughly how much did your listed parts run you?

[AnimalHippie]

Bro, great looking rig!!! Awesome thread you have here!!!


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[JimInMiami]

Originally Posted by smog

Nicely done Jim! Roughly how much did your listed parts run you?

Thanks Smog. Apologies - I didn't add it all up, but if you already have a TRX-4, WAY less than the $650 a new TRX-6 will set you back. If really you want to know, the price for the items can be found by clicking on the parts number on the exploded view Traxxas web page. Your budget would also vary considerably depending on body choice, wheels, tires, etc...

[JimInMiami]

Originally Posted by AnimalHippie

Bro, great looking rig!!! Awesome thread you have here!!!

Sent from my iPhone using Tapatalk

Thanks for the kind words!

[smog]

Originally Posted by JimInMiami

Thanks Smog. Apologies - I didn't add it all up, but if you already have a TRX-4, WAY less than the $650 a new TRX-6 will set you back. If really you want to know, the price for the items can be found by clicking on the parts number on the exploded view Traxxas web page. Your budget would also vary considerably depending on body choice, wheels, tires, etc...

I hear ya.

I have always been disappointed that Traxxas did not release the X6 as a kit. Reading through your post the idea of purchasing a sport kit plus your parts list popped into my head. It would essentially be a TRX6 kit. Sure, there would be a few minor details missing, but the kit is essentially there.

I can get a sport kit up here for 400 bucks Canadian, but RTR X6 is pushing 900 bucks. That is a 500 dollar disparity. Lots of play money there...

[JimInMiami]

Originally Posted by smog

I hear ya.

I have always been disappointed that Traxxas did not release the X6 as a kit. Reading through your post the idea of purchasing a sport kit plus your parts list popped into my head. It would essentially be a TRX6 kit. Sure, there would be a few minor details missing, but the kit is essentially there.

I can get a sport kit up here for 400 bucks Canadian, but RTR X6 is pushing 900 bucks. That is a 500 dollar disparity. Lots of play money there...

You could totally create your personal DYI TRX-6 kit going that route!

[1FSTLS1]

Originally Posted by smog

Nicely done Jim! Roughly how much did your listed parts run you?

I just made a shopping cart with all the parts listed above on Traxxas web site came to $166.50

[smog]

Originally Posted by 1FSTLS1

I just made a shopping cart with all the parts listed above on Traxxas web site came to $166.50

Beauty

Doing it?

[JimInMiami]

Originally Posted by 1FSTLS1

I just made a shopping cart with all the parts listed above on Traxxas web site came to $166.50

Do it, and post pics of your build!!

[1FSTLS1]

I am thinking I need to build this. Maybe with two sets of dual wheels in the back.

[JimInMiami]

Originally Posted by 1FSTLS1

I am thinking I need to build this. Maybe with two sets of dual wheels in the back.

Oh, talk about traction, yeah man!

[AK KRAWLER]

Originally Posted by JimInMiami

Man, oh man!!! It will likely not be a Traxxas, but you really got that 6x6 bug biting me pretty bad and I 'm out of Benadryl.

Awesome job on the TRX-6 conversion!

I am starting to collect parts for a build. Not sure where it will end up, but I knot will be fun.

[1FSTLS1]

Need to figure out part numbers for end links? Was it the TRX or the SCX10 that had curved end links? https://traxxas.com/products/parts/2742 ?

[JimInMiami]

Originally Posted by 1FSTLS1

Need to figure out part numbers for end links? Was it the TRX or the SCX10 that had curved end links? https://traxxas.com/products/parts/2742 ?

Axial makes the curved ones, but the regular straight Traxxas ones will work for this build.

[JimInMiami]

Originally Posted by AK KRAWLER

Man, oh man!!! It will likely not be a Traxxas, but you really got that 6x6 bug biting me pretty bad and I 'm out of Benadryl.

Awesome job on the TRX-6 conversion!

I am starting to collect parts for a build. Not sure where it will end up, but I knot will be fun.

Thanks, perhaps an SCX10 II based chassis is more your style?
Here's my other rig - this one's based on the Axial Raw Builder's kit. But honestly, if I were to do again, I would start with the SSD Trail King, as they are SCX10 II compatible and the quality is soooo much better.

[AK KRAWLER]

Another awesome build my friend!!!

So far, the parts I have gathered are SCX10ii, you are correct , but...
AR60's, 2.2 Tires and hopefully a flatbed... Only time and money will tell

[xagoras]

This is a great project and it's bugging me for a while that the TRX-6 isn't avaialble as a kit to build. I was thinking to get the Chassis kit and the spare parts to do this. I do have some in my parts box from other projects.

I was thinking to add a spool in the rear axle and keep the middle one lockable. In the exploded views, it shows locking cables in both rear axles. I'm not familiar with the TRX-6, so what's the deal here? I know it has 2 diff servos, so how does it work in the RTR? Or are the exploded views for reference only?