JimInMiami
Quarry Creeper
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/TRX-6-Mercedes-Benz-G63-AMG-6X6-88096-4-Intermediate-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.
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/TRX-6-Mercedes-Benz-G63-AMG-6X6-88096-4-Intermediate-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.
Last edited:
