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Old 05-31-2022, 09:10 PM   #21
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Default Re: TRX Based 8x8

The cab is sick! Should look like a beast when you’re done.


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Old 05-31-2022, 09:32 PM   #22
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Default Re: TRX Based 8x8

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Originally Posted by JimInMiami View Post

The cab's arrived


(I'm making a single-post thread-jack) - those cabs are SO cool, I would love to build a performance crawler using one with an external cage and a shorter bed... (but I haven't got the skills!)

The other day I saw this incredible cab-under truck - much LESS suited for rough terrain, but kinda nifty, nonetheless:



It was a prototype from Strick and it was meant to have a trailer sitting on top, and another being towed behind:
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Old 06-01-2022, 11:25 AM   #23
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Originally Posted by durok View Post
(I'm making a single-post thread-jack) - those cabs are SO cool, I would love to build a performance crawler using one with an external cage and a shorter bed... (but I haven't got the skills!)

The other day I saw this incredible cab-under truck - much LESS suited for rough terrain, but kinda nifty, nonetheless:



It was a prototype from Strick and it was meant to have a trailer sitting on top, and another being towed behind:
That's badass!
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Old 06-01-2022, 10:22 PM   #24
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Default Re: TRX Based 8x8

Hey, Jim - question - is that cab you got the Cross RC HG-P802 cab?

Enquiring minds want to know!

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Old 06-01-2022, 10:58 PM   #25
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Default Re: TRX Based 8x8

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Hey, Jim - question - is that cab you got the Cross RC HG-P802 cab?

Enquiring minds want to know!

Looks like the HG P802 cab to me!
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Old 06-02-2022, 09:08 AM   #26
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Originally Posted by twade984 View Post
The cab is sick! Should look like a beast when you’re done.
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Thanks, I think it's gonna look good and I also have the fenders for the front wheels on order. I hope to mockup the chassis this weekend to determine if Axle #1 links work as intended. Once that's proven, I should have a roller soon.
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Old 06-02-2022, 09:10 AM   #27
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Looks like the HG P802 cab to me!
Indeed it is, I found it on eBay: https://www.ebay.com/itm/325164586754 It comes green or sand (beige) by the way.
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Old 06-02-2022, 09:11 AM   #28
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Originally Posted by durok View Post
Hey, Jim - question - is that cab you got the Cross RC HG-P802 cab?

Enquiring minds want to know!

Correct sir!
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Old 06-05-2022, 09:30 PM   #29
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So progress has been slow, life is seriously interfering with my hobbies but did manage to reassemble the chassis rails and install the axle #1 link mount.



It's wedged in there pretty solid, so I think a dollop of Goop will do the trick once everything's finalized.

Side view:



I was getting ready to pat myself on the back, when I noticed an unforeseen problem..... The blasted drive shaft is fouling on the driver's side link mount at about 3/4 compression





Was able to solve 90% of the problem doing 2 things:
1. adjusted axle #2 upper link to pitch the driveshaft down and away from the link mount and,
2. dremeled (is that a verb?) the link mount down about as mount as I dared to gain clearance.



It's still just touching with both shocks fully compressed but not with only the driver's side.



So crisis averted next step will be to mockup axle #1 to see if everything clears and articulates as it should. Stay tuned folks and thanks for following along.
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Old 06-09-2022, 02:00 PM   #30
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Default Re: TRX Based 8x8

Was able to successfully mockup axel #1 mounting, tho I had to custom fab rods from 4mm all-thread as the TRX-6 rods were too long for this application.



I wasn't able to mount the links in the "double-sheer" manner intended for them as my setup doesn't leave enuf room between the link mount and the side rail, but I'm counting on Traxxas having over-engineered this so my setup still's strong enuf for trail duty.



Next step is to modify the stock unequal length front axel shafts to work with the TRX-6 rear axle housing that I'm using as axle #1
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Old 06-10-2022, 12:25 AM   #31
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I like where this is going so far but now you've got me wondering if it would be easier the make a a similar TRX6( by cutting two 6s in the middle and splicing the two rear ends together.

I don't have my 6 in front of me so I can't really visualize it but I imagine it would make it simpler to configure the twin axle/link setup.

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Old 06-10-2022, 10:10 AM   #32
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I like where this is going so far but now you've got me wondering if it would be easier the make a a similar TRX6( by cutting two 6s in the middle and splicing the two rear ends together.

I don't have my 6 in front of me so I can't really visualize it but I imagine it would make it simpler to configure the twin axle/link setup.
This might help with visualization: my extended chassis alongside the stock TRX-6 one.




And I think you're onto something! If one were to cut the stock TRX-6 chassis in the middle of where the skip plate is and splice in another rear section to mirror the existing one, then the problems I had getting the link mount for axle #1 to fit go away!!

You'd need to make sure your joint was really solid as the center of the chassi would be subject to the largest forces due to the long "lever arm" effect. I live in an apartment and don't have the means to braze, but that would probably be the way to go.

The only remaining issue would be mounting the front bumper which might or might not end up too high depending on the body/cab being used.

Thanks for the contribution, others deciding to tackle this project might benefit!!

Last edited by JimInMiami; 06-11-2022 at 08:47 AM.
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Old 06-10-2022, 06:19 PM   #33
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Originally Posted by JimInMiami View Post
This might help with visualization: my extended chassis alongside the stock TRX-6 one.



[IMG][Imgur](https://i.imgur.com/6sqPOOM.jpg)[/IMG]



And I think you're onto something! If one were to cut the stock TRX-6 chassis in the middle of where the skip plate is and splice in another rear section to mirror the existing one, then the problems I had getting the link mount for axle #1 to fit go away!!



You'd need to make sure your joint was really solid as the center of the chassi would be subject to the largest forces due to the long "lever arm" effect. I live in an apartment and don't have the means to braze, but that would probably be the way to go.



The only remaining issue would be mounting the front bumper which might or might not end up too high depending on the body/cab being used.



Thanks for the contribution, others deciding to tackle this project might benefit!!
I didn't even think about the amount of toques the middle of the chassis would need to withstand. Nothing some brazing/welding couldn't solve. I'd imagine.

Now that I think about to though, I'm not sure how well you could mount the "rear" four link of the second axle to the front of the center skid.

My be a worthwhile experiment for someone who can afford a couple TRX6s to cut up.

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Old 06-11-2022, 08:56 AM   #34
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Now that I think about to though, I'm not sure how well you could mount the "rear" four link of the second axle to the front of the center skid.

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The "rear four link" would mount just as it does on the TRX-6... just in the reverse direction. That wouldn't be a problem, though to avoid bump steer issues, better to turn axle #1 into a 3-link + panhard rod which is easily accomplished with some minor trimming as per below.

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Old 06-11-2022, 09:04 AM   #35
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So last nite's project was to finalize assembly of axle #1. Recall that to get the wheels turning in the correct direction, a TRX-6 rear axle housing (part #8837) https://traxxas.com/explodedviews/TR...-Rear-Assembly must be used.

Of course that axle was never meant to be used for steering, so while the knuckle and C-hubs fit, the front TRX-4/6 axle shaft DO NOT. The solution is to trim and modify the long TRX-4/6 axle shaft to fit. To spare those wanting to replicate this build the trouble, below are the measured lengths:

Passenger side: 73MM



Driver's side: 62mm



Notice that you'll have to grind down the end of the shaft to create the flat bit that fits into the locker/differential.
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Old 06-11-2022, 09:08 AM   #36
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When I mocked up the mounting for axle #1 a couple days ago, I notice that the axle's link mounts would hit the steering servo under compression, so some trimming to lower their height was needed.

Stock with location for new hole indicated:



Modified

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Old 06-11-2022, 09:15 AM   #37
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And the finished axle#1



I noticed that this setup resulted in a slightly wider wheel-to-wheel distance and so had to use a slightly longer tie rod to compensate.
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Old 06-11-2022, 02:34 PM   #38
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Originally Posted by JimInMiami View Post
The "rear four link" would mount just as it does on the TRX-6... just in the reverse direction. That wouldn't be a problem, though to avoid bump steer issues, better to turn axle #1 into a 3-link + panhard rod which is easily accomplished with some minor trimming as per below.



That makes sense. Like I said, it's hard for me to visualize the ideas floating around in my head without my 6 in front of me. You're pictures are very helpful.

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Old 06-16-2022, 11:59 AM   #39
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Yesterday evening I installed both steering servos, made minor adjustments to the links to get axle #1 pinion pointing better toward the driveshaft and hoped to finalize the assembly of the two front axles. Unfortunately I ran into yet another snag. The axle #1 upper link mount was still hitting the steering servo arm at about 3/4 compression despite the trimming I'd already done.

So I pulled axle #1 drilled new holes and retrimmed the upper link mount as much as I dared per the pic below.



Tonight I'll reassemble and check clearances, if it's still hitting, I'll just have to limit shock compression with some spacers on the shock rod.
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Old 06-17-2022, 08:52 AM   #40
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There are still adjustments to be made (Panhard rod needs shortened, etc.), but this thing's gonna work!!



Here you can see how much wider axle #1 turns out to be (about 12mm). I'll have to use wider wheels hubs on axle #2 for it not to look wonky. My radio doesn't have mixing functions, so both servos connected to channel #1 using a Y-connector.



Y'all let me know if there's still interest in following the build as to get a roller, it's pretty much a bolt-on job using a mix of standard TRX-4 and TRX-6 parts.

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