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davidwj95

Turning a CR01 into a monster truck

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The CR01 used to be my favourite slow speed runner but now I prefer my mst cfx or hi lift as they both do scale crawling/trail driving more realistically.   

I've not used the CR01 for a while and thought it could be my next project. 

I've been wondering if it's possible to turn the CR01 into an 80s style monster truck.   Maybe faster motor, bigger wheels  (clod sized?) And possibly removing cantilever shocks and replacing with a more conventional set up.

The axles and gearbox seem quite robust but I'm guessing the plastic prop shafts would fail.

I'd love to hear if anyone has done anything like this with this model and see some pics.  

 

20210207_084239.jpg

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I think @Saito2did this with his CR-01.

From what I have found, his recipe was 

- 12T titan 550 Motor

- Unlocked diffs

- Rearrange the top structure so the battery is to the rear

- Ditch the cantilever damper/free standing spring setup for standard coil overs set at an angle

I found this in a thread on Clodtalk, no pics though. 

I read that the gearing may be a challenge to turning it into a high-powered MT as it is built for crawling.

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The CR-01 sounds like a great donor for a monster truck project and my advice would be - start converting and see what happens.  I'm not sure what mods you'd need to get genuine Clod Buster wheels on but JConcepts make a couple of Clod-sized wheel alternatives with variable offsets.  Clearance behind the tyres will always be an issue with Clod-sized wheels so you'll have to see how you get on and adjust / widen as necessary.

Conventional shock mounts would probably suit the monster style better and give more options for tuning.

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Thanks for the replies.  I had a look at JConcepts wheels and tyres on modelsport.co.uk.  they are really nice and they do some in 2.2 size which might be more suitable.   The wheels and tyres will come to about £100 so I'd be removed to change those last when I'm sure the concept will work.

I'm thinking about increasing the power first then I can mess around with the shocks to get the handling right.

Good point about the battery position, I hadn't thought of that.  

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Axial do some 2.2 monster truck wheels on a 12mm hex that might be a cheaper alternative. Maybe not the look you're going for though.

https://wheelspinmodels.co.uk/i/273898/?gclid=CjwKCAjwvMqDBhB8EiwA2iSmPPi3ajXlSQaGebiAnwLemm-mXxxIH7K1qwiGPkSLrJrcHu_Ikwc1fhoC9ksQAvD_BwE

I'm sure you can get them in silver, not just green!

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On 4/11/2021 at 11:36 AM, Badcrumble said:

Axial do some 2.2 monster truck wheels on a 12mm hex that might be a cheaper alternative. Maybe not the look you're going for though.

https://wheelspinmodels.co.uk/i/273898/?gclid=CjwKCAjwvMqDBhB8EiwA2iSmPPi3ajXlSQaGebiAnwLemm-mXxxIH7K1qwiGPkSLrJrcHu_Ikwc1fhoC9ksQAvD_BwE

I'm sure you can get them in silver, not just green!

The builder’s Kit SMT10 comes with them In a darkish gray. So does the RTR GraveDigger version . The MaxD rtr came with Orange ones 

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I put clod tires on mine, with 4WS. Looked the part, but the tires rubbed the links terribly. I'm sure there's a way around it, but I just moved on.  Some Axial BKT's would be a great match. 

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On 4/10/2021 at 11:52 PM, Badcrumble said:

I think @Saito2did this with his CR-01.

From what I have found, his recipe was 

- 12T titan 550 Motor

- Unlocked diffs

- Rearrange the top structure so the battery is to the rear

- Ditch the cantilever damper/free standing spring setup for standard coil overs set at an angle

I found this in a thread on Clodtalk, no pics though. 

I read that the gearing may be a challenge to turning it into a high-powered MT as it is built for crawling.

@Saito2 - do you have any pics of what you did, or could you share your findings please? Interested to know what it came out like. :) 

 

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Yes, I did do this to one of my CR01s one time. Sorry, I never took pics. Badcrumble hit all the main points of what I did. Even with the biggest pinion possible fitted, the gearbox is still geared a bit too low. The Titan motor brought it up to a speed where it was acceptable but it still was not quick by any means. I used WT01 wheels and HPI Wheely King tires IIRC. One issue the CR01 had was, at full droop, the driveshafts would begin to bind from the extreme angle. I made some simple drop-down plates to lower the center transmission cradle a tiny bit which reduced the driveline angle. In the the end, Axial made a SMT10 kit which made made my CR01 truck irrelevant in my fleet and I wound up selling both. 

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Would it be possible to swap in an Axial transmission? I'm sure I've heard of this being done with SCX10ii and other transmissions.

I want to say by @OldSchoolRC1 on the rccrawler forum.

But by the time you have done all that, you might as well have bought an SMT10?

Maybe one day I'll build one of my CR-01s....

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thanks @Saito2 :) and @Badcrumble  ;) 

I was admiring some nice monster trucks and found myself thinking that I have a rather large hole in my collection where one should be, but I'm ashamed to say I'm not and never have been a fan of the Clod chassis. The it occurred to me that the overall chassis setup of the CR-01 isn't a million miles away from a MT so why not give it a go? The gearbox was what I figured would be the main issue, which I, along with Badcrumble, led me to swapping it out. So then I started looking at Axials, and I saw the SMT10, and figured that was probably the cheaper option, if not the most satisfying :) 

I guess along with the pinion you'd really need to find a replacement for the sun gear to get any decent improvements in gearing?

image.thumb.png.72b768e093abde24ad7067fa8fd3ddee.png

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https://www.modelsport.co.uk/product/tamiya-rock-socker-truck-cr-01-385123

This could give some ideas as to what it looks like.

I'm really no expert, but I've found in cars with low gearing a higher KV brushless motor can help. The high KVs with lower torque is offset by the low gearing to balance into something workable. Because the gearing is low, it's not too much strain on the motor either.

 

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I had to go digging in the vault to find these - I knew I had some pictures somewhere. Forgive the quality, digital cameras have come a long way. 

IMG-0093-SM.jpg
IMG-0094-SM.jpg

Transmission was not a problem IIRC, it's quite strong and the gearing was fine...I ran a Holmes outrunner on 3S for a while with a rock bouncer set-up and the transmission took it in stride. For the clod experiment I think I had a 23t pinion in there with a 22t Kyosho 550 and it felt pretty good. Again, the stock clod offset didn't quite work with the links, though there are so many more options out there now for clod wheels I'm sure it could be made to work. 

 As far as transmissions, my 3 remaining CR's have 1 stock, 1 Vaterra 2 speed, and 1 Element transmission - recently upgraded from an Axial for the 12% OD. 

May be hard to see but it is shoehorned in there

20200522-155035sm.jpg

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On 4/13/2021 at 8:19 AM, Dakratfink said:

The builder’s Kit SMT10 comes with them In a darkish gray. So does the RTR GraveDigger version . The MaxD rtr came with Orange ones 

The. Axial part # for the gray one is 

AX 31464. 
I just recently ordered a set of 31461 (green ones) myself. 
if you go this route you can either mount Axial’s own BKT replica tires , or J Concepts makes a few MT tires designed for 2.2 wheels. They are a little less beefy than full size clod rubber, but still beefier than a 2.2 crawler tire 

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I can confirm that the stock SMT10 wheels/tires will work fine on the CR01, using them on mine currently.  Mine is still a stock CR-01 crawler truck with 4WS, no real modifications.  As others have said, the one thing you'll want to change for sure to make it into a real monster is the transmission, it's geared very well for crawling, not so much for speed. 

 

IMG_0998.JPG

IMG_0997.JPG

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On 9/7/2021 at 2:07 PM, OldSchoolRC1 said:

 

IMG-0093-SM.jpg
IMG-0094-SM.jpg

 

 

Returning to this thread as I have a used CR-01 on its way and a strong temptation to deviate from stock, what damper length do you typically use on your builds @OldSchoolRC1? I've seen the G-transitions you have used listed as 80 or 90mm.

I have long admired that Blazer shell @87lc2, is it a discontinued Proline body? Is that a 312mm wheelbase?

I've struggled to find the Axial BKT tyres in the UK so I am thinking of going for the HPIs that @Saito2 used. Likely pairing them with a 285mm wheelbase body for that 'small monster' look.

I'll have a few goes as a stock crawler first though to get a feel for it.

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Wheelbase on that Proline Blazer body is 11.2" (285mm).  Fit the CR01 wheelbase perfectly.  Pretty sure they're discontinued now, part number is PRO324400.

For the monster look you can also use Wheely King tires, or the new MST monster truck tires, they look really good and should be available everywhere. 

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2 hours ago, Badcrumble said:

Returning to this thread as I have a used CR-01 on its way and a strong temptation to deviate from stock, what damper length do you typically use on your builds @OldSchoolRC1? I've seen the G-transitions you have used listed as 80 or 90mm.

It varies. I'm running 90mm Axial Icon shocks on #3 at the moment, they fit on OK without adding some standoffs to the chassis.  My Jeep is running some 100mm Vaterra shocks with some small standoffs, and the Crawler Bug does indeed run the G-transitions. That's a custom cut chassis though, not especially comparable. (Number 4 is in bits ATM, but uses the stock suspension)

The monster version above has 120mm 3Racing shocks IIRC. Definitely needed some standoffs on the chassis for the best performance, and has custom mounts on the axles to stand up the shocks..

Part of why I enjoy the CR01 so much is it is so easily modified. There are holes everywhere, it's like a Tamiya Erector set.  

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3 hours ago, Willy iine said:

Oh man, I was wondering what to do with my CR01.. I think I'm going to get those SMT10 tires and repurpose my truck too!  Thanks @Saito2@87lc2 and @OldSchoolRC1!!

Yea, the CR01 is an odd bird.  I bought mine from @Saito2 a few years back just because I always thought they were interesting.  I used it as a regular crawler for a while, but enjoyed my traditional 4-link trucks more and found I wasn't using it much.  Since I've turned it into a mini-monster I use it all the time when the trails are wet.  Great in the mud due to the low gearing.  

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1 hour ago, 87lc2 said:

Yea, the CR01 od an odd bird.  I bought mine from @Saito2 a few years back just because I always thought they were interesting.  I used it as a regular crawler for a while, but enjoyed my traditional 4-link trucks more and found I wasn't using it much.  Since I've turned it into a mini-monster I use it all the time when the trails are wet.  Great in the mud due to the low gearing.  

It is.. I had a hard time liking it in stock form and turned into a shelf queen unintentionally.  I really like the wheels/tires you're running.  Which ones are those?  I looked around but could not find them.   TIA!

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