The rebuilding of The Grunt (2.2 pimp cane clod)

[Nova's Ark]

The veterans of the site already know this rig. This was dezfan's 2.2 pimp cane clod named "The Grunt". He won the 2007 points series in 2.2 in CMRCRC with this rig and his driving skill.




I acquired this in a trade from him. I had already built two 2.2 shafty comp rigs that I was ultimately not happy with. I came to the decision that a rig with proven characteristics that I could invest a bunch of seat time and money into was going to be my next step. This rig is it. I had to install my ESC, BEC, TX, RX and battery to get it running:




Out of the box it impressed with some of the things it could crawl around my house and property.

[Nova's Ark]

It's first day out on the rocks at a local crawling spot was a different story though. The badlands were not hooking up, the clod stall was bad, and the torsion style pimp cane chassis was not working for me. Also the 2S lipo was only lasting 20 minutes with the dual motors. Frustrated, I came home and began to plan out my next moves.

Pariah, a fellow RCC member hooked me up with a Thunder Power 3S lipo. Huge improvement. It allowed me to gear down. I installed 8 tooth pinions front and rear. It made a large improvement on the clod stall and the dud would actually hold. So I picked up a few more 3S lipos after that.

I then turned my attention to the rims and tires. They were not gripping or conforming to the rocks. The tire would not wad up like I was used to. I disassembled the rim and was surprised to see no weight. I was also surprised to see the bead of the Maxx / 40 series badlands still attached. (The tires are Maxx size / 40 series with a 2.2 moab side wall glued over them.) They also still had the Pro-Line Maxx Size foams in them in a start cut pattern. I debated on trimming the side wall at first, because I was concerned about side hilling and side wall support, but ultimately I did.

I removed / cut the side wall from the Badlands. It made a huge difference. But it also lightened the tire. I added stick on lead weight and also drilled air holes into the beadlocks. I did this to all four wheels. I also removed the Pro-Line foams and added ACE Doughnuts. The fronts now weigh in at 1pound 2 ounces each and the rears at 13 ounces each. I love this wheel, tire and foam combo. It works so well for the rocks we climb in East Texas.

[dezfan]

It'll never work!

[Nova's Ark]

I have a small obstacle course in my back yard that my son and I practice on. It is good enough to give you a rough idea of any rigs abilities and limitations. While crawling on it, I did not notice that a knuckle screw had backed out and fallen out. I had the grunt pretty bound up and I broke a Hot Racing aluminum Axle C. After it was confirmed that I could not get a replacement C from anyone, I went to ebay and ordered an Integy pair from RCSuperStore. I have ordered from them before and always had great prices, fast shipping and good service.

I installed the new axle tubes and C's and waited for the weekend. We went out crawling that weekend, and in three hours I did this to both stock front axle shafts.



So with that, Pariah had a new set of Thunder Tech CVD's I bought from him. I am not sure if people already do this or not, but here is trick for clod guys that run CVD's. This comes from racing nitro 1/8 scale buggies and monster trucks. Hot bodies makes CVD boots. They are a little small for the TT CVD's, but if you cut the two smaller ribs off, they install perfectly. You can add some CA glue to the boot on the side that goes over the axle side of the CVD. With the boots installed, you can fill them with grease which will stay in and it will also keep the dirt out which will help them last for a long time. I installed them and we out crawling the next afternoon.

[Nova's Ark]

With the front CVD's installed, we went out crawling the next afternoon. While out crawling, I played around with weight and battery placement. I moved the lipo from off the front axle to the back bone of the pimp cane to try and save the battery from rock rash. Not a good idea. It was amazing, but just that little bit of weight movement, changed the lines the grunt would or would not crawl. Lines that had been made earlier in the day with the battery on the axle, now could not be made with the battery on the back bone.

With this new revelation, I took velcro straps out of my pit box and started adding more weights (rocks) to the axles and chassis in different positions to see how the pimp cane would react and what it would and would not crawl. It was fun and interesting. That got me to thinking about ESC placement and trying the best I could to move everything to below the tops of the tires onto the axles and off the back bone of the pimp cane.

I did have the front case fail on me that day though. I was crawling some insane lines and was putting some extreme stress on the case and tubes. I was straddling gaps betweens rock and crawling vertical basically. I would drive up to the rock and get the front tires up on it, then engage dig, and get the front tires all bound and wadded up against the rocks, then disengage the dig and slowly crawl up.

It was hard on the front and rear case because the rocks had crevices on the bottom and the tires wanted to be sucked into the crevice. After an hour of doing it, the front case finally got so weak that it would not hold together enough to keep the brass axle ends into the locker. It's amazing to drive / watch because no other 2.2 shafty (at least locally) can crawl the lines I can with the grunt.

So I am replacing the front case with another plastic one but I am not going to shave as much off the housing as dezfan had. I added 1/4 & 1/2 ounce stick on lead weights to the inside of the case surrounding the locker. I had to shape some of them to clear the gears. It is all held in with Shoo Goo.



I also picked up a HS-82 micro servo and micro switch from Radio Shack for the new dig. Dezfan had sent me the link for Franky Rizzo's dud switch and that looks like a winner. So I redesigned the dud set up tonight. What a pain in the @$$ drilling through the RC4WD Clod mount plates. Why does everything they build have to be out of hardened steel?!?!

[Nova's Ark]

So after that last weekend of crawling (a month ago), The Grunt has been sitting disassembled. Not only did I damage the front case, but the pimp cane had some issues:

New compared to old back bone


I also picked up more of these allen bolts with nylon lock nuts to replace the nylon bolts the pimp canes come with. The nylon stretches over time and creates slop between the back bone and axle.


I did use the down time to score some good parts for The Grunt though. I picked up a Thunder Tech racing clod behind the axle steering kit for it and a new Hitec 5955TG steering servo. I want to take advantage of the CVD's turning capability. I have full aluminum gears to install front and rear as well. I also picked up a new AR6000 receiver so that I can use my DX6 with this rig also.

We have a comp this Sunday. I should have been working on The Grunt, but I was busy finishing my 2.2 scaler and helping my son get his GC1 AX-10 ready for the comp instead. I work better with a little pressure so this rebuild will be quick this week. This is all I finished tonight. More updates tomorrow.

[dezfan]

Holy sh!t man, I'm going to call you the DESTROYER!

[run2jeepn]

Nice work and a nice rebuild... keep it coming....

[Nova's Ark]

Originally Posted by dezfan

Holy sh!t man, I'm going to call you the DESTROYER!

LOL As long as I can drive and build this rig as good as you did, you can call me what ever you want.

I like this rig and the design. I like the pimp cane so much I already have a 17inch pimp cane clod super to finish once The Grunt is done. I haven't thought of a name for that one yet.

[Nova's Ark]

Originally Posted by run2jeepn

Nice work and a nice rebuild... keep it coming....

Wow. Thank you R2J for the kind words, you are the man

[Nova's Ark]

This single picture is very deceiving considering how much time I spent on this axle tonight. I basically put in four hours tonight. Here is where all the time went and why it took so long.

One thing I noticed immediately about the Thunder Tech CVD's was that it widened my track width. I did not like that at all. I asked dezfan what my options were. He told me that he had already broken two sets of the smaller CVD's so I knew I did not want to go that route. I already knew stock axles would not hold up either.

Thankfully dezfan had included the purple 14mm hexes R2J sells for the smaller clod CVD's with the Grunt. So I drilled them out to fit the TTR CVD's. I then cut the outer TTR CVD axle shaft down 3/16. I am not super narrow, but at least I am back to the track width I started with when The Grunt arrived. It's as narrow as I can be unless I get small axle c's and different rims.

I am not sure how long the 14mm hex will hold out yet. However I did redrill the hole for the cross pin bigger. It's now 3/32 with a 3/32 hardened steel cross pin. I want to run TTR straight axles in the rear and I am saving up for those. I will cut them the same way so the track width stays narrow.

Here's where the time went:
1. drilled axle cross pin for hex to 3/32
2. drilled the purple 14mm hex 21/64 to fit over the TTR CVD
3. cut 3/16 off each TTR CVD axle
4. cut 3/16 off each TTR CVD end bolt
5. drilled the front beadlocks 21/64 to fit over the CVD
6. cut the plastic hex that come with the TTR CVD's off and filed it smooth to fill in the 12mm side of the Erickson bead lock for added support of the beadlock and to give the TTR CVD end bolt more surface to tighten
7. installed all aluminum gears and shimmed the brass ends going into the locker for zero slop / side to side movement
8. cut my own plexiglass motor sight hole cover
9. installed the TTR BTA steering kit but modified it - I learned this trick from Picaroon. If you install the servo plate below the TTR axle brace (you will have to cut and modify the servo plate for clearance) It lowers the servo for a better COG and it straightens out the servo throw / linkage so that you get no binding. He did it on my pimp cane clod super and it works really well. So I did it to The Grunt as well.
10. installed a Hitec 5955TG steering servo
11. front axle weight is 4 lbs 3oz and I still have a custom battery tray and 3S lipo to add to it

[dezfan]

Mmmmmmm, beefy!

[Nova's Ark]

Our comp was postponed 1 week due to rain. It was a great blessing to me because I still had a lot to do The Grunt. I finished it up late today.

[Nova's Ark]

I am exhausted and will come back later and edit the post with more detail and tech.

New dig - FrankyRizzo style. It works greats!




Mamba Max mounted on rear axle using a RC4WD axle plate inside a modified Traxxas receiver box.


I don't understand what TTR was thinking when they designed this BTA kit. It does not work properly even if you installed it per there instructions. I had to ultimately mount the servo with the output closest to the tire in order to clear the lathe motor. I did not want to do this because it meant the servo wire would be closest to the tire.

To help prevent frayed servo wires, I installed heat shrink tubing over the wire and heated the tubing to form the wire into a bend. I also drilled a very small hole in the pimp cane and removed the servo wire from the plastic end so that is could fit through the small hole in the back bone.

The TTR servo plate is cut for clearance and mounted underneath the TTR axle brace (opposite TTR instructions). I then had to use 1/8 plastic servo mount spacers to position the servo even lower. I ground the BTA steering arm for clearance. I also filed some of the clod axle case for clearance.

I am using a 1 1/4 length aluminum servo horn that I drilled and cut 1/8 off. I am using some turnbuckle that was in one of my pit boxes for the steering arm. This modified steering works well, has maximum steering and no binding. The servo did not get hot in two hours of crawling pushing two wheels that weigh over a pound a piece plus the weight of the front axle. The only issue I still might need to address is the fact that servo mount is tilted back. The mount itself does not freely move, but I would need to make a small bracket to hold it in a vertical position instead of tilting back as it is now.

Heavily modified Thunder Tech Racing BTA


It took hours to get this steering right. The only thing limiting turning is the CVD itself.

[Nova's Ark]

Modified TTR CVD and 14mm hex in order to narrow front wheel base but still make it as strong as possible.


The only thing mounted to the back bone is the AR6000 receiver for the DX6 and the lipo battery tray.


I tried very hard to mount the lipo on the front axle. This is the absolute last place I wanted it mounted. I might make a custom lipo pack later in order to get it back on the axle.

I really wanted all the weight on the front axle. This 2200mah 3S lipo pictured lasts about an hour. However it will not clear the tires when mounted on the axle. If I use my 1300mah 3S lipos, I only get 25 minutes or so crawl time. I just prefer to not have to switch out batteries every half hour.

[Nova's Ark]

Obligatory flex shot

[dezfan]

Looks good Eddie, I'm starting to miss that pig!

[run2jeepn]

Looking good.... On your TTR CVD's whats your hex to hex width?

[Nova's Ark]

Originally Posted by dezfan

Looks good Eddie, I'm starting to miss that pig!

Thanks dez. It is heavy like a pig, but it sure doesn't move like one. I have built, bought, sold and traded a lot of crawlers and parts, but I just plain like this rig. The aspects of the pimp cane are very impressive and the history of the rig is cool also. I don't see this one ever leaving.

Originally Posted by run2jeepn

Looking good.... On your TTR CVD's whats your hex to hex width?

I will measure Monday after work and get back to you on that R2J. I can tell you though, that it is the same as the brass 12mm hexes on stock clod axles. The rear axle tube and axles on the rear of The Grunt are stock and the front and rear beadlocks measure the same in track width.

The only way I could get any narrower, would be with different beadlocks. But then they would hit the large axle C's that I am using. So I am basically as narrow as I can get. I am happy with that, the turning radius is great now and I have the strength of the large TTR CVD's up front.

[Nova's Ark]

Current specs on The Grunt;

- JP customs 2.2 pimp cane chassis
- Clod Axles
- Full aluminum gears w/ bearings (front and rear)
- Integy Aluminum front axle tubes
- JP customs front aluminum knuckles
- ThunderTech Racing CVD's in front (now modified)
- ThunderTech Racing BTA steering kit (now modified)
- Hitec 5955TG steering servo
- Axiom 65 turn motors
- 8 tooth pinions front and rear
- Mamba Max ESC
- CC BEC (set to 6.3 volts)
- DX6 TX and AR6000 RX
- 3S lipo
- Radio Shack micro switch for dynamic dig
- Hitec HS 85MG micro servo to activate dig

I finished up The Grunt about 6PM Sunday evening. We loaded up my truck and my son and I went straight to a local crawl spot to test it out. The weather conditions and the condition of the park were pretty bad due to several thunder storms we have had for the last three days. The rock was wet, along with mud, puddles and misc debris everywhere. We met up with three other local crawlers that were already there and had practice gates set up.

I would prefer to not crawl my comp rigs in those type of conditions, but I needed the seat time with The Grunt and my son needs it with his GC1 AX-10. The Grunt did well. The new dig works flawless. It makes such tight turns now with the new dig and new steering. The dig is also much more predictable. No more guessing if it will hold or not, or when or where to engage assuming it will not hold. I highly recommend this dig over the old on / off switch.

It flexes much better this time around. The reflex seems better as well. I know that some of that comes from the extra weight in the front and repositioning of electronics to get everything below the tops of the tires. It seems very stable. It will stand on it's side for about 30 seconds before slowly tipping on it's lid.

I tried a couple really hard lines that The Grunt had made before and a few it could not to test if the rebuild brought improvement. However the conditions were so poor that true results could not be determined.

Before this rebuild I had been using a JR XS3i tx and RS310 rx with The Grunt. This time around I switched to the DX6. I like the stick radio better. It seems easier to me to manage the clod stall with the stick over the pistol grip. However I found myself moving the controller in my hands in the direction I wanted The Grunt to go. It was similar to playing a video game. With both hands down on the box / stick controller, the position and feel is similar to holding a video game controller. I thought that was funny. Especially since I don't have that tendency with a pistol grip controller.

Overall I am very pleased with the rebuild. Weather permitting, our comp will be this coming Sunday.