A Newbies 2.2 Crawler Build Diary (On a Budget!)
In the Beginning…
I got into the R/C Hobby just before Christmas 2006. I bought my triplet boys a Tamiya car each. A Gravel Hound, a Baja King and a Mad Bull. Great fun building them.
Then I started to tinker…
The Gravel Hound had a full Yeah Racing Blue Alloy upgrade from Dinball’s RCMart with Titanium turnbuckles. The Baja King got Alloy dampers and Red Alloy Motor Heat sink. The Mad Bull needed a lot of tweaking so I fitted a Tamiya ESC to replace the mechanical one, and a full set of Oil-filled shocks. I fully ball-raced them all too.
Then I wanted one that I could play with…no one else, no kids - just me!
I bought a tatty Super Sabre chassis with some unrecognisable buggy shell placed on top. I stripped every part, and rebuilt with new gearbox parts, ball races, ball connectors, new bumper, new body and decals and new suspension arms plus a Tamiya Dirt Tuned motor I was going to fit in the Mad Bull or the Baja King. I never finished it. I completed the body, fitted it and it was then that I discovered RC Crawlers…the Super Sabre had to go!
I’m a Land Rover nut and I used to trial Landies years ago, so this really appealed to me. I joined http://www.ukrcrc.com/forum/ read the tech articles, drooled at some of the awesome rigs, then began to gather the parts. It seemed simple enough, axles, shocks, chassis, tranny and big wheels…but it ain’t that easy!
WolverineX’s Land Rover MKI
Bearing in mind I had no donor vehicle, I found two TLT axles on Ebay and bought them both for around £60. I ordered a Junfac 1/10 chassis conversion kit from Korea, then some cheap 2.2 Monster truck wheels with spiked tyres from Seben Racing in Germany.
Then I wondered whether the popular Traxxas Stampede/Rustler/Bandit transmission would fit into the Junfac chassis? I thought it’d fit right in. I didn’t realise the huge difference between it and the TLT Transmission…I’ll just have to wait and see.
While waiting for the chassis to arrive I stripped the axles and fitted some shiny metal bearings instead of the bushes. I opened up the differentials and cleaned them up, now I could either lock them with JB Weld, Hot glue or an extra bevel gear. I decided a set of Tamiya Diff Bevel Gears (#50602) was an easy and non-permanent way solution. You simply drop a bevel gear in between the others, which locks everything up nicely. If you ever want to free up the diffs, simply remove the bevel gear!
The Super Sabre sold on Ebay for a surprisingly good price, so with the cash in Paypal I bought two packs of Traxxas Half Shafts (#1951), two packs of Traxxas Steel Output Yokes (#4628X) and an Integy 55T Lathe motor from http://www.ukrcrc.com/Store/. From the USA I ordered the Traxxas 272 Magnum Transmission, complete with Slipper Clutch. I sourced a cheap M-Tronics Viper Dash No-limit ESC and a new set of oil filled Traxxas T-Maxx 3.3 standard shocks with Red springs (about 100mm length).
I couldn’t resist starting the build so I started with the Tracer chassis. I bought some Thread lock for the upper and lower suspension link arms then assembled the brace mounts to the axles.
I attached the links from the axle braces to points on the chassis. At this point I realised I needed the TLT chassis pipes to assemble the chassis sides, as I had only bought TLT axles I had to make some from 6mm Alloy tubing bought from B&Q cut into 50mm lengths. I then fitted the Traxxas shocks, Junfac Alloy Skid plate, locked the rear steering and added the wheels with foam and tyres. Very impressed! Plenty of axle articulation until the bottom of the shocks binds on the front axle brace.
I haven’t added all the chassis tubes yet as I’ll be pulling it apart to shoehorn in the Traxxas transmission.
No parts arrive over the next week or so, I can’t wait so I buy some more M4 all-thread or studding from B&Q and started to build the drive shafts. As seen in Tech section on http://ukrcrc.com/site/index.php?option=com_content&task=view&id=32&Itemid=43
After discussion on the forum, general opinion was that with a 55t Lathe motor and Stampede tranny a 12tooth pinion and 96tooth spur gear should be just about right. I also ordered the HPI Defender 90 body from Modelsport UK as UKRCRC were out of stock again and I didn’t win the UKRCRC Competition! (Damn!). I‘d prefer a hardtop but this is easily the best Land Rover body out there!
When it arrived, I washed the Defender shell with washing up liquid and a sponge and let it dry. I then chose Tamiya PS-2 Red as the main colour (my1:1 Defender is red) applied the included HPI window masks and sprayed away. When the red was finished and dry, I carefully scored the protective film around the Roll Bar, Wheel arches and bumpers and removed it, then sprayed them Satin Black. A quick spray of black inside just about finished it off.
I found some Tamiya Body Mounts on Ebay so fitted them to the chassis. There are two mounting points on the pick-up bed of the Defender body so I placed the mounts to fit them, for the front ones I had to place the body on and shine a strong light up underneath to see where I should drill the holes. Then its out with the Dremel and the reamer bit to make the 6mm holes.
It looks really good and still looked ‘Scale-ish’. The body is larger than I thought (1/8th?) and with the 1/10th Tracer chassis the front wheels are slightly in front of the arches and the rear are slightly behind which means I’ll have to cut back the wheel arches to allow for the articulation I’m after.
When I finally got the Stampede Transmission, it was a real head-ache trying to work out how to fit it in! First I stripped it all down cleaned the grease out of the diff and filled it with hot glue to lock it up. Then replaced the standard Traxxas spur with my 96 tooth 48 pitch HPI spur and tightened up the slipper clutch.
Slipped away to my shed where I spent all day assembling, un-assembling and measuring until I decided to widen the chassis halves by fitting 60mm tubes and have the Stampede tranny mounted vertically with the spur-gear and housing sticking out the side like the TLT tranny does. The motor has to be mounted quite high up to clear the lower link fixing points so I had to use the Dremel to hack the chassis, and cut off the rounded mounts on the Stampede base.
A few spacers and M3 cap heads fixed the tranny firmly in place.
I then re-assembled the chassis and quickly realised that the shocks needed to be mounted differently because of the wider than standard chassis. I used 2mm spacers and they were OK. The front wheels touch the springs at full articulation and full lock but only just, I’m happy with it as it is.
All I’m missing now is the 12tooth pinion which is out of stock…
Started to think of where to place the battery, upfront of course, but low might be a problem. I managed to fit my stick pack pointing down, towards the front, over the servo, and kept it there with a large elastic band while I made a pivoting cradle out of alloy sheet bent around the stick pack to form a ‘U’ shape and then fixed it to the chassis sides. The stick pack is easily removable, held in place with Velcro or elastic. For the receiver, I made another alloy tray and located it to the rear of the chassis.
The 12 tooth 48 pitch pinion arrived and I spent ages searching my shed for a 1mm Allen Key for the tiny grub screw. I fitted the motor on to the Transmission. Made sure I didn’t forget the dab of Threadlock on the pinion grub!
Onto the M-tronics Viper Dash ESC. Following the instructions was easy enough, I didn’t use any of the Power Caps supplied. A tidy bit of soldering was required. That done, I fixed the ESC to the chassis with a single bolt and a touch of Hot Glue. I pinched the receiver and radio gear from my kids Tamiya Mad Bull and quickly connected the servo lead and ESC cable, connected the battery, using Deans type connectors and turn everything on! It lives!
Disappointingly though it was a little jerky, and not very smooth going forward, I don’t think anything is binding in the drive train as I attacked the steel yokes with a Dremel to get more articulation clearance…I’m a bit stumped…the battery was fully charged. The soldering connections seem ok, all are solid and I used plenty of Flux. I took it outside and went up some kerbs etc. It was a very capable climber plenty of power there.
Re-soldered a couple of points on the electronics, it seems a little better but I have ordered another ESC with connections already on, too see if that makes a difference. It also has Reverse which I didn’t realise was not a feature on the Viper Dash.
Took it to the local park, and drove it around the ruins of the Castle. Things are going well, it only stutters at very low speed and if you give it full throttle it doesn’t always go straight away! Have to see if the new ESC is any better. I noticed that the Crawler is quite top heavy, the high mounted motor in the Tranny doesn’t help, I’ll have to get the centre of gravity lower down somehow.
The ESC arrived. It’s an M-Tronics Viper ECO27 with standard Tamiya connectors for battery and motor so there’s not as much soldering to do. I fitted it straight away and tried it in the living room it’s a lot better but still not as smooth as I’d like at slooooow speeds, I reckon it’s just the low gearing.
WolverineX’s Land Rover MKII
Hmm…now that it’s running I’m looking to improve it by building another chassis that’ll sit the tranny lower down. I just wasn’t happy with the top heavy characteristics so I ditched the chassis and made my own chassis plates and tubes built around the Stampede tranny which is as low as possible, sitting horizontally on the belly pan.
I managed to find some 4mm Aircraft grade aluminium plates. Marked out a similar basic ’T’ shape to the Tracer. I bolted two plates together and chain drilled the basic shape. A rough file smoothed the edges and a finishing file made it all nice and smooth. I made a tray for the Tranny and that gave me the chassis’ width. Made some new tubes and worked out where to fit the links. At this point it started to veer away from being a Scale Crawler as the wheelbase is almost 13”. Too long to compete in the 12.5” wheelbase 2.2 Class but I was happy with the looks and carried on regardless. When all the link holes were drilled, larger holes were drilled elsewhere and countersunk to lighten the frame. The tyres catch the body a lot, and I don’t really want to cut much more off it.
The stick battery is as low as it can go, just a millimetre from touching the front servo at full shock compression.
Managed to get hold of a cheap TowerPro MG995 Hi-Torque servo and fitted it to the front steering, with an alloy servo horn that won’t flex! I thought I’d get away with a standard servo but it just wasn’t powerful enough against rocks. I also made a servo mount plate out of 2mm alloy using the plastic one as a template. Makes the whole servo flex free!
WolverineX’s Land Rover MKIII
Now it’s a runner, I just look at it and think of little jobs to do then do it. I cut the lexan side window to make it look half open (that idea came from our very own member Flaming Servo!). I hated the lexan front and rear bumpers so I cut them off and made an alloy rear cross-member and front bumper similar to a real Land Rover, added tow-balls made from TLT link brackets and alloy Ball-ends in a vain attempt to try and claw the scale look back. Now the tyres caught on the alloy bumpers so a set of axle wideners from the UKRCRC Warehouse were ordered, fitted and tried out. Body still catches slightly at full lock/articulation so I moved the shock mounts on the chassis forwards about 10mm raising the ride height but still keeping the shock slanted.
I posted a couple of pics up in the UKRCRC gallery and Curt noticed the bend in the plastic axle ‘C’s. I think a set of Alloy Fat Rock Axle ‘C’s are required! Everywhere in the UK was out of stock of Axle C’s but Wallaz came to the rescue with a spare set he had for sale. Fitted them the day they arrived. A new set of Pro-Line MOAB tyres arrived too. The cheap spiked truck tyres were more suited to mud or loose gravel, they weren’t really much good on the rocks and almost every other 2.2 rig has MOAB’s so they must be good. But…just like the spiked tyres, the MOAB’s also popped off the rims as I hadn’t glued them on.
I have the MOAB’s, now I need some 2.2 beadlock rims, so I go to Junfac to try out there 2.2 Mudrock Beadlock wheels and a set of red alloy Cyclone beadlock rings. Feedback on these cheap wheels seems positive at the moment. You can get a set of 4 for about £20 inc. delivery which took ten days to arrive and that’s including a Bank Holiday weekend! They look really sweet.
It was annoying me that I couldn’t legally compete in the 2.2 class because of the wheelbase, so I shortened all the stock Junfac links and relocated the shock into a position where I got more axle travel, lowered the body 15mm and trimmed the Defender’s arches back some more and ditched the alloy bumpers...stuff the scale look!
Right then, that must be it…I just look at it now and then and think what’s next?! Hard to say…I’d like some alloy steering knuckles as the stock TLT ones - although they’re not broken, appear to be a weak point. I understand from the knowledgeable Curt and Moogie that F350 alloy knuckles will fit, but that will have to wait until funds are available. Other thing I’d like to do is enable the 4 wheel steering (although not allowed in competition on 2.2’s) and fabricate a soft top for the body…I suppose they’re never finished these Crawlers!