Thrift shopping at its best, a MRC build...

[JBcustoms]

(Note: If this needs to be moved please let me know, its a scaler, but also a MRC!)

So, anytime I am at the thrift stores I always roll over to the toys to see if I can find something cool to play with. I ran across this beach toy that looked very close to a Jeepster so i had to have it! Originally inteded on making it a small r/c crawler and started searching around for axles that would fit it well and I found out the Losi mini Crawler was just about the right dimensions for this little guy. Eventually fond a MRC on the local craigs list, it was actually a stock parts rig assembled from all the stuff the previous owner swapped out and upgraded, so I ended up with a complete roller for $50! I plan on swapping the wheels from the stock 1.9s to a more fitting 1.5 wheel/tire combo for better scale looks. Currently working on a custom tuber style chassis for it, its my first attempt at brazing so its taking a minute to get used to it, but coming along well I think. Well, here it is:

When I first picked it up:


Lowered it and stretched the wheelbase for an idea of where I wanted it to sit


A little detail in the interior already, but will probably be detailed more in the future


Started pulling it apart to start the modding process


Plastic is nice and soft so it was easy to do some trimming


Does anyone else still draw? Figure everyone else uses CAD these days... and this is a 1:1 scale drawing of the Jeep itself, actual size! it fit on an 8.5x11 piece of graph paper!


Day I picked up the parts rig


Stripped down and ready for lots of mock-up and visualization


Looking decent, the Losi was more than a perfect size for this thing, wanting to go with 1.5 wheels and tires though




Good amount of room under the hood on this guy, hoping to get the trans, steering, and electrics under here...


Made a carboard frame from the dimensions on my plans so I could be sure it was going to work out, drew up the plans quite some time before getting the donor rig








Trimmed out the passenger seat to make room for the frame and rear suspension


Made custom links using the standard method




Made a rear axle truss that will also serve as a upper link mount out of 1/4" square brass




Did another for the front that will also be the shock mounts


Getting there...


Started on my framerails using the same 1/4" brass as the axle trusses, the square was a little difficult to bend, and it kinked in a couple places. Should have filled it with sand to help prevent that










Using the stock skid for a transfer case mount and LCA mounts, trimmed down the stock frame plates to drop iy away from the floor of the Jeep to make room for the TC


I should have enough room in there










So here it sits, still have much to do, including getting rid of that cage and brazing my own!

 

[Crawling Calvin]

So how long did the carboard chassis hold up for ;-) A trick that brass musical instrument builders use is soapy water frozen inside the components they need to bend without kinking.

I like how your using a pre-existing shell and working around that. Not many people seem to do that any more but if your going for a semi-scale rig it works beautifully. Keep up the good work and can't wait to see it running "thumbsup"

 

[JBcustoms]

Thanks for the tip! I have heard of filling tubes with sand to help with the kinking but never using soapy water then freezing before. Honestly dont think its much of an issue, only seems to have affected the square tubing i used on the framerails.

I got a little more progress done today, built the rear shock mount. I will let the pics do the talking.











Lots more to do!

 

[howyadoin]

Very nice, love all the custom work.

 

[JBcustoms]

Built the front shock hoops today... ride height is taller up front, hoping the trans/servo/etc mounted up front should help level it. Will be playing around with springs once its all together to fine tune it.













More work to do!

 

[j0e]

Looking pretty awesome, man.

What'd you use for the links, m2 all thread?

 

[JBcustoms]

I used 6-32 all thread, think it was the smallest tap I could find at the Ace Hardware my GF works at.

 

[JBcustoms]

Updates on this cold christmas eve. Decided to get the trans mount finished up:









Here is the almost finished mount. I wanted to be able to remove the transmission as easily as possible, this design will allow me to access all four trans screws without removing the mount itself. Also, I will be doing a drivers side drop transfer case and this shifts a bulk of the trans over to the passenger side for the driveshaft.











I am waiting on another set of Losi rod ends to show up so I can do the upper links on the suspension, then I will decide where exactly I need to locate the transmission and attach it to the frame.

 

[JBcustoms]

Got some more links in for making the uppers. I have the rears done and setup how I want, just need to braze the frame mount in. The links clear the shocks at full compression, which is good, but I will also be limiting the rear travel so its ready to be brazed in. I will be doing the front in a similar fashion, but need to work around the transmission so it will take a little longer. On to the pics...









Its snowing a lot here in Denver, so instead of working on the real Jeep, progress will be made on this one

 

[JBcustoms]

Yeah, deals can be found if you look hard enough. I lucked out with this as the previous owner literally upgraded almost every part on his and this was the leftovers, almost a complete rig! A little more progress:

Broke an end making the uppers for the front, was thinking I had threaded the rod in enough and then went for a little more...


Went ahead with getting the front together anyways, even though I am missing a link. I considered three linking it for a moment but since I need to order more ends anyways the decision to keep it four link was made. I still need to braze in the upper mounts front and rear. The geometry is almost identical Fr and Rr, the only difference being the upper links on the front are spaced wider apart to accommodate the transmission.


Worked on the front using the passenger side link as that side has the clearance issues. At full compression there is no contact, plenty of clearance even when articulating.


I still need to make the steering link and servo mount on the frame. Once that is done I can work on the trac bar. I have what i hope will work for a transfer case on the way, only time will tell.

Oh, and if you think $50 for a MRC roller is a deal, you should see what was given to me for free the other day:
http://www.rccrawler.com/forum/tamiya-bruiser/518501-freebie-given-me-last-night.html

 

[JBcustoms]

Getting the steering setup, not much else to do these days but wrench on the crawler. The mount will bolt in like the transmission so i can remove it easily for wrenching on it. I may trim down the unnecessary metal, then again may leave it on as it blocks the view of the engine bay when the body is installed.

Pics:


May just have enough room for a receiver in here, would be cool if I could fit the esc and receiver here.


Servo arm clears the tie rod. Need more rod ends and I can get the steering finished up and build the trac bar.

 

[JBcustoms]

Transfer case arrived! I am using a transmission for a Traxxas Summit VXl, their 1/16 truck. Already having a few Losi shafts with the 4mm yokes made it an easy choice as I am on a budget, $10 shipped off of ebay. Obviously needed to make some modifications to it to make it work for me, but it was quite a simple process. The internal gear ratio on this is almost 2:1 so i will be playing with spur and pinion combos to accommodate adding this in the driveline, happy I can do simple math

Trans as it arrived


First thing I did was flip the input shaft to the other side of the case so i can tuck it as low as possible and have it line up well with the transmission.






I then shaved off all the mounting tabs that were molded on, two of which were then open holes into the case. To remedy this I used Frog tape and some epoxy to fill in the holes. The frog tape was recently developed for painting/masking, the glue swells when wet preventing runs or leaks. Worked like a charm!










Then I modified the main shaft so the driveshaft yokes would tuck up closer to the case. I shortened the wheelbase of the Losi MRC and need as much room as possible for the driveshafts to prevent binding during suspension articulation. I have modified them slightly to help with that. The main shaft mod was as easy as trimming it down and adding the flats for the shaft set screws.

In the first pics, the yoke on the left was as far as they would install when stock, right is after modification.




Main shaft modded


Slight clearance issue with the front output and case


Filed the case slightly and both fit well


Now I need to fab up a mount and it will be installed, then its time to work on connecting it to the transmission


Its coming along!

 

[joe122]

Very very impressed. That is over the top cool to build your own frame. I also had the same plan after finding an unusual Jeep body. Wasn't sure where to put the thread as it is all Losi MRC but I went the TCS Crawler L-Trail frame rail route (I won a set so that started it). Your skills are awesome. Not trying to steal your thread, mine is in the 1.55 build section, and I'm not sure it's in the right location there either! Kind of a build without a home!

Will be watching your progress.

One picture of mine, not done yet.....

 

[Crawling Calvin]

I would keep the front servo mount solid strictly because mini's need every bit of weight they can to keep traction and ultimately your loosing like a really minor bit of weight for a potential loss in strength. That said keep up the good work. I am amazed at how creative you have been on the build with filling things in but that is what makes customizing things so fun ;-) you can do whatever the heck you want!

 

[joe122]

Thanks! Just mounted the servo last light, it parallels the grill and solidly mounts a bracket that bolts between the frame rails, very much like yours in fact. Still impressed with your frame fabrication. Also concerned about adding weight. My Lipo pack is velcro'd under the hood just to get as much as possible over the front axle.

 

[JBcustoms]

I imagine using all this brass its going to be heavier than a stock MRC and mounting the trans and electronics under the hood will be keeping weight forward over the front axle as much as possible. Not too concerned about performance, mostly just enjoying the build and cant wait to drive it!

 

[joe122]

Yep, when you build something from scratch the maiden voyage is what its all about. THEN YOU BREAK IT JUST SO YOU CAN FIX IT!

 

[JBcustoms]

Spur gear came in yesterday, having to compensate for adding the VXl trans as a transfer case. Calculating ratios, a stock MRC has a 14t pinion and 60t spur which is around 4.29:1, transmission is 7.59:1 and axles are 2.64:1, for an overall motor/tire final drive ratio of 85.96:1. I added in the Summit VXL trans which is 1.94:1 between the trans and axles. Calculating it all out I found I needed a 50t spur gear, and a 22t pinion. This pinion/spur gives me a 2.27 ratio going into the transmission. Run through all the calculations and I end up with a motor/tire final drive of 88.24:1, slightly lower than the stock ratio which should help with the additional weight. Also planning on running 1.55 tires, probably the smallest diameter I can find which will lower the strain on the drivetrain.

Now my question is: Which motor do I run?

 

[mrG]

Your build gets a big "thumbsup"

 

[Dualdigger]

I went with the xtreme 380 motor and they are great, more torque and speed than the stock motor. Highly recommended.