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Old 09-24-2010, 02:40 PM   #1
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Join Date: May 2010
Location: Madison, NJ
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Default Project :: Old Dog. Teaching a Maxx some new tricks

Hey everyone, I've been working on a custom build for the last 2 months or so. Just slowly picking away at it in my free time. This is my first custom build, I must say it has been a lot of fun, but also a lot of work. As it stands, it's just about finished, but I figured I'd post it now anyway. Here's a little write up and some pics. Let me know what you think.

I started this project because I wanted to find a simple way for the Maxx trucks to lower the center of gravity and make it handle much better, and to do so without spending a small fortune. Itís my attempt at making it track worthy against some actual truggies I don't know how true that is yet, but that was the goal I didnít want to half-ass it, and Iíve had this idea kicking around in my head for some time now, so I made a new chassis.

(Side note, a screw kit will be used when everything is done)

















One of my main goals was to make it a bolt on conversion. I wanted to use as many parts from an existing Maxx truck as possible. I wanted to put a 1/8 scale drive train into a Maxx. I originally tossed around the idea of mounting a center diff in place of the 2 speed transmission. But that seemed like it would be the easy way out, and also posed a slew of obstacles; finding proper length dog bones and working the brakes to name a few. I decided to just dive in head first and see what happens.

The material I am using for this is .125Ē (3.1 mm) thickness aluminum. I donít know the grade, it isnít tempered. What I do know is it is incredibly difficult to bend. Just the center to rear brace piece took my whole weight with leverage to bend it just a few degrees, itís only 3/4ď wide where bent, soÖ. I was lucky in that I got the 31Ēx20Ē sheet of aluminum for free.

The clutch bell needed for an 1/8 scale diff are different than the stock Traxxas ones. For starters, they are different size bearings. The real issue comes from them being too long to work on the engine. I originally thought I could just shim it and that would take up the slack, but no, you would need about 3/8Ē of shims. The front clutch bell bearing just barely rode on the crankshaft, not cool. Again luck comes my way. I realized I could just shorten the back of the clutch bell, side by the flywheel. I know someone with a benchtop belt sander, problem solved there. I took off little by little until it fit just like a stock one. Surprisingly the inside diameter of the 1/8 bell was only about 1-2mm larger than 1/10 bells, so the clutch should still engage fine.

Throttle/Brake linkages were the toughest part of this build. I couldnít replicate a typical 1/8 setup where the servo is on the right side of the diff. The Traxxas mill sits more forward than a .21 does, making the carb run into the diff. It is to the point where I had to remove one of the 2 rear brake discs. I had to have the slide on the left side of the engine. That makes things really cramped. After a few days of staring and thinking and trying new placements, I stuffed a servo and the stock throttle bell crank in there, right in front of the engine. Perfect

The exhaust was 2nd on the list of tough ones. I searched for a long time to find a header that would work for me. Problem is they donít seem to make headers designed to go around the left side of the motor, around the ez-start setup, like what you see in 1/8 scales. I first tried to bend a header to what I needed, that was a waste of time. I ended up with a crushed, kinked useless piece of metal. So I did the next best thing I could come up with, copper pipe. I measured an aftermarket header at 1/2" inside diameter, so off to Home Depot with the motor, that got me some funny looks . A few pieces and some Silver Solder and I was good to go. The solder I used melts at 420*-460* So to pre-answer that question, if the header were to de-solder itself, I have bigger problems going on. I also couldnít use the stock pipe, luckily I had one still laying around from my old xxx-nt, if that doesnít work well, I have a few others I will try. Tough to gauge how it will react to the longer header along with everything else being different.

As it sits now, I have the shocks in the most layed down position. Gives it exactly 2" maximum ground clearance. If the shocks were stood up, it'll probably give it somewhere around another inch. All that is left to do is pickup some steering servo mounts, mount the wire to hold the pipe on, and setup the throttle and brake linkages. Once everything is done, I will bring the chassis to a machine shop to have them mill out the engine mount screw areas, like on an 1/8 chassis, that flat milled countersinking style. And while it's there I will have them bend up the sides of the chassis for added rigidity. The bends will only be about 1/4"-1/2" in from the sides, so there is no way for me to bend that myself without a bending brake.

Well, that's enough typing for now, pictures speak volumes, here's the link to the album of pics I took throughout the build... Project::Old Dog
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