Savage ML-E
 

Savage ML-E (mid length electric) project thread.

This build will be based off my previous build with the following major changes:-

- TVP length with be exactly halfway between stock and XL
- CAD drawn, machine cut TVPs\center diff plate and battery plate (should be much quicker without all the hand crafting)
- Custom motor mounts
- Completely flat chassis underneath (using a flat rear diff plate)
- Kydex skid plate
- Center diff instead of a Slipperential
- Vorza diff casings(spider gears) front and rear so that the drive train only uses 8x16 bearings
- Lowered battery tray with lower profile 4S battery
- Xerun 150A ESC, Tenshock X802 2100kV 6 pole motor
- Front CVDs to allowed increased steering
- other tweaks and new parts that I'll cover as I go


The main motivation for this build is that while I loved driving my original build it lacked aerial performance and steering. One way to get better aerial performance would have been to use heavier wheels and\or a faster motor but I didn't want to go that way due to reliability concerns. The alternative that I chose was to sacrifice a little driving stability for more aerial performance by shortening the chassis. Doing so will also add some steering. On top of that there has always been the question of should I stay stock or go XL... well how about somewhere in the middle? :)

Some initial CAD pics, TVP with some positioning mock up
http://i1010.photobucket.com/albums/...-TVPmockup.png

2D of motor mounts
http://i1010.photobucket.com/albums/...otormounts.png

I'm also going to have a go at mirroring the build on Savage Central. If it takes up too much time though I will probably let it slide and just maintain this one.

Received most of my orders this week. I'll go through the parts I'd like to comment on as I get time.

First up are wheels and tires. I've choosen what will likely be a popular combo, Pro-line Desperado 3.8" wheels with 3.8" series Badlands tires. This will be the first combo I'll try. I'm not keen on moving away from J Concepts Rulux wheels as they are just so damn hardy but the new Badlands need Traxxas beads. I've driven on quite a few different MT tires now and the old Badlands MT were my favorite for offroad traction. What I didn't like about the old MT Badlands and the new ones are that they just aren't large enough, diameter and width wise to suit a savage if you want a decent monster truck look. The new Badlands also have two additional flaws, they are too low profile IMO and also they don't come with shaped foams anymore. Anyway, time for some pics and weights.

Pro-Line Badlands 3.8" (tire and foam) - 157gm
Pro-Line Desperado 3.8" (1/2 offset) - 75gm
Total - 232gm

and for comparison

Stock Flux wheel\tire - ~300gm
Pro-Line Badlands MT - 214gm
Rulux wheel (MT size, 1/2 offset) - 49gm
and my the combo I was using
Rulux (half-ups, 1/2 offset) + inner bead mount HPI GT-S tire - ~370gm

As you can see, the new combo is incredibly light. I think it will be too light and I won't get the aerial control that I'm after but I'll it them a go.

http://i1010.photobucket.com/albums/...E/IMG_1001.jpg

http://i1010.photobucket.com/albums/...E/IMG_1005.jpg

Can you do a pic next to an old badland MT for a size comparison?

Comparison shots of stock Flux GT2, Badlands MT and Badlands 3.8". Outside diameter between the Badlands is virtually identical.

http://i1010.photobucket.com/albums/...E/IMG_1019.jpg

http://i1010.photobucket.com/albums/...E/IMG_1017.jpg

Started rebuilding the shocks.

A little dirt had built up over the last year :P
http://i1010.photobucket.com/albums/...E/IMG_1013.jpg

Bought some Axial o-rings to try instead of HPI ones to see if they help the leaking any.
http://i1010.photobucket.com/albums/...E/IMG_1014.jpg

I'll be trying out some RC Skins shock covers on them. The bad horsie ones just got shredded by rocks in the end. The new rear guards will help cover them a bit more.

Also grabbed some silver springs. Might need them as the truck will be rather light.

The new build will have a lower cg due to the choice of a 4S battery.

Old battery - 6S 4000mAH 40C, 695gm
New battery - 4S 5000mAH 35C, 573gm

However, the lower weight of the new battery could be a problem. I was running a 6S 5000mAH in the old build and the truck handled a touch better than with the 4000mAH. One option could be to bolt some solid steel bars to the inside of the TVPs just below the battery tray to get some more weight in the back. The rear of the TVPs will be completely solid this time with no cutouts and deeper due to the flat bottom so that might help.

The height of the new battery is about 9mm less than the old. The battery will also sit lower as the new battery plate will be positioned lower. So the top of the new battery should be sitting over 1cm lower than the old.
http://i1010.photobucket.com/albums/...E/IMG_1022.jpg

You can use this moulded foam..

http://www.amainhobbies.com/product_...serts-Yellow-2

Thanks mothman, those look much better than the ones that come with the new Badlands. I was going to glue them up this weekend, lucky you jumped in before that, cheers :)

Wide ass basic foams that come with 3.8" Badlands. I'm guessing Proline expects you to trim these to size.
http://i1010.photobucket.com/albums/...E/IMG_1036.jpg

Been trying to get some work done on the diffs. This is how my diffs usually end up. Silicon fluid turns blacks and eventually leaks out and gums up the bearings :(
http://i1010.photobucket.com/albums/...E/IMG_1032.jpg

So as I mentioned in the first post I would like to try the mod to use the Vorza diff cases. I tried to test fit the case into the stock Flux bulk but I'm having a problem. The assembly below won't fit in the bulk, it's too wide. The problem is the Vorza diff case is slightly wider than the stock Flux case. If I leave out the two shims it will fit but then the gear mesh isn't as snug as the stock setup. Anyone who has done this can you chime in please? Jahay?
http://i1010.photobucket.com/albums/...E/IMG_1037.jpg

I think you can get away by removing some of the material from the diffcup. Just use some emery paper on a hard and flat surface (glass coffee table works great) and and sand the end of the diffcup in circular motion. This should remove enough material. Since the shims are so thin anyway you will only have to remove very little. Just do your best to keep it flat. This will also move the crown gear in the direction you need it to go (towards the pinion).

BB: Had hoped to get away with not using any modified parts. I think I will have to try this though. The Vorza crown gear has a raised area (under the internal bevel gear)that looks thicker than the washer that is on the Flux crown gear. So it seems that decreasing the width of the cup might be better for the internal mesh as well. I tried to simulate that by leaving out the diff gasket and testing the internal mesh, seemed fine.

As per my dodgy digital verniers
Width of Flux cup - 20.95mm (from bearing mount point to where the crown\gasket contacts)
Width of Vorza cup - 21.82mm

Shims are 0.2mm each so i need to remove about 0.4mm from the Vorza cup. This will make it ~21.4mm which is similar to the Flux cup plus the two other shims.

I do recall needing only 1 shim for a snug fit in the bulks, but gear mesh was spot on. Perhaps the Vorza cup you have is slightly out of tolerance. Did you measure any others?

What is your reason to shorten the wheel base?

JasonB: I have 3 Vorza cups and they all measured about the same. The stock setup calls for 2 shims on the crown gear side and with the stock cups this feels perfect. With 1 shim there is a tiny bit of play in the crown gear mesh which might be ok in practice.

With 1 shim and using the Vorza cup I couldn't get the diff seated in the bulk in a dry fit test. Just too wide.

I have the first diff completed now. I used 120 sandpaper on some glass and this ground it down quite quickly. I ground the first cup down to about 21.4. After assembly the internal gears felt a touch tight but the diff fitted in the bulks nicely with 2 shims on the crown gear side and none on the other. The crown gear mesh was perfect as expected.

http://i1010.photobucket.com/albums/...E/IMG_1057.jpg

Second diff cup I have ground down to around 21.5. Hopefully this will be the happy medium of internal gearing meshing nicely and the cup still being able to fit in the bulk without being too tight.

coolhandcountry: I explained the shortened length in my first post in the paragraph before the pics. Was there something specific you wanted me to comment on about the shortening?

Nope, to wide for the 3.8 Badlands...