Project Lego Technic

Not your average Savage Hop ups. These are highly modified, with some home-made parts.

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johny723
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Project Lego Technic

Post by johny723 » Fri Feb 08, 2013 1:38 pm

this is the start of my "new" project. Let me introduce the first teaser photo

The savage-like truck with a center diff based on a truggy chassis. I saw this ofna lx-2 ultra chassis on ebay for 11 USD including shipping, so decided to give it a try... more photos and various parts to come :D the goal is to build my own truck just like I used to build trucks from lego technic when I was a boy. I will try to overcome the flaws and downsides of a stock savage truck by using parts from other manufacturers and models. Another goal is to keep it a budget build as I will be mostly recycling spares I already have :D Stay tuned!

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Synk
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Post by Synk » Fri Feb 08, 2013 7:46 pm

In my opinion its the tvp's that define the savage.

I like the sound of your project though. When i was a kid i made a 4wd lego truck with lego diffs. Come to think of it it was a lot like a savage.
savage x ss Lrp zr.30, octane cage and mod radio box, ofna mid tank 250cc, integy saver front/rear hubs, sv250 mod 3 spd, no mix arm throttle, hitec 5645 5625 servos, 4xbb 4xstd shocks w/35wt, flux drivetrain, 30k wt diff oil,  new era wing, tonys screws

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Post by bigbigbrig » Sat Feb 09, 2013 3:53 am

Make sure you put braces from the top of the diff cases to the top of the center diff.
It will keep the chasis from bending.
I did it on my racing truggy to keep the chassis from flexing.
You can see the purple brace on my truggy.
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Post by johny723 » Sat Feb 09, 2013 8:02 am

I know it will not be a savage, but majority of parts will be from the savage line. I have had these parts as spares for a long time but my other savage simply doesnt break much, so I will finally find them some application.

the braces are a must for any pan style chassis, I have some beefy cen gst turnbuckles to use them as braces. But I still think that chassis flex to a certain level is not bad, look at xray cars, they really take advantage of chassis flex. I think it is beneficial for both handling and duability. It transfers the force from impact to the whole car and helps the car stay on the surface with all wheels.

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Post by johny723 » Wed Feb 13, 2013 11:20 am

drilled some holes into the lx2 chassis to mount savage bulkheads and steering bellcrank. I also found some dogbones that have correct length to fit with hyper 7 center differential.
Last edited by johny723 on Wed Feb 13, 2013 12:03 pm, edited 2 times in total.

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Post by johny723 » Wed Feb 13, 2013 11:21 am

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Post by mrgrouchyguy » Wed Feb 13, 2013 2:09 pm

Wow, this like a cool project, will be nice to see how it holds ups.

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Post by johny723 » Wed Feb 13, 2013 5:10 pm

I chose a pan chassis platform because of low CG and both the front and rear kick-up. The front kick-up is achieved by using savage bulkheads plate mounted to the originally rear end of the chassis, which is now front, and the rear kick-up/anti squat is the former front end kickup. I hope it will help me put the power from my CC 1520 to the ground instead of wheelies. The anti-squat angle is not as significant as the front kick-up angle, but I am sure it will improve the handling. Image

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FluxNZ
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Post by FluxNZ » Wed Feb 13, 2013 7:27 pm

Clever project you have going Johny :)

Will watch for updates.
Savage Flux HP - Mild Mods.
Savage Flux 5SC/5T - Custom built.
HotBodies VE8.

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Post by johny723 » Thu Feb 14, 2013 12:16 pm

time will tell how clever they are :D
some specs I calculated. The real numbers might eventually be different. As you can see the project is at the very beginning:
length from bumper to bumper cca 62 cm
width with LST wheels cca 49 cm

I plan to use this bumper from baja 5t instead of the stock savage bumper. The stock one is just too weak and bendy. Image

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Post by FluxNZ » Thu Feb 14, 2013 2:02 pm

I have one of those bumpers sitting here as well and they are nice and beefy.

Nice socks by the way :D
Savage Flux HP - Mild Mods.
Savage Flux 5SC/5T - Custom built.
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Post by johny723 » Sat Feb 16, 2013 12:35 pm

some first mock-up pictures of the fron brace. It is a cen gst rear turnbuckle. Pretty beefy, 6mm thick in the middle.

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Post by FluxNZ » Sat Feb 16, 2013 3:54 pm

Thought you could run two of the turnbuckles off the bulkhead TVP bolt points but it looks like the steering will get in the way.
Savage Flux HP - Mild Mods.
Savage Flux 5SC/5T - Custom built.
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Post by FluxNZ » Sat Feb 16, 2013 4:05 pm

Thought you could run two of the turnbuckles off the bulkhead TVP bolt points but it looks like the steering will get in the way.
Savage Flux HP - Mild Mods.
Savage Flux 5SC/5T - Custom built.
HotBodies VE8.

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Post by johny723 » Sat Feb 16, 2013 5:19 pm

Yes. The steering wouldnt work in a full range. But these cen gst turnbuckles are really strong so I think that 1 for the front end is enough. The rear end will have 2 of them though. If there is such flex that 1 front brace is not enough I will use a piece of angled aluminum mounted to both bulkheads to get rid of the flex completely.

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Post by johny723 » Sat Feb 23, 2013 6:31 pm

a small update- I realized I need longer chassis braces for more support of the chassis. The cen gst turnbuckles are hollow Image
the hole is 4mm in diameter. So I found some tie rod ends that have utilize M4 rods . I have some from LST shocks, so I cut a long M4 bolt
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to put it into the turnbuckle body to get the length I need.
A 4mm thick screw would get bent after the first bump, so I used an alu tube to strenghten it. I didnt have one with thick walls, so I put together 2 alu tubes.
Image

The bolt goes into the 6x4mm one and they are pushed into the 8x6mm alu tube. Image
Both the tubes and the bolt are glued together with a red threadlock. I dont think it can bend now!
exploded view Image

the final look Image

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Post by johny723 » Mon Feb 25, 2013 2:17 pm

a rough mock-up picture of bulkheads mounted to the chassis + braces, all in their final places. (lots of unfinished work to do)
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Post by johny723 » Wed Feb 27, 2013 12:02 pm

final assembly of the chassis braces. It took more time than I expected...

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Post by johny723 » Sun Mar 31, 2013 5:40 pm

the project had to be put aside because I had to spend all of my time on more important things, duties and obligations and didnt have any time for a hobby.
I also realized an issue that had to be solved. The center shafts were too angled and my tests showed lots of excessive heat that was generated when the motor was spinning the drivetrain. Enough heat to melt the threadlock on the grub screws holding locking the diff outdrives on the diff pinions. A recipe for nightmare... Not to mention the premature wear on diffs and dogbones it would cause...
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So I had to figure out a completely new chassis layout. It took me ages to come up with something usable as my resources were pretty limited
and I tried to keep the chassis balance and had to take into account the holes and cut-outs of the ofna lx ultra 2 chassis I am using in this project.

Soooo, after innumerable hours of putting the things together again and again, combining all the driveshafts I had with the center diff, thinking about the best servo, battery, esc and motor mount at the same time, with a view of ultimate reliability and ease of maintenance set in mind, I finally found a way how to do it properly.
I decided to use the lst2 CVD as the rear center shaft and the front center savage dogbone as the front dogbone. the motor mount will be on the right side, with the servo in front of it and the esc behind. The battery will be on the left side.
the chassis braces are not complete yet, but the picture shows them in their mounting places

I decided to use another brace between the bulkheads to stiiffen the chassis up a bit as this will not be a light truggy, but a true monster truck that will hit 14+ pounds with LST2 wheels ands tires. It will be made of the material of the PCB boards, the same I already used to attach the braces to the bulkheads.

it may look simple, but it took me ages to get it to this form, while respecting all the things I mentioned, but I think it was worth it. I hope that I will put it together and run this week. With the most difficult obstacles and problems already overcome, it cant be that hard to finish :D
Image
more photos to come!

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Post by LLkoolskillet » Sun Mar 31, 2013 5:43 pm

Gotta love trial and error. Great stuff so far
[img]http://i1105.photobucket.com/albums/h358/LLkoolskillet2/skillet1.jpg[/img]

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