My Project Blackfoot

Although not considered a traditional monster truck, they still have monster coolness.
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BloodClod
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My Project Blackfoot

Post by BloodClod » Sat Oct 13, 2012 4:24 pm

Bought this truck off ebay some time ago and finally got around to working on it. As I took it apart I was quite disappointed at the state it was in with many parts cracked or broken, wrong screws/nuts used, etc... Fortunately most of the essential "Blackfoot" (i.e. stuff I can't rip off a re-re frog) were there. :)

So I got to work on some carbon-fiber parts.

First up the rear end got some new parts.

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Both the mounting points of the rear shock were cracked so on the front I fabricated a new mount. On the rear I glued up the hole in the arm and made new brackets which both reinforce the arm and at the same time offer adjustability in terms of the shock mounting and rear damping characteristics.

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Both the rear outer arm brackets were shot too... so I replaced them too.

The next part took a lot more time to work on...

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Here's the bellcrank steering system I designed for the Blackfoot. I originally designed a similar system for my frog. However, the different steering geometry of the blackfoot required the design to be tweaked somewhat. The revised steering bridge, coupled with the shortened steering links reduced bumpsteer significantly and should improve handling. Here's another picture of the truck with the steering system installed.

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In his excellent thread here, Andyrt200 experimented with various ways of adapting a 12mm hex drive to the front of the Blackfoot. I took a similar route and here's the result.

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Now I can run wheels off current models like the Blackfoot III without worrying about replacements. :)

The front end is largely complete and I'll be moving on to the rear end next.

Here's a picture of the truck as she stands.

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Let me know what you think. :)
... was once the totalitarian admin here trying to be god...

BloodClod
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charliechristmas58
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Re: My Project Blackfoot

Post by charliechristmas58 » Sat Oct 13, 2012 4:33 pm

That orange is a popping. like yhe looks of the truck :D
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming to the Lord,
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Diamond Dave
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Re: My Project Blackfoot

Post by Diamond Dave » Sat Oct 13, 2012 7:10 pm

That sure does look good, keep the progress going and the pics comin!

Sure will be nice when you feel it is complete.

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andymac0035
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Re: My Project Blackfoot

Post by andymac0035 » Sat Oct 13, 2012 8:02 pm

I always liked the look of the original Blackfoot.
I agree the red really "pops".

Is that a 4-slot silver can you got there?
(sure looks like it)

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SFC K
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Re: My Project Blackfoot

Post by SFC K » Sat Oct 13, 2012 9:54 pm

I love the mods you did to this! I would love to some day replicate it on mine! :wink:
Jeff

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Re: My Project Blackfoot

Post by BloodClod » Sun Oct 14, 2012 5:11 pm

Thanks guys, glad you like the build so far.

andymac0035 wrote:I always liked the look of the original Blackfoot.
I agree the red really "pops".

Is that a 4-slot silver can you got there?
(sure looks like it)
yup! I hear they are faster than the silver cans in production today... is that true?
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BloodClod
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BloodClod
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Re: My Project Blackfoot

Post by BloodClod » Sun Oct 14, 2012 5:12 pm

Quick update... here's an experiment I worked on today - slider shafts!

I already have a set of Tamiya universals but I thought slider shafts would be cool. Machined the differential outdrive and axle to fit and voila! :)

As it was a test I only finished one side so far... will do up the other side tomorrow.

Image
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andymac0035
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Re: My Project Blackfoot

Post by andymac0035 » Sun Oct 14, 2012 5:30 pm

You might have to shorten the female (outer) shaft sleeve if it bottoms out on compression.
Other than that, it looks pretty good.

And yes! 4-slot silver cans are faster. I put a pair of them in a terminator with a Novac Super Duty XR and 16.8n nimh....and it was pretty quik. 14.4v was all they really needed, but I had more 7-cell packs that 6-cell packs at the time. They don't like 3S lipo's though..... :roll: :shock: :mrgreen:
They went really good for about 5-10 minutes.....then I smoked one of them. :|

It's kinda' funny, as I had brushless in the truck initially. 60A esc's and 3200kv motors on 2S lipo.
I had some tuning issue's and pulled them in favor of the brushed set-up.
When I posted a vid of it running the brushed set-up on 12 cells nimh, people thought it was just as fast as before.

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TamiyaTony
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Re: My Project Blackfoot

Post by TamiyaTony » Sun Oct 14, 2012 10:54 pm

Very, very nice 'Foot you've got there. This looks like it's gonna be a very inspired build. Keep us posted.
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SFC K
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Re: My Project Blackfoot

Post by SFC K » Mon Oct 15, 2012 1:26 am

I just looked through that thread by Andyrt200 and I am very impressed. I bookmarked it and will adapt some of his ideas to my spare BF...Thanks again and keep your mods a coming! :wink:
Jeff

BloodClod
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Re: My Project Blackfoot

Post by BloodClod » Wed Oct 17, 2012 3:42 pm

I managed to hook up the rest of the truck tonight. The steering system works very well and achieves 2 things. The first is near zero bump-steer. I took the following 2 pictures to compare the steering at normal ride height and with the suspension fully compressed.

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The second thing I wanted was for the setup to achieve good ackerman angles. I was able to set the steering up to my liking. :)

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Heres a picture of the rear end. I managed to finish up the slider shaft for the other side of the transmission and it all goes together very well. I've currently hooked up a 10.5T motor to the transmission and it really rips! To prevent the differential from coming apart, I did a modified "oldfrogshot" mod - managed to do this without drilling or tapping any screw threads and I managed to install a thrust bearing as well for smoother diff action. Everything is held together with a locknut so I don't have to fiddle with locktite and yet the diff is easy to service when needed. No pics of this as I was too busy putting it altogether but I can try to take some photos later.

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Electronics include a 120Amp hobbywing esc.

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Here's the truck as it currently stands. :)

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This is the shell that it came with. It's got scratches and is well worn but structurally is in great shape for a restoration.

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Some rain today made the local track too wet to run the truck there but I did test the truck on the road and initial impressions were very good. The steering tracks very straight and steering is quick, responsive and consistent. The 10.5T seems a bit too fast but I've got to test it on track to be sure. Even on the high grip tarmac the truck seems to handle pretty well without ever feeling too top heavy.

So the first run was a very positive experience. I'm hoping track performance will also exceed my (somewhat low) expectations. lol!
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BloodClod
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Kingclod27
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Re: My Project Blackfoot

Post by Kingclod27 » Wed Oct 17, 2012 4:07 pm

that is one of the cleanest chassis's Ive ever seen...Very nice truck sir
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BloodClod
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Re: My Project Blackfoot

Post by BloodClod » Mon Oct 22, 2012 5:48 am

The rain still comes and goes just enough to keep the offroad track wet. :(

The truck has been a blast to run everywhere else though. lol!

I was checking up on the diff and took a picture to show my take on the "oldfrogshot" mod.

I started with the stock outdrives and like everyone else just carefully tapped the center shaft out of the "long" outdrive.

After machining the outdrives to fit the slider shafts, I used a 3x40mm screw (I found this in the Tamiya mini4x4 section) which fits through the stock outdrive holes without modification.

A spare thrust bearing from my Tamiya 501 spares was fitted next to the screw head and then a locknut in a plastic diff nut retainer was used to tighten up the whole assembly.

The funny thing is I found the diff nut retainer on a parts tree on my table but I have no idea whatsoever as to which kit it came from. The tree is labeled "F" and has some other plastic 3mm nuts on it but other than that has no other identifier.

Anyway, this assembly does 2 things for me - firstly with the thrust bearing in place the diff action should be smoother than simply letting the screw head spin on the outdrive during diff action; and secondly, with the locknut in place adjustments and disassembly are easier.

The bad news is that you probably can't do this on the stock outdrives dunning the Tamiya universals or stock dogbones - this is because during the suspension compression the driveshaft plunges into the outdrive quite deeply so it may interfere with the diff screw and nut. I am able to do this because only because of the slider shafts.

Here's a pic... I'm sure someone here will find a way to maybe do this to work with the stock bones.

Image

:)
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BloodClod
email: bloodclod@hotmail.com
website: http://www.cool.per.sg/bloodclod

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SFC K
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Re: My Project Blackfoot

Post by SFC K » Mon Oct 22, 2012 9:05 pm

That is a great idea! I ran mine yesterday and noticed a lot of chattering in the rear case. Does your truck do the same with the new sliders? Mine is driving me nuts and it is hard to tell where it is coming from other that the case. I really don't want to take it all apart again.

I wonder if the outputs are moving in and out causing it? If I tried out your mod, I would have to figure out something for the locknut end... :?
Jeff

BloodClod
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Re: My Project Blackfoot

Post by BloodClod » Tue Oct 23, 2012 8:53 am

SFC K wrote:That is a great idea! I ran mine yesterday and noticed a lot of chattering in the rear case. Does your truck do the same with the new sliders? Mine is driving me nuts and it is hard to tell where it is coming from other that the case. I really don't want to take it all apart again.

I wonder if the outputs are moving in and out causing it? If I tried out your mod, I would have to figure out something for the locknut end... :?
If your gearbox is chattering then chances are it's the bevels in the diff skipping. It's a common problem with this gearbox as the metal gearbox sides warp under heavy load and can't hold the diff together. The so-called "oldfrogshot" mod was thought up by a friend of mine and is rather popular with these gearboxes. His mod involved a 2.5x25mm countersunk screw threaded into the opposing diff outdrive and held in place with a good dose of locktite. I simply improvised his mod to include a locknut and thrust bearing. Same principle - essentially securing both diff halves together to prevent them pulling apart.\

I think you could get away with my version of the mod if you could find or fashion slightly shorter dogbones.
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BloodClod
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