Amphibious Tractor

A fine winter romp from yesterday.


Notes for my sanity:
-Need cushioned front Walking beam stop ~4" travel due to crazy endos
-Steering brakes, way to allow fluid from master cylinder reservoir to accommodate pad wear
-3/8" rebar chevron grousers (cannot road these) or angle iron track extensions for winter.
-Foot throttle too sensitive, needs dampening/resistance for rough romping
-Look into high speed engine stuttering

RichieRichOverdrive wrote:

How's the vibrations with the engine mounted solid like that? Or is it mounted solid?

Its on stock motor mounts.

RichieRichOverdrive wrote:

That's awesome man! I can only hope to do something of that sort one day myself

I'm sure you will!  

Your tracked machine is just so cool! Pretty fast already!

That thing sounds so good!!

The tracks kind of look like a german tiger, especially in the front where they come up. Sounds super cool. Wish you were going to put a tank top on it, but it's still really neat the way it is.

3000.00, Wow, that's cheap. I got that in mine already and I still can't drive mine.

prancstaman wrote:

3000.00, Wow, that's cheap. I got that in mine already and I still can't drive mine.

Now dont beat yourself up, for your one scorpion I went through three builds lol. Many components I reused from previous builds which exaggerated the low costs.

Interesting side note, I broke the 25mph barrier today in the Amtrac. Also i learned a valuable lesson in allowing master cylinders to vent back to the resevoir. Had to let the brake fluid cool down to relieve pressure off the poor steering brakes.

I don't understand what went wrong with the brakes. Did you block off some kind of stock vent to start with? Shouldn't stock parts be good to go?

mr.modified wrote:

I don't understand what went wrong with the brakes. Did you block off some kind of stock vent to start with? Shouldn't stock parts be good to go?

Since I am using cheap clutch master cylinders, they do not have a check valve from the reservoir to the piston. I was running into large travel distances on the steering lever, where they wouldn't do anything until the lever was pulled back 3-4". I added a stop on the steering levers that kept the piston ahead of the reservoir port so fluid wouldn't bypass back into the reservoir anymore. Heat from constant steering, expanded the brake fluid in the now closed system putting a constant pressure on the brakes, until the fluid cooled. At least that is what think happened, because once it cooled the brakes weren't locked up any more.

Bear in mind I am turning a 2500lb machine off the diff, which creates a lot heat. I think in hindsight, actual brake master cylinders would be the way to go. For now though I am just going to baby it . Also when I rebuilt the brakes off the junkyard Ford 8.8 I put these brake pads on so they are extra friction(y): http://www.rockauto.com/en/moreinfo.php?pk=274261&cc=1362451&jsn=755

But now I am rambling...

Yes, if you have the piston past the feed hole for the system, the fluid is pretty much trapped. And yes, if the fluid is heated, then it will expand and actuate the brakes. From thermal expansion and retraction of the fluid. It doesn't take much since the pads are pretty much hugging the rotors when not applied.

I handle tech calls at my job about brake systems, hear alot about this because someone forgot to adjust the brake booster push rod, drive the car for about 10 minutes and the brakes are locking up and let go when cooled.

Master cylinders would cut the movement too with bigger pistons. I talked to this guy before Christmas, he used a master cylinder/booster for his clutch, just because it uped the volume. It was an S10 with an LS in the bed and a manual transaxle, Pretty slick.

Great to see you back frosty, latest version is looking pretty good!

Oh now I see. So then also, with the piston in the master cylinder partly pushed in already, fluid would not be able to keep up with pad wear either right? It's like the reservoir is isolated.

Wow, this thread is becoming a throwback members thread. Great to see the posts.

Lovin this build. Good to see something different from time to time.

I really like the way you think

Keep up the great work!

Another romp video I made for fun.

mr.modified wrote:

Oh now I see. So then also, with the piston in the master cylinder partly pushed in already, fluid would not be able to keep up with pad wear either right? It's like the reservoir is isolated.

Exactly! I think what I'm gonna do is try a higher quality clutch master cylinder first (like an Aisin) and if that doesn't work I'll bite and go with larger brake cylinders.

That thing is frigggggin nice. When you gonna paint it?

mr.modified wrote:

That thing is frigggggin nice. When you gonna paint it?

I still have quite a bit of modifications that I need to weld on, so probably late spring I will start painting it.

Today I got the machine stuck down in the gulley, went down fine, but not so much going up lol.  The problem is without grousers, it can't bite in the frozen ground so it just spins track.  My original exit route was an old shallow grade access trail, but it must've washed out because there was a good 5ft drainage ditch going through it.  So I will borrow some chain from work this week and pull it up with the D2.  For now it will rest where it is tarped up.  Its good to learn the capabilities of your machine though!

Excellent. Got my vocab for the day too. I knew what you were talking about in the context of the writeup; I now know what a grouser is. LOL

Forgot to completely weld one of the track guides fully hawoops. Also did a twist and turn test to check track resiliency, it passed!

Got a loose lugnut in there. Looks like.

mightyraze wrote:

Got a loose lugnut in there.  Looks like.  

You are so observant!  

That thing is a tank, not a tractor dude!  So cool.

Looks like easy problems to have. What's the latest on the surging? The motor sounds okay to me in the videos.

mightyraze wrote:

Got a loose lugnut in there.  Looks like.  

Hehe, yeah a lotta stuff is loosening up, sprocket tooth bolts, idler clamp bolts etc.. I guess thats why they invented red loctite lol

Crazy_Carl wrote:

Looks like easy problems to have.  What's the latest on the surging?  The motor sounds okay to me in the videos.

I cleaned the carb and the surging went away for the most part. For some reason though the engine is very cold blooded. If it isn't above 40° you gotta use ether to start it. At this point though I am satisfied with its operation and I'm probably not gonna stick anymore time into it.

Yesterday I took the tractor through the partially frozen swamp.  Does pretty good as an ice breaker!


Leak spotted comrade!!!