[2020 Build-Off Entry] AK's Jacobsen Rally Tractor Build!

Well I might as well go at it again this year... I tried to sell this tractor to no avail, so here it is!









Going for a crawler build here, but gonna try and keep it fairly simple.

So far my crazy ideas are:

- 18hp Kohler Magnum in place of the original 14hp Briggs.
- Kenda Scorpions staying on the rear and off-brand 21" tires up front.
- Allis-Chalmers B-110 front axle and a leading arm/4-link front suspension setup. (Tim Cameron style )
- A nice rugged gearbox steering setup (still need to find one)
- Keeping the Foote transaxle but rasing the frame off it about 1", and probably attempting to fix the dual ranges.
- A couple heavy skidplates.
- Bumpers front and rear, maybe some lights too.
- Brake setup is still to be decided

- *SEPT 26 - CHANGED PLANS TO RALLY TRACTOR BUILD (Page 4)* -

I'll probably think of more stuff, but that's the basic idea so far!

Good luck to everyone else!

Approved MightyRaze - Feb 9, 2020

Welcome aboard the 2020 Build-Off!

Heck yeah! Sounds like a good plan.

Nice! Whatever plan you go with for the brakes, just make sure they're reliable (as I know you will)... I'm very experienced in what happens when unreliable brakes are in use..

@Murraymountain yeah you got that right. I've used many of trees for brakes at the bottom of my back yard over the 14 years of living here. Sketchy steep back yard straight down to a 12' drop off down to the road. Never mow in the morning when dew is in the ground lol. Really not fun either way. Brake traction going down or brake traction going up.

[adm]Unlike most of the other topics where we have some lenience, let's keep the build-off topics on target. Makes review at the end of the year easier!

Thanks...[/adm]

Well I ended up getting the engine bolted down, and did a little mock up with the front wheels:





Not too bad! The track width is a bit narrow in the front though, as you can see:



I'd like to widen it a bit when I put the Allis axle in, which I should be able to do by spacing the hubs out a bit. Also the new axle will be about 4" further forward than the stock one, so that should make things a little better as well.

So far it looks like most of this should be pretty straight forward. Let me know what ya think!

@AllisKidD21 looks great. Arw the rears the 22x10x8 or the 22x11x8 Scorpions?

Thanks, they're actually the 20x10's. I thought they would look okay but now that I see it with the new fronts I'm thinking they are a little on the small side. Might have to invest in some new ones!

@AllisKidD21 They looked abit small but didn't cross my mind they could be the 20s.

Little bit of progress today. First thing I decided to address was the part of the grille where the hinges would usually be, as it was broken off. Since this thing already has a hold down at near the dash I just made a simple little bracket to allow it to be kinda locked in at the front, then just bolted it to the grille.



The slot fits around this little shoulder bolt at the front of the frame.





 
Works good! Wanted to get the front end setup mocked up a bit next, so I dropped the front axle.

The center pivot was crazy wore on this thing, already had about 3" of suspension travel!



Then the Allis axle:





Looks like it should work nicely! Did a little mock up with some old shocks too, just to get an idea of clearances:





Looks like I should be able to made it work. Also after some thinking and checking clearances for link bars, I decided to scrap the leading arm idea and try out one of the 1-link setups that seem to be quite popular. I think it will work out nicely and should be pretty rugged if I build it right.

Hopefully I can get started on it soon!

That allis axle is pretty slick, cant really tell it's been moved forward.

Your hood is in way better shape. Mine isn't fixable where it broke. The stretch looks stock with that thing.

That axle is sick!

Thanks fellas! Yeah it's hard to beat those Allis axles, one thing that makes it perfect for this build is that the ends with the spindle knuckles bend back:



That puts the wheels a little closer to where they were originally so the wheel base isn't too long, while still being able to have some suspension travel because of the axle being past the front of the frame.

Should work great by the looks of things!

Got some parts for the Jake today so I made a little bit of progress on the front end situation.

Basic Princess Auto coilovers:



Not the most rugged units and not really made for long travel, but I think they should do the trick.

First thing I did was perform a little spring rate test with the engine in place to if they would be too stiff.



They sagged a couple inches once the jack fully dropped so I think they should be perfect for this application.

Going to go the 3-point center link route for the 1-link joint, then some 1/2" steel to make the mount bracket:



3/4" bolt to hold it in place, should hold up.

Flipped 'er up for some underside welding:



Got the tabs welded to the crossmember, and the whole thing is only tacked on as I'm not positive that's where it'll stay. Might be okay though.



Should be heavy duty enough, haha. Tomorrow I'm gonna start on the wishbone and them maybe even get the coilovers mounted up. Let me know what ya think!

you going with a panhard bar or a triangulated 2 link to prevent the axles side to side movement, or do you have something else in mind for that

Yeah I'll have a track bar for sure, even for a triangualted two-link I would think it would be neccessary. This one is only a one-link setup though.

i was thinking more along the lines of 2 links going to the center of the axle to the outer edges of the brace where the 1 links is, or 2 links going from the frame bracket for the 1 link on the frame to the outer edges of the axle

Ah... kinda sounds like you're picturing a triangulated 4-link setup, that's what you get if you have both of the link setups you mentioned put together. A tri-4-link is indeed run without a track bar as the two different triangulations keep the axle centered.

However, for a 1-link like I'm building, a track bar is required.

what i was picturing is more like a 3 link, something like this except no panhard and with the 2 side links coming to a v

Made some good progress so far today! After I got everything configured, I cut out my wishbone pieces and tacked them together:



Used some nice 3/16" wall tubing, should hold up nicely.

Tacked welded to the axle:



Looking good so far!



Flipped it back up again to finish welding the mount, and I had to cut away at the old exhaust deflector to for some clearance.





Then with a block of wood between the axle and frame, she was sitting on all fours!





Pretty happy with it so far, I think it should work out pretty good. Still have to do a little more bracing, and figure out a way to jam the threaded end from turning, but that stuff should be easy.

Next up is coilovers and track bar. Let me know what ya think!

Done well bud

Nice, Big nut to stop the threaded end moving  LOL, Honestly, I don't know if there is a real concern for that movement.  I don't think it would twist enough to change the length of the monolink.  It would always revert back to where it was.  Only concern I can think is dirt wearing it down over time.

Looks good man. Makes me wanna build a rock bouncer now...