Muckmudd's 2018 Build off "Astro Rat" [2018 Build-Off Entry]

I'm thinking
0* toe
0* camber
10* positive caster?
What do you guys think?

That sounds about right! There should maybe be some KPI to help with weight transfer when turning at high speed.

I think you'll want a degree or two of negative camber. Don't go full ricer, but widen out the base just a hair

So have the king pin tilted but have the camber be at 0*
KPI is like scrub radius or something like that right?

I assume by "scrub radius" you mean ackerman angle? Where the inside tire turns just a little bit sharper so it can make that tighter turn?

Haha CQ. You know I even considered it for a minute just for the stance and look but I still want it to steer properly. You think a few negative degrees would help?

I thought ackerman angle was where you put the tie rod tabs according to the length of the frame and that triangle you make with the king pin and the middle of the back of the frame?

KPI stands for King Pin Inclination, it's basically the angle of the king pin off the spindle when looking from the front of the axle.

I think just a degree or two, and maybe one degree of toe in. I think that helps it track straight. nothing crazy or you'll just wear out tires, but I think a degree or two is good

Yes, that triangle between the spindles and the center of the rear axle is ackerman angle

Well that degree of toe in is always adjustable at the end with the tie rods so i'm just gonna forget about it until I get there.

@muckmudd The direct steering in that first video that you liked seems like a good setup for speed so it should fit this rig. Imagine that the steering shaft is kinda like an axle, it will need a bushing or bearing at the top and bottom, and some means to keep the shaft from moving up or down, this is usually some kind of shaft collar. I used to believe in eye-balling a little toe in until I actually aligned my tractors with zero toe in or out and they handle so much better now. KPI helps the wheels return to the straight ahead position while driving. My Wheel Horses have a lot of KPI and I have definitely experienced this phenomenon. It helps the wheels come back to straight when exiting a turn.

Yeah. What's a good amount of KPI? I will have to go fins some bearings and start working on the front end pretty soon I guess since I don't have much else to do before I can get proper pulleys, my chain in the mail and work out some drive train stuff.

i’m getting close to building my front axle for mud rat so I will measure the KPI on the wheel horse spindles that I’m going to use for it.

8*-10* KPI is good to use. It's what I have on Mutt. I added like 2* of positive camber too while I was at it, but you don't have to do that. I think I added 10* (ish) of positive caster too, it's helped a good bit.

I just measured the Wheel Horse KPI... it was 9 degrees right in between 8 and 10.

Ok I will add some KPI as well guys. It should keep it on track. I'ts not gonna be the most accurate though I can tell you because its proably just gonna be somewhat eyeballed lol. I'll try my best to make them the same on both sides at least.

you don't have a protractor laying around?

Yeah but i'm sure not going to be whipping out the dial indicator and the digital micrometer haha.

You can get close enough with a protractor. Don't have to go into trigonometry with it lol.

Ok then we're good!

Just checking in to say that the build is sorta on pause 'till I clear up some space and take a break with fixing and selling yard equipment. It's just the season right now and it's very busy. I am Still trying to find out where to get a 9" pulley with a 1" bore though...

Thanks for the heads up!

Not much done recently but I am gathering parts and thinking. I might get a local shop to make me a 9" pulley to fit the engine. I painted some stuff that started to rust and I think the front grille looks mint. I am planning on welding in the rear axle and mounting doing some painting this weekend. I started on the front axle and I removed the old one. I will be posting more pictures now that I have a phone.

Oh, yeah, the main reason I posted the sprocket was to ask you guys how I think I should attach it to the axle. I don't think that welding 2 lock collars on and screwing it in the axle would hold it well enough. Maybe I should cut a little key way and slide it in? if I did that though, I would have to file a slot in the hub.

If you don't need to take it back off the axle any time soon, welding it direct would be an option. I know it's kind of a hack job way to do things. But depending on if you think the axle or gear will need to be replaced often, it might be a good way to go. A key would be nice, but sounds tough to file a key way into the hub. Are you using a keyed axle? Maybe you could weld on keyed collars and put keys in them? As in, just have the key next to it, or on both sides?

Yeah I was thinking of that too, however I think that its just as hard as cutting a slot into the hub as opposed to cutting it in come collars.