Topic: "L" Spindle set-up

[Rooster]

Well we started the front axle today, should be all welded up tommorow. Although I can weld, for a piece this important I left it to my friend who is a welder by trade.
I decided to not use the heim joints, as I may be pushing the rules as it is, lol, if this when passes my next one will include the adjustabilit of heims.
The stock craftsman axle had 10* of KPI built into it, so I left it at that.
Tracking width was 36" stock, our rules allow up to 42". I marked the axle tube even with the chassis, then cut it off 2" inside of that. These "stubs" mount to a plate on the outside of the chassis and a 2x2 tube welded between the plates on top of chassis for a brace. This should give me a 40" tracking width.
If I ever decide to use this mower in a ARMA race, I can move the inside hub in 1" per side.
The stub axles were welded in with 13* of caster. The mower will have 1-2" of rake in it so actual camber after lowering the rear should come out to between 11.5 - 12*. Depending on the actual finished rake.

I took some pictures, but having problems getting them into computer.

Thanks all for the help, as you can see I took advice from everyone. Hope it works well!

[Wheelhorseracer]

That should work fine...

Sounds like you took in the info here and made great choices for your build...

[Rooster]

Thought I'd add some pics.
Here is what I started with.

In stock form it actually had a few degrees...forward caster(I'm not sure, never heard of caster refered to as + or - ?)

This photo simply reference for placement. You can also see the 10* built in KPI.
Hope to have photos of completed rebuild tommorow.
"Weld shop" was closed today. Buddy had to work and we had storms all day.

[Wheelhorseracer]

Positive caster is when the kingpin tilts backwards... it causes the wheels to come back to center easier, and in our case helps with the jacking effect. BUT... excessive positive caster will cause a lot more of the tracks irregularities to be transfered to the steering wheel and will cause a toe in condition if you use bushed components in your steering. With the use of heim joints this will be minimized as there is no chance for deflection in those units. If you run different caster in each side, you will feel a pull to the side with the least amount of caster.



Negative caster is when the kingpin tilts forward. Think of a shopping cart.. when you increase the speed the tire begins to wobble uncontrollably. It is difficult to drive. It makes the steering very wobbly.

Most of the time you can run the positive caster angles the same on a tractor, where cup and other stock cars will split the angles from side to side to increase or decrease the turning ability of the front tire on corner entry. It is possible to see cars with as much as 6 deg in the left front and only 2 degrees on the right front.

I'm running an aggressive set-up with 10 degrees of positive caster and 12 degrees of KPI. It is difficult to turn the wheel without the tractor moving, and will still give your arms a work out during a race...

[Rooster]

Well finally got some pics of almost completed front end. Still alot of work to do rearranging drag link and tie rod to clear frame. Tie rod will have to go to top front. Pics aren't the best, but for a camera phone in my dirt floor garage they are best I can do.

Here is a front view of the new build

An attempt to show the caster....the square plates will get the corners cut off and look much better.

And from above, it is hard to see. The rear has not been lowered yet so as of now it only has about 3* instead of the built in 13*

Well, building gurus...am I ARMA legal?

[George Herrin]

Learn to do them as a thumbnail so dail up guys can see em... I don't wait on pics to down load.

[Wheelhorseracer]

That looks really good...

BTW... I hope you are not running the stock bushings in there... they won't take the abuse and will deflect during a turn... I'd hate to see you gouge the kingpin and have the spindle break off during a race...

Maybe you could put a steel bushing in there and add a grease fitting at both ends of the axle to allow you to grease them?

[Rooster]

Sorry, I thought I was doing pics right...will read tutorial again.
Was planning on building bushings and grease fittings. I am thinking , with a little modification, some old Trans bushings will fit. Not being cheap here, never cheap on safety oriented stuff, but thinking more of the lubricating qualities of the material.


 

Heres the thumbnails for the other pics.....I am not getting the "modify" option for that post...guess because I have posted after I don't know. Could one of you moderators change them?

Sorry...LOL..got it down now, wasn't using right code.

[George Herrin]

Looks like a stock axle except you raised it and changed the angles a bit. Hope it holds up under race conditions. I have seen em break under mowing conditions.

[Wheelhorseracer]

That's a good point... aren't the stock ones just sheet metal bent into a rectangle... with the side forces put on those you might want to upgrade to a heavier square tubing..

Then you can drill for a good bushing and put you king pin right through and know it will never break...

[cycloneracer]

I highly recommend starting over.  That stock axle won't take it.  They are simply pressed steel.  On my first racer I used the J spindles.  I took a piece of 1X2 square tube and got double wall pipe that the spindles would fit into.  I then notched the box iron so the pipe would set in the box.  Welded it all up solid.  Just be aware that if your pipe is to close of a fit before you start to weld it won't fit when you are done.  You will shrink the double wall pipe when you weld on it.  I had the machine shop mill the pipe out or you could drill it if you had a GOOD BIT and Good Press, so it had about .050 clearance BEFORE I welded it together.

Hope this helps
Paul

[Rooster]

I am the machine shop...sooo that won't be a problem.
Yeah it is a stock axle.....so you are probably all correct.
I will have to check into the rules.
Basically what I was trying to accomplish was the same thing that I have seen on a couple of other mowers there, only a little more engineered and alot stouter than how they had done it.
BUt you guys have a lot more experiance, and you don't think it is safe, so if they're rules allow it ...I like grinding anyway Lol.
Most of all I hate hospitals....a few more hours in the shop= a few less trips to the ER!

[Wheelhorseracer]

Do the rules allow you to widen the front and rear axles? Some have a maximum allowable width  This would be the best time to do that.. if you are allowed 42 inches or anything like that it will make it drive better... but only if the rules allow it....

Also you would be able to lower the front end... would they allow the L to be inverted so that it comes out at the top?...

[cycloneracer]

Which group are you planning on running with?  The Kansas Outlaws, the Midwest Lawnmower Racers, or Semow?

One other tip,  Keep the top of the beam the same level as the top of the frame.  It will make your engine mounting a lot eaiser.  To get the drop you want with the J spindles make the ends of the axle go up once it is past the edge of the frame.  So you won't have a straight beam, it will be kinda U shaped.

Later
Paul

[Wheelhorseracer]

Good point....