TECH: Drop tube axle and jig

I am building a Dragmaster style dragster. I have an orginal to copy. And when it came time for the front axle I use the orginal Dragmaster axle as a pattern. And used a ford axle as material to make a jig with. The dragster axle is shorter than the Ford so it needed shortened. So i found the middle of the axle and measured on each side of it and took out the same amount on each side. Well I messed up damn tape measure must be defective or something. ha, ha. But it dont mater all its just a jig and the middle isnt the importiant part any way. Then I put the king pins thru both axles to hold them together. Found a piece of 2x3 .125'' and cut the top out of it and set the ford axle down in it and welded it in. Now the jig was finished time for making the real axle.

 

For the axle material I used 1 5/8'' .120 wall 4130 moly. Put it in my bender and bent both ends. Then Tom Masa machined me the king pin bosses. Took the axle to work and put it in the mill and fish mouthed it to accept the bosses. I suppose this could be done in a drill press with a hole saw too if you had a big enuff vise to hold it. Next I dropped the king pins thru the new bosses and into the jig. Set my tube inbetween them and welded it. Got my self a dragster axle.

 

Simple, elegant solution. From the looks of that jig you are getting set up to go into production. Weld is impressive to.

 

That came out really nice. Good job. Can't wait to see the rest of your dragster.

 

HA HA! You had to do math, sucker...hehehe...looks great bro, makes me wanna steal a TIG welder and learn to do chrome-moly...

 

very nice!!!!!!

 

Great job! Thanks for sharing how you did it....

 

how straight did they end up after you pulled them off the jig?? I had a guy build up a similar jig to build midget axles for me. the welding process would tend to pull them out of alignment about a degree between the two of em.

 

Great work. Your going to the top

Rusty

 

Nice work . Thanks for sharing .

 

Nice job KING.

 

Now you need to make a jig and copy the frame!

 

btw, off topic, but are you the same "king chassis" that makes mini/micro sprints??

 

Question, how do you remove the axle from the jig with the caster you have in the kingpin bosses? It does'nt look like you could get it off after welding it.

 

looks like you tap the kingpin out of the ford axle

 

That's not caster.

 

Caster, camber, I always get the two mixed up. You should see me try and align a front end! LOL.

 

nice work! pretty soon, i won't be able to afford your help...

 

I dont know. I will have to look at that now you mentioned it. Do you mean like caster or camber changes? The camber must be ok because the king pin comes out easy. I will have to look to see if there is different caster. Thanks for postin that question.

 

Yes there is a hole in the bottom of the jig and you tap out the king pin.

 

nice tech! you almost make it look easy!

 

It's neither. It's king pin inclination.

Excellent post Brian!!! Gonna copy that procedure here in the next few weeks.

 

No, not me. I tried to buy that domain name and those guys have it already. I think Im gonna send Vinney over there with a Louisville Slugger and take care of some business. ha, ha. Looks like those guys build some nice sprints!

 

KERRY just pointed out that it is called king pin inclimation.

 

Yeah, if you look at the spindle note that spindle isn't perpendicular with the kingpin. I forget the real purpose but I believe it helps them come back to center.

 

Here's a better description from Wiki

The kingpin inclination angle, amongst other thing, creates the phenomena of the return of the wheels to straight position after a steering operation, it also tends to maintain this position after an impact with an obstacle that attempts to alter the trajectory,

This natural effect, which is vitally important, due to the inclination of the kingpin, derives from the fact that the wheel, when turning about this oblique axis, forms an inverted cone,

The hub is at it’s highest point relative to the ground, when the wheels are in the straight ahead position, when steering to the left or right, the hub lowers down nearer to the ground, consequently the wheels would tend to go beneath ground level, as they are unable to do this, this causes the body to rise up into an unstable position, thus, when turning the steering wheel, the driver not only generates the turning of the wheels but also, because of the weight of the vehicle, causes the raising up of the body, as soon as the driver ceases with the steering action, the body, due to the natural tendency by its own weight, goes to it’s lowest point, with this movement, causing a turning action which takes the wheels back to the straight line position, obviously, the heavier the vehicle or the bigger the kingpin inclination, the greater will be both the force exerted by the driver in the steering action and the speed with which the steering goes back to the mid position,

The evident result of this is that the weight of the vehicle tends to take the wheels to the straight line position.

 

I'll always want to help you Steve. Your the man!!!!

 

I ran into a distortion problem on the kingpin bosses that I accurately machined on a lathe. I welded them to the fish-mouthed tubing without the kingpin in the hole (jigged it via a different method). The KPI ended up bang on. The kingpin would NOT go through the boss. The cooling weld had distorted the straight hole through the boss. Guess it will end up being a light duty trailer axle some day.

 

Couldn't you just ream the holes out? They can't be off that far. And it doesn't have to be perfect since the kingpin is locked by a setscrew in the boss.

 

are your King Pin bosses made out of 4130 aswell? or did u weld 4130 to mild steel? heard that was unsafe...