Technical Front axle alignment on 30 Tudor.

So, when are you going to loosen the u bolts and try to square the front axle?

That's the advice I'm seeing above, all other measurements being accurate.

 

Hopefully tomorrow. I've been working on the rear suspension and will need to move the car to gain good access to the front.

 

OK, stop right there. You adjusted the rod ends in/out to get the axle in its current position being 1.5" out of square? Why would you do that, and then ask why your axle is not square to the rear axle centers? Model A frame rails aren't parallel, so are you determining the axle is "out of square" with the frame rails, or the center of the rear axle? What points are you measuring from? Is the frame square corner to corner? In other words, right front to left rear, and left front to right rear? There's so much you've left out information-wise that it's impossible to know what you're doing, and why things aren't, or don't appear to be right.

 

Right. So the question I have is why would one adjust the rod ends that way? Why not just do them the same and make the front and rear axles square with each other. It doesn't make sense.

 

So you can go around a corner faster? Only works one direction though.

 

I’m assuming that he’s a little new to this and bought a never finished project. Didn’t realize the axle was canted until he had to adjust the rod ends differently. Now he’s looking for advice on how to correct the axle, which he has now received.

 

Everything has been stated as being square and correct........... except the crossmember. There has been no mention as to whether the crossmember is in fact perpendicular to the chassis centre line.

 

Throw that puppy on a trailer and take it down the road to @marty Stroud. He can straighten you out and fix whats wrong.

 

It sounds like he will be ok once he gets that front spring U bolts loose and moves the axle so it will be straight in the crossmember.
BUT, we don't know what front axle and spring is in the car, I have a '46 axle and spring in mine and the spring is a little wider than the stock Model A spring. I don't remember what I did to make up for this but I had to do something so the spring would fit as it should into the crossmember. Also isn't the top spring (even on a Model A) leaf tapered on the edges so it fits the radius of the inside of the crossmember? I just mention this stuff so the OP will be aware of things that may cause some interference when moving the axle.
one other thought, is the axle "centered" in the frame? end to end? are the shackles at equal angles?

 

If I read the OP correctly, he cross measured the frame to determine it is square, as much as the engine and trans allowed. I take this to mean he was not able to measure all the way to the front cross member. So perhaps the front of the frame is tweaked and not square?

 

Maybe go back a couple steps.
Drop four corner points on the frame to the floor and get your diagonal measurements without interference from the drivetrain.

Once you know the frame is square, establish a reference point on each side that is the same. Bottom rivet on the front body mount on an A frame usually are even. I mark that point with a centerpunch mark.

Use that point to measure to the front axle at the perch bolt. Loosen the U-bolts and square the axle (there is room for the spring to move around in the crossmember). Adjust the wishbones to fit and if everything is right they should be the real close to the same length. Then measure to the kingpin, should be pretty much equal unless the axle is bent or ?.

Use the same point to square the rear axle. Then measure between the front and rear axles and that should be the same; if not go back and see why.

You don't mention the type of wishbones; but if they are Model A and you mounted them with bolt-on Speedway mounts your caster is probably way off. Check with a angle finder.

 

Once the bolts are loosened it's going to take 3/4" adjustment on each side to get the axle squared up. One side pulled back, and the opposite side pushed forward. 1.5" is a lot, but you wont take all that up from one side, just half at each side to fix it.

 

Used to skew the front axle on the sprint car about 1/2 in.

 

Update:

Today I had a chance to work on this.

I raised the car so the axle hung free. I then popped the rear of the wishbones (adjustable) from the brackets and loosened the front spring u-bolts.

It took a little muscling (especially for a disabled old fart) but I was able to shift the assembly and get the axle ends within 1/16 of an inch of each other. I'll tweak a little more.

Thanks for the guidance everyone. I learned quite a bit.

I didn't want to go into excruciating detail at the beginning, because I had already done the equivalent of what many of you recommended as far as checking for the frame being square, etc. I knew the front spring and axle were not square with the frame. I didn't know if there was enough play in the spring/frame area to rotate it, or if that's the way to solve the issue. You answered that.

Now for the rear end - I'll start a new thread for that.

 

Good for you.

 

Thanks - I did use the Speedway bolt on mounts. I'm not thrilled about the caster - it looks like I need to drop that mounting point a couple more inches to get it at a decent caster. When I can find someone to make mounts with the right drop I'll do it.

I figure I'd attend to that once I solve the front axle angle issue (which I just did)

 

That’s a good report! These cars are pretty dang simple. You’ll pick it up quick.

front axle should have about 7 deg caster. I generally check at the top of the kingpin

 

We usually pie cut and weld the wishbones just behind the yoke to correct the caster; this keeps them decent looking instead vs hanging low and appearing out of place.