Technical Model A front spring question

So, how does one know if the spring tension is the same on both front wheels without scales? Reason I ask is my car sits crooked and it’s driving me nuts. Rear air bags, one solenoid so both have same air. Sits 1/2-3/4 low on rr. For some reason I suspect the LF tension. Little thing is so light I think even shock tension could have an affect.


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Sometimes if you crank up on the two "U" bolts that hold the spring in the crossmember unevenly, it can cause a slant. Loosen the nuts and see if it evens out.

 

A newby came into my shop with this problem, back in '78, before the Posies and others started making the 'short order rod parts'.
A spring company had reversed eyes on his main leaf, a quick glance told me the main leaf was not symmetrical.
Measured it, removed the spring: Main leaf was 1.25" longer on one end.
The guy wanted to just drill another centerbolt hole, but the leaf was more curved on one end, just a mess.
I could have warmed it, anvil'd it, and reforged it. But why?
Wayne Blechl's '34 store had a stock of reversed eye mains, from a reputable spring mfr. The leaf cost $28.00! Just another story from the archives... LOL

 

Yes, check U-Bolt adjustment length. Next, if you still think it's the Spring take it out and swap it around and re install. If it now sits low on opposite side you'll know it's the spring. For sure measure from center hole to spring eye length. Common issue with old springs being re worked.

 

That makes a lot of sense. I’ll give this one a chance to settle a bit maybe. Car hasn’t actually been driven yet. Just got it running last week.


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clamp the main leaf in the vise exactly in the center with a piece of angle iron or other straight edge with it, now measure from straight edge to spring eyes, they should be the same on each side

 

This would be to check and make sure the Arc is correct. You still need to make sure each half is same length.

 

You should have two pair of solenoids. One pair, for each side.

If you only have one, how do you get air out?

If you have a tee'd line, there is no inherent roll control, and no ability to hold the rear at level.

 

One fill solenoid and one vent. I thought about putting another set on it to compensate.


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You should. It will help with the leveling issue, and it will handle way better.

 

So if there is 50 psi in the bags on a tee’d system isn’t there always 50 psi in both bags? It can’t move from one to another. It balances.


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No, Physics does not work that way. Air can very much move from one bag to the other.

If go around a corner, the body will roll to the outside, placing a higher load on the outside bag. Since it is currently plumb directly to the inside bag, the outer bag will be collapsed, as all of its air will be pushed to the inside bag.

This will promote body roll. It will also prevent the rear from ever holding level.

Unless you are on perfectly level ground, have the corner weight perfectly balanced in the front, and never move the car, your car will never be level.

 

Since you have an "A" front spring/axle assy, you'll have to devise a rig to use on your floor jack in order to reach in above the axle and raise the front of the car, picking it up by the crossmember, all on level floor, of course, at the center of crossmember.
If the rear is still off, you'll know your problem is in the rear susp. If it's level, yes it's in the front.
Air bag susp. with the bags tied together on air line can, as Gimpy says, make for spooky handling.
I had an OT '94 Lincoln MKviii with air bags all around and the rears were tied together from the factory. Long, sweeping high speed curves could be spooky until you got accustomed to it. Going into the turn, you could feel the outside rear corner drop as you entered the turn and the air bags offered none of the roll resistance you get when the susp. is not tied together and equalizing. Quite disconcerting till the front and rear anti-roll bars caught up and transferred the pressures and added some roll resistance. Once you got accustomed to it, all was OK, but without the anti roll bars front and rear, it would have been dangerous.

 

Does the spring bolt show through the hole in the crossmember?

Charlie Stephens

 

I’m not doing any high speed cornering. Lol Just sitting here static. Loosening and retighting the front spring helped about 1/8 inch.


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I think that you missed the point of my previous post:

"Unless you are on perfectly level ground, have the corner weight perfectly balanced in the front, and never move the car, your car will never be level."

You won't fix the front, if the issue is caused by the rear, unless you fix the rear.

 

After cornering and all back to level ground it should be level correct. I understand that in a corner one bags will compress the other will extend but once back to level it should equalize correct?


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Charlie, this is actually a spring behind the axle setup. Not a Model A original setup.
Thanks


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No. Your understanding is not correct.

Again, the car will only return to level, as you have currently have it constructed, if your front corner weights are exactly equal.

I can guarantee they are not.

 

Does not matter. The spring pack bolt still needs to be in the center hole of the crossmember.

 

I have un-done countless setups, like your's, for customers.

They have complained of the car never being level, and the handling dangerous.

I could literally (an often did) get my guys to grab the wheel arches of a car, and tilt it 15º, in the parking lot of my shop, and have it stay in that position.

 

Ok, on a level surface sure as a front end rack it should be level. I can’t say my flooring is perfect but I’ll check it. With it aired up against the shock stops the front still seems off. Back appears close. Sorry if it seems I’m thick. Just trying to rationalize it in my head.


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As I have said, ONLY if your front corner weights are equal, will it be level, with no inherent level control in the rear.

Add two more solenoids.

 

Also, if you have rubber, or poly bushings in the rear, and the rear was not laser-level when you tightened up the suspension bolts, the bushings will try to hold it at the position where they were tightened.

 

That’s very possible. I actually thought about that. Loosening everything and retighting.


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Too, front spring shims help level things, side to side. (After Gimp's rear bag fix)

 

Those U bolts are supposed to be holding that spring dead tight against the crossmember. There’s no uneven tightening or adjustable anything with those bolts. The bolts aren’t leveling jacks. The spring is tight against the crossmember and that’s that.


You can use tapered shim between the spring and crossmember to jack the leveling around but shim needs to be welded in or have a hole in the center. If you go with hole in the center the spring pack needs a longer centering pin.

 

You aren’t going to “know” anything about your issues without those scales. Most cars don’t set static with even weight distribution. And while driving the weight shifts.

You’re car sets low on the right rear,,,, is that with your body weight in the drivers seat?

 

Is the top leaf in the spring beveled on the front and rear edge to be able to fit "snug" in the cross member??
Paul in CT

 

You can use small spring "caster" wedges to use for shims. They come in different degrees so finding one to work shouldn't be a problem.

Just remember a little goes along way because your changing it at the apex of the spring arc.