'40 Ford-New suspension, wrong wheelbase question

Hey guys, I was over at my Dad's today helping him with the front suspension in his '40 Coupe. He just purchased an entire dropped axle kit from Chassis Engineering. Axle, spring, shackles, spindles, brakes, split wishbone mounts, the whole bit.

Here's the problem. With the new front suspension all mounted up and the car at ride height, the front wheels sit about 1" too far back in the front fender openings. I know that many cars have this problem, my '41 did. My question is how to fix it without moving the front crossmember?

The only thing that I can think of is to heat and bend the spring perches down and back to move the axle forward 1". Moving the axle 1" closer to the spring/shackle leaves barely enough room for the nuts that secure the shackle to slide up in.

The thought had crossed my mind to just cut and weld the spring perches. I am very confident in my welding abilities, but man, that's a lot of weight on those perches. I just don't know about this option.

What do you guys think? Is there an option that I haven't thought of? Anyone else have this problem?

 

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I'd call Chassis Engineering, maybe you don't have all the right componants.

 

Thanks. Yeah, I wish it were that easy. No, there's no wrong components from Chassis Engineering.

There is no frame damage, so that's not a factor. The only thing that it can be is something in the wishbones. Wrong wishbones maybe? I've never heard of this, but................? Are there any wishbones out there that put the spring closer or further away from the spring? Maybe all '40's have this problem but it sure looks a bit silly and I've never noticed one that looked this bad.

 

I have the same parts and the same problem in mine. I chalked it up to a combination of caster angle and dropped axle, with maybe some influence from the fiberglass fenders eek: don't tell anyone ), which I don't think are exactly the same shape as originals.


I'll be watching for a solution on this one.

 

Interesting. I bought the same kit for my 36. I'l be watching this one.

 

I've had the same problem with several applications. Sometimes there is no real pratical fix. Look at some unrestored originals and you'll see the same issue.

 

If you move the crossmember, would that fix it? It doesn't make sense to me why it does that. It's not like you have control arms that change arc through the compression? If you lowered the back the same amount , wouldn't it cancel it out?


Where's ElPolacko when you need him............

 

What's the caster angle?

If you have 5 degrees of negative caster (kingpin tops to the front) and then go to 5 degrees positive (kingpin tops to the rear) you'll probably make up the missing 1".

My old Motors Manual shows 4 1/2 - 9 degrees positive caster for the 40's.
6 degrees positive is a good place to start.

 

I'm with C9...

 

i just went out and looked at my stock 40 and the tire might be a 1/2" back, but thats would be the most. with a 5.5 its looks like its centered but with a bigger tire it might make the 1/2" more visible.

 

The caster is set at 6° positive right now. Of course the rear of the radius rods are just setup temporarily until we get this wheebase issue worked out. I played around with the caster angles just to see how much affect it would have on the wheelbase. The LEAST amout of caster that I could get with the radius rods attatched was 4° positive. This improved the wheelbase issues by a bit, but not only was it not enough to fix the problem entirely, I'm not willing to risk the negative effects of having that little caster.

Here's a little diagram that I made up to help explain why a dropped axle/lowered spring would have an affect on the wheelbase.




This is a little bit exaggerated but it shows how the spindle (and therefore the wheel and tire) follows the 6° caster angle on a dropped axle. In essense, a 1" dropped axle would have less affect on the wheelbase than a 6" dropped axle.

Moving the front crossmember forward would correct this because the axle location is determined by the front spring. My Dad is not willing to go to that extreme. That is why I'm looking for an alternative. Altering the wishbones or shackles to move the axle closer to the spring would accomplish the same thing. The trick is finding a safe method to acheive this.

Has anyone ever made a set of offset shackles?

 

You see I am at the point on my chassis where it is in bare metal. It would be much easier to move the crossmember now. Of course, it might be less noticeable on mine since it is a pickup and the opening are a little different than a 40 pass car.I have the 4" dropped axle, the spring, shackles etc from CE. That would suck to get everything painted and ready to assemble, only to find out the wheels don't center up,which is where I think you prolly are.

 

This might sound stupid , but what about doing some sheetmetal work to the fender to center the wheel?

 

Yeah, this was basically a running, driving car that was mildly lowered using all of the stock front suspension with a couple of leaves removed. I has good paint on it, so moving the wheel openings is not an option.

Roothawg, I would say that if you can do a mock up with the body and fenders on the frame, that would be the best way to go. You could just put it all together with just the main leaf or maybe the main and second leaf so that it sits at close to it's final ride height. That way you can be 100% certain that the wheels will end up where they need to be. Obviously moving the front crossmember would be SO much easier at this stage than with a completely assembled car, like I'm dealing with.

That being said, I don't know if the trucks have this problem or not. My guess would be that they do, but that's just a guess.

 

I had looked at changing the crossmember to a CE as well. The advantage of doing so is that it clears the fuel pump and adds another 1/2"-1" of drop. I'll do some calling tomorrow and see what CE says.

 

Now, I have a '36, '38, 2-'40 coupes and a '40 pickup, all but the pickup with dropped axles, and I don't see a centering problem of the wheel/tire in the fender opening. I run 165R15's on stock 5" wide Ford rims. Everyone remarks how perfect the stance is on everyone of these cars (I worked hard to get them that way).

But, having said that, I do have that problem on my '47 sedan delivery that has a stock axle with a radius rod split kit.

Ya' can lengthen the radius rods if they're split to push the axle forward, but ya' can only go just so much and the axle will hit the rear flange of the front crossmember. Ya' can cut the lip a little and go with another u-bolt nut that takes a smaller wrench size and trim the u-bolt plate a bit. You'll have to hunt those nuts down through a specialty fastener place. But all this will still put the spring in a bind with the shackles. I releived the bind some by heating and bending the radius rod shackle mount for proper parallel alignment.

You'd have to check for clearance issues, but why couldn't you just offset the spring shackle plates a bit? They're so short that I can't see how there could possibly any significant bending moment applied to flex them. If ya' walk through a junk yard I'm sure you'll see O.E. offset shackle applications that are much longer than the ones we're dealing with.

I'm glad I just thought about that. I may try this on my '47 .

Remember, it doesn't have to be perfect to the tape measure. It only needs to look perfect when you cast an eye ball on the car setting at normal ride on a flat surface from 10 - 15 or more feet away .

 

Yeah, this is definately a "to the eye" thing. I have no idea what the stock wheelbase is on a '40 Ford nor do I care. This just doesn't look right. The eye will always tell the truth.

I had thought about just pushing the radius rods forward, but I really don't want to put the spring and shackles in a bind.

Offset shackles.................. Hey, who said that?

 

The wheels aren't centered on my '40 & it's bone stock (for now). Here's a pic - it's not perfectly square to the car, but you can see the wheels aren't centered - rear too.

 

Thanks Flat Ernie.

Here's a picture that Dad just sent me so that you can see the problem.



The wheels don't look too bad when the car isn't lowered, but when you get that fender right down by the whitewall........... YUK.

Whoohoo, ya dig them rear wheels, doncha?

 

Are the front fenders Original ones for that car? I have seen that result with pickup fenders on a pass car......

 

It's not as exaggerated as I had envisioned....

 

The white-wall makes it more noticable. What is the back tire going to look like with a white-wall in there to show that it is too far forward? Looks to me that both ends will need some alignment. Neal

 

Choprods- to the best of my knowledge, the fenders are original ot the car. I don't know the entire history of the car but supposedly it was built in the mid sixties as a hot rod. From looking around the car, it is obvious that the car was well cared for over the course of it's life. There are a few minor issues that need to be delt with, but for the most part, it looks pretty good. This car looks pretty original as far as the body goes. Most of the panels still have that crappy tar undercoating on them. The car didn't have this issue (at least not as bad) with the stock axle underneath it. I don't think that the fenders have been changed, but I could be wrong.

Roothawg- Yeah, it isn't "that bad" but it's bad enough that I would really like to do something about it. Especially now since the radius rod mounts have not been installed yet.

J'st Wandering- I'm not too concerned about the rear. We don't have the correct wheels and tires yet, but when we do, we will have to lower the rear a bit to make up for the taller tire. The rake will stay the same. At that time, I will make a lowering block with an offset hole to center the rearend, if I have to that is. The rear looks worse that it really is due to the perspective of the photo. In reality, it doesn't look to be off by more than a ½" or so, but of course we will have to reevaluate it once the correct wheels and tires are on it and it's at it's final ride height.

 

Yep, Ya might as well fix it. If it bothers ya....it always will.

 

OK, so we have established that yes, there is a problem, now what to do about it?

What are your thoughts on any of the above mentioned methods to try to eliminate or at least minimize the problem?

I think that at this point, I am shooting for the offset shackle method, but I would still like to hear you input on the subject.

 

Instead of cutting the arm of the perch, just cut 3/4" off the front of the shackle eye of the perch and weld it on the back side -- this is if you can move the axle 3/4" forward and still have crossmember clearance. Hopefully you haven't welded any of your splitting kit in yet. You'll probably need to move that forward as well.

FYI - I think most axle manufacturers recommend the use of 35-36 wishbones with their axles because most new axles are narrower between the perches than 40's. You'd think it wouldn't matter when splitting wishbones, but maybe it does, hence your problem.

 

Very good idea. Thanks, I'll look into that.

 

It seems like you want to work with what you have, but I'll throw out another suggestion.

Stock axle, stock front spring, lengthened shackles, front pan hard bar, non-split front bones. Has worked well for me on my 41 PU, which has the same frame as your pop's car. My shackles are 3" eye-center to eye-center. Remember, the spring is 60 years old, so it probably sits the same as a new reverse eye spring by now.

With this setup I had to grind a little of the metal off the bottom of the steering box gusset, but just a little. This gave more travel room for the driver's side bone. Passenger side had no issues.

I have a reverse eye from posies that I'll install some day. We'll see if its the same.

Using longer shackles does mean the flathead oil pan will get closer to the steering tie rod. I had to remedy this with a flathead truck oil pan.

The attached pic shows the ride height. The angle makes the front tire look pulled back like on your pop's, but its not.

Good luck,

Mike

 

Baron von Mike, Thanks, that sounds like a very viable plan. Ultimately it will be Dads decision whatever we do. How long are your shackles?

 

Guess it got lost in the previous post. Stock shackles are 1.5" eye-center to eye-center. I made mine 3" eye-center to eye-center for a total 1.5" of drop. Given that the old spring is probably 2" down from stock, I have about a 3" dropped front end. Any lower and I'll have to split the bones. There's just enough travel without splitting at this point.

You could get a less drastically dropped front axle, and then do the rest with shackles. The less drastic dropped axle should help your off center problem.

Good luck!