Projects Model A rear ?

My next project is a Model A frame with no rear kickup. I'm using an original arched rear crossmember to put a MEDIUM arch buggy spring mounted on top of an S-10 axle. The only brackets I've found say they're for use with a HIGH arch spring which I do not want. What are my options so I can still put it all on top of my axle as opposed to in front of or behind my axle which changes the wheelbase which alters other calculations such as wheelbase, body position, etc......? Thanks........Bob

 

Make your own, then you know it'll be the way you want it.

 

I agree with Xtrom, fairly simple to fabricate. Flat stock and round rod or tubing for the shackle.

 

Speedway to me the medium spring would bottom out on the axle on a bump whereas the high arch spring wouldn't. I'm having trouble visualizing why one wouldn't and the other would. What would help, changing height of mount or something else?....Bob

 

Can Speedway tell you how much the spring will settle with the car's weight on it?

 

why would the height of the spring have anything to do with the desired shackle angle or the hole for the mount? the house of fab weld on look good to me, put them the same width apart as the A axle and who cares what spring arch is

 

Exactly as rusty states, you can fab the height of the rear end side of the shackle mount any height you want. The spring stiffness has nothing to do with the height of the spring shackle loop.

 

The main considerations:

You need clearance between the top of the differential housing and the spring-to-crossmember attachment hardware. For the sake of discussion, let's say this is 3". (I don't purport this to be correct, depends on spring stiffness, pothole sizes in your municipality, how fast you drive over speed bumps, etc. Maybe a professional builder [e.g., "Pete"] could chime in on what a standard design value would be.)

There needs to be sufficient clearance between the spring and the frame rail. This can be less than the 3" design "bump", since the spring upward movement relative to the chassis gets smaller, the closer you get to the spring center.

The accepted "rule of thumb" at the axle connection is to have the shackles at a 45 degree inclination. Due to the arched design of the "A" spring, the outboard end of the spring will move out laterally almost as much as vertically at the 3" design bump. There must be ample room so that the spring does not hit the axle or the spring perch, when the shackles go to vertical, and beyond.

Design clearances and shackle angle should be based on a full compliment of passengers, and a full gas tank.

The spring perch support will have a very high loading; with the shackles at 45 degrees, shackle tension is 42% greater than the corner weight supported. Hopefully you can find a perch engineered and certified for your application. I'd be wary of the design that connects to the top two backing plate bolts, unless so certified; I'm skeptical that the srock bolting or axle housing flange can withstand the additional imposed loading.

Not sure I've seen these on rods, but it would seem prudent to have rubber bump stops to avoid shock loading, at the diff housing and under the chassis.

 

But, it has everything to do with how far apart he puts them. Most guys are putting a spring into a car with a different weight than a stock A and expecting everything to just settle right into place.

And, to make matters even cloudier, the OP said he had a medium arch spring, which I think he's implying came from Speedway. So the stock A measurements are thrown out the window. He doesn't know what mounts to use and seems like he can't figure out where to place them. He needs to ask Speedway what the spring height and eye-to-eye measurement is going to be when the car is assembled. Think they can tell him?

 

Let me tell you this. This is from my Personal first hand experience. You can in Fact hang a Model A spring behind or in front of your rear Axle housing without changing the Wheel Base. You just need to be able to think past the instructions. Don't just follow the crowd and think for yourself.

 

The problem is, that he doesn't know the spring rate so unless he provides more info it's trial and error. If he can find out what the spring is from he can get a better idea of where he needs to place the mounts. If it's an after market Speedway spring he can call the manufacturer and get the info. He also needs to provide the weight of the rear of the car. It all comes down to proper shackle angle at ride height and vehicle weight to give the shackle ample "swing".

 

Please explain.......Bob

 

It all gets down to how bad you want something and your Welding and Fab skills. Then you have to think outside the Box. Kit parts are to make the seller money, not specifically to help you get what you need. Move the rear spring behind the rear Axle and in some way extend the spring mount. There is a lot to take in on these 2 photos but it runs a Stock A spring behind the rear axle as well as spring in front and has Stock Model A wheel base. Also no kick at all, 3" axle to frame clearance on both ends at ride height.

 

Also, here's what it took in pieces to build that Frame.

 

Do you have a better picture of the X member tied into the frame?
r


Sent from my iPhone using H.A.M.B.

 

Do these help?

 

Pist-n-broke, let me ask the next obvious questions. Are you mounting your radiator in the stock location? If so, how are you going to get your fan close enough to your radiator? Are you stretching a hood or running without one.

 

Yes, the stock Rad mount tabs bolt in the Stock cross member bolt holes. The piece of Wood is 1" thick. I like that space for the blade to core distance. No hood sides just a Hinged pair of Tops when done. Yes, a tad longer than a stock Model A hood. It's been a while but I think it was 4".

 

So I'll add this being your asking good questions. You may have just noticed how much space I have behind the breather cap. This was the result of where and how I placed the 36 X member. My driving force on this project was to use all Ford parts. With my parts list having a set of 39 Pedals I wanted them to be in the proper place behind the Firewall and in good position to the Toe Boards. That was how I placed the X member to, steering, firewall, and toe boards. This pushed the Trans and motor ahead just a bit but not so far that I got into trouble with Fan to Rad. It had nothing to do with the Wheel Base. The front and Rear crossmembers were placed directly to keep Wheel base stock to Model A. It just all kind of fell into place. Getting the fan to clear the early dist and mount in the center of Rad core I had to build my lower two belt pulley and the mount for the Fan to manifold. That's how I got the 1" space for the fan. Nothing to it really,,, right?

 

rdynes01 did we loose ya? We should get back to the rear spring issue. To me spring rate and Hot Rods really isn't a big deal. Ya make them do what you want. Just don't get over involved in engineering things. Henry already did that for the Model A's, we just have to modify things to do what we want. The number one thing to do if your going to run any Model A spring is to get the mounts on the Axle housing in there correct place. Most guys follow directions with the Kits, then they try to determine what's wrong.

 

Very cool, I admire your ingenuity and ambition. Keep us posted.