Hanging a rear in a Model A

WZ JUNK · February 26, 2004, 06:48:35 AM

I am helping a friend with his Model A project. I boxed a frame for him today and he will take it home tomorrow. I need to help him setup his rear axle next. He is using a buggy spring and wishbone radius rods. I need to figure out a way to know where to weld the mounts on the rear for the spring. We will be using the Speedway spring mounts as that is what we have. I have thought about locating an original rear to make a jig to locate the mounts but I am concerned about getting the pinion angle right. Can anyone give me some information on how to locate the position of the mounts on the rearend assembly?

Charlie Chops 1940 · February 26, 2004, 09:46:10 AM

John,

I've got that dimension written down at home somewhere for the '32. I'll look tonight.

Charlie

Bib_Overalls · February 26, 2004, 09:48:28 AM

Quote from: "WZ JUNK"I am helping a friend with his Model A project. I boxed a frame for him today and he will take it home tomorrow. I need to help him setup his rear axle next. He is using a buggy spring and wishbone radius rods. I need to figure out a way to know where to weld the mounts on the rear for the spring. We will be using the Speedway spring mounts as that is what we have. I have thought about locating an original rear to make a jig to locate the mounts but I am concerned about getting the pinion angle right. Can anyone give me some information on how to locate the position of the mounts on the rearend assembly?

Mike Bishop (AV8 on this board) talked about this in his book on building traditional hot rods. The flat floor in a Model A is problematic. Particularly so if you are going to use an original rear spring. Mike shows you how to get about 3" of drop with reversed spring eyes, a simple "Z" at the rear, and a little metal work in the trunk. Anything more requires more fabrication and more extensive sheet metal work. I'd consider using a later spring mounted in front of the axle. If your friend is planning on running "wishbones" from a Ford rear end DON'T. They were not designed to withstand torqe. All they did was keep the axle square to the torque tube.

GPster · February 26, 2004, 11:05:33 AM

Memory has it that the center of the shackle mount bushings should be 48" apart. That will be tight with the backing plates on any reasonable sized rear end if he's planning to keep the tires under the fenders. When I built mine, I used the spring hangers on the back of the axel in '48 style and used the "A" spring and built a reversed "suicide"style spring hanger off the top of the "A" crossmember so I could keep the "A" spring for "Quick-Change" rear end style. I boxed the "A" rear crossmember so that the leverage of the spring on the new mount wouldn't twist it. My car sat at a nice height for an un-fendered/channeled coupe but with 2 people in the car the rear end axel tubes would hit the boxing plates on the crossmember. If this car is to be fendered and has a decent size tire on the rear end he might not have this troublebecause he won't go this low. "Z"ing will be necessary if he wants to be this low. I think on most "A" bodiesyou can just step up the floor of the trunk and leave the inner-fender panels alone but they will probabley get bent on the bottom when the axel hits them. Might creat a problem if this car has a rumble seat. One thing that I did later on my car and quick enough that it stayed a driver, was to use coil springs mounted behind the axel. I built a pair of coil spring cups that mounted behind the crossmember and mounted them so their tops were no higher that the top of the frame rails and their outside edge was no further out than the out side edge of the rear crossmember. I then built a pair of spring cups that mounted to the back of the rear axel housing so that they were directly under the the spring cups on the frame then I used a couple of short/light duty coils (off the front end of a Corvair) and built a track bar to keep it straight. Maybe because this all would be behind the axel he'll have room to run the radius rods that he's got and still keep the floor flat . An idea for pinion angle with the stock spring might be make your spring mounts for the axel housing and then make pieces to weld to the axel that will provide a companion flange for the spring mounts. If the spring mounts are like some I've seen their bottom end that welds to the axel is shaped like a "C" with a 3" diameter. If this edge is set on the housing the it will supply some support and bolts through this mount into a flange won't be prone to shear. This way the centerline of the axels will stay in the same place as you rotate the axel to get your driveshaft angle. I've got to quit writing because I'm loosing myself. GPster Need anything for your wife's convertable? I saved the dash gauge panel out of my '53 when I junked it.

WZ JUNK · February 26, 2004, 12:57:00 PM

I set this frame up using Mike's book as a guide.

WZ JUNK · February 26, 2004, 02:01:35 PM

GPster, sent you a PM yesterday. I now have a pretty good idea of where everything should go and I think I will use some kind of temporary clamp to position the hanger. I can then put the weight of the car on the spring and rear and move them around until I get it where I want it. I probably won't do this for some time but it will give more time to figure it out.

GPster · February 26, 2004, 02:50:04 PM

I checked my mail and saw your suggestion to look at something but there was nothing printed to let me know where it was. I don't visit that site and I have no idea how to get into it and where to look to find something that I don't know what it is. I appreciate your seeing something and thinking about me but I have no idea what you think I might be interested in. I would think that you meant your message to have a site with a bunch of red letters with a line under them but that didn't happen. GPster

WZ JUNK · February 26, 2004, 05:34:41 PM

Quote from: "GPster"I checked my mail and saw your suggestion to look at something but there was nothing printed to let me know where it was. I don't visit that site and I have no idea how to get into it and where to look to find something that I don't know what it is. I appreciate your seeing something and thinking about me but I have no idea what you think I might be interested in. I would think that you meant your message to have a site with a bunch of red letters with a line under them but that didn't happen. GPster

GPster try this http://www.jalopyjournal.com/ubbthreads/showflat.php?Cat=&Board=UBB1&Number=317004&page=0&view=collapsed&sb=5&o=14&fpart=3#Post318275

Charlie Chops 1940 · February 26, 2004, 09:26:54 PM

Joe is right on that shackle center dimension of 48". I guess I would set up the angle for the driveline, tack it together and then set it with just the main leaf under a bare frame to see where it comes out.

Charlie