I’m in the mock-up stage of my 28/29 Model A Tudor chassis. I have my front end sorted out mostly. In current configuration I am using a stock axle (not dropped, may send it out to get dropped depending on how the chassis sits to get a stance I like), spring over perches, posies reversed eye 2” drop spring, split bones, and stock crossmember. What I am currently planning is a 9” rear (planning on a healthy overhead valve motor and hitting the drag strip) and transverse A spring (not purchased yet, waiting for a posie to be back in stock). I know I will need to step the frame in the rear so the tire matches the wheel wells. I have my wheels and tires on the way so I will have these available to mock everything up. What I have a question about is how do I determine the distance between the axle centerline and the top of the loaded A spring in the rear end? I’m wanting to set my rear end position relative to the frame so I can get the correct pinion angle in relation to my motor and trans before I start welding up perches and the Pete and jakes ladder bar brackets. This is a first full build from the ground up for me. I’m getting into*****ysis paralysis on this part. My first instinct is to weld up spring perches to my housing, get an A spring and install it, mount my rear wheels and tires, mock up the body, measure, then completely disassemble everything and step the frame. However, I can see that getting the pinion angle correct will be a***** shoot and will have to cut off the perches and fab them up again. Or is there something glaringly obvious that I’m missing and I need to step back and re calculate? If it helps you guys out, I’m planning on using 820-15 Firestone bias ply for a street tire.
IT’s everyone’s question on their first go. you’re trying to nail it on the stance put the target moves as you put it together. You know weight will lower the stance ( but you don’t know the weight and you don’t know how much). So it’s easier to shim on top of a spring to come up than it is to come down. There’s adjustable swivel type hangers for camber and similar ones for the rear. You’re going to have to keep in mind that you’re going to probably need to change something so make the changes easy. It sure helps a bunch to look at another one and see what you like or don’t. Figure what you might need to change.
Thanks! I really should start a build thread. I finally have a garage to work in so things will be moving faster I hope
You can start with tacking your spring brackets on the housing so the pinion is a few degrees up with the brackets vertical. When you mock everything up you'll be able to see how far off you are.
Where’s a pic of something with the stance you like ? That will help a bunch. You’re using a high arch spring? Is that for quick change clearance,,, you said your going 9” higher arch means higher frame and deeper Z to get back down. Drag strip ,,, fat tires tucked in a little on a narrow axle or all hanging out on a wide axle.
This is what I am aiming for. My budget just doesn’t have room for a quick change right now, even though that may be an option in the future. I would ideally like to run at bonneville at least once. I may change up to wanting to run a flat head, budget is again deciding motor for right now. I can’t find a Posie A spring in stock, I see that speedway sells a high and medium arch spring that looks to be more like a model T spring.
If you got the parts from P&J, then give them a call and speak to Jason. He’ll walk you through the whole thing. He’s very patient and helpful from my experiences.
Might be a good idea to make the rear shock mounts also useable with coil overs…just in case you or someone else wants to change things in the future. That’s what I did/am doing with my coupe!
So that looks like a 32 frame under that to me on my little phone screen. And a suicide front axle. Those have different kinds of spring mounts,
Good catch on the 32 frame, I hadn’t noticed that before. I’m going to stick with my A rails, still undecided on suicide front, though it will help a bit with setting front ride height.
Corey, the chassis you describe sounds a lot like the one I built for my '29. If you would like to drive down here, you are welcome to measure mine, as a baseline, and adjust the height of the rear kick to suit your liking. I used a stock Model A rear spring. You can also check out the thread below.
Personally, I think you're headed the wrong direction with 9" housing, A Spring mounted on top and then a Z to get things back down to something you like the looks of. I'd Chuck that idea. Now I know this is a Banjo housing but just look at what's going on there. Remember, there is no "only" way to hang a rear housing. You can do the same thing with weld on brackets and the 9". The Roadster body I mounted on this chassis has a flat floor from toe board to spring crossmember and actual trunk space. P.S. I don't follow the rules and I don't think like most builders.
Yes. The Roaadster has a Stock wheelbase. If a person didn't want to do that a simple perch mounted off the back of the Crossmember much like a T Rodster front mount will also do the job. This chassis was Way simple to do. Sits very well and everything used was cast off parts from Customers over the years, every piece is O.E. Henry (not that it matters). The floor as mentioned is flat front to back with a Trans tunnel being the exception.
A side shot on full springs. Body is Channeled 6". Rear tires are 31" tall. Without being Channeled and a fender on it there was 1.5" between top of tire and fender touching.
You mention Bonneville. That is ENTIRELY DIFFERANT deal. SCTA requires cars to have such extensive safety equipment that it pretty much dictates a stand alone race specific car. The best option to see what it is ike is the USFRA 130mph Club which allows you to get a taste of LRS racing with a street ride. Utah Salt Flats Racing****ociation Look here^^^^^^
Marty, I really like the idea of stacking the rails like that. I am not a fan of deep Z’s. I will be headed past you this Friday on my way to Salem, I may end up stopping out in troutdale on Sunday to watch some racing on my way back and get some ideas, depending on time. I would like to take you up on your offer when I’m closer to getting the rear mocked up. I need to send the rails to the blasters to get them cleaned up. When I got the frame back in 2015 I foolishly used the brush on rustoleum to stabilize the rust… what a mess I created!
The nice thing about this setup is the axle attachment to the spring hanger can be adjustable during the build for pinion angle rotation. Takes a little trickery, a few tacks and and muffler clamps
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