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Technical Low Model A Rear suspension/wishbone setup

Discussion in 'Traditional Hot Rods' started by yblockguynz, May 15, 2017.

  1. yblockguynz
    Joined: Jan 2, 2017
    Posts: 5

    yblockguynz

    Hey guys, this is my first build, and first post about it. Building a low y block powered traditional looking 1928 model a Tudor with my dad bryan (kiwi 4d). We are in the process of doing a z in the rear and setting up suspension ect, we have a 45-46 setup and the frame we have was built for a pickup And extended to suit rear spring, problems we are having Is that with the height we want to achieve the wishbone will clash with body and chassis. What other options are put there? Besides 4 link as we want to keep traditional theme
    Thanks guys
    The Kilsby's from New Zealand

    [​IMG][​IMG][​IMG][​IMG]
     
  2. yblockguynz
    Joined: Jan 2, 2017
    Posts: 5

    yblockguynz

    We have realised it's not possible to run 46 style wishbone spring mounts without hacking the body to much, so will be running a standard type spring over diff and shortening chassis to suit, just need an alternative wishbone setup


    Sent from my iPhone using The H.A.M.B. mobile app
     
  3. Tim_with_a_T
    Joined: Apr 30, 2011
    Posts: 1,078

    Tim_with_a_T
    Member

    I'll let others weigh in on this, but that rear axle you have is a '35-'36, not '45-'46. I can't quite tell from the photos, but it looks like someone put juice brakes on it already. As you probably already know, the Model A had the spring on top of the axle, and that axle you have has the spring behind. There are lots of different ways to get the rear lower than stock, some of them easier than others. Like I said, I'll let others weigh in on this.
     
  4. Kiwi 4d
    Joined: Sep 16, 2006
    Posts: 3,174

    Kiwi 4d
    ALLIANCE MEMBER

    My son is learning on a steep curve and knows what he wants , and has a vision for the look, but yes the rear is 35/36 with juice brakes.
    Yep. To do a 6 or 7" Z with the spring behind with 35/36 radius rods on a model A Tudor with a model T spring isn't going to happen. You need to cut a big slice of wheel arch away to clear the spring, thats going to look like crap. we found this out tonight and went "oh yuck cant do that" back to the drawing board.
    Ok if we mount the model T spring over with a bigger Z to make up the difference it seems the rear radius rods won't play ball and of course will interfere with the body and very close to the frame. We don't really want to run 4 bars with a severe Z . We desire tradition with a low stance. 4 bars sounds ugly. kind of defeats the aim, there has to be a more traditional way.
     
    Last edited: May 15, 2017
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  5. yblockguynz
    Joined: Jan 2, 2017
    Posts: 5

    yblockguynz

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  6. dentisaurus
    Joined: Dec 11, 2006
    Posts: 395

    dentisaurus
    Member
    from Boston

    Would 1/4 elliptical leaf spring suspension work for you ?
     
  7. dentisaurus
    Joined: Dec 11, 2006
    Posts: 395

    dentisaurus
    Member
    from Boston

  8. 97
    Joined: May 18, 2005
    Posts: 1,959

    97
    Member

    Son of Bryan! ..
    What's your real name?
    I was going to mention the 35/36 diff....
    I presume you are going to use a flathead box , or modified later gearbox behind that Y block. ? If not you don't need / probably cant use the torque tube....
    In the absence of other strengthening 36 bones are not strong enough to use to locate the diff without the torque tube.
    If you are going to use the torque tube it will need shortening to fit the Model A and therefore you are going to have to shorten the radius rods and the torque tube anyway,
    Cut the brackets off the 36 diff and make some new ones closer to the center to avoid the chassis, and at an angle that will let the shortened radius rods meet the shortened torque tube at the original place. The spring will need to be shorter too, but as you already have a step in the chassis you can possibly use a front spring from a 35-48...unless you are going with a quickchange.
    Get hold of Marty in Napier ( rockabillybassman here on HAMB) he built his tudor with spring behind, extended chassis, and made it work.
    There are a few good threads on HAMB with pictures .
    cheers
    CC8
     
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  9. 97
    Joined: May 18, 2005
    Posts: 1,959

    97
    Member

    Ah I forgot to mention that you will need to cut the radius rod tubes where they join the forgings and realign/reweld them when you change everything else ,the tubes are welded to the forgings in the first place so it will not create a weakness.
     
  10. Tim_with_a_T
    Joined: Apr 30, 2011
    Posts: 1,078

    Tim_with_a_T
    Member

    As you can see, lots of ideas and many ways to accomplish this. Since you're cutting the frame to do a Z, if it were me, I would put in a flat rear crossmember and run a reversed eye '35-'40 spring, maybe a 4" Z if necessary. They don't have near the arch of a T or A, and that gains you trunk/interior room that you will need. Make sure you know your tire diameters, wheelbase, front suspension setup, etc. before you start hacking away. One change usually results in three or 4 changes right behind it, which can significantly add time and $$.......ask me how I know.

    As for notching the wheel well arch to clear the spring, I see what you're saying now. I don't think it would be too noticeable once the wheel/tire was bolted on, though. The fact that you're thinking about all these things in advance shows you're putting in the effort to build a quality rod. Something that works for me, that I wish I would have exercised sooner, is to take a bunch of dimensions of the parts I have and go sketch some concepts roughly to scale. It forces you to encounter any interference and cuts needed as you draw.
     
    Last edited: May 15, 2017
  11. Tim_with_a_T
    Joined: Apr 30, 2011
    Posts: 1,078

    Tim_with_a_T
    Member

    I see from the pictures and after re-reading you already have a frame. Can you post pictures of what you have as far as front suspension, rear suspension, frame, wheels, and tires go? That will help us narrow down what's going on. After realizing you have a completed frame to work with, I'm thinking I'll take back my suggestion to change up the rear crossmember and spring until more photos are present.
     
  12. 97
    Joined: May 18, 2005
    Posts: 1,959

    97
    Member

  13. 97
    Joined: May 18, 2005
    Posts: 1,959

    97
    Member

  14. My photo gallery is a total Train Wreck. I have photos of my Roadster Chassis done with the body off but can't find them. I will go take some from under it to show what it fits and looks like. Here is the short story. Narrow banjo rear. Probably 37-38 housing with spring hangers forged on the bearing ends, factory stock. Model A rear spring, No kick in the frame, 46-48 wish bones. No frame contact or issues.
    Here is a photo before finish and without bones.
    Test fit #1 003.jpg
    Notice there is only a main leaf and that is just for location and fit. At this point there is 3/4" space. As I build the spring pack that space will grow. I still did a 1" C for axle clearance. I will get a few more photos with body on latter for ya. My body is channeled 6" and this is how it sits with 32" tall rear tires.
    20151023_094028.jpg
    And of course this project is Still not done, Dang!
    The Wizzard
     
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  15. yblockguynz
    Joined: Jan 2, 2017
    Posts: 5

    yblockguynz

    Thanks guys, my name is Andrew
    a whole lot of good info. Back to the drawing board we go, will be running a custom opendrive diff, this one is just for mock up purpose, probably going to use a pinched 32 style centre crossmember.
    at this stage we are planning to adapt a t5 box, run 16" wires 600 16 fronts and 700 16 rear.


    Sent from my iPhone using The H.A.M.B. mobile app
     
  16. COLEMAN BROTHERS CUSTOMS
    Joined: Mar 19, 2014
    Posts: 14

    COLEMAN BROTHERS CUSTOMS
    Member
    from So Cal

    Guys are giving you good info here. So, we now know you'll be going with a T-5, so no torque tube.

    I think the 'A' & 'T' rear springs are the prettiest ones to use on a traditional Hot Rod. But, if it's going to be really low, nobody will see the spring anyway. So, I'd do as what somebody already suggested, and use a flatter spring. You wouldn't need so much of a 'Z' in your frame and could save precious floor space. You could even use a front spring that would be narrower so you could get the perches inside the frame rails.

    To use the (also the prettiest) '35- '36 rear radius rods, you could make some extended mounts out of 1/4" plate. Weld the pieces of plate to the bottoms of the oval shaped mounts on your axle tubes with matching holes to mount your radius rods. If you made plates that were about 4" long, you could probably gain enough clearance so you wouldn't have to cut up the wheel wells. I wish I could draw you a picture...

    Since you won't be using the torque tube, and if you use the stock radius rods, you'll need some kind of torque arm(s). You could run two rods from the top of your axle tubes, and join them to the ends of your radius rods, where those will I assume be mounted to a crossmember with heim-joints or bushings. You could also run one torque arm from the top of your banjo differential to the same point on your crossmember.


    Oh, forget it! Just run coilovers... Ha!
     
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  17. DOCTOR SATAN
    Joined: Mar 21, 2014
    Posts: 711

    DOCTOR SATAN
    Member
    from okc

    I think a guy sells the plates on classifieds, so you can see what he's talking about
     
  18. It sounds like you need to lock in on what your doing before I jack up my Roadster to get photos. Right now it sounds like my info won't apply. That's okay. My advice now is just make some struts and weld your housing to the frame at what ever ride height your looking for. I do that quite often. Let's me move things around without actually making parts that then latter get cut up again. I also advise against using Just 36 bones on an open drive rear end. You will soon regret it if you do.
    The Wizzard
     
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  19. 97
    Joined: May 18, 2005
    Posts: 1,959

    97
    Member

    Andrew,
    Look forward to meeting you and getting a look at your project next time I come through. Though maybe you should just elbow the old boy out of the way and get the keys to the 32 from from Wendy , that will be far quicker than building the Model A. Leave that for him to do , seems like he has too much time on his hands anyway.:D
    Seriously though As you have explained your final configuration there are some things to consider.
    35/36 diff is narrower than open drive 46 etc.... i.e Jailbar, and there are some challenges using a mixture of the two.. it can be done but requires some juggling of factory components.
    Back to the suspension , as you are using a transverse spring, you will need a torque arm and substantial radius rods, If it were me I would probably be using a FRONT wishbone from a 42-48 car . Much stronger than 36 parts, and there is a step in the arms which could be used to your advantage.
    Several Hamb builds have used the idea... Check out Pete's modified build here
    https://www.jalopyjournal.com/forum/threads/28-modified-build-downunder.282490/
    his frame and suspension problems and solutions were very similar to what you are up to. I think the rear suspension stuff starts on page two.
     
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  20. 97
    Joined: May 18, 2005
    Posts: 1,959

    97
    Member

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  21. Kiwi 4d
    Joined: Sep 16, 2006
    Posts: 3,174

    Kiwi 4d
    ALLIANCE MEMBER

    Yes 97 ,I started a build on our own 32 pickup, which we have nearly all parts for, Now on the back burner, then it started before Xmas, our owned since new 1970 Chrysler long parked I stripped it repainted it got it legal after 10yr sleep. Stripped a buddy's 29 Roadster ,reengineered some, custom painted etc, gone. Then bare metal redo on a family members 57 that he has had 30yrs but not been on the road 27 of those. Then a full repaint on my sons lovely Triumph Tiger bike.
    I have 3 toys on the road, so it would be selfish not to help on his Tudor. Early days yet.
    Any one got any spare 46/48 front radius rods, swap for 35/36 rears.
     
  22. 97
    Joined: May 18, 2005
    Posts: 1,959

    97
    Member

    Hi Bryan ,
    I think Steve M had one on trade me a few weeks ago...didn't sell if I remember correctly. I know of a couple of other people, will call you tomorrow.
     
  23. big duece
    Joined: Jul 28, 2008
    Posts: 6,315

    big duece
    Member
    from kansas

    Did you lengthen the A frame 6-7" to compensate for the behind the spring setup?
     
  24. You must lengthen the frame rails to keep stock wheelbase. My Roadster is stock wheelbase however with the front axle also being spring in front I went more than the 6" for the rear.
     

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