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Model A rear buggy spring

Discussion in 'The Hokey Ass Message Board' started by Diamondhead, Jan 6, 2009.

  1. Diamondhead
    Joined: Nov 2, 2008
    Posts: 47

    Diamondhead
    Member
    from Kentucky

    I am hoping some of you "Model A" experts can shed some light on a very confussing issue I am dealing with on the dimensions for the rear buggy spring on my Model A. My spring purchases are mounted at 49 1/2" eye to eye. The spring, at rest, unmounted, measures 44". In researching available Model A springs the dimensions of the spring at rest is 39 1/2" . My question is, are there two different springs used on a Model A or has my spring stretched to 44"? If 39 1/2" is the correct dimension, does that spring stretch to mount to purchases spaced to 49 1/2". Any hely will be greatly appreciated.
     
  2. Diamondhead
    Joined: Nov 2, 2008
    Posts: 47

    Diamondhead
    Member
    from Kentucky

    Please excuse my misspelling of perchs as purchases. Hopefully you got the idea anyway
     
  3. Bruce Lancaster
    Joined: Oct 9, 2001
    Posts: 19,602

    Bruce Lancaster
    Member

    There are a LOT of different Model A rear springs, and 2 or 3 front ones. The range would be from roadster to pickup truck...not only different numbers of leaves but different thicknesses of some leaves to adjust for each body style. Most frames are stamped at the left rear with the number of leaves for the frame's intended use!
    I don't think there is an eye-to-eye published spec for the different springs, and such a spec would be useless except for new original springs of each type. Current dimension would partially depend on number of pothole hit since 1928...in any case, loose spring is substantially shorter than installed spring. Spring is spread with either a special jack type spreader or by weight in order to get shackles in. This has to be done carefully... a misused spreader can become a missile if anything slips.
     
  4. 60'shotrod
    Joined: Nov 18, 2007
    Posts: 2,907

    60'shotrod
    Member

    Diamondhead. Your spring has to spread/pushed out at the eye ends towards the spring perch.It has to under tension when mounted to the axle.Not under tension it will spring-back to it's unmounted width.I used a block of wood and a couple of BIG G-clamps to flatten/extend the spring(DON'T GET YOUR BALLS TO NEAR).The spring shackles sit at about 45 degrees when fitted/under tension.Hope this answers your question.

    Nick.
     
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  5. Bruce Lancaster
    Joined: Oct 9, 2001
    Posts: 19,602

    Bruce Lancaster
    Member

    With an A, I would do the same but with weight instead of clamps. Pieces of wood or 2 short pieces of U channel to raise spring a bit and provide skids, stack trunk/ rear of vehicle with your fattest friends, tool boxes, and cement blocks. The clamps scare me...if you use them, have chains linking them to chassis in case the slip or bend. Spring contains a LOT of energy when stretched...
     
  6. 60'shotrod
    Joined: Nov 18, 2007
    Posts: 2,907

    60'shotrod
    Member

     
  7. Zombie Hot Rod
    Joined: Oct 22, 2006
    Posts: 2,416

    Zombie Hot Rod
    Member
    from Bronx, NY

    Put the first leaf in, the stack the rest on top with a long piece of threaded rod through the middle. Put a nut on each end and tighten it up until the spring is fully compressed. Then cut off whatever length of threaded rod is sticking out.

    I find this to be the safest way to put a rear spring in.

    You can also use a spring spreader if you've got on handy (or you can make one fairly easily).
     
  8. A Chopped Coupe
    Joined: Mar 2, 2004
    Posts: 1,133

    A Chopped Coupe
    Member

    What everyone else said is true. The real dimension that needs to be correct is the perch eye to eye distance, which you have got right.

    What I did, was to take the spring apart. To do this you will need C clamps (and you can put
    a chain around it if that will make you more comfortable), compress the C clamps, then unscrew the center nut and bolt throught that goes through the spring. Slowly unloosen the clamps until all the pressure is of the spring and you can remove all the individual leaves.
    Then, take the main leaf and attach it to the shackles, then to the perch. Bolt the shackles together. Then (with C clamps) start building the spring pack back together, make sure that the center bolt is going into each leaf as you put them together.
    I have done this three times without and issues.
    Also, when you get the spring together and back in the chassis, the shackle should be parallel with the axle housing or ground....................it isn't until the chassis is loaded that
    the shackle should be a 45 degree angle, just like the picture I have enclosed. If the shackle is at a 45 with the chassis unloaded, when you load it you will more than likely go past 45 and risk hitting the axle housing/bottoming out the spring/shackle.

    IMHO
     

    Attached Files:

  9. pasadenahotrod
    Joined: Feb 13, 2007
    Posts: 11,750

    pasadenahotrod
    Member
    from Texas

    You don't have a T-looking A rear spring, do you? It might be the first true roadster rear spring I have seen in years if you do!
    Except for the roadster spring all the A rear springs when loose have a sort of droopy appearance with the eyes pointing down and out.
    The true roadster spring however has a lower crown and a more-defined reverse arch which leaves the eyes pointing farther out and down than the other rear spring packs. It is the original spring found only under the rear of 28-31 Roadsters.
    They were the only desireable A rear spring to be found and bought at any swap meet for years and would bring a nice $100 bill 20 years and more ago if in nice shape.
     
  10. Diamondhead
    Joined: Nov 2, 2008
    Posts: 47

    Diamondhead
    Member
    from Kentucky

    I appreciate the advice and warnings when dealing with springs. A person could easily get hurt. On a standard Model A spring is the "at rest unmounted" measurement between the eyes 39 1/2"? And does that spring dimension mount to 49 1/2" perch's or is there another measurement for the perch's for a 39 1/2" spring?
     
  11. HemiDeuce
    Joined: Aug 9, 2004
    Posts: 923

    HemiDeuce
    ALLIANCE MEMBER

    If your spring is 39 1/2", it must be a 8 leaf spring, and it would mount on the stock Model A perch dimensions. A stock 7 leaf Roadster spring is about 40 1/4" eye to eye.
    HemiDeuce.
     
  12. brokenspoke
    Joined: Jul 26, 2005
    Posts: 2,581

    brokenspoke
    ALLIANCE MEMBER

    I've been looking for a roadster spring for a long time..Your the first one who knows that they are shaped differently...A-Springs .com will make one if he can find one to go by...rare spring indeed
     
  13. Diamondhead
    Joined: Nov 2, 2008
    Posts: 47

    Diamondhead
    Member
    from Kentucky

    What is a stock Model A perch dimension?
     
  14. HemiDeuce
    Joined: Aug 9, 2004
    Posts: 923

    HemiDeuce
    ALLIANCE MEMBER

    49 1/4" is the stock Model A Perch Dimension that I have measured.
    HemiDeuce.
     
  15. Diamondhead
    Joined: Nov 2, 2008
    Posts: 47

    Diamondhead
    Member
    from Kentucky

    Does that mean a spring measuring 39 1/2" unmounted will expand to mount on 49 1/4" perches? I ask that question because everything I have found indicates a standard Model A spring unmounted measures 39 1/2". I am trying to get this point clear so I know which spring I need to purchase for a perch dimension of 49 1/4".
     
  16. A Chopped Coupe
    Joined: Mar 2, 2004
    Posts: 1,133

    A Chopped Coupe
    Member

    HemiDeuce is correct, out of the half dozen 30/31 Model A's I have measure they have been
    between 49.125 to 49.225 eye to eye.
    I put mine at 49.125.

    The original spring on my Coupe was from a roadster. But when I had to move the perces inboard 2" (to 47.125" eye to eye) I took the main leaf to Moore Spring and had them copy it only 2" shorter. I can't remember what I did with the main leaf but may have given it to a member of the Model A club in Stockton.

    Diamondhead,
    remember that the perches are 49.125 eye to eye............then you need to add 1.5" for each shackle (bolt to bolt distance/eye to eye) which totals 3". So if you were to use the 39.5" spring (I have never seen one this short as most of the ones I have touched have been over 40") you would actually have 42.5 (if you take the 39.5" spring and add 1.5" for each shackle X 2 = 3" for a total of 42.5") where the shackles would attach to the perces. Hope that makes sense.

    When you are measuring for a spring don't forget to add for the shackles...............
     
  17. DE SOTO
    Joined: Jan 20, 2006
    Posts: 3,757

    DE SOTO
    Member


    So Does that mean the 2 i have that are 40 1/4 are ROADSTER

    And the 39 1/2 is a STANDARD A ?

    See, Ya DO learn new things everyday :D
     
  18. pasadenahotrod
    Joined: Feb 13, 2007
    Posts: 11,750

    pasadenahotrod
    Member
    from Texas

    Only if the two "roadster" springs are distinctly different from the other one.
     
  19. Diamondhead
    Joined: Nov 2, 2008
    Posts: 47

    Diamondhead
    Member
    from Kentucky

    By including the shackle dimension, bringing the mounting points of the spring to 42 1/2" you would have to stretch the spring 6 3/4" to reach the mounting perchs. Is that an acceptable amount of stretch for the spring? The tech at Posie spring indicated normal stretch for their springs is 5".
     
  20. A Chopped Coupe
    Joined: Mar 2, 2004
    Posts: 1,133

    A Chopped Coupe
    Member

    Diamondhead,



    Since you have the original spring why not install it and take some measurements. Can you
    do this?

    Is this on a stock type axle or have you not yet welded the perches in?????

    Which perces do you have.................hopfully not those SpeedWay type!!!!!!!!

    When you install the spring (unloaded) the shackles need to be parallel.......to the axle/ground. When the chassis is loaded they need to be close to 45 degrees.

    I have never measured the stretch. but 3.3125" per side doesn't sound beyond reason.
    What I suggest, is that you call a local spring shop, tell them you are looking for free (unloaded length) of a Model A spring and see what they say. When I took my spring to Moore Spring they had a very old book and they looked up whatever information they needed. Unfortunately I looked at the book but didn't pay any attention to all the information. Again, I have never seen a rear spring that short for a Model A. Where did you find this information?
     

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  21. Bruce Lancaster
    Joined: Oct 9, 2001
    Posts: 19,602

    Bruce Lancaster
    Member

    Use the original and don't worry. Free length is affected by amount of say from use...all springs relax a bit after use, and 75 years does a lot...
    I have Page's manual here, and one pic is of a chassis with spring being hoisted off of the rear axle; this spring would still be slightly tighter than actual free length because it is still bolted tight into the X member. Guesstimating from the photo, I'd say 4" from perches at each end. The V downward angle is very much sharper than the same spring shown totally installed, of course. This is on a new 1928 coupe that was totally torn down to illustrate the shop manual.
    The only issue that would need addressing is if spring has sagged or weakened so that it becomes too long under full car weight...shackles pushed out too far beyond 45 produce sway. A spring deliberately dearched for lowering will need a new shorter main leaf because of this.
     
  22. Toast
    Joined: Jan 6, 2007
    Posts: 3,772

    Toast
    ALLIANCE MEMBER
    from Jenks, OK

    Wow, lotsa great info on this thread. I am preparing to do a similar mount on my A and had some of the questions.
     
  23. Diamondhead
    Joined: Nov 2, 2008
    Posts: 47

    Diamondhead
    Member
    from Kentucky

    In summary, here is what I have come to understand. The stock distance between perches, eye to eye, is 49 1/4". A new spring can be between 39 1/2" - 40 " eye to eye unmounted. The shackels will offset 1 1/2" on each side resulting in a spring mounting dimension of 46 1/4" eye to eye. This means the spring must extend approx 6 1/4 inches overall from its unmounted state, 3 1/8" on each side.

    Stretching a spring this much creates a tremendous amount of stored energy and could be lethal if not controlled and done properly. I have seen several different methods suggested and will not recommend any but suggest anyone attempting to perform this procedure review ther various approaches and determine which one provides you with the most safety. Posies Spring suggest disassembling the spring and mounting the primary leaf first. Then stack the remaining leafs and drawing them together with the center assembly bolt. If you are fortunate enough to have access to a spring stretcher that would be another alternative. Which ever method you choose, always consider the safety of others and yourself before execution of the procedure.

    If anyone disagrees with my conclusions, please let me know. Knowledge is the assembly of present facts and understandings which grows with additional input.
     
  24. Bruce Lancaster
    Joined: Oct 9, 2001
    Posts: 19,602

    Bruce Lancaster
    Member

    Conclusions are correct...energy in a Ford spring being installed is tremendous.
    Installing a spring-behind setup is much easier to do...
    Ford method for A was a huge forged enclosed clamp (think O-clamp rather than C) that dragged rear closer to crossmember while spring ends skidded out along two pieces of channe to meet shackles. I would do this but use simple weight in the trunk to motivate things, since Ford tool is rare and costly and available substitutions have a much greater possibility of becoming missiles.
    Any tooling you use needs safety chains around axle, since if it slips you will discover you have an EXCELLENT Medieval siege weapon, capable of taking you right out through the wall with ease.
    AC&R offers a spreader with jog in middle for Model A, and also a simple but scary one-side spreader. Both are fabricated from hardware and would be easy to duplicate.

    Spreaders here: http://www.partsformodelafords.com/store/category.cfm?Category=27&StartRow=11

    AC&R tools are primitive but serviceable. The traveling version could probably be assembled right in Home Depot, but has great potential as an anti-personnel device.
     
  25. Bruce Lancaster
    Joined: Oct 9, 2001
    Posts: 19,602

    Bruce Lancaster
    Member

    Also...spreaders can be jiggered with heavy-duty U clamps like normal spring clamps but MUCH stouter to work on revrsed eye springs, but as always excercise great caution and use restraint chains. I would STRONGLY prefer the slider approach with reversed eyes.
     
  26. PAPASMURF
    Joined: Jun 7, 2004
    Posts: 508

    PAPASMURF
    Member

    Sorry to hi-jack but what is common practice when you have to weld spring mounts on the rear? Do you just weld at the above dimensions without the springs in place? Im going to have to do this as I want to use the A rear member and spring on top a later axle.
     
  27. A Chopped Coupe
    Joined: Mar 2, 2004
    Posts: 1,133

    A Chopped Coupe
    Member

    Diamondhead,

    Please believe me when I say I'm not throwing stones here, but where did you find the information on a Model A spring being 39.5 inches eye to eye relaxed. My original front
    spring was 30" eye to eye relaxed. It just sounds too short to me.

    I have never seen a spring this small for the rear of an A, and yes, stretching it over six inches is quite a lot of stored engery.

    About the spring spreader, spreaders are for non-reversed eyes, and if you have a non-reversed eye it may work. For a reversed eye spring it won't, although somewhere I saw
    a reverse eye spreader that had been made by someone.

    I have done the long allthread rod through the spring and tried to assemble it this way, but as the tension increased as you added more springs..........I eventually stripped the threads.
    What I did was to use the allthread rod with large washers on top and bottom, screw the nut and little, then put 6" C clamps on the spring, then screw some more....etc. At some point in time you need to take the allthread rod out and replace it with a much stronger nut
    and bolt.............I used the stock one.

    One other thing to remember, the more tension you put on this spring, the stiffer it will become and the harsher the ride will be.

    IMHO
     
  28. Diamondhead
    Joined: Nov 2, 2008
    Posts: 47

    Diamondhead
    Member
    from Kentucky

    The 39 1/2" dimension came from several sources, Posies Rod and Customs, Ozarks Ford Parts, several sellers on the H.A.M.B. and Ebay. In your experience, what dimensions have you seen for an unmounted A rear spring? In getting information from measurements of older springs, I have received ranges from 40" to 44". It is hard to determine from that what the true dimension is suppose to be. Manufacturers of springs for replacement have been consistant with the 39 1/2" dimension.
     
  29. A Chopped Coupe
    Joined: Mar 2, 2004
    Posts: 1,133

    A Chopped Coupe
    Member

    The measurements I have taken off original A springs from Roadsters/Coupes/Sedans
    have been from 40.225 to 44.125".
    These were original springs with either 8/11 leaves.

    Let me go back to question. Do you have a stock Model A spring?
    If so, then put it on the frame/alxe and see where you are.

    If you haven't welded the shackles on...............go do it and then try the spring you have.

    Another question..........what axle are you using and what car is this going on.
     
  30. Diamondhead
    Joined: Nov 2, 2008
    Posts: 47

    Diamondhead
    Member
    from Kentucky

    That is where this whole question started, when I started reworking a botched suspension job someone did on this 31 Tudor. The spring perchs were on the top of the axle and the spring bottomed out on the perch eye supports which were set at 47". I am not sure if this is a Model A ot T spring so I started to research what I had. The spring has only 5 leafs and shows where 3 were removed. The unmounted distance between the eyes is 44". In reworking the suspension I decided to move the spring perchs from the top of the axle to the rear of the axle to provide more distance for my 4 link setup. From the information I could find for a Model A buggy spring the perchs needed to be at 49 1/4" eye to eye. I purchased new perchs made to mount the springs behind the axle and set them to this dimension. I have mounted this spring and determined it is way to weak for this application. Now I am trying to determine the proper spring for this application. This may appear to be backwards, i should obtain the right spring first, but I didn't know the spring I had would not work until I mounted it. So there you have it, the start of another new adventure in building a hot rod.
     

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