how to lose the iso leaf springs

Chassis, Suspension and wheels

  1. Ed Dorey

    Ed Dorey Well-Known Member

    Messages:
    130
    Likes Received:
    13
    Joined:
    Dec 3, 2015
    Location:
    Kearney, mo
    What is the easiest way to change the iso to a regular mount. I saw something about swapping shock plates but didn't say with what model. I figured I'd ask since all the other threads are quite old. Any help is appreciated.
     
  2. Duke5A

    Duke5A Well-Known Member

    Messages:
    186
    Likes Received:
    61
    Joined:
    Apr 6, 2018
    Location:
    Michigan
    Do you have a factory rear sway bar? If so you're going to need plates from Firm Feel that go between the axle and spring that have the provisions for the end links. For the shock plates you use a set from a B body and then you can run B body shocks as well. The part I'm fuzzy on is what to do with the locating pin in the springs. It's been a long time since I did this. I've got pictures on the computer at home - I'll post them tonight.
     
    Ed Dorey likes this.
  3. BudW

    BudW Moderator Staff Member

    Messages:
    3,276
    Likes Received:
    888
    Joined:
    Mar 4, 2012
    Location:
    Oklahoma City
    You have options.
    Any option is better than the existing rubber.

    - Some people like to replace the rubber ISO bushings with polyurethane biscuits.
    That option reuses all your existing hardware.
    I highly recommend using new U-bolts/nuts (Chrysler calls the U-bolts, clips) with any change in the area – sense you are working with 30 to 40-year-old fasteners.

    Most of the people who has gone this route has been happy with the results – but I do have a concern:
    The hardware is not that strong. The area in blue circle(s) tend to fail. When that happens, the leaf spring will drag the ground and tire will be touching the body (rear inner fender area) – so car will need towed at that point.
    IMG_2456a.JPG
    This is only picture I could find. Someone added overload springs to this setup (which I would have done differently).

    - My recommendation is to either use FFI’s setup (which anything FFI has is kinda pricy, but it is a complete kit). This will still use the upper part of the ISO clamp – but it touches the spring now.
    ISO delete kit.JPG
    http://www.firmfeel.com/fmj_body_mopar_iso_delete_kit.html
    The assembly will be (top to bottom): differential, upper shock bracket, leaf spring and then the new FFI bracket.

    OR find an older shock plate from any non-pickup/van made about ’60-72 (except for ’70 E-body or A/B-body’s with 7¼” differentials – sense they have a smaller diameter differential tube). That includes all C-body, all ’71-74 E-body and most A and B-body’s made between '60-72). If you see a Chrysler part and it looks like below, then it should work if the bolt pattern is "square" (about 3½” square).
    shock plate.jpg
    Shockplates1.jpg
    Both were taken from eBay. The lower is a Repop set.

    The shock plate goes under the spring this time. The assembly will be (top to bottom): differential, leaf spring then shock plate.
    Using older shock plates – you will also need to use older shocks sense the lower side went from downward stud style to sideways stud style (note: just look for a ’66-70 B-body rear shock instead of an FMJ rear shock). The shock dimensions are the same once installed.
    Shocks.jpg
    The top shock "looks" your original rear shock. The bottom one looks like what you would use if you replace the shock plates.
    BTW, I really dislike working on the upper (shock) style nuts. Removing the nut from a rusty shock - will remove part your hair and will typically make a person toss things around in your garage (in anger). Just replacing with older shock plates (for older style shocks) will reduce your stress level for future shock replacements.

    The older shock plate will need to have the leaf spring center bolt replaced with smaller bolt OR you can drill out the shock plate center hole to match the FMJ larger center bolt. Either method will work fine.
    BudW
     
    Ed Dorey, Jonnyuma and Kernel Sanders like this.
  4. Jonnyuma

    Jonnyuma Well-Known Member

    Messages:
    309
    Likes Received:
    68
    Joined:
    Nov 6, 2011
    Location:
    A Dirty Little Town in NW Oregon
    The Firm Feel kit is a little spendy ($265) for what it is. Depends on whether or not you enjoy lying on your back in junkyards disassembling old rusty cars... I used to, but not so much anymore. Every year the temptation to just not get back up and take a nap while Im under there gets stronger. Getting old really does kinda suck.
     
    Oldiron440 and Ed Dorey like this.
  5. Derekb

    Derekb Member

    Messages:
    23
    Likes Received:
    10
    Joined:
    Apr 11, 2018
    Location:
    Usa
    When i had a 8 1/4 under my car cut the pads off and welded standard pads on

    pick is with the ford 9 under the fifth IMG_20170308_100250.jpg
     
    Ed Dorey likes this.
  6. BudW

    BudW Moderator Staff Member

    Messages:
    3,276
    Likes Received:
    888
    Joined:
    Mar 4, 2012
    Location:
    Oklahoma City
    Spring perches are fairly cheap ($15-20 (US)) – and sometimes not worth the effort to cut off to reuse (IMO).

    Nice picture, Derekb.
    What is your opinion as to drivability/ride after removing the ISO-clamps?

    BudW
     
  7. Derekb

    Derekb Member

    Messages:
    23
    Likes Received:
    10
    Joined:
    Apr 11, 2018
    Location:
    Usa
    Handles just like any other leaf spring car.

    You don't have to cut the pads off you just need some round stock the size of the locating pin in the stock pads then drill the center of thr round stock the size of the locating bolt in the leaf springs.

    You will need shock plates if your not going to run a rear swaybar you can save some money and get some afco plates I paid around $20 each for the ones on my car.
     
    Last edited: Jun 8, 2018
    Ed Dorey likes this.
  8. BudW

    BudW Moderator Staff Member

    Messages:
    3,276
    Likes Received:
    888
    Joined:
    Mar 4, 2012
    Location:
    Oklahoma City
    I meant before vs. after.

    There are many versions on how to adapt to the 1-7/16” hole size on rear differential (steel plate welded in place and drilled, (big) nuts with captive washer(s), replace with new spring perches, and the list goes on).

    The method I prefer is: get some 1¼” flat steel stock (1” might work as well), cut to size so the square/rectangular piece fits inside the hole (some filing on corners is fine). Get a pair of older style leaf spring center bolts. Drill a hole in center of your freshly made squares the size of the center bolt ends. Take a pair of clamps and clamp both sizes of leaf spring by the old center bolt (to hold springs together temporary). Change out the bolt(s), installing the "square" per side (on top side of spring). I'm using the term "square" loosely, in this case. Place the squares, so they are parallel to spring. After spring center bolts are installed, remove clamps and attach differential.

    Note: a person could drill the hole on shock plates to size of the existing center bolt heads – but it has been my experience that: “A” the old center bolts are not quite long enough for the above-mentioned plate(s) and “B” working with 30-40 year-old fasteners are not fun (or some cases, non-reusable due to rust) – so if you have to get new spring bolts, you might as well get the older style (which are more readily available, anyway).


    Note: I prefer to remove differential with springs attached to it. Just before removal, add a pair of tires (a couple of lug nuts each) – so the assembly is easier to move. Same for reassembly. Loosely attach springs to differential, with a pair of tires in place. Wheel the assembly into position. Attach front spring nuts to snug (both sides), then rear spring hangers. Remove wheels and tighten all fasteners to specs.
    This method is the one I have found to be easiest – and I have removed a lot of differentials in my life.

    I went to AFCO’s web site https://www.afcodynapro.com/ and I didn’t see any shock plates there – unless it is/was a discontinued part (or something like that).
    Do you have more details on your shock plates? $20 is a very good price.
    BudW
     
  9. Derekb

    Derekb Member

    Messages:
    23
    Likes Received:
    10
    Joined:
    Apr 11, 2018
    Location:
    Usa
    It was a long time ago when I got them and there were not black
    Afco 20249
    Afco 20250
     
  10. Derekb

    Derekb Member

    Messages:
    23
    Likes Received:
    10
    Joined:
    Apr 11, 2018
    Location:
    Usa
    Ride is the same handling is a little better. Doing the poly b body iso upfront was a way bigger change to handling.
     
  11. Duke5A

    Duke5A Well-Known Member

    Messages:
    186
    Likes Received:
    61
    Joined:
    Apr 6, 2018
    Location:
    Michigan
    This is how I did mine the second time around...the plates between the spring and axle that have the sway bar tabs on them are solid pieces. I bought them from Firm Feel, but I don't see them on their site anymore. They were part of a kit, but they sold them to me individually. Bottom shock plates are from a B body (unsure of the year. Shocks are Edelbrock IAS (discontinued), also for a B body.

    The sway bar and even the links are factory pieces. I've since replaced the links with much stiffer Firm Feel pieces.

    IMG_3227.JPG

    IMG_3228.JPG

    IMG_3230.JPG
     
    BudW and Ed Dorey like this.
  12. bill55az

    bill55az Well-Known Member

    Messages:
    139
    Likes Received:
    3
    Joined:
    Mar 21, 2011
    Location:
    AZ and UT
    FMJ rear end links are no longer found at the parts places, unless you ask for mid 90's Chevy S10 FRONT end links....just a hint.
    Bill55AZ is still alive, however the Parkinson's Disease is making things difficult, so I quit the hobby.
    I live near Logan, Utah where a big car show is held every 4th of July.
    Anybody live near Northern Utah?
     
    80mirada likes this.
  13. 80mirada

    80mirada Well-Known Member

    Messages:
    827
    Likes Received:
    226
    Joined:
    Sep 3, 2012
    Location:
    Wisconsin, West Bend depends
    Glad you are still kicking, but to bad about the Parkinson's. My Grandmother suffered with it for a long time.
     
  14. lowbudget

    lowbudget Well-Known Member

    Messages:
    496
    Likes Received:
    90
    Joined:
    Feb 27, 2011
    Location:
    Vernal Utah
    I live In Vernal which is Northeastern Utah.