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Technical 1940 Buick (& 37-57 BOP) Front Suspension Conversion

Discussion in 'The Hokey Ass Message Board' started by Pickled_asparagus, Jan 24, 2015.

  1. Pickled_asparagus
    Joined: Aug 12, 2009
    Posts: 47

    Pickled_asparagus
    Member

    Suspension Gurus, I am looking at converting the front suspension on my '40 Buick Coupe to ball joint style using the conversion referenced in nthis crankshaft coalition article:

    http://www.crankshaftcoalition.com/wiki/1937-1957_Buick_Oldsmobile_Pontiac_suspension_upgrade

    I noticed this is also posted in a rather dated thread here and it didn't look like any of the members who posted there had posted anything since, so here goes.

    The car is currently all stock, but instead of sticking a substantial amount of money into the stock front end, I came across the above article. I prefer to not stub the car and this seemed like a workable alternative for my skill level. This all being said, I want to collect all the parts before I begin the swap. I have discovered a couple issues while researching this and wanted to see if anyone had any advice on the following:

    -The 1958 Pontiac Lower control arms required seem to be EXTREMELY hard to find (at least in Wisconsin). I have scoured Ebay, emailed Frank's Pontiac Parts, visted several specifically vintage junkyards (5,000+ old cars) around here and have turned up none.

    -The current Lower control arms on my car are 20" from Center of Kingpin to Centerline of the pivot shaft. '58 Pontiac Lowers are 18" and as the article states, I would need to drill new mounting holes. Not a huge deal, but next would be my possible solution.

    After thinking about this, I noticed further down in the article, one of the authors welded some 3/8" plate into the stock lower control arms of his '49 Olds and used Ford Courier Lower Balljoints becuase the profile was narrow enough.

    -Would there be any major disadvantages to lasercutting 3/8" or 1/2" plate to the correct profile and just welding it into my existing Lower control arms and using the Courier Balljoints? Does anyone have any experience with this?

    If the stock suspension supports the weight of a huge, morphedite straight 8, I'm pretty confident any Nailhead, Early Olds or Aluminum 215 I get my hands on will be equal or lighter.

    Uppers are not a problem as many late 50's BOP's will work. I plan to just order the CPP Spindles and keep drum brakes of some form. The car currently stops fine after I converted to a manual dual bowl jeep master cylinder.

    If anyone has done this conversion or has input it would be greatly appreciated!

    [​IMG]
     
  2. Pickled_asparagus
    Joined: Aug 12, 2009
    Posts: 47

    Pickled_asparagus
    Member

    I neglected to add earlier, if anyone has some '58 Pontiac lower control arms, I would be in the market to buy.

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  3. Pickled_asparagus
    Joined: Aug 12, 2009
    Posts: 47

    Pickled_asparagus
    Member

    Has anyone ever made their own control arms from scratch? I really can't imagine it's all that difficult to build tubular front control arms. I have the ability to laser cut plate for spring pocket and balljoint mount and use DOM tubing for the structure.

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  4. missysdad1
    Joined: Dec 9, 2008
    Posts: 2,812

    missysdad1
    ALLIANCE MEMBER

    What is your reason for wanting to change control arms?
     
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  5. treb11
    Joined: Jan 21, 2006
    Posts: 3,301

    treb11
    ALLIANCE MEMBER

    As far as making control arms, if you know the changes and are/have a good welder, mihgt try this. Use the original control arms to build a jig that locates all the mounting and attachment points. Backwards engineering. Then any dimensional changes can be made to the jig. Then pieces are fabricated to replicate the attachment locations. Fill in the gaps with DOM. Easy ;)
     
  6. Pickled_asparagus
    Joined: Aug 12, 2009
    Posts: 47

    Pickled_asparagus
    Member

    My reasons are identified in the initial post.

    I like the jig idea. It's 20" from center of pivot to center of kingpin. The arms are completely symmetrical. The only other key dimension is for the spring pocket but that seems like an easy fabrication. The only part I'm unsure of is the interface between the pivot shaft and the control arm.


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  7. BJR
    Joined: Mar 11, 2005
    Posts: 5,993

    BJR
    Member

    Look at 60's gm cars you may find just what you need.
     
  8. shabby chick
    Joined: Jul 23, 2011
    Posts: 8

    shabby chick
    Member
    from georgia

    It been since Jan 2015 since your post on 1958 Pontiac suspension upgrades, how is it working out. I too am considering the change to 1958 Pontiac control arms. I have a complete upper & lower set of control arms, spindles etc. for a 58 Pontiac. The lowers are rusty in spring purch but usable. I want to get 3 to 5 degrees of neg. caster to improve high speed control.
    I had given up on the idea as the car operated fairly well up to about 65 mph, but recent out of town trips, (Steel in Motion and other ) are making me rethink the idea.
     
  9. Pickled_asparagus
    Joined: Aug 12, 2009
    Posts: 47

    Pickled_asparagus
    Member


    I actually haven't begun this, as I live in Wisconsin and right now it's getting nice out. The car runs & drives so I have resisted the urge to take it apart!

    Your swap should be fairly straightforward. On the Lower Control Arm in your car, measure the distance from the center pivot to the center of the balljoint. If it's 18", they will bolt in. Mine on my '40 Buick are 20" so I have to redrill the mointing holes, but chances are, yours should bolt in. You already have the hardest part to find (the '58 Pontiac lowers) so I say go for it!

    I'm not sure what kind of upper control arm mount your car has. Mine has a lever shock type integrated into an upper control arm that needs to be removed. I have to fabricate an angle bracket & weld to the frame to bolt the upper control arm to. This can be accomplished 1 of 2 ways:

    1: Buy the right size angle from the crankshaft coalition article mention above and drill the holes or....

    2: (Easiest for me) wait until winter when I draw the angles up in Solidworks, lasercut them w/holes at the correct angle, and form them on a brake press. This seems like alot, but if you have access to a manufacturing facility is quite easy. I will share the CAD .DXF file required for laser/plasma tables when I create it.

    It doesn't sound too difficult with some moderate fabrication skills, but I'll try to keep this thread up to date!
     
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  10. shabby chick
    Joined: Jul 23, 2011
    Posts: 8

    shabby chick
    Member
    from georgia

    Thanks for your responce, I too will probally wait until colder weather as the car season is in full swing in my area and it drives fairly well up to 60 to 65 mph. I have been doing my research. Kanter sell a rebuild package for the 1958 front end for apprx 475.00. Scarebird sells the disk brake adpator. I plan on doing mine in stages. I will probally set it at 4 degrees of postive caster an retain the armstrong steering for awhile. I am considering retaining the master brake cylender where is is for awhile.
     

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  11. hotrodpontiac
    Joined: Mar 30, 2008
    Posts: 3

    hotrodpontiac
    Member
    from Arizona

    I'm actually getting ready to do the same to my 50 Chieftain. I recently purchased a 58 Chieftain for the parts, unfortunately it is way to clean to part out. I am going to pull the lower arms and measure them so I can make my own lowers. I will post the pics and measurements in a couple weeks.
     
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