Difference in GS/Skylark rear upper control arms?

Discussion in 'Chassis restoration' started by copperheadgs1, Dec 10, 2008.

  1. copperheadgs1

    copperheadgs1 copperheadgs1

    Just curious if anyone knows the difference between the Skylark and GS rear upper control arms? I know lower arms are boxed on handling package cars but has anyone noticed anything on the uppers. They carry a different part number in assembly manual. I want to change my crusty originals for some nice rust free ones I bought from someone on the board and wanted to know difference. Maybe different bushings?
  2. gstewart

    gstewart Well-Known Member

    my 72 gs has F41 suspension and the upper control arms are not boxed. the lowers are boxed.
  3. rustedgoat

    rustedgoat Member

    From the factory I've seen on 12 bolts the upper drivers side arms had a small reinforcement plate spot welded over the bolt hole from the factory and is slightly notched to allow clearance for the rear housing. The passanger side is the same as 10 bolts. I'm not sure what you would get as an over the counter replacment part but the modified arm will fit on the passanger side with no issues.
  4. cpk 71

    cpk 71 im just a number

    I boxed my own uppers on my car don't know if it makes a difference but i did'em anyway.
  5. copperheadgs1

    copperheadgs1 copperheadgs1

    They are not boxed but the assembly manual shows a different part number for a GS. Both sides are listed the same. I have the new(used) ones in hand. Will have to crawl under and see if I can see any difference.
  6. pglade

    pglade Well-Known Member

    As previously mentioned I think I've seen some with the reinforced bolt hole...but maybe this was a change GM made during one year or in a model year.
  7. wkillgs

    wkillgs Gold Level Contributor

    My 66 assembly manual shows 3 different part numbers for the bushings.
    The control arms are listed as 'assemblys'....they have bushings installed.
    I'd bet it's the bushings that are different, and not the metal arm.

    The reinforced upper arms were used on 12 bold apps due to there being less metal around the bolt hole.
    There's an awesome web page out there on A-arms/control arms.....somewhere.
  8. Keith Seymore

    Keith Seymore Well-Known Member

    Shouldn't make any difference. The uppers are in "tension" and the lowers are in "compression" during launch.

    However, it doesn't hurt anything (...other than a slight increase in mass - lol) and you get the personal satisfaction of a job well done. :TU:

  9. Duane

    Duane Member

    The original rear uppers (at least for the 70-72 cars) had different application codes depending on the year/suspension package. The bushings may have been the major difference, because many show no external differences.

    For the "nut cases" (and I won't mention any names here) you can often tell which plant they came from because of the way the application codes were "installed" on the parts. Some plants had the codes stamped into the part, while others used either a paper tag or a paint stamp.

    There's some more useless information for ya.
  10. cstanley-gs

    cstanley-gs Silver Mist

    I guess this was an option? I dont think my 72 lowers are boxed...
  11. copperheadgs1

    copperheadgs1 copperheadgs1

    Curtis, the boxed lower arms were part of the handling package that included rear sway bar..................Duane I prefer Pecans.:laugh:
  12. Duane

    Duane Member

    Ya well I meant to add .............for the "nut cases" like me but just didn't get it done.:laugh:
  13. GStage1

    GStage1 Always looking for parts!

    Uh oh.......old age is setting in for Duane??????:shock: :Dou: :bla:
  14. cstanley-gs

    cstanley-gs Silver Mist

    That explains it... no rear sway bar for me.
    - I did just pick up a 1 1/8 front bar though - will install after christmas -:beer
  15. copperheadgs1

    copperheadgs1 copperheadgs1

    Curtis, just remember bigger front bars add weight over the front end if you are into straight line peformance not good.............I am getting the sudden craving for mixed nuts?:Do No:
  16. cstanley-gs

    cstanley-gs Silver Mist

    If I were a racer... but im just a driver.
    never been to the track... my original 350 wouldn't turn any heads anyway.
    Im hoping the 1 1/8 bar will stiffen the front a little more with less roll around corners.
  17. rustedgoat

    rustedgoat Member

  18. copperheadgs1

    copperheadgs1 copperheadgs1

    I got an unbeleivable improvement in less body roll just swicthing to Polygrahite sway bar bushings only. Did not use the poly bushings in control arms. In my opinion that would give a bigger improvement that using bigger bar. Most noticable when coming off circular Highway ramps. Car hardly leans at all.
  19. BlackGold

    BlackGold Well-Known Member

    Ditto. Polyurethane sway bar bushings (frame mounts and end links) are the best bang-for-the-buck improvement you can make to your handling. High-performance tires and shocks are a necessity in my book, too. I would add a rear sway bar before adding a bigger front bar (or do it at the same time).

    Since I'm a nut case, I'll mention that on my Lansing-built '70 Olds, the application code is stamped into the upper rear control arms, while it's applied with a paint stamp on the lowers.
  20. wkillgs

    wkillgs Gold Level Contributor

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