The Studeblogger

Saturday, July 28, 2007

Front End Rebuild, Pt. 4: Kitchen-table A-arm bushing installation.

I'm starting to reassemble my front-end parts now, whilst waiting (and waiting and waiting) for the final few bits that are on backorder at SI to arrive (grrrrrrr). One of the most discussed topics on the SDC Forum is front-end rebuilding, and it seems every so often someone posts a question about installing new the bushings that hold the control shafts in place.

The factory shop manual describes a complicated procedure that requires a pneumatic press and several custom installation tools once made by Kent-Moore (presumably unavailable today - I've contacted Kent-Moore via their website, but got no response). Well, most guys I know don't have these tools and have no hope, 50 years later, of finding someone who does. So after a little searching, I found this A-Arm Bushing Service Kit made by Minnesota Pneumatic Products (MPP). I got mine off eBay for about $50. The set consists of a large screw-type c-frame and several adapters for pushing bushings (excuse the rhyme).

What you'll need: The aforementioned service toolkit, a 7/8" socket, your A-arms, control shafts and new bushings. I stripped and refinished my old A-arms after inspecting them for damage, coating them with Rustoleum primer and gloss black. Same with the control shafts after carefully sanding the machined ends to remove the rust scale that had accumulated inside their bushing sleeves. (My suspension apparently was original - it had not been serviced or renewed since it left the factory. Amazing.)

Check out the new bushings. You'll see that they're "stepped." This shoulder prevents them from being pressed completely into the A-arms, since this would bind the control shafts and keep them from turning freely. Start by pushing the small end of the bushing into the A-arm by hand, then put the receiving end of the c-frame around the interior of the arm, and use the small press adapter on the threaded shaft. You'll also find that the service set has a selection of thin rings; choose the one that fits best around the exposed rubber on the outside of the bushing and slip it on; this will make sure that the tool presses on the outer metal sleeve of the bushing instead of pushing on the rubber, and centers the force as well so that the bushing doesn't go in cockeyed.

(Sharp-eyed readers will note that the adapter ring is not installed in the photo above. It took me a bit to realize that I needed to do this, since the tool set comes without instructions.)

Now, using your socket wrench, tighten the c-frame's screw and start the bushing into the A-arm. After a few turns, STOP! At this point, you MUST install the control shaft, since there will not be enough room to fit it in if you wait until the bushing is fully seated. Just insert one of the control shaft's ends into the opposite hole in the A-arm, and then swing the other end in and slide it into the bushing you're installing. DO NOT use any kind of lubricant or anti-seize on the control arm ends! I know it's tempting, but these were meant to operate dry.

Crank the screw until the shoulder on the bushing is about ready to meet the A-arm. Continue the procedure on the other side of the A-arm, capturing the control shaft end in the bushing as you press it in.

Look at the control shaft and slide it all the way toward one of the bushings. Do you see shiny machined metal? There shouldn't be more than .015" of end play in the control shaft; if there is, you'll need to press each bushing a little at a time to close the gap between the bushing end and the shaft's shoulder. Make sure that the shaft doesn't bind; you should be able to turn it easily by hand with a bit of resistance.

Voila! You're done. You can install the capscrew and washer combination that torques the control shaft to the outer bushing, but DON'T TIGHTEN IT until the A-arms are installed in the car and the weight of the car is on them; these need to be in "at rest" position before those bolts are tightened. If you tighten them in any other position, the A-arm will put a twist on the rubber and whenever the car is at rest, which wears it out prematurely (and we don't want to have to do this ever again, do we?). Bolt it to the frame and move on to something else!

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  • Hi,
    Enjoy you blog.
    Does the A arm bushing service kit work with the larger lower control arm bushes?

    By Anonymous Geoff, at 3:34 AM  

  • Sorry so late getting back Geoff; you've probably found out by now that the kit does indeed work with the lower A-arms as well. Good luck with your rebuild!

    By Blogger Clark, at 10:09 AM  

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