I can't add much here other then to say it may make sense to heat the drill bit prior to attempting to drill the holes into the bushing material in an effort to try and prevent it from splitting as the bit passes thru.
Those bushings look rather unforgiving to anything short of a perfect straight line with the drill bit though.
I wonder if putting the bushings in the oven at some low and slow temp similar to one used to cook a pot roast for X period of time and then removing them to cool would permanently soften the Poly material stiffness enough to avoid needing to drill so many holes?
Or, maybe a safer method would be to Boil them in hot water, cool them, then boil them again, then cool...etc for a few cycles to see if they permanently soften
One thing about Poly is that it "moves" out of it's own way pretty easily. I performed the modifications but have yet to install the arms on the car (I was under the car for 5 hours figuring out torque arm noises only to realize it's the fucking exhaust mid pipe hitting the mounting cross member
) and one thing I noticed is that my 1/8" holes are not quite 1/8th inch because the poly gave slightly when the drill bit went in. I did my best to "hog" them out but you can only do so much. They look like they will be fine, no cracks or anything and the bushings went into the arms reasonably well.
Here is the HOW TO:
Necessary tools:
Propane or MAP Torch
Hammer (standard hammer is all you need, no need for a sledge)
1/8" drill bit
Cordless Drill
Dremel or other rotary tool with cut off disks, wire wheel (optional) and sanding wheel
Open air space (don't do this inside the garage, do it outside, you'll thank me!)
Patience (lots of it)
2x4 about a foot in length helps out.
Step 1: Buy used set of control arms from someone on your forum of choice, or buy new ones from Ford. I bought mine from a member on S197Forum for about $50 shipped for all 3 rear control arms. I didn't need the UCA but why the hell not?
Step 2: Burn the bushings out. If you have never worked with rubber bushings before, here is a huge tip, they DO NOT burn fast enough to truly burn them out. Instead of trying to light yourself on fire with the rubber burning, heat up the metal ring holding the rubber in place. On each end of the arm there is a half of the sleeve that has glue on it and a half that does not. Heat the side that has the glue, it'll be obvious since the "lip" on the one side of the bushing is not restrained.
Step 3: Continue to heat that metal sleeve... no seriously.
Step 4: Continue to continue to heat that metal sleeve... yes seriously continue.
Step 5: After about 5 minutes of heating that metal sleeve quickly put the control arm on the 2x4 and pound the metal sleeve in the center with the hammer until the bushing pops out of the arm. If it wont pop out with some good whacks, repeat step 2-4 again.
Step 6: Finish all the remaining bushings
Step 7: With the dremel with the cut off disk, clean up the inside of the metal sleeve until it is shiny silver. Do this with the "lips" as well. Get as much of the still intact rubber off as you can with the cut off disk and maybe see if a wire wheel will help remove it all. I didn't have one so I didn't use one.
Step 8: Use the sanding wheel to smooth the inside of the bushing bore and remove the ridges. It will look like this when done:
Step 9: Do this for the remaining 3 sleeves
Step 10: Step back and marvel at your masterful work:
Step 11: Test fit the bushings and ensure that they slide in and out of the arm easily. If they don't, go back to Step 7 and repeat until the bushings are firm to put in and take out but not so firm as to require a hammer. Repeat Step 7 if the when putting the metal sleeve in makes the bushings too tight.
Step 12: Draw on the bushings where you are going to drill. Leave space to the center bore as well as the out side edge of the bushing.
Step 13: Using the 1/8" drill bit, drill the 8 holes in the bushing taking care to ensure that there is roughly 1" of solid bushing material at the center of the arm. This equates to 1" of drilling on the tall side of the tall bushing and a half inch on the back side of that bushing and roughly .6" and .4" on the other side's shorter bushing. It's not as much as it looks so take your time! I drilled the caps first and used them as a "guide" and I left the bushings in the arms while drilling to remove the "compression factor" from the equation.
Step 14: Lube everything up and assemble the bushings. I put lube on the under side of the caps where they touch the outside of the metal sleeve as well as the inside of the sleeve bore since I'm 99% sure these bushings are going to rotate in the sleeve as much as they are going to rotate around the metal sleeve running through them. This is kind of a "poor" design on Prothane's part but what can you do? I suppose you could design your own and build your own! This is the more preferable route since it allows you to step the durometer of the poly as you get away from the super hard "center". Maybe someday when I have more free time I will do this with stuff from McMaster. We will see how these hold up to daily driven abuse.
Step 15: Marvel at your work then install on the car:
I can't stress the patience part enough during this install. If you think you've heated up the sleeve enough to break the glue free, continue to heat it up because chances are you haven't. This is probably the most painless way to get those things out of the arms so do yourself the favor and do it this way FIRST and you can't exactly overheat the sleeve to ruin it so you might as well er on the side of hotter than cooler.
