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C5/C6 Corvette: Poly Control Arm Bushing Install Tricks and Tips!

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  • C5/C6 Corvette: Poly Control Arm Bushing Install Tricks and Tips!

    C5/C6 CONTROL ARM BUSHING FAILURES

    Over the years we have seen repeated control arm bushing failures on C5, C6, and C7 Corvettes. In this post we will cover the installation of polyurethane bushings for both the C5/C6 generation Corvettes (1997-2013), which use virtually the same control arms, uprights, and hubs (they are interchangeable). We will also cover why we recommend polyurethane upgrades for these cars vs other options, like Delrin or metal spherical bushing upgrades.



    After a year of track abuse on a 16 year old C6 Corvette, shortly after installing MCS coilovers and dropping some lap time, one of the stock rubber bushings failed. This wasn't on some super grippy Hoosier, it was on some rather underwhelming 275mm Hankook RS-4 tires, which we would barely consider 200 Treadwear. These make 1.15g lateral and braking. Now this wasn't surprising, and the moment it happened on track I knew exactly which bushing it was - because it was starting to push out slightly and we noted this on a pre-track inspection.

    That failure began some updated research, budget inspection, end use review, and even class rules discussion before we went right back to the same Energy Suspension bushing upgrade for this car that we have done on previous Corvettes, namely the 2002 C5 Corvette below.

    WHY WE CHOSE POLYURETHANE BUSHINGS OVER DELRIN OR SPHERICAL

    We don't claim at Vorshlag to be "a Corvette shop", but people who work here and our customers have owned, raced, worked on and driven many of these cars from the C4 generation through the C7. In reality a "Corvette" isn't some magical unicorn - it is "just a car" with the same type of "suspension bushings" like almost any other. These Corvettes suffer the same failures and respond respond to the same bushing upgrades as a Miata, or RX8, or BMW, or Mustang.



    We have a lot of seat time and have done a plethora of upgrades to the 2002 Corvette above, which was our first Corvette bushing install. After 7 years of abuse has gone onto the grease-zerked Energy Suspension poly bushings we installed into this car in 2015, and zero issues since, we have full confidence that these are worthy of Corvette use. The car above has been autocrossed with 345 Hoosier A7s, 315 Yokohama A052s, and tracked as well. These bushings still look new, and only require an annual squirt of grease to stay squeak and stiction free.

    During our 7th track test on our narrow body C6, even before we had upgraded from the rather low grip 275mm Hankook R-S4 tires (1.15g lateral), a front bushing popped out of the control arm. This was bound to happen, as this is a common failure on C5/C6/C7 Corvettes when heavy braking and cornering loads are put into the suspensions, either with sticky aftermarket tires and/or from significant suspension upgrades.



    There was one upper control arm bushing that had pushed out of the sleeve under heavy braking on the RS-4s, and this would only get worse the more we ran higher grip tires on this car. Replacing one bushing with another OEM unit would be beyond foolish, as this is a very common failure. We have had customers who tracked their C6 cars that had multiple bushing failures when new, and replaced them repeatedly under warranty. The "common fix" is to swap to spherical bushings on all of the rubber bushings. Of course there are numerous downsides to any option, especially sphericals...



    I spent time looking at the various options again in 2022, now that I am tracking and Time Trialing in a 2006 C6. The fact that "everyone on the internet" goes with sphericals to replace the rubber bushings is suspect, but there is a lot of the "heard mentality" on this "upgrade", mostly because the shops pushing these make a lot of money doing this work - it is an expensive piece of kit and requires some significant work to install them.

    The price is the first downside - two thousand dollars for a spherical bushing kit is a LOT of cheese. Then there is the work to install these, often including a step to send the control arms to the manufacturer or qualified shop to have the round openings machined / honed to a precise OD so that the sleeves and bushings slide in and don't rattle. The third problem is NVH - Noise, Vibration and Harshness. With ZERO deflection at all of the control arm mounts, even the slightest pebble in the road will transmit all of that ride harshness and noise into the cabin. And then there is the wear issue...

    Another downside - sphericals are not legal for the SCCA TT Tuner class we wanted to run, so that option was out for my C6. This isn't unusual for some Time Trial or Autocross classes, either. The Delrin bushing kit from Ridetech would be Tuner legal (it is plastic and "not metal") but still $1400 for the kit, with as much work as any other to install, and likely will make the ride quality as bad as the metal sphericals.



    In addition to added NVH (noise / vibration / harshness) there is a RAPID wear and replacement cycle with sphericals. We had a customer stop by in his C7 Z06 recently, who both daily drives and does 2+ track days a month in his C7 - often on Hoosier or other high grip level tires. He had so many OEM bushing failures on his C6 Z06 (fixed under warranty) that he preemptively upgraded his C7 to spherical bushings. And they worked great, for about a year...

    He had been chasing a very loud rattle in his C7, and had torn apart the car looking for the noises. He ruled out swaybar end links, wheel bearings, and other items. After asking me to take a test drive in the car, it took me about 30 yards of driving to know what had happened. The rattle was LOUD and constant. After getting to the end of our driveway I got out, popped the left front tire's sidewall with my fist and - BANG! BANG! BANG! - showed him how to replicate the noise. The sphericals were completely worn out after one year of use. You see, unlike the sphericals we use in top mounts, Corvette control arm bushings are MUCH closer to the ground. In this location the unsealed, metal-on-metal spherical bushings get sprayed with water/rain and that is mixed with road grit and sand. That water + grit spray is a combination that a metal ball and socket cannot exist with and it just EATS metallic bushings.



    We also wanted to keep some decent street manners, and you NEVER run open sphericals in the control arms on street cars. To keep our C6 from turning into a "miserable to street drive" car with loud rattles and bangs, plus the SCCA TT Tuning class rules we were building around, we went with the same Energy Suspension bushing kit we used on that car (the C5/C6 bushings are identical).

    POLY BUSHING INSTALLATION TIPS & TRICKS

    The Energy Suspension bushings for the C5/C6 come in two colors (red or black, no functional difference) and there is a kit for the front (ENS-3-3176) and another kit for the rear (ENS-3-3177). All in you are looking at about $150 for all of the parts. And if you value your time at $0 per hour, get this kit. Otherwise to save 5-8 hours on this install, we have another option, linked below!



    Normally when ordering Energy Bushings I go for the RED color option, to show the bushings better in pictures, but that color was out of stock so we went with black (add an R to the end of the part number kits above for Red, add a G for Black). They come with some small packets of grease but I'm going to show you a trick to make these poly bushings SQUEAK FREE for life - it involves adding grease zerks to each bushing. This is a pain in the ass, but if you plan on keeping your car for more than 6 months, you want to DO THIS STEP.



    Since doing this install on our C6 we have found that aFe/PFadt makes a BETTER poly bushing kit for the C5/C6 Corvette, shown above. Why is it better? Because it comes with the same style polyurethane bushings of course, but ALSO includes new sleeves, cross pins and washers. You do not have to re-use the T-bar cross pins, and that will save you a LOT of time, frustration, and mess. The install for that is still going to take you 4-6 hours, but not TWO DAYS like the Energy kit. The cost is roughly 4x more for the PFadt kit but again, if you value your time at all it is the smarter move!



    Getting the control arms off the car is relatively easy - support the car in the air so the suspension can droop out all the way and more (preferably a 2 post lift, but also on tall jack stands), remove the wheels, and then remove one control arm at a time...


    **********FINISH WRITING THIS SECTION BELOW*************


    Removing all traces of the bonded rubber from the cross-pins is the time consuming part. That step is skipped with the $1400 Delrin and $2000 spherical kits above, as they provide new cross pins. But so does aFe with their bushing set - note the top left image. Sure its over $600 vs the $150 for the Energy set, but not having to spend HOURS to cut and clean the rubber from the stock cross pins is huge. If you value your time at $0/hour, get the Energy kit. If you operate with "time = money" then get the aFe kit and save the frustration! I was ignorant about this aFe option and we burned lots of hours getting these cross pins ready.



    First you need to remove the bushings from the arms. This is relatively easy. Grab the T-bar shaft in the vice and yank / twist / pull the arm and these usually pop out. Older cars are a little easier now than when they were new. That's the easy part.



    Some folks like to burn the bushings off, but it makes a stinky, smoky mess. Here Doug used a serrated blade and carefully cut most of the rubber off, then a Scotch-Brite pad on a die grinder removed the rest. It makes a HUGE stinky mess, but less than the fire method.























    Last edited by Fair!; 07-27-2022, 09:57 AM.
    Terry Fair - www.vorshlag.com
    2018 GT / S550 Dev + 2013 FR-S / 86 Dev + 2011 GT / S197 Dev + C4 Corvette Dev
    EVO X Dev + 2007 Z06 / C6 Dev + BMW E46 Dev + C5 Corvette Dev
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