1970 Corvette Rear Suspension & Frame Restoration
Note: This page is Graphics intensive due to a large number of photographs. I hope it's worth the download time! :-)
I started on the restoration of the rear suspension and drive train in February, 2002 when I noticed the right rear wheel bearing making noises and having excessive play. I was going to just pull the right trailing arm and take it to Tony's Corvette shop for rebuilding. But the while I'm at it's quickly took over. Next thing I knew I had removed the exhaust, spare carrier, left T-arm, rear differential, rear spring (not original), half shaft and drive shaft. :-)
Here are a few AFTER photos to whet your appetite:
And to get an ideas of just how much was involved, here are some BEFORE pictures:
This other page has more BEFORE pictures.
It only took a few more turns of the wrench and the gas tank was dropped. It was not the original gas tank, and it was not configured correctly for my '70, plus it barely held 16 gallons of fuel, so I ordered a correct new tank from Quanta with the Anderson logo, while I was at it. :o) What looked like the entire back half the car was loaded into Greg's pickup & dropped off at Tony's Corvette shop where Jose took on the rebuilding: replacing the bearings, bushings, new seals in the differential, powder coating the cross member, hot tanking the grunge and sand blasting the rust, sending out the bolts and dust shields for plating etc... They also found and restored a nice set of original rear strut rods for me since my car had replacements with the large ends. One of the things I love about their shop is that they actually listen to their customers. Tony took the time to discuss all the options and pros and cons of the various finishes with me. And they restored the components exactly the way I requested. :-)
Here are a bunch of mid-disassembly and other assorted detailed photos.
Now, before you all start e-mailing me with your critical NCRS judge like observations, I must explain my rationale behind the finish on the differential, half shafts and drive shaft. Yes, they do have cast blast paint on them, and yes, I do expect to get a deduction for the non-original finish when I get the car judged. I realize that from the factory, they were bare metal. But after all this work, I don't want rusty bare metal down there! And I have less than zero desire to HAVE to get under the car on a monthly basis with oil to keep the natural metal natural. This '70 is not a trailer queen - I hope she looks like one - but she doesn't want to live that kind of sad and lonely life. :o) In 2.5 years of ownership I have put 10,000 miles on her. And I've loved every single mile! So for me, and I'll admit to anguishing for weeks over bare steel or paint, this was the right decision. Your mileage may vary. :-)
OK, back to the restoration. I tracked down and purchased a used original 9 leaf spring and restored that myself (flat grey primer paint and new liners from Paragon).
A bunch of rear spring pictures & other originality details are here.
I also tracked down a set of new AC Delco Reactec shocks. Supposedly the reactec shocks (with the appropriate paint) are about as close as you can get to the original configuration shocks without going the NOS (ie. nearly impossible) route. I used Krylon Stone Grey gloss paint, which according to the Krylon sheet at Ace hardware, is the new replacement color for Dove Grey Gloss. However some NCRS friends have indicated that they are a bit too pale. So I'll have to find some Dove Grey leftover on a shelf somewhere and repaint them, if a bit of driving doesn't darken and tone them down some. Wishful thinking!
Then began the arduous 3 month task of restoring the frame - in my spare time. Admittedly, there isn't too much spare time with a 7 year old daughter, full time career, part time grad school (engineering) - so any normal person might have the frame restoration done in considerably less calendar time. I'm estimating that I spent at least 100 hours with an assortment of wire brushes with air power, battery power, electric power and good old elbow grease powered tools. All with the body on the car, and the car on jack stands. One might ask why I just didn't pull the body and be done with it, but our garage does not have the vertical clearance, and frankly, I just didn't want to go there! I'm saving that for my next '70 restoration - which will be a yellow LT-1 Convertible. :-)
The original frame had mostly a light coating of cosmetic rust. About a quarter of the frame still had the original paint on it - mostly on the sides and the top of the frame. Only the left rear portion of the frame, just in front of the wheel had metal scale. Of course after wire brushing the scale left a somewhat dimpled finish in the steel, but at least the rest of the frame could be wire brushed down to shiny bare metal.
I did find the VIN number stamped into the frame on the driver side, right in the back of the wheel well just where it passes under the body. I managed to get a photograph which partially shows the frame VIN stamp. (0S404102)
I removed everything from the frame which I could - brake lines, junction fittings, brackets. I loosened the fuel lines and took all the clips off. I cleaned up the fuel lines and the brake lines. I replaced the rear cross over brake line as the original was quite rusty. The cross member and straps holding up the gas tank was removed, wire brushed and repainted. I also took off the Alarm horn and restored that while I was at it.
UA6 Horn restoration photos are here
I cleaned up the rust on the rear plenum drains and gave them a light mist of clear. If you take a paper towel and rub it over the clear just before it's dried it dulls it down nicely. You can also breathe on the part raising the humidity forcing a more matte finish. The metal support on the backside of the rear storage area was also restored. I masked the rivets and fiberglass around it and painted the bracket black.
While in the back of the car, I found that I was going to have to 'deal with' the rear body mounts. Unfortunately the rear vertical metal cage portion which is riveted to the body - the part sandwiched between the body glass, and the rear wheel well glass - was rusted into oblivion. I was really surprised to see just how much corrosion was back there, considering that the factory masking tape was still visible on the body mounts in the wheel wells! Greg was able to take his pneumatic panel cutter (sheet metal cutter) and cut the corroded rivets out. I then chipped out the remaining bits of metal and sealed the exposed metal edges of the body mount. Eventually when / if I do pull the body on the car I'll replace those, but the other three sides and the bottom of the mount was in fine condition, so that's how it's staying for now. :-) Or else I might just take it to Tony's and let them deal with it. :-} There are photos of the rear body mounts in the 'before' picture webpage.
I removed the rocker panel covers and restored them. To tell you the truth, that was the hardest part of the entire restoration. The screws were so rusted in place, even several days of soaking with penetrating oil had no effect. I stripped a few screw heads on one side and enlisted the help of my husband. He proceeded to strip a few screws - I wasn't the only one having a particularly blonde day. ;-) Then began the drilling and easy-out approach. Who ever named them easy outs had rocks in his head. We broke one off inside the screw! Then came the grinder with an assortment of stone bits on that hardened easy out. What a pain. Finally the last screw head was ground down and the panels were removed with only one small scratch in the soft anodized aluminum. The rocker panels are the original ones with the front tabs (very difficult to find!) so you can imagine how stressful that was!
I cleaned off the blue over spray, road tar and 30 years of grime, polished, freshened up the black paint and put a light misting of clear acrylic on them. They look pretty darn good if I do say so myself. :-) I also cleaned up & painted the calipers, making sure to keep the machined areas free of paint. The brake calipers were rebuilt in December 1999 by Tony's Corvette when I first purchased the car. The calipers had some rust on them in a few places, but were otherwise in fine condition. A few minutes with the pneumatic wire brush (soon to become my best garage friend) and a few wipe downs with lacquer thinner and they were ready for high temp gloss spray paint and new organic brake pads.
Then I started wire brushing. And brushing. And brushing. Even though I wore a breathing mask, ear muffs and a full face mask I managed to get rust crud in all the nooks and crannies of my body. ;-) For the most part I used the air tool at about 50 psi with 1/4" shank coarse cup style and disk style wire brushes. I took the cordless zip tool to get into the nooks and crannies with the smaller wire brushes (ala dremel bits). In order to get the rust up high on the outer sides of the frame, partially hidden by the body, I fabricated a simple hand sanding tool. I took strips of the open mesh drywall sandpaper and stapled it to a paint stirring stick. It worked excellent for getting the surface rust off in those narrow spaces. One note of caution: when a wire brush is nearing the end of it's life and you rotate it at 20-30,000 RPM, it becomes the most efficient wire projectile body piercing weapon imaginable! <grin>
With all the rust turned into dust, I then used simple green and cleaned the entire undercarriage from the front of the doors aft. I also restored the emergency brake hardware, the drive shaft tunnel, the plates for the seat bolts and all the other riveted plates on the underside. For the most part I was able to wire brush the rivets with the soft little Dremel brushes, mask them off, and paint the brackets. Unfortunately I couldn't quite get the big support which goes up over the underside of the tunnel down to bare metal, so it still has the old car 'patina'. At least it's got the big corrosion off it now. :-) I did find some date codes on that part.
Once all the little things were restored and the rust dust all cleaned up, I wiped the entire undercarriage down with lacquer thinner. Then I carefully masked off everything with masking tape and glossy mail order catalog pages (paint doesn't bleed as quickly through gloss paper). I masked the fuel lines and brake lines with little paper tubes so that I could lift and paint under them. I then cleaned the exposed areas one last time with lacquer thinner.
Finally, I painted the frame and wheel wells with John Deere Blitz Black paint in rattle cans. I must say I am impressed with their paint can spray quality. The tips put out a real predictable pattern from the first spray until the last. I've started saving their spray tips for using on my other cans. Now, if the paint holds up as well as it has been touted, I'll be all set. :-)
With the frame restoration finally completed, and less than one week until Vintage Thunder XI (Mason Dixon NCRS Club annual drag racing event) I turned the corner and finally started reassembling! With the AIM in hand and Greg's help, we installed the gorgeous differential and trailing arms. I opted to be as close to the original installation as possible, and used the original hole style shims. As a first guess we installed the same number / thickness shims as were put there by the factory. The rear suspension (with the exception of the rear spring and strut rods) had never been out of the car before, and still had all the original U-joints and hardware. I cleaned up all the hardware on the wire wheel stand. I reused all the original hardware, with the exception of the brake caliper bolts. I referred to my before pictures and tried to get the bolts and cotter pins and washers oriented as they were from the factory, before disassembly. This includes the cotter pins on the differential mount. I followed all the torque specs in the AIM and the torque procedure in the service manuals.
I printed out a high resolution copy of my build sheet which was found behind the dash. I had it laminated and I foam taped it to the gas tank. I also signed & dated the tank and glued on a '70 Registry business card before installation. :-)
The new Maryland rear leaf spring compressor (a simple 2x4 cut to length <g>) was used to install the spring. ;-) The restored 9 leaf spring gave her a lower stance in the rear than before. This was immediately obvious sitting in the driver's seat, looking over the hood. But she is now closer to factory specifications.
Being under the gun, and having to prove to the doubting Thomas I married, <g> that I could get her back together in time, I didn't take too many step by step reassembly photographs. Suffice to say, it all went back together just fine. I spent every waking minute when I wasn't in the office in the garage. I even took a few days vacation from my desk job to finish her up. Can you detect an obsessive-compulsive personality? ;) It was 4am Thursday night (errr.... Friday morning) when the exhaust was finally installed and aligned (well sorta). ;) But she was together! The next morning (which came waaaaaay too soon!) I made it up to Tony's Corvette Shop for a 4 wheel alignment where Jose (after scolding me for driving it with the camber that far off!) got to tweak one of the T-arm shims. :-) At least the T-arm pins came out easily, after having only been installed for barely 24 hours! :-) I was quite the sleep deprived zombie by Friday night when I gave Sophia a quick cleaning, checked the fluid levels and hit the sack!
The next day, June 8, 2002 - four long months after taking Sophia off the road, I set a new personal best in the 1/4 mile at Cecil County Dragway - 15.04 seconds at 91.6 mph. Plus I won the Mason Dixon Vintage Thunder XI Ladies Eliminator and Top Eliminator trophies! Moral of the story: A beautiful restored smooth polished, painted undercarriage, suspension and drive train is worth about 0.2 seconds over an ugly old rusted one.
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