The on-going saga of the Purple Impala

3279 Views 28 Replies 7 Participants Last post by  UttenBear
Hey all -

So I'm planning to document the trails and tribulations of re-fitting and reviving my 1968 Impala Custom Coupe in this thread. She was sitting on the side of the road for 10 years, about 15 miles from the house. She'd been there so long, and is such a vivid Purple, that she was being used as a landmark for directions. In fact, when I called the tow company to move her from her resting place, the tow driver knew exactly the car I was referring to, w/o detailed directions. Besides just being a hellava project, we started this adventure in July 2020 - my kid was supposed to take Autoshop in the Fall. I had a feeling that just wasn't going to happen due to COVID. So I figured, either we'll have a good old time tearing her down for an in person show and tell, or we'd get lucky and their would be some good bones for him to start learning the basics on underneath that purple paint.


Originally a 327, but when I found the previous owner, he’d dropped a 350 in her. "We got it to turn over once." There was a 3 speed TH350 attached to it - however that won't be going back in, I'll use it as a core swap on a 700R4. The plan is to build her up as a reliable, large but modern-ish daily driver. Nothing is sacred, very much the opposite intent as the pure-restoration crowd - I'm just looking to keep her wrapper as true (sans color) as I can.

The interior is gunna need a total make-over - however the bones are good, and the seat frames are good, just gunna need to strip them down and rebuild them.


Once we got her to the house, we started to tear her down bolt by bolt, with the intention of doing a frame up re-build. I didn't want to drop an enormous amount of cash, only to find frame repair welds and rusted frame supports.

A few things came to light as we stripped her down. First, the engine was fully seized, and whomever tried to get it in... well they had some interesting ideas about about how to do it. I knew the engine was highly suspect when it wouldn't hand turn at the crank, and when I saw the (no joke) speaker wire running along side the ignition wiring I pretty much wrote the engine off right there. Indeed it was seized, with rods bent, and a suspicious crack in the case once we yanked it out - however it was a great lesson for the kid about how it works and what NOT to do to an engine.


We did find out that its got a set of Hooker mid's on it, and that there has been some kind of work done on the rear-end (new shiny cover) - but the details for that needed to wait until we get the body off the frame, and replace the front end.


We ripped out that dead 350 (turned out to be from an early 70's Vet, and terribly, terribly abused) and tore it down for sport, from there we set to getting the frame yanked out for a deep inspection. That meant dissecting the poor beast bit by bit. The good news is that you can get a whole new wiring kit for the 68's - so along with the included diagram and the shop manual, I just ripped up all the questionable life choices that had been foisted upon this poor car in the past. I'm used to working on motorcycles, so the fact I could literally work inside the engine bay of the car was a total trip for me.

Once she'd been prepped the big day came: The splitting. I'll post the stop action video later - it was a wild experience.

From here, we inspected the frame and body. ZERO issues on the frame, and "normal" issues on the body for a 50 year old car. That meant that we were free to start ordering parts, and tearing down the very worn out front end.


The lower control arms were chewed up by a RightStuff brake bracket install that was doomed to grind down the bolt to a prison shank. The upper arms were mostly okay, but had a couple of speed holes in them that didn't give me a warm a fuzzy feeling. The steering linkage was pretty rusted out, and it looked like steering arm had been caught on something or used to pull stumps in a prior life.

{Part two coming...}
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Part Two - A lesson in Frugality vs Quality

Here is a link to the video of me and the kid splitting the frame from the body. Lots of planning and stress to get this done, and it paid off - the actual event was smooth and predictable.
Link to stop action video

From there, I was left with a very accessible frame to inspect and teach with.

I made a spreadsheet of needed parts, and went to town researching, and referring to my 68 shop manual. Even with a lot of study, I made some good choices, and bad choices. I made choices that I thought were good, only to get into it, and learn they were bad - or at least naive. My biggest lessons learned:
  1. Just cause they say it will fit on a 68, doesn't mean it will.
  2. Parts that say they work on "66-69" Impalas will almost always mean grinding or "fussing" over them or the frame to make it fit
  3. Just because it LOOKS like the more expensive part, doesn't mean it's as good.
Most of this was learned on the control arms and springs. While I ordered Global West upper control arms, I ordered some Jegs look-alike lower control arms - that turned into an entire war over 2 centimeters of geometry differences. I learned that a few centimeters is enough to foul up the entire work stream. While I was cursing over the front arms, we scrubbed out the frame, and painted it inside and out with rust reformer, after a good sanding. All the spots found were really surface rust, so that is it's own blessing.


Taking a break from the arms for a bit, I started measuring out the landing spot for the transmission, and was treated to the discovery of a frankenstien special support bar. Previous custodians had chewed a hole through the mount and just bolted it in - no bushings, it wasn't even straight. With help from the folks here, I found a solid looking bar fit for a 700R4 on the interwebs. I may have to grind and weld a spot or tow to get it to seat once I get to that point, however, for now it looks fantastic.

I went back to cursing at the springs and the control arms for a bit. Enough was enough, so I sprung for a complete set of GWest front end suspension parts. They went in like butter. I mean night and day.

I did one side of the car, and the set the kid loose on the other. I cracked open the "deal" on a Right Stuff brake kit that I'd tracked down, and stopped cold. I did a dry-run mock install and discovered that this kit was no different from the one I'd taken off - it was going to chew the control arms as well. Nope, not doing that - got a kit from Wilwood and was treated to the same smooth and predictable installation that was afforded to me by the Global West parts.

From there we bolted in the Front End rebuild kit from CCP. I can also say that this is a solid collection of parts. I had to get new spindles for both sides of the car (Was not expecting that... but glad I measured twice on that one...) and then we finished up the odds and ends. I picked up a set of 15" Cragar steelies with snow tires to act as shop rollers - and probably as real winter tires when the time comes.


That catches us up to the present! Next up, now that she's down on all four tires, is to tear apart the back-end - replacing the rear suspension with UMI parts, new springs and shocks. While in the middle of that, I'll be tearing apart the 10 bolt 8.2 rear-end to clean it up and prepare it for the full time daily driver life. The whole plan looks something like this:

  • Paint / treat Rear Frame
  • Remove Shocks and springs
  • Remove Control Arms
  • Teardown Rear-End - Refit
  • Rebuild suspension and re-integrate Rear-end
  • Run new fuel lines for EFI
  • Run new brake lines
  • Mate up the new ATK 350 with a 700R4
  • Install Engine and Tranny on frame
  • Install drive shaft
  • Put Body back on Frame
  • Install new engine wiring
  • Modify for EFI and install new gas tank
  • Fuel line tests
  • Engine start up
  • Replace floor pans
  • Re-wire the rest of the car
  • Install power window kit
  • Re-furb seating
  • Sound deadening, carpet installation
  • Interior trim
  • Re-install seats
  • Overhaul Dash and instrumentation
  • Re-fit / re-install steering column and wheel
  • Road-tests
  • Strip Paint and prepare for bodywork
After that step, I'll be taking a good hard look at if I want to get into body repair, or if I'll be sending it out to the professionals. Fit and finish may be a challenge that I don't want to take on.
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Looks like a fun project. What are your engine plans? An LS motor?
Looks like a fun project. What are your engine plans? An LS motor?
This ATK 350 is currently snoozing in the box,with it's Holly Sniper fan boys waiting impatiently.


I considered an LS swap, but the upfront cost and weirdness of getting into a 68 was not worth it to me. I decided to spend on the overall rebuild, and if the 350 EFI set up doesn't do it for me, I might re-calculate and swap in an LS after she's eaten this one up.
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Looks like a lot of fun! Have fun with the project. I bet that 350 will be a great cruising partner once you get the EFI dialed in.
Thanks for describung your journey, That is one cool project. Was the car yours to begin with so you have the title?
Thanks for describung your journey, That is one cool project. Was the car yours to begin with so you have the title?
I got lucky - the fella I bought it from actually HAD a title.
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Good wrenching session tonight. Pulled off the rear shocks, springs and track bar. After my front spring adventure, this was cake.


So if you’re yanking the springs off a 68 Chevy, here are the Cliff Notes:
  1. Put jack stands just in front of the rear control arms, in front of the body mount.
  2. Get a good jack, a piece of wood, and lift the back end up so the springs are compressed.
  3. Yank off the wheels to make maneuvering easier.
  4. Remove the TOP screws on the Shock absorbers.
  5. Remove the bottom bolt holding the shocks in. Once the bolt is gone, so are the shocks.
  6. The pan-arm / track bar binds up the rear end a bit. I had to remove mine because I need a new one - you should consider removing it, and examining / cleaning the hardware.
  7. Loosen the bolt holding in the bottom of the one of the springs. Leave the nut fully threaded, but loose.
  8. Slowly lower the Jack holding the rear axel.
  9. The springs should be snug on the control arms, but much less compressed.
  10. Remove the lower nut and bolt. Wiggle the cup out of there and put it in a safe place.
  11. With a hammer and a big flathead screw driver, tap the plate under the spring out.
  12. Gently whack the spring a few times with a 4lb hammer towards the rear axel - it will fall out with a satisfying ring.
  13. Jack up the rear axel again, until the reaming spring is juuuuuust compressed. Repeat from step 7

The rear of the car is solid, but a lot grimier, with more surface rust than any other part of the car. However, I learned A LOT from the more complicated front suspension rebuild - so tonight went well.

I’ve got to get a 15/16 Inch wrench to remove the upper and lower control arms - which arrives Friday. So, I’ll spend my next wrenching night sanding, cleaning and painting the frame, as much as I can.

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I had enough trouble with wrench clearance on the front of the rear lower control arms that I welded a socket to a piece of bar stock. Big improvement for assembly.
I had enough trouble with wrench clearance on the front of the rear lower control arms that I welded a socket to a piece of bar stock. Big improvement for assembly.
Yeah, I've identified that as my next boogy-man / the boogy-man in this element of the re-build - I decided to tread water until I get the 15/16 wrench in hand... that said, I'll take your fix into consideration. I need to start practicing with my new welder anyway - and I guess all I need is "strong" not "pretty."
I have a 15/16 wrench and it doesn't quite grab enough to get the correct torque. Just grind the chrome off and a socket will weld just fine.
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I have a 15/16 wrench and it doesn't quite grab enough to get the correct torque. Just grind the chrome off and a socket will weld just fine.
Whelp, before I make a franken-socket, I'm going to try an offset wrench and see where I get. Fingers crossed.....
So, after some cussing and about $60 worth of various wrenches, I’ve gotten the rear end off the frame, and pulled the rear control arms.

as JustJohn mentions, getting a firm hold on the rear lower control arm bolt at the frame is a real PIA. I tried to take his advice, but I couldn’t find a 15/16” socket small enough to get into the frame to grab the nut.
What I learned is that a 70 degree offset wrench will do the trick. Good luck finding one - I now own a 45 degree set as well.


Regardless, once I got the wrench, it was easy days getting the bolt out, and the arm off. My lower control arms look every day of their 50 year life.

Once freed from the frame, we carried the rear end over to the work bench, and just to gauge its weight, I dead lifted the 8.2 10 bolt. My guess is just under 200 lbs. So, me and the kid lifted it up on the bench, which should have 250 lbs of capacity to spare. Nothing bent or groaned, and it’s still up right, so looks like my estimate was mostly correct.


Once up at a civilized height, we started to break it down. The axels look good, and there wasn’t anything too bad found inside this much derided GM 8.2. That said, I’ve found 2 things that gave me pause:


The main ring gear has scoring across 5 teeth, I can also see some bites in the pinion. Once I got the center pin out, I also was treated to some abrasion on that as well. Finally, there is a little bit of a deform in the case itself (right hand photo) that I’ll evaluate more of once I pull out the differential carrier.

I didn’t have a lot of hope that is be able to just change the oil and reuse this rear-end - but I did have just a little. Well, that’s been dashed at that point. A 390HP/420fpt engine will be sitting in front of this, so I’m on the line anyway. No real choice here but to tear it down and prepare to replace all the innards. That’s still a lot cheaper than a new 9” all-in-one rear end.

Come Monday I plan to have a chat with the folks from Yukon on my best bets here. As long as I’m in there, I’ll be targeting a Positration upgrade, and bump my rear ratio up to at least a 3.73 - since she’ll be more of a Highway cruiser than street burner. By my guess I should be turning 2K RPM at 60mph and just shy of 2.5K at 75 RPM with a 700R4 using that ratio. It should also play nice with a 2200-2500 Lockup stall converter - at least by the book.

About to run to the store for more brushes to paint the remaining frame exterior - I’ve got high hopes that the rear-end rebuild will be more straightforward than my front rebuild. Wish me luck.
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Best laid plans and all.... the rear-end rebuild took a lot longer than expected - that said. It's done.
Tire Wheel Vehicle Car Motor vehicle

Lessons learned here: The '68 8.2 uses the C-10 flanges. This makes getting the right brake set a little challenging. Also, you'll need to get a spacer for between the caliper/parking brake mount and the flange to have the right axle offset to make the install work. That 2.47 number matters a lot.

The other lesson learned is that new axles are built much beefier than the old ones. Besides having to make sure that your axle bearing inner diameter matches the axle journal (DO NOT TRUST online stores to give you the right dimensions - there are 2 different sizes floating out there) you have to make sure your wheel studs are press in, or they are using low profile bolt heads on screw-ins. The tolerance on the Wilwood brake set ups are the reason I really like them - but its a double edged sword.

Outside of that, this was a practice in precision and repetition. Probably took me a good 14 hours of 2-hour sessions to yank it, tear it down, clean it, track down parts, make historical discoveries, recover from historical discoveries, and then what seemed like endless build-measure-disassemble-adjust-build-measure cycles. I went the route of a crush-sleeve eliminator in order to have a more recoverable path.
Watch Product Analog watch Font Clock

This is a huge upgrade from stock. From drum brakes to 12” discs. From an open differential to a Limited-slip differential. Nearly stripped axels to brand new Mosers. Flimsy Diff cover to a load bearing B&M cover. From a 3.55 to a 3.73 final gear ratio. Outside of the upgrades, every bearing, race, bolt, washer and nut has been replaced where it could be.

Photograph Automotive tire Tire Blue Light

I feel more than confident that this should be able to handle the 390HP/420lb torque that the new engine can put out.

Besides: It’s Purple now. 😀

Next up: Refitting the rear-end to the frame with all new control arms, springs, and shocks.
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What was the hardest part rebuilding the entire rear-end of the Impala?

The 🤬 Coil Spring Retainers. This one tiny screw and block inside the rear spring is a nightmare to get started. If they’d given me .2 more inches on the little screw it would of been cake.

Anyway, the frame is back on the ground with new control arms, new coil springs (with insulators) new shocks, and shiny new bolts all around.

Hood Automotive tire Motor vehicle Bicycle fork Rim

Bumper Motor vehicle Gas Automotive exterior Engineering

I don't know why, but fresh, new, shiny, over-spec bolts on a cleaned, treated and painted frame, makes me very very happy.

I have to get a new standard panhard bar because the new beefy differential cover won’t work with the one I’ve got, but this would be the first time I can get around an incompatibility for less than $100. I also have a non-UMI rear sway bar that will need new bolts and custom spacers to work - so I'm seriously thinking about dropping a few bucks to just have the whole rear (sans Panhard) match.

Next up… plumbing: Fuel lines and Brake lines. NiCop line, fittings, and pro-flare tool ordered. Moving right along... once the plumbling is done, the real fun: Engine and Tranny mounting. Can't hardly wait!
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I had some panhard clearance issues on mine since I just had to have the aluminum girdle cover. My solution was to clearance the (solid) bar some and machine a new lower mounting bolt with a hex about 1/2" thicker. It's tight but works perfectly.
I've seen some more extreme solutions on Impalas that included fabricating a new mount. Too much in my opinion to open up 1/4" clearance.
Cylinder Auto part Nickel Metal Household hardware
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What was the hardest part rebuilding the entire rear-end of the Impala?

The 🤬 Coil Spring Retainers. This one tiny screw and block inside the rear spring is a nightmare to get started. If they’d given me .2 more inches on the little screw it would of been cake.

Anyway, the frame is back on the ground with new control arms, new coil springs (with insulators) new shocks, and shiny new bolts all around.

View attachment 30172
no splash shield cover on your rear rotors?
Good eye - I'm actually fabricating some for the car. The didn't fit dead on / comfortably - and I had a need to get the frame assembly on 4 wheels to continue my work.

no splash shield cover on your rear rotors?
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That does bring up an interesting philosophical conversation: A few associates and pals think I'm wasting my time building out dust/splash guards at all. Anyone here have interesting opinions they'd like to share?

no splash shield cover on your rear rotors?
I didn't worry about them on mine but it's a fair weather convertible.
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