Author Topic: Original inspection paint marks on underbody  (Read 6967 times)

hotrod68

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Original inspection paint marks on underbody
« on: May 19, 2006, 03:25:19 AM »
Hi all  :). I'm doing a frame-off on my '68 and I soft-cleaned the front suspension and found the factory paint marks--but the rear suspension marks have been lost via rust/changed components, etc... Does anyone know what colors GM used on the rear, and on what parts? I.E. were there paint marks on the shackle nuts or spring mounting points to show they had been tightened? I've seen original orange marks on the nuts of '69 Firebird brake backing plate bolts, for example, but have no idea what my '68 would have had. Any help would be greatly appreciated  8).  Thanks, Barry
HotRod'68  1968 SS350 coupe undergoing frame-off resto/rod. 386/350/4.11s
Butternut Yellow    black standard interior

JohnZ

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Re: Original inspection paint marks on underbody
« Reply #1 on: May 19, 2006, 05:54:19 PM »
The car assembly plants didn't paint-mark fasteners to indicate they had been torqued; occasionally a finished car selected for the daily quality audit had plant-installed fasteners marked as they were checked with the car on a hoist in the off-line quality audit area, but there was no paint-marking of fasteners on the line. Some fasteners that were installed by the supplying component plants (like backing plate bolts) may show paint marks, but only assembly plant-installed fasteners were torque-checked in the assembly plant quality audit.
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hotrod68

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Re: Original inspection paint marks on underbody
« Reply #2 on: May 20, 2006, 06:09:27 AM »
QQ John?
  I found clearly-defined lavender and orange paint splotches on my front suspension--what do they mean if not assembly line inspection marks? I also found yellow paint marks on the bottom of the subframe and under one A-arm. I'm just curious to understand  what they represented when the car was produced. To this day GM uses lavender, green and red (among other colors) factory inspection marks. I'm simply trying to unravel the puzzle.  ::)
HotRod'68  1968 SS350 coupe undergoing frame-off resto/rod. 386/350/4.11s
Butternut Yellow    black standard interior

JohnZ

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Re: Original inspection paint marks on underbody
« Reply #3 on: May 20, 2006, 06:23:47 PM »
The practice of paint-marking fasteners in the car assembly plants didn't start until well into the 70's (except for randomly-selected audit cars); what you found are inspection markings on the components, applied at the component plants, before shipping the parts to the car assembly plants.
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hotrod68

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Re: Original inspection paint marks on underbody
« Reply #4 on: May 21, 2006, 03:14:21 AM »
Ahhhhh  ;D  Thank you, sir! I hate to be a pain, but could you tell me why they marked the components prior to assembly? Was it for part/model identification on the assembly line or something like that? My right spindle had lavender on it, the left one had orange. Both outer tie rod ends had orange paint on them. There was an L-shaped yellow mark under the right-side upper A-frame where the jounce bumper hits, and a long, scrawled yellow grease paint mark on the bottom of the left-side frame rail forward of the spring. I'm incredibly curious about this stuff and I appreciate your time.  :) Thanks.
HotRod'68  1968 SS350 coupe undergoing frame-off resto/rod. 386/350/4.11s
Butternut Yellow    black standard interior

JohnZ

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Re: Original inspection paint marks on underbody
« Reply #5 on: May 21, 2006, 03:35:12 PM »
Components like spindles (knuckles) and steering linkage are critical safety items, and knuckle forgings were Rockwell hardness-tested after heat-treat and machining; OK parts were usually marked to verify visually that they had passed that test. They were inspected again after component plant assembly (spindle, steering arm, caliper, hub & bearings, rotor, splash shield, etc.); the car assembly plant just took the spindle/hub/rotor/caliper assembly out of a rack and attached it to the ball joints.
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hotrod68

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Re: Original inspection paint marks on underbody
« Reply #6 on: May 23, 2006, 04:12:56 AM »
So the early paint markings essentially meant nothing? There was no "paint code" to indentify parts or their location on the car? If I understand you correctly, the paint marks meant the components had merely passed Rockwell hardness standards and were approved for the assembly line, and were randomly marked with varying colors of paint. Thanks!
HotRod'68  1968 SS350 coupe undergoing frame-off resto/rod. 386/350/4.11s
Butternut Yellow    black standard interior

JohnZ

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Re: Original inspection paint marks on underbody
« Reply #7 on: May 23, 2006, 02:51:55 PM »
So the early paint markings essentially meant nothing? There was no "paint code" to indentify parts or their location on the car? If I understand you correctly, the paint marks meant the components had merely passed Rockwell hardness standards and were approved for the assembly line, and were randomly marked with varying colors of paint. Thanks!

Yup, that about covers it.
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x77-69z28

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Re: Original inspection paint marks on underbody
« Reply #8 on: June 02, 2006, 05:05:48 PM »
i must have one of those audit cars then, because my front end is covered with paint markings on the upper and lower ball joints, spindles, tie rods and drag link. they have the identification stamps on the parts, but definately have paaint after assembly!
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hotrod68

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Re: Original inspection paint marks on underbody
« Reply #9 on: June 13, 2006, 03:52:12 AM »
Hey x77--mine had orange markings all over the place on the front suspension, as well as lavender. It also had yellow marks on the subframe. Was yours preserved well enough to tell if the castle nuts and cotter pins on the ball joints and other suspension components had been painted as well?
I found paint on the components, but the nuts and cotter pins were just rusted zinc with no way to tell if they had been painted on the assembly line as proof the parts had been tightened to specs, which is the core of my question. Maybe I have an audit car, too!
HotRod'68  1968 SS350 coupe undergoing frame-off resto/rod. 386/350/4.11s
Butternut Yellow    black standard interior

112@67

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Re: Original inspection paint marks on underbody
« Reply #10 on: July 22, 2006, 06:53:03 PM »
My 67 SS/RS convertible has been restored for many years now and I recently purchased a factory inspection marking kit. This kit came with NO directions. Could anyone help with information on what colors go where? Is there any literature out there on this? I was told all cars were different....Thanks for any help you could provide.....

firstgenaddict

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Re: Original inspection paint marks on underbody
« Reply #11 on: August 01, 2006, 01:58:20 AM »
They were all pretty muh different... only put back on what you found during the restoration!
James
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Re: Original inspection paint marks on underbody
« Reply #12 on: August 01, 2006, 02:45:42 AM »
They were all pretty muh different... only put back on what you found during the restoration!

I couldnt agree more!!  If you start "making them up", so to say, it will look like exactly that in most cases.

I've never seen two cars with the same original markings, and the markings on the same car from one side to the other are usually different.  I was surprised to find identical spindle markings on a Judge I broke down last week.  First one I have come across like that.

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