C3 (late) Chassis ID Paint Marks

[Tom R.]

I did a search on the topic of chassis paint marks and read through about a dozen archived threads on the topics that went back to solid axles and thru early C3...that be 1971. I understand paint was used for alignment marks and/or inspection.

This summer enroute to BG, had a chance, thanks to Tom Hendricks, to study two low mileage Pace Cars at Bud's Chevrolet. So looking for what the intent of these chassis paint markings were recognizing that the threads conveyed that much is left to speculation but there were also some knowns.

We'll start with the pitman arm and robin eggshell blue. Reading the AIM, I suspect it has to do with an inspection and the 70 lb of torque.

pitman.JPG

Of course the ever popular relay rod yellow

relay_rod.JPG

Trailing arm with a splash of the robin eggshell blue...have no idea on this one. Also note, I believe yellow on universal support bracket.

trailingarm_blue.JPG

This paint is what I believe is the strut support

strutsupport.JPG

[Tom R.]

Re: C3 (late) Chassis ID Paint Marks

Here's another trailing arm with a daub of orange

trailing_arm.JPG

Finally, I've seen this on many low mileage late model C3s with four-speeds. its the mounting bolt on the crossmember. The color is consistenly the same as the GM engine blue color and almost appears to have been painted along with the engine/bellhousing but not sure how it ends up as a mounting bolt. Hoping someone may offer some insights. There's a prize

trannybolt.JPG

[David H.]

Re: C3 (late) Chassis ID Paint Marks

I believe the blue painted bolt indicates it is metric thread. It could also indicated a treated bolt for use in aluminum. (The hangers for the spare tire hub on my 1980 had the same blue paint on the head - steel bolt through aluminum - to slow corrosion.

[Tom R.]

Re: C3 (late) Chassis ID Paint Marks

This is a driveshaft alignment mark using yellow paint from 1978 L48 M38

driveshaftalignment.JPG

[Edward J.]

Re: C3 (late) Chassis ID Paint Marks

Here's another trailing arm with a daub of orange

[ATTACH]33479[/ATTACH]

Finally, I've seen this on many low mileage late model C3s with four-speeds. its the mounting bolt on the crossmember. The color is consistenly the same as the GM engine blue color and almost appears to have been painted along with the engine/bellhousing but not sure how it ends up as a mounting bolt. Hoping someone may offer some insights. There's a prize

[ATTACH]33480[/ATTACH]

Tom, I was a GM tech around the era that GM was switching over to the metric fastners the blue paint was to identifly it was metric . back in those days there was still alot of SAE fastners and Metric so it helped when taking something apart when you saw the blue paint. As David says it may have been possiable that mostly aluminum was the first to see these fastners but cannot remember for sure,but do recall some of the A/C brackets and p/strg. nut on the rear of the pump being Metric. any way for what its worth maybe someone elese has some insite.

I am sure that your posts will come in handy for some of the later C3 Cars.