hackmansr

Can anyone tell me the correct rear end finish or color for a 1969 Cutlass. The car is a California car and I am degreasing and cleaning it. I figured it was a good time to give it a more original finish/look.






Thanks

rcorrigan5

When I did my '68 (a Lansing car which has been in my family since it was new), the original color of the differential and axle assembly appeared to be GM chassis black so that's how I refinished it. GM chassis black doesn't quite rise to the shine of semi-gloss black but it is pretty close. I used Seymour GM black spray cans, which is emulates what used to be called GM chassis black.


Randy C.

hackmansr

Thanks for the reply Randy. Picture is kind of hazy, but it looks good. I got this car from the original owner, and I know the rear end is unmolested. While cleaning I even found the factory color inspection swabs on the rear end. I am actually wondering if the entire rear end on this car was bare metal from the factory, as there is no black paint around any of the factory markings. I imagine that different assembly plants might have used different, or no, finishes.

rcorrigan5

A car I will start working on in the near future is a '69 4-4-2 convertible(Fremont car, I found and bought it in Selma (near Fresno) in 1987 but am just now getting to it; originally delivered to Van Ness Oldsmobile in San Francisco). When I get a chance to look underneath, I'll let you know what I find. I've only looked at the rear end assembly a couple of times and I don't recall if I saw any paint or not - I was just there to find out what the differential gears were (3.23 open) and that's it.


One of the things I've found interesting in my "Olds Research" is that dealers weren't too happy with Fremont cars, as compared to Lansing cars. The dealerships in Oregon and Washington would get new cars from both assembly plants back in that day and I've been told that the quality control at the Fremont plant back then was lacking, some say severely. I'm wondering if the lack of paint on your rear end assembly (or perhaps rear end assemblies in general from Fremont) would be one of those "oversights"!


As a side note, I had a '70 GTO (Fremont car) that I bought in Ripon (near Modesto) in 1986 from its original owner. The original owner told me that they had only requested the standard 400ci engine but it came with a 455. They claimed that because it had the 455 decals on each side. When I looked closer, I discovered the car indeed had a 400ci engine but it had the 455 badges on each side and a 455 emission and tune-up decal under the hood. So much for quality control on that car!


Anyway, I'll let you know what I see. It may be a couple more months before I get to see it. Maybe someone else will chime in before then.


Randy C.

hackmansr

Interesting stuff Randy. Back in the day, or at least in the 70s I knew a couple guys that worked at the Fremont plant. Unfortunately they are no longer around, as they could have been a great source of info. I actually bought a brand new 70 W31 from Paddleford Olds in Palo Alto back then. I wish I had more pictures of it, as I don't remember any details of the rear end. The 69 Cutlass I have now was also bought new at Paddleford Olds the year before I purchased mine. I know some GM vehicles had natural finishes while others had the same parts painted. I'm sure it had to do with where they were made. Let me know if you check yours out further. It looks like a nice 442!

hackmansr

Trying to determine my rear gearing ratio. The car is a 69 Cutlass, 350, 2bbl, auto and it has the original rear end. I have cleaned it and am ready to paint it. I was looking for the stampings that identify it. I have checked both tubes (every inch), and the carrier and there are no numbers stamped on them any where. The original owner says nothing ever happened to the rear end, i.e. it is all original. It is an O type, 12 bolt cover, non-posi. I turned the wheel 10 times and the yoke turned 12.75 times. That's not right, so I'll check the ring and pinion when I pull the cover to change the oil. Has anyone ever seen one that is not stamped? It is a Fremont, CA built car. Also, should the cover be natural finish, or painted?

hackmansr

Update: ring gear = 40 teeth, pinion = 16 teeth. Based upon those numbers I am guessing it is actually a 2:56/1 ratio.

BlackGold

Assuming you had one wheel on the ground while you spun the other,
12.75
divided by 10
times 2
gives you 2.55. So it's likely a 2.56 rear. The "times 2" is needed because it's not a posi and only one wheel is turning during your test. Correct me if I'm wrong.


I think you miscounted the teeth. Probably 41 and 16? That gives you 2.56.

hackmansr

Just finished the rear end and now it's ready for re-install. Thank you to all who answered my questions about paint finishes and gear ratios.

Octania

12.75/5 turns of the RING GEAR = 2.55
Watch some youtube videos of a differential to see how turning one wheel makes the ring gear turn half that many times.
closest factory ratio is 2.56, so, "Bob's your uncle" [wrapped that up].
The ring gear should have stuff stamped in, including the tooth counts


I think you miscounted the teeth. Probably 41 and 16? That gives you 2.56.
=======================
At least one of the tooth counts is almost always a prime # such as 41, in order to evenly spread the wear while used.

rcorrigan5

Looks pretty, hackmansr! Looks like you went with an original color for your shocks as well! I found some things on my '68 that had no paint on them that I chose to protect with paint anyway. And some things (like the steering box) I coated in that oily thick substance (visquine?) to keep from rusting over. I still haven't gotten to my '69 but I should be able to look at it next week...but your differential assembly looks great!

Randy C.

Octania

here are a couple of good ones


the best:

rcktdoc

Rearends were bare metal and got coated with a wash Black paint at the end of the assembly line.This was done to most any bare metal parts under the car so when it went to the dealer and sat on the dealers lot for any length of time it didnt have flash rust on the bare metal parts.

Greg