COPO 12 bolt carrier ID?

[scuncio]

All,
How does one identify a COPO 12 bolt carrier? I bought what was explained to me as a GM HD over-the-counter carrier from 1970. How can I tell this apart from a regular 4-series carrier?

Thanks, Tony

[iluv69s]

they have a number of subtle but important differences....a few pics would help. I sold an NOS unit last year and I still have pics to compare to.

or contact Eric..he is a member here... 69L72RS....he really knows them things well....he has always been a great help to me when it comes to the COPO rear info.

[SSRSBOB]

McNeishs book has very detailed photos and part numbers. Also a written chapter on this 234 carrier. Axle gears have 16 teeth. Springs plates are different. Springs are different. I'm looking at the photos right now. #140 spider gears same as open rear 12 bolt.

Bob

[iluv69s]

The easiest way to tell looking is the spring plate openings...I believe the COPO unit the openings are round as opposed to oblong...(Off the top of my head).It is very difficult to count the teeth on the gears without taking it apart. Another thing I found with the service replacement is that the hole in the carrier itself is different than the factory installed units...and yes, jerry's book is very informative on the subject.

[SSRSBOB]

His book has all the anal details. Natural color posi springs rated at 75lb each, stds are green rated@ 50 lbs. 18 clutches. Photos of the posi plates and the holes are round. I talked to him on the phone several times since I sent my boy's engine to him. Wealth of info. Glad I hooked up with him thanks to this site. He was selling these units at the dealer he worked at back in the early 1970's. Say's they are stronger than the Moroso brute unit. Service 234 units do have the large hole for easier spider gear installation.

Bob

[scuncio]

Thanks for the help. If anyone can post a picture of the spring plate openings I would appreciate it!

[scuncio]

Does anyone know how to decode the ring gear flange stamp E 9 J?

[SSRSBOB]

If you have the 1969 Camaro book, they are on page 62,

Bob

[69L72RS]

Here is a picture of the internal parts of a 3916234 carrier.
Also, note that round holes in the preload plates does not guarantee it is a COPO unit.

[69L72RS]

A 1965/66 unit with 10T/17T internal gears looks really close to a COPO unit. The early plates also have a round hole but are the standard width and length to fit the standard internals.