Rear End - Non-Posi?
Thread Starter
Pro
Joined: Sep 2016
Posts: 720
Likes: 205
From: Michigan
Rear End - Non-Posi?
Hi All,
Was doing a little digging on my differential in my '69 Coupe.
Looks like based on the codes (as best as I can read them) that I've got a non-Posi rear end, with a date code which could be in the ballpark for my late July of '69 vehicle production.
From what I can read, it looks like:
"1 AK 717 69 W"
Seems a little "off" on the formatting, but the numbers are worn down pretty well. I'll try to clean it better soon, and maybe try a white crayon to highlight the numbers better.
That would make this Diff, a 3.36 non-Posi, built in Warren on July 17, of 1969 (?).
Main question has to do with the standard, base rear end, not being posi-traction, and if that is necessarily a bad thing for my car.
Based on the build figures I found, about 95.4% were ordered with Posi (G81). So wondering if I should be upset that I happened to get one of the remaining 4.6% that didn't want to opt-up for the Posi, for a mere $36.90.
Would I really notice a difference in driving? I don't try to lay rubber much, so minimal effect there.
What is the real difference between a Posi and a non-?
Other than the obvious of both wheels being driven together?
Is the non-Posi still trying to drive both wheels, even under a limited-slip condition?
Thanks in advance for the education.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
If you aren't planning on street-racing, drifting, or drag racing the car, you won't notice the difference. Oddly, the Posi-Traction rear axle was not included in the base model build until 1971. In 1969, the original buyer saved a grand total of $46.35 on a nearly $5000 car. 
Race Director
Joined: Oct 2000
Posts: 12,684
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From: Shamong, NJ
So when you decide that you want to show off for the neighbors, by power braking in the street, you're only going to leave one black streak of rubber down your street. Beyond that, unless you're planning on driving in snow or mud, you're really not going to see any difference.
Race Director
Joined: Mar 2003
Posts: 11,608
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From: Eustis ( Area 51 Bat Cave ) Fl
I didnt try it yet on my 69 with 68 donor chassis and who onows what diff but is it correct if i jack up the car in rear both wheels off ground, in netural and hand turn one wheel if posi the other wheel turns same way if not the other wheel turns oppisite way...
Le Mans Master
Joined: May 2002
Posts: 5,086
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From: Lebanon Township New Jersey
That is correct.
Team Owner
Joined: Mar 2002
Posts: 44,686
Likes: 1,833
From: Huntsville AL
If you aren't planning on street-racing, drifting, or drag racing the car, you won't notice the difference. Oddly, the Posi-Traction rear axle was not included in the base model build until 1971. In 1969, the original buyer saved a grand total of $46.35 on a nearly $5000 car.
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Thread Starter
Pro
Joined: Sep 2016
Posts: 720
Likes: 205
From: Michigan
Now - what if I turn one wheel either way, and the oppo wheel doesn't move at all???
Car up on jack stands, in neutral, with park brake off.
Neither wheel seems to affect the other.
However, each wheel does turn the main prop shaft when turned.
Something amiss in my diff?
Car up on jack stands, in neutral, with park brake off.
Neither wheel seems to affect the other.
However, each wheel does turn the main prop shaft when turned.
Something amiss in my diff?
Melting Slicks
Joined: Feb 2017
Posts: 3,232
Likes: 1,232
From: PHX AZ
Marisa Tomei
What your lacking is the clutch pack in the rear, that sends power from tire to the other, when the first tire loses traction.
So when you decide that you want to show off for the neighbors, by power braking in the street, you're only going to leave one black streak of rubber down your street. Beyond that, unless you're planning on driving in snow or mud, you're really not going to see any difference.
So when you decide that you want to show off for the neighbors, by power braking in the street, you're only going to leave one black streak of rubber down your street. Beyond that, unless you're planning on driving in snow or mud, you're really not going to see any difference.
THAT ALL CORVETTES WILL MAKE TWO BLACK EVEN MARKS WHEN LAYING RUBBER!
Do you have a very very early 69? 68 posi was optional 69 it was 'supposed' to be standard equip. Before anyone jumps me...ANYTHING could be deleted during those years.
I own an 'everything delete' car (except for posi! lol) 4 spd tho.
You could even delete the 4 spd and get a 3 spd! (really, really, cheap owner!)
Thread Starter
Pro
Joined: Sep 2016
Posts: 720
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From: Michigan
Thanks L46. That was a good chuckle. Loved that movie and her role in it.
"Did you say 'Yutes'?"
TOP 10 movie lines of all time!
My build date is July 24th of '69.
Researching the options, I found that posi was an option for '69, but was over a 95% runner. So I apparently got one of the cheapies.
it's hard to read the stamping on the diff, but it does appear to be an AK.
Any other tips on making old worn stampings more readable? I wasn't too successful with white crayons so far.
"Did you say 'Yutes'?"
TOP 10 movie lines of all time!
My build date is July 24th of '69.
Researching the options, I found that posi was an option for '69, but was over a 95% runner. So I apparently got one of the cheapies.
it's hard to read the stamping on the diff, but it does appear to be an AK.
Any other tips on making old worn stampings more readable? I wasn't too successful with white crayons so far.
Last edited by Bergerboy; Apr 17, 2017 at 07:08 PM.
Race Director
Joined: Mar 2003
Posts: 11,608
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From: Eustis ( Area 51 Bat Cave ) Fl