Author Topic: Odd rear code on '69 Z/28  (Read 7778 times)

nuch_ss396

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Odd rear code on '69 Z/28
« on: August 13, 2007, 02:48:34 AM »
Guys!

I'm looking at a 04/69 built Z/28 that appears to be original ( except for the original blown engine ). 
Odd thing is that the rear has an 05xx assembly date and is a BS code ( 3.31 posi ).  I'm at a
loss as to why the axle assembly is the month after the assembly of the car.  Could this possibly
be legit?  I've heard of cars being sidelined for "repairs", but the entire rear assembly.  Any thoughts
on the matter would be appreciated.  One possible clue is that the axle tubes were later welded to
the center casting in some sort of strengthening or repair operation.  3 owners back said it was like
that when they owned the car.  It also looks like driveshaft loops were on the car at some point as well.

BTW, the M-20 is the original per the matching partial VIN.  There is no POP or documentation available.

Lastly, how unusual was the 3.31 posi in the '69 Z/28?

Steve
69 SS 396, Hugger Orange, D/80, D/90
Chambered Exhaust, N/66, THM400, 3:73 posi

Steve A.
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KurtS

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Re: Odd rear code on '69 Z/28
« Reply #1 on: August 13, 2007, 03:39:41 AM »
Steve,
If you send me the VIN and full axle code, I'll take a look at it.

But a 3.31 axle in a Z is very unusual.....
Kurt S
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Jerry@CHP

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Re: Odd rear code on '69 Z/28
« Reply #2 on: August 13, 2007, 12:17:08 PM »
Drag racers weld the tubes to the center section so that they do not spin in the center section under load while racing.  Running rear racing tires puts a lot of added stress on the rear axle.

I have only documented one or two Z28s with a 3.31 rear axle and that's going back almost 30 years.  The M20 would be the right trans with the conbination.

Jerry

RPOZ28

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Re: Odd rear code on '69 Z/28
« Reply #3 on: August 21, 2007, 12:15:10 AM »
How about one with a 3:55 ratio.

GBA283

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Re: Odd rear code on '69 Z/28
« Reply #4 on: August 21, 2007, 01:32:17 AM »
My 3rd week of may Z has a bs rear in it.not sure if orig or not.

L78 steve

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Re: Odd rear code on '69 Z/28
« Reply #5 on: August 24, 2007, 03:43:55 PM »
My 3rd week of may Z has a bs rear in it.not sure if orig or not.
You should check into the dates,It would be interesting to see if it was so equipped
69 Z/28 Dover White X33,ZL2,PS,M20,Std.int.04C
67 SS/RS Mt. Green 1W,2LGSR,3SL,4K,5BY,07C
70 Nova L78 Blk. Cherry,Sandalwood,M21,02B

nuch_ss396

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Re: Odd rear code on '69 Z/28
« Reply #6 on: August 25, 2007, 01:46:18 AM »
Steve,
If you send me the VIN and full axle code, I'll take a look at it.

But a 3.31 axle in a Z is very unusual.....

Kurt,

You should have my email by now.  Sorry for the delay.....

Steve

GBA283

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Re: Odd rear code on '69 Z/28
« Reply #7 on: August 27, 2007, 12:49:57 AM »
Nope.12/02/68,

L78 steve

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Re: Odd rear code on '69 Z/28
« Reply #8 on: August 27, 2007, 02:43:25 AM »
My 3rd week of may Z has a bs rear in it.not sure if orig or not.
Nope.12/02/68,
I have a Nova with a rear dated 6 months prior to the body build.Could still be possible yours is orig.

Jerry@CHP

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Re: Odd rear code on '69 Z/28
« Reply #9 on: August 27, 2007, 02:59:18 AM »
Wow,

That 69 Z28 with an M21 and 3.55 gear would be hard on clutches.

Jerry

JL8Jeff

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Re: Odd rear code on '69 Z/28
« Reply #10 on: August 30, 2007, 02:05:59 AM »
Wow,

That 69 Z28 with an M21 and 3.55 gear would be hard on clutches.

Jerry

I know somebody else who has the 3.55 rear in his 69 Z28 and he's running the crossram setup as well!  Last time I talked to him he wasn't having any problems and was surprised how well it drove.  My 70 L78 car has the 3.55 posi rear but it also has a little more torque than the 302.  ;)
1969 Z28 JL8 4 wheel disc brakes, #'s match, crossram, GM fiberglass crossram hood, TI, Minilite wheels - being restored

jdv69z

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Re: Odd rear code on '69 Z/28
« Reply #11 on: August 30, 2007, 12:15:13 PM »
I have to agree with Jerry. I have a stock 69 Z with M20 and 3:73 gears, and I wouldn't want any less gearing than I have now. I do not think I would enjoy driving a crossram equipped car with a 3:55 rear gear in stop/start traffic on a hill. My first car was a 57 Chevy with too much cam requiring revving to find the torque range, and it was a pain in the butt in traffic, and a nightmare in stop/start traffic on a hill, even with 4:88 gears that it had at the time. Of course it was my daily transportation, and that is very different from a weekend cruiser. A lot can be forgiven in a car your don't have to drive to work everyday.

Jimmy V.
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Jerry@CHP

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Re: Odd rear code on '69 Z/28
« Reply #12 on: August 31, 2007, 01:05:33 AM »
A Z28 with 3.55s and an M21 would be a 15 second car, with the cross ram, probably high 15 second car.

Jerry

L78 steve

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Re: Odd rear code on '69 Z/28
« Reply #13 on: August 31, 2007, 08:56:22 PM »
Guys!

I'm looking at a 04/69 built Z/28 that appears to be original ( except for the original blown engine ). 
Odd thing is that the rear has an 05xx assembly date and is a BS code ( 3.31 posi ).  I'm at a
loss as to why the axle assembly is the month after the assembly of the car.  Could this possibly
be legit?  I've heard of cars being sidelined for "repairs", but the entire rear assembly.  Any thoughts
on the matter would be appreciated.  One possible clue is that the axle tubes were later welded to
the center casting in some sort of strengthening or repair operation.  3 owners back said it was like
that when they owned the car.  It also looks like driveshaft loops were on the car at some point as well.

BTW, the M-20 is the original per the matching partial VIN.  There is no POP or documentation available.

Lastly, how unusual was the 3.31 posi in the '69 Z/28?

Steve
Can a 04C body have a 05/15 rear installed from the factory?Could the car have been sidelined due to an unavaliable 3:31 axel?Can someone tell me from the VIN when it(the VIN)was issued?

JohnZ

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Re: Odd rear code on '69 Z/28
« Reply #14 on: September 01, 2007, 03:56:17 PM »
Can a 04C body have a 05/15 rear installed from the factory?Could the car have been sidelined due to an unavaliable 3:31 axel?Can someone tell me from the VIN when it(the VIN)was issued?
[/quote]

Not likely. Once the body started the assembly process, they weren't "sidelined"; at 65 per hour, there wasn't any place to put them, and once the body arrived from Fisher and was scheduled, it was locked in sequence.

What's the VIN?
'69 Z/28
Fathom Green
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nuch_ss396

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Re: Odd rear code on '69 Z/28
« Reply #15 on: September 01, 2007, 04:40:03 PM »

Can a 04C body have a 05/15 rear installed from the factory?Could the car have been sidelined due to an unavaliable 3:31 axel?Can someone tell me from the VIN when it(the VIN)was issued?
[/quote]

Steve,

Your VIN places production in or around the 3rd week of April '69.  As has been discussed previously here, production would be +/- one week from that.
04/69 Norwood VINs were in the 628000 to 635000 range ( close approximation ).

Nuch

nuch_ss396

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Re: Odd rear code on '69 Z/28
« Reply #16 on: September 03, 2007, 04:07:41 PM »
Well,

It's starting to look like maybe this rear may not be original to the car.

Indications I'm getting from members here is that one month is too long
to sideline a car - for a rear.

So, that leaves me with this question:  If a rear failed under warranty,
would a complete rear be ordered, or just the components to rebuild it?

Jerry, did you ever hear of an original rear housing failing that early in the
cars life ( one month )?  I've seen where an axle tube broke under hard
acceleration, but this was a COPO car.  Did/do the Z/28's have that kind
of torque? 

I'm just trying to explain the existence of this rear in the car at this point in time.

Steve

L78 steve

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Re: Odd rear code on '69 Z/28
« Reply #17 on: September 03, 2007, 05:01:27 PM »
It's probably not.Even though the 3 previous owners say it is.With the evidence of some drag race history who would use a 3:31 for that purpose?Unless they swapped gears in the BS housing,it does have the welded tubes.I've checked for a build sheet under the seats with no luck.What other locations should I look?

L78 steve

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Re: Odd rear code on '69 Z/28
« Reply #18 on: September 03, 2007, 05:03:20 PM »
Also,whats the deal with the X3 mark behind the rear seat back?

nuch_ss396

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Re: Odd rear code on '69 Z/28
« Reply #19 on: September 04, 2007, 01:59:01 AM »
Also,whats the deal with the X3 mark behind the rear seat back?

The X3 was to signify an X33 car.