If I were a Diff stamp. Where would I be?
Race Director
Joined: Dec 1999
Posts: 19,610
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From: Forked River NJ
Re: If I were a Diff stamp. Where would I be? ('79ProwlerOrange)
They should all be stamped. Look on the housing where the cover meets the housing. If you are laying on your back looking straight up at the carrier it should be there. Wish I could draw on your picture. But it is right behind where your bracket for the camber rods are
Thread Starter
Melting Slicks
Joined: Sep 2001
Posts: 2,218
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From: Glendale AZ
Re: If I were a Diff stamp. Where would I be? (Gordonm)
Look on the housing where the cover meets the housing. If you are laying on your back looking straight up at the carrier it should be there. But it is right behind where your bracket for the camber rods are
mucho grasas
chad
Safety Car
Joined: Dec 1999
Posts: 3,607
Likes: 839
From: PA
Re: If I were a Diff stamp. Where would I be?
Is it in area A, B , or C (C is "facing" towards the front of the car)
It will be in flange that you have marked as "A", but it will be on the bottom side the differential (by the exhaust pipe in your photo). The area is not machined and the stamps tend to be lightly struck, so you'll need to clean the area well and look closely. As Gordon noted, all original differential housings were stamped.
Original differential housings also had a paper tag attached to the machined area that mounts to the crossmember. The tag is white paper with the broadcast code for the differential/ratio in red letters. It can't be seen with the differential in place and is usually in pretty rough shape anyway... Still, it can sometimes be used to identify a particular differential.
Good luck in your numbers search!
Regards,
Thread Starter
Melting Slicks
Joined: Sep 2001
Posts: 2,218
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From: Glendale AZ
Re: If I were a Diff stamp. Where would I be? (Rowdy Rat)
ah HA found it! Much thanks guys!
Here is what I found
AW (space) W (space) 100 (space) E (space) 1
Could you double check the Black Book and Tell me what I got?
There is a heavy coat of what looks,feels like Blue RVT siclone gasket maker. Did GM use that stuff back in 71?
Probally not, wich could mean that the diff had been rebuilt in the past.
thanks again :cheers:
Here is what I found
AW (space) W (space) 100 (space) E (space) 1
Could you double check the Black Book and Tell me what I got?
There is a heavy coat of what looks,feels like Blue RVT siclone gasket maker. Did GM use that stuff back in 71?
Probally not, wich could mean that the diff had been rebuilt in the past.
thanks again :cheers:
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Safety Car
Joined: Dec 1999
Posts: 3,607
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From: PA
Re: If I were a Diff stamp. Where would I be?
People say a picture is worth a thousand words...
This is the differential stamp on my '70... Photo taken laying on the ground, looking up.
This particular differential is a 3.70 to 1 ratio for 1970; the format for other years will vary.
1 CFA 1 6 70 W
The first "1" is the shift number (1st shift)
"CFA" is the broadcast code for the gear ratio (3.70 to 1)
The second "1" is the month (January)
The "6" is the day of the month
"70" is the year (1970)
The "W" is the positraction source (Warner Gear)
The format for your '71 will be a bit different. It will begin with two letters for the ratio code, a letter for the axle plant, one to three numbers for the julian day of the year, a letter for the positraction source, and a number for the shift.
Let us know how you make out.
Regards,
This is the differential stamp on my '70... Photo taken laying on the ground, looking up.
This particular differential is a 3.70 to 1 ratio for 1970; the format for other years will vary.
1 CFA 1 6 70 W
The first "1" is the shift number (1st shift)
"CFA" is the broadcast code for the gear ratio (3.70 to 1)
The second "1" is the month (January)
The "6" is the day of the month
"70" is the year (1970)
The "W" is the positraction source (Warner Gear)
The format for your '71 will be a bit different. It will begin with two letters for the ratio code, a letter for the axle plant, one to three numbers for the julian day of the year, a letter for the positraction source, and a number for the shift.
Let us know how you make out.
Regards,
Thread Starter
Melting Slicks
Joined: Sep 2001
Posts: 2,218
Likes: 0
From: Glendale AZ
Re: If I were a Diff stamp. Where would I be? (HEARTBEATUSA)
Thanks Heartbeat and Rowdey! you guys are Da Bomb! (just dont say that at the airport). :jester
Do you know the procedure for marking the driveshaft or something and counting the rotations to vefery the actual gear ratio inside the "pumkin"?
chad
[Modified by 71'AirStrike, 5:40 PM 10/19/2002]
Do you know the procedure for marking the driveshaft or something and counting the rotations to vefery the actual gear ratio inside the "pumkin"?
chad
[Modified by 71'AirStrike, 5:40 PM 10/19/2002]
Thread Starter
Melting Slicks
Joined: Sep 2001
Posts: 2,218
Likes: 0
From: Glendale AZ
Re: If I were a Diff stamp. Where would I be? (HEARTBEATUSA)
WOO HOO!
you guys just saved me 600 bucks.
I am currrently doing a major rear end rebuild on the vette. I had budgeted on doing a rebuild with the diff and going to a 3.08 ratio.
Well its already at 3.08!
Ill check that off my "to do" list
thanks again
you guys just saved me 600 bucks.
I am currrently doing a major rear end rebuild on the vette. I had budgeted on doing a rebuild with the diff and going to a 3.08 ratio.
Well its already at 3.08!
Ill check that off my "to do" list
thanks again
Safety Car
Joined: Dec 1999
Posts: 3,607
Likes: 839
From: PA
Re: If I were a Diff stamp. Where would I be?
Here is what I found
AW (space) W (space) 100 (space) E (space) 1
AW (space) W (space) 100 (space) E (space) 1
Looks as though our last posts crossed paths...
Per my last post, your differential decodes as follows:
AW - Ratio Broadcast Code (3.08 to 1)
W - Axle Plant (Warren Motive)
100 - Julian Assembly Date (100th day of 1971 - April 10, 1971)
E - Positraction Source (Eaton)
1 - Shift Code (1st shift)
Looks to be pretty good for a mid to late build 1971 Corvette.
I'd clean up the differential with some solvent to get the grease, dirt, and other assorted garbage off of it... Which will make spotting any leaks easier. I'd also seriously consider changing the old fluid for new differential lubricant and positraction additive.
Regards,
Race Director
Joined: Apr 1999
Posts: 10,866
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From: Beverly Hills/Pine Ridge Florida
Re: If I were a Diff stamp. Where would I be? (Rowdy Rat)
Great info, BUT....if you found "blue goo", you know somebody has been in there in the past, and MIGHT have replaced the original 3.08's with ????
Jack the rear of the car up in the air. (be careful, etc.). Mark the driveshaft with a piece of chalk. Mark one rear tire with chalk lets say at 12:00 o'clock. Rotate the tire one revolution, and count the number of times the driveshaft turns. Do this several times to get an average.
3 times???? You've got 3.08's. 4 times???? Probably 4.11's. 3 1/2 times??? Probably 3.55's and so on. I rebuilt the diff in my 69 last winter. Original 3.08's in the original case, etc., BUT I chose to put 3.36 gears in it. SO...if you look at my rear case, it's still stamped AW....but the ratio has been changed. Chuck
Jack the rear of the car up in the air. (be careful, etc.). Mark the driveshaft with a piece of chalk. Mark one rear tire with chalk lets say at 12:00 o'clock. Rotate the tire one revolution, and count the number of times the driveshaft turns. Do this several times to get an average.
3 times???? You've got 3.08's. 4 times???? Probably 4.11's. 3 1/2 times??? Probably 3.55's and so on. I rebuilt the diff in my 69 last winter. Original 3.08's in the original case, etc., BUT I chose to put 3.36 gears in it. SO...if you look at my rear case, it's still stamped AW....but the ratio has been changed. Chuck
Racer
Joined: Aug 2002
Posts: 253
Likes: 0
From: Strongsville Ohio
Re: If I were a Diff stamp. Where would I be? (71'AirStrike)
The rear axle identification numbers are stamped on the underside of the rear carrier housing between the rear spring and the rear strut arm bracket.Rowdy Rat shows the correct location
Melting Slicks
Joined: May 1999
Posts: 2,897
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From: Moon Township PA
Re: If I were a Diff stamp. Where would I be? (71'AirStrike)
Do you know the procedure for marking the driveshaft or something and counting the rotations to vefery the actual gear ratio inside the "pumkin"?
[Modified by 71'AirStrike, 5:40 PM 10/19/2002]
[Modified by 71'AirStrike, 5:40 PM 10/19/2002]
Gary