How can I find what gear is in this rear?
03-19-2008, 11:22 AM
#1
Drifting
Thread Starter
How can I find what gear is in this rear?
I have a complete rearend out of a C5, but I don't know what gear is in it, what's the easiest way to find out? Is the ring gear marked with the ratio anywhere?
03-19-2008, 11:39 AM
#2
Drifting
If the gears have not been changed just look on the diff. It will have a tag with the ratio listed. If it was out of an auto it will be 2.73 standard or 3.15 performance. If It was out of a Z-06 it is 3.42 unless its been changed to a different ratio. Do a search on gears.
03-19-2008, 11:48 AM
#5
Team Owner
Mark a tooth on both the ring and pinion gears, count the teeth on each, divide the ring gear teeth by the pinion gear teeth and the answer is the ratio-i.e. 10 into 41 equals 4.10. 
03-19-2008, 11:49 AM
#6
Safety Car
If you are certain this is a "factory" rear end ... on the plate with the GETRAG logo on it .... above the Getrag name is the GM part number .....
12551769 is a 3.42 (Manual transmission)
12554837 is a 2.73 (standard for an automatic)
12556313 is a 3.15 (optional with the automatics)
12551769 is a 3.42 (Manual transmission)
12554837 is a 2.73 (standard for an automatic)
12556313 is a 3.15 (optional with the automatics)
03-19-2008, 11:50 AM
#7
Race Director
Mark the output shaft and rotate the input shaft. If you rotate the input shaft 3.42 times to get a complete turn of the output shaft, it's a 3.42. If it's closer to 4, then you either have a 3.90 or 4.10.
You could also take it apart and count gear teeth.
You could also take it apart and count gear teeth.
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CFight (01-15-2023)
03-19-2008, 02:12 PM
#8
Team Owner
Member Since: Apr 2001
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although the OP didn't include any info (such as tranny type) it appears he has a manual shift C5.
If that's the case; the factory rear axle ratio for all manual shift C5's was 3.42:1. That's all they installed.
If that's the case; the factory rear axle ratio for all manual shift C5's was 3.42:1. That's all they installed.
07-13-2013, 06:01 PM
#9
How did you know the OP had a manual shift? From the BJB 00200 info? What does that info translate to?
I ask because I would like to know what AHA 00134 means on my 1997 auto GETRAG trans.
I understand that my metal tag on the rearward portion of the case lists the GM part number 12554837, the GETRAG part number 625.0.0012.01, and the serial number AHA 00134. Do either of those last two number sequences reveal a build date?
Thanks for your help!
07-13-2013, 08:01 PM
#10
Burning Brakes
Mr. Mercury,
How did you know the OP had a manual shift? From the BJB 00200 info? What does that info translate to?
I ask because I would like to know what AHA 00134 means on my 1997 auto GETRAG trans.
I understand that my metal tag on the rearward portion of the case lists the GM part number 12554837, the GETRAG part number 625.0.0012.01, and the serial number AHA 00134. Do either of those last two number sequences reveal a build date?
Thanks for your help!
How did you know the OP had a manual shift? From the BJB 00200 info? What does that info translate to?
I ask because I would like to know what AHA 00134 means on my 1997 auto GETRAG trans.
I understand that my metal tag on the rearward portion of the case lists the GM part number 12554837, the GETRAG part number 625.0.0012.01, and the serial number AHA 00134. Do either of those last two number sequences reveal a build date?
Thanks for your help!
07-13-2013, 08:15 PM
#11
Racer
Member Since: Jan 2013
Location: Jasper Texas
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St. Jude Donor '13
Old School is the best School, or you can count the input rotations vs. one output rotation.
Last edited by OneCylinder; 07-13-2013 at 08:37 PM.
07-13-2013, 11:12 PM
#12
Hey, thanks, RedZMonte. My ignorance of ZO6 transmissions has been exposed!
Mea culpa.
In my haste, I probably incorrectly described what I was asking for.
The salient questions of my original post:
(1) Does my GETRAG differential serial # AHA 00134 reveal any hidden information? (ie: build year, build date, plant location, use designation)
(2) Does my GETRAG differential part # 625.0.0012.01 reveal any hidden information?
My 1997 has an RPO sticker showing M30 (automatic) and GU2 (rear axle 2.73 ratio). Of course the gearing in the rear end could have been replaced.
However, I’m asking if Mr. Mercury - or any member - knows how to decipher the GETRAG part numbers and serial numbers.
The OP’s serial number is BJB 00200 (from post #4 in this thread). Mine is AHA 00134 (from post #9 in this thread). And member DeBaGo has a 1998 with AHJ 00735.
Has any member decoded these alpha-numeric sequences for C5s?
If yes, please supply me with their site name!
Thank you, thank you!
Mea culpa.
In my haste, I probably incorrectly described what I was asking for.
The salient questions of my original post:
(1) Does my GETRAG differential serial # AHA 00134 reveal any hidden information? (ie: build year, build date, plant location, use designation)
(2) Does my GETRAG differential part # 625.0.0012.01 reveal any hidden information?
My 1997 has an RPO sticker showing M30 (automatic) and GU2 (rear axle 2.73 ratio). Of course the gearing in the rear end could have been replaced.
However, I’m asking if Mr. Mercury - or any member - knows how to decipher the GETRAG part numbers and serial numbers.
The OP’s serial number is BJB 00200 (from post #4 in this thread). Mine is AHA 00134 (from post #9 in this thread). And member DeBaGo has a 1998 with AHJ 00735.
Has any member decoded these alpha-numeric sequences for C5s?
If yes, please supply me with their site name!
Thank you, thank you!
Last edited by GoGo87U; 07-13-2013 at 11:17 PM. Reason: addition
