Possible to have 3.42 on A4 2002 ?
01-28-2018, 10:22 PM
#1
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Possible to have 3.42 on A4 2002 ? I know the 3.42 was not an option on the 2002 A4 5.7 LS1 models.
However, I recently acquired an additional 2002 SS A4 that has a 3.42 rear gear. I opened the cover up to do some routine maintenance and what a horror show of filings and grit on the inside cover magnet. Car has 47,000 miles and from appearances underneath you would bet that zero maintenance was more the norm. When rotating the gear assembly I came across a white stripe on the gear ring that has the ratio of 3.42 clearly stamped. It took some hard cleaning to be able to read the numbers and I find it hard to believe the differential was ever opened up. The crud was unbelievable. When you see this type of neglect it is easy to understand why these parts fail. This vehicle was produced for the Canadian market and spent its entire life around Montreal until a few months ago. The rear end housing is factory original and has various paint markings that appear to be factory made. I'm going to take it down to a drive line specialty shop for a thorough check up. It is amazing that it continued to function and there are no apparent noises coming from the assembly. Would there be any markings on the outside assembly that would tell me if the complete unit was swapped in from another donor car ? Some decoding hints could hopefully help me understand what I've got here.
However, I recently acquired an additional 2002 SS A4 that has a 3.42 rear gear. I opened the cover up to do some routine maintenance and what a horror show of filings and grit on the inside cover magnet. Car has 47,000 miles and from appearances underneath you would bet that zero maintenance was more the norm. When rotating the gear assembly I came across a white stripe on the gear ring that has the ratio of 3.42 clearly stamped. It took some hard cleaning to be able to read the numbers and I find it hard to believe the differential was ever opened up. The crud was unbelievable. When you see this type of neglect it is easy to understand why these parts fail. This vehicle was produced for the Canadian market and spent its entire life around Montreal until a few months ago. The rear end housing is factory original and has various paint markings that appear to be factory made. I'm going to take it down to a drive line specialty shop for a thorough check up. It is amazing that it continued to function and there are no apparent noises coming from the assembly. Would there be any markings on the outside assembly that would tell me if the complete unit was swapped in from another donor car ? Some decoding hints could hopefully help me understand what I've got here.
01-29-2018, 03:09 AM
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As mentioned above, 3.42 was never available on any auto trans LS1 F-body. It could, however, be found on performance package 3.8L V6 examples with an A4.
As also mentioned above, I'd suggest checking the SPID sticker to determine original driveline equipment for this example (also, make sure the VIN on the SPID matches the dash VIN). Based on your description, it's most likely that the entire rear end was swapped in from a donor M6 example, but it's also possible that this car may have originally been an M6 and received an auto trans swap (though, even if it's a super clean swap, it would likely still have the release button on the ignition cylinder had it been an original M6). Here are the RPOs you'll need to look for:
Original A4 V8 car would have: MX0, M30 (auto trans, 4L60E) and either GU2 (2.73) or GU5 (3.23) - but, if it's an original SS (WU8) car then it could only have come with GU5 (3.23) for an auto.
Original M6 V8 car would have: MM6, MN6 (manual, T56) and GU6 (3.42). There was no other optional rear for an M6 V8, SS car or not.
As also mentioned above, I'd suggest checking the SPID sticker to determine original driveline equipment for this example (also, make sure the VIN on the SPID matches the dash VIN). Based on your description, it's most likely that the entire rear end was swapped in from a donor M6 example, but it's also possible that this car may have originally been an M6 and received an auto trans swap (though, even if it's a super clean swap, it would likely still have the release button on the ignition cylinder had it been an original M6). Here are the RPOs you'll need to look for:
Original A4 V8 car would have: MX0, M30 (auto trans, 4L60E) and either GU2 (2.73) or GU5 (3.23) - but, if it's an original SS (WU8) car then it could only have come with GU5 (3.23) for an auto.
Original M6 V8 car would have: MM6, MN6 (manual, T56) and GU6 (3.42). There was no other optional rear for an M6 V8, SS car or not.
02-01-2018, 07:40 PM
#6
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Thank you for the replies.
It gets a little better, or worse, from my initial post.
I went back to the differential cover and thoroughly went through all the junk attached to the magnet and lo and behold I found several rice kernel sized pieces of metal. In my mind they would be like a very tip of a rotating gear. I did a complete flushing of the housing and no sign of any more small metal. Keeping in mind that the assembly was operating fine and no noticeable gear noise or whine, could that junk have been left behind when there was an initial problem prior to a gear change ? And the small pry marks on the housing lip seem to point to someone screwing around that may not have been experienced with differential workings. As stated the ring and pinion look great with no uneven wear but there are hidden spider gears that could have been slightly shaved.
Also after degreasing the axle assembly I now can see raised coding on the bottom of the middle case. So I will send that info forward as soon as I climb underneath hopefully this weekend. It is a real SS and the build codes call for the 460LE and a 3.23 rear ratio.
Another interesting point is that I ordered replacement ignition and glove box/ rear hatch keys from Chevy dealer. The rear hatch key works like greased lightning but the ignition key inserted but would not unlock the ignition switch to start mode. In comparing the new key to my old one it is day and night. So the dealer ordered a new security chipped ignition key uncut and we copied the one I have. Works like a charm. This could make one wonder if the ignition assembly was replaced but no wear or abuse marks are on the column. Interesting but no record of theft or catastrophes.
OK, I'll send those codes. I have refilled and sealed up the differential. I plan on testing, very gently, the drive ability at least to an experienced shop.
It gets a little better, or worse, from my initial post.
I went back to the differential cover and thoroughly went through all the junk attached to the magnet and lo and behold I found several rice kernel sized pieces of metal. In my mind they would be like a very tip of a rotating gear. I did a complete flushing of the housing and no sign of any more small metal. Keeping in mind that the assembly was operating fine and no noticeable gear noise or whine, could that junk have been left behind when there was an initial problem prior to a gear change ? And the small pry marks on the housing lip seem to point to someone screwing around that may not have been experienced with differential workings. As stated the ring and pinion look great with no uneven wear but there are hidden spider gears that could have been slightly shaved.
Also after degreasing the axle assembly I now can see raised coding on the bottom of the middle case. So I will send that info forward as soon as I climb underneath hopefully this weekend. It is a real SS and the build codes call for the 460LE and a 3.23 rear ratio.
Another interesting point is that I ordered replacement ignition and glove box/ rear hatch keys from Chevy dealer. The rear hatch key works like greased lightning but the ignition key inserted but would not unlock the ignition switch to start mode. In comparing the new key to my old one it is day and night. So the dealer ordered a new security chipped ignition key uncut and we copied the one I have. Works like a charm. This could make one wonder if the ignition assembly was replaced but no wear or abuse marks are on the column. Interesting but no record of theft or catastrophes.
OK, I'll send those codes. I have refilled and sealed up the differential. I plan on testing, very gently, the drive ability at least to an experienced shop.
Last edited by Redrokit8; 02-01-2018 at 07:44 PM. Reason: further explanation
02-02-2018, 06:18 PM
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If anyone could shed some light on the following rear axle housing codes, it would be much appreciated.
At each end of the axle housing there are Green and Yellow hash marks by the Sway Bar Bushing mounts.
At the bottom of the center section of the differential there is a series of numbers as follows. 28041414. Underneath these numbers in small letters are GM-01 and then there is a clock style dial that has an arrow pointing to 5:00. There also is a small white painted 93 on the housing that does not appear to be of quality like a factory marking. More like a possible bin number etc.
No other markings that I have found.
Let me know if you can decipher any of this.
At each end of the axle housing there are Green and Yellow hash marks by the Sway Bar Bushing mounts.
At the bottom of the center section of the differential there is a series of numbers as follows. 28041414. Underneath these numbers in small letters are GM-01 and then there is a clock style dial that has an arrow pointing to 5:00. There also is a small white painted 93 on the housing that does not appear to be of quality like a factory marking. More like a possible bin number etc.
No other markings that I have found.
Let me know if you can decipher any of this.
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02-02-2018, 06:33 PM
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I'm familiar with some of the axle codes for older GM rears from the '60s/'70s such as 8.2, 8.5 and 8.875", but I don't have any information on specific casting numbers for these late model 7.5" versions.
Regardless, you know it didn't come stock with that gear ratio since the SPID codes indicate GU5 and an original automatic car, and if there are pry marks that indicate someone has been in there since it was originally assembled then it's most likely the original rear with a gear swap (vs. a swapped axle assembly from an M6 car).
Regardless, you know it didn't come stock with that gear ratio since the SPID codes indicate GU5 and an original automatic car, and if there are pry marks that indicate someone has been in there since it was originally assembled then it's most likely the original rear with a gear swap (vs. a swapped axle assembly from an M6 car).
02-03-2018, 09:23 PM
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Thanks for the comments. This vehicle was purchased mainly for weekend fun. I did have another 2002 SS that I installed a complete Moser 12" axle assembly, gears etc. It was great for the high H/P motor and 6 speed. However, along with the strength came a lot of gear noise. I tried 3.73 originally and then 4.11 replacements from Moser. They refused to acknowledge that their set ups make sometimes excessive noise. I ran everything in per their instructions and all I got was a curt answer that I must have done something wrong on my end. BTW, the 4.11 ran quieter. So I may now try to find a reliable assembly from another source. Any recommendations would be appreciated.