rear end ratio puzzling
Thread Starter
Junior Member
Joined: Dec 2009
Posts: 30
Likes: 0
From: St.John's, Newfoundland, Canada
Car: 1986 Camaro Z28
Engine: 355 4 bolt 4bbl
Transmission: T-5 manual
Axle/Gears: 3.73 posi.
rear end ratio puzzling
I've got an 86 Z28. the option list on this site says that the LG4 automatic only came with a 2.73 rear. But my RPO's are LG4 (305 4 bbl) MD8 MX0 (700 R4) and GU5 (3.23) rear gears. Also on the right axle tube there is PH stamped and I can't find any info on that. It is also a Canadian car if that makes a difference.Thanks.
Joined: Aug 1999
Posts: 19,282
Likes: 103
From: Lawrence, KS
Car: Met. Silver 85 IROC/Sold
Engine: 350 HO Deluxe (350ci/330hp)
Transmission: T-5 (Non-WC)
Axle/Gears: Limited Slip 3.23's
Re: rear end ratio puzzling
I've got an 86 Z28. the option list on this site says that the LG4 automatic only came with a 2.73 rear. But my RPO's are LG4 (305 4 bbl) MD8 MX0 (700 R4) and GU5 (3.23) rear gears. Also on the right axle tube there is PH stamped and I can't find any info on that. It is also a Canadian car if that makes a difference.Thanks.
https://www.thirdgen.org/forums/tran...-10-bolts.html
JamesC
Re: rear end ratio puzzling
When in doubt, trust the RPO codes. Just make sure the vin on the SPID matches the vin on your car. The tech data on this site isn't 100% flawless, it's just a guideline.
Member
Joined: Dec 2006
Posts: 454
Likes: 0
From: Evington,Va
Car: 93 Formula,88 T/A,01 WS6
Engine: 93 LT1,88TPI305,01 LS1
Transmission: 93 700R4,88 700R4,01 T56
Axle/Gears: 93 3:73's,88 3:42,01 3:40
Re: rear end ratio puzzling
It's an old car. My experiance is people don't usually change gear oil in the diff as a maintenance thing. Spend a few bucks, pull the cover off and get the numbers off the gears. Mystery solved and new oil in diff.
Thread Starter
Junior Member
Joined: Dec 2009
Posts: 30
Likes: 0
From: St.John's, Newfoundland, Canada
Car: 1986 Camaro Z28
Engine: 355 4 bolt 4bbl
Transmission: T-5 manual
Axle/Gears: 3.73 posi.
Re: rear end ratio puzzling
Thanks guys. Doesn't really matter though cause just bought a posi carrier and a set of 3.73's.
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iTrader: (1)
Joined: Aug 2008
Posts: 1,485
Likes: 5
From: Short Summer, VT
Car: 1985 Trans Am T-Top
Engine: 305 TPI
Transmission: T-5 5 Speed
Axle/Gears: 3.42 posi 1LE 10 bolt
Re: rear end ratio puzzling
Mine didnt match the data either. I dont have my rpo's but my car should have had 2.73 , but i opened the diff and it has 3.42. The brakes werent hooked up right either, so im guessing th Po swapped in an axle from a V6 car.
Thread Starter
Junior Member
Joined: Dec 2009
Posts: 30
Likes: 0
From: St.John's, Newfoundland, Canada
Car: 1986 Camaro Z28
Engine: 355 4 bolt 4bbl
Transmission: T-5 manual
Axle/Gears: 3.73 posi.
Re: rear end ratio puzzling
Its got drum brakes. Its a 10 bolt 7.5 with 26 spline axles.
Senior Member
Joined: May 2006
Posts: 581
Likes: 0
From: NY
Car: 00 SSEi / 94 C4
Engine: 231 / 383
Transmission: 4T65E / ZF 6sp
Axle/Gears: 2.93 / Dana 44 3:45
Re: rear end ratio puzzling
Joined: Oct 2001
Posts: 12,232
Likes: 1,166
From: Il
Car: 1989-92 FORMULA350 305 92 Hawkclone
Engine: 4++,350 & 305 CIs
Transmission: 700R4 4800 vig 18th700R4 t56 ZF6 T5
Axle/Gears: 3.70 9"ford alum chunk,dana44,9bolt
Re: rear end ratio puzzling
One of my cars is rpo 4 2.73 open.
the axle is coded 4 2.73 posi but it has a (GM gears) 3.08 open..
I have looked and looked 4 any clue 4 a rear swap but cant find any..
the axle is coded 4 2.73 posi but it has a (GM gears) 3.08 open..
I have looked and looked 4 any clue 4 a rear swap but cant find any..
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