I just found my '83's buildsheet in perfect condition yesterday. It lists 3.73 rear axle. My car has the LG4, T-5, and WS6. Never heard of this before. I thought they only came with 3.23's.

 

Probably a special order. IIRC 3.23 would have been the standard gear.

 

My first new car was an '83 Z28 with the LG4/T5 and it came standard with 3:73s......I think the automatics came with the 3:23 ratio.

 

yes it was an available rear end for the year, with that engine and tranny combo. the G92 option.

 

GM lists 3.73 standard on '83 Pontiac F-Body LG4 w/MM5.

 

I have an 83 T/A with a 305 CrossFire and it has 3.42's

 

So....if your car came with WS6 and a 5 speed its a good chance it came with 3:73's?

 

I know it was std equipment on the L69 cars in 1983, but I don't think it was standard on an LG4...

 

I've never heard of that gear being standard on ANY LG4 car. And that goes back to car shopping when these cars were new. An avaliable option maybe, but not standard.

I don't know about a "good chance" of any particular combo, since that would depend on what the original purchaser ordered; but I'd guess that if somebody was buying one of these cars before the L69 came out, and wanted to upgrade it as much as possible in a performance kind fo way, that they would have been more likely to order the special gear along with a T-5 & WS6, than any other combo. But that's not near the same as saying there's a :good chance they would have ordered it that way; just a less poor chance than with some other combo.

I also don't recall Cross-Fire cars coming with 3.42s, or that even being an option. Most of those were either 2.93 or 3.23. But I wasn't interested in Cross-Fire at all, at the time, so I could easily be wrong about what was available.

 

My GTA has the 3.23 rear with a 350 and my CrossFire pulls way harder off the line same tranny must have a bigger rear and I have calculated the rear using the calculator on this site and it came to about a 3.42 using rpm at certain speeds there were more options on the earlier thirdgens for rear than the later ones, you could get 4.10's or 3.73's as the biggest rears where the newer ones the biggest was a 3.23 with auto and 3.42 with the T-5

 

I wouldn't bother with the "calculate" thing, these tachs aren't accurate enough for that. They practically always read high, which will make you over-estimate the gear ratio. Which is what most people who are proud of their cars will tend to do anyway.

The only way to really know what gears you've got is to pull the cover and look.

 

All 520 5spd Daytona TA LG4 cars came with 3:73's, I was thinking all 83 LG4 WS6 5spd card did as well.

 

I have 3 different Pontiac documents that list the same for the Firebird line and all 3 are before the introduction of the L69.

----------1983 FIREBIRD--------
------------------------------Fed. & California Emission
----------------------------------STD----OPT

LQ9 2.5 LITER (151) L4 EFI
--------------4 Speed Manual----- 3.42---__
--------------5 Speed Manual----- 3.73---__
--------------200/C Auto 3-------- 3.08---3.23---3.23(STD. High Altitude Emission)

LC1 2.8 Liter (173) V6 2BBL
--------------5 Speed Manual----- 3.42---__
--------------200/C Auto 3-------- 3.08---__

LL1 2.8 Liter (173) V6 BBL HO
--------------5 Speed Manual----- 3.73---__
--------------700/R$ Auto 4------- 3.73---__

LG4 5.0 Liter (305) V8 4BBL
--------------5 Speed Manual----- 3.73 ---__
--------------700/R$ Auto 4-------- 3.08 ---__
----------------(Base & SE)
--------------700/R$ Auto 4-------- 3.23---__
--------------(Trans Am & SE with WS6 or WS7)

LU5 5.0 Liter (305)
Cross-Fire EFI
--------------700/R$ Auto 4--------- 2.93---3.23


RB83L69 is correct that the LU5 CrossFire only came with 2.93 & 3.23 both years.

4.10 in a thirdgen?

 

82RECAROTA, before you said my rear would be 3:23, but this post says that its a 3:73? I have the 4bbl Lg4 with the T5.

 

JLP

Did further research for '83's

 

ok cool thanks bro.
Also, is it possible that someone ordered smaller gears rather then just getting the standard 3:73's with their LG4 and 5 speed? I think Im just going to pull the cover off the rear and find out for sure, this is really bothering me...

 

Jack up the rear, put it in N, and get under it. Turn the driveshaft untill the wheels turn exactly once, and that could help you get close at least (ie. 3-3/4 turns = 3.75 = 3.73 gear)

Should work anyway.

 

JPL

Haven't found any other factory listings for '83 beside the LG4 w/5-Speed - 3.73. Maybe a dealer swap job or somebody else.

I remember your other post on the subject. Serves me right for using the "Tech Data". Sorry.

You can use Air_Adam's way or yours (good time to change the fluid anyhow)

 

In High Performance Pontiac states in March 2003 that thirdgens could have in 1983 3.23, 3.42, 3.73, or 4.10 could be optioned and in 1984 they have all but 4.10, also states that T-5 came standard with 3.73 and auto could be optioned with any rear gear, and I know for a fact that my CrossFire pulls harder than my GTA off the line and the RPM's at 60 are GTA=little under 2000 CrossFire=almost 2500, both with 700R4

 

4.10? That can't be right... I've never heard of a 3rdgen with factory 4.10 gears. I don't think any F-body has had those gears since about 1972.

 

Thanks for the answer!

 

My car is an '83 T/A that had the LG-4 and came with a T5 tranny, and a 3.73 open rear end. Either that or the posi was fu-bared.

My 350 has made short work of 2 rear ends since then.

 

Or when in doubt and you don't wanna open it up, slide underneath and take a look at the casting number(axle code) stamped on the differential housing. That would seem to be the easiest way to findout.

I did that a long time ago to be sure they REALLY put the 3.45 in my '87, lol. Hey, you never know!

So here ya go, print it out, go have a look, and you'll know exactly what they installed, versus what they were supposed to have installed.

 

My 83 T/A came with 3:73 gears from the factory.

This was on a WS-6 5-speed car.

The best of my research could uncover, was in the "Illusrtated Firebird Buyer's Guide", by John Gunnell. Page 160.

It stated that the Trans Am came standard with the 5.0 liter V-8, 5-speed trans., and a 3:23 rear axle.

There was no mention of the 3:73, other than for the 190 hp. H.O.
And then, it was stated that this was a standard gearing for this motor.

The only thing I would like to add, is that the L-69(H.O.) also came standard with WS-6 performance package. So, with that, it would seem that the 5-speed cars without WS-6, would get the 3:23 standard, and the WS-6/5-speed cars got the 3:73 standard.

But that's just my take on it, decide whatever makes sense to you.

 

Mecham put a 3.73 rear in my 82 MSE.

 

My 83 T/A has 3.73's and has the LG-4 with the 5-speed and WS-6. I think I have read where the combo of the 5-speed and the WS-6 in 1983 got you the 3.73's.

I don't know if this is true or not but I have heard that the Pontiac T/A's pretty much came standard with a positraction rear axle unlike the Chevy Camaros. I have yet to see a T/A with no positraction from the factory other than a wore out posi unit. I have seen plenty of Z-28's with a peg leg though.