[Pontiacmuscle]

What did the '79 T/As with the 403s and Th350s come with for a rear gear ratio and were all '79 T/As Posi?
Thanks,
~PM~

[poncho-mike]

As far as I know, limited slip was standard on the Trans Am.

Below is my experience with 79 Trans Ams:

403 cars were equipped with 2.41 gears
400 4-spd with a/c were equipped with 3.23 gears

The single 301 4-barrel car I parted had a 2.41 gear also.

Mike

[khkiley1]

Was the '79 T/A 4Spd available with 3.5ish gears ? Didn't count, or check, but did the math on the speedo/tach and it comes to about that on mine.

Thanks,

Kurt

[Jim Rotella]

All 1979 W72 T/A's came with 3.23 posi rear axles. The early literature states that all 403 cars came with 2.41 gears, but I had a '79 WS6 403 Trans Am and the build sheet shows a 2.73 rear axle. There must have been an in year change in the 403 cars.

Jim

[Pontiacmuscle]

What about the non-ws6 cars with the 403?

[Jim Rotella]

The 1979 Pontiac Buyers Guide lists the 2.41 posi axle as the standard axle ratio on 403 T/A's, but it lists 3.23 as an available ratio with the 403. It also says that 3.08 is the standard ratio for a 403 in High Altitude Certification, but this is a very early buyers guide and may have been updated later. Another powertrain listing I have shows the 2.41 standard with the 3.08 optional in High Altitude and 3.23 optional for Federal and California certification. No where did I find any mention of a 2.78 ratio available, but I owned a '79 T/A that was built in Van Nuys in April of '79 and was shipped to a dealer in Souix Falls SD. The build sheet says 2.78 rear axle but there is no optional rear axle listed on the window sticker, which would indicate that it was the standard rear axle. There must have been some changes in gear ratios during the model year.

Jim

[Mr W72]

According to Pontiac documents I have the following axle ratio usage applies.

"Effective October 28 1978 the following axle ratios were used with the 403-cid cars. All non WS6 cars would have came with 2.41 axle ratio, no optional ratio was offered

Federal Emissions
403-cid together with J65 front and rear disc brakes and with A/C changed from 3.23 to 2.73
403-cid together with J65 front and rear disc brakes and without A/C remains 3.23
Both axle ratios (2.73 or 3.23) require WS6

Calif Emissions (NB2)
403-cid together with J65 front and rear disc brakes and A/C has been changed from 3.23 to 2.73. WS6 package is required

High Altitude Package (NA6)
403-cid together with J65 front and rear disc brakes and A/C has been changed from 3.23 to 2.73 and is available with or without WS6
403-cid together with NA6 high altitude will now be 2.73
C60 A/C is required option with NA6 High Altitude Package
An August 31 1978 Pontiac memo shows 3.08 axle ratio with the NA6 option requiring A/C but was change 2.73

WS7 Option
L37 301 automatic 2.73
L37 301 4-speed manual 3.08
L80 403 Federal Emissions with A/C 2.73
L80 403 Federal Emissions without A/C 3.23
L80 403 Calif Emissions 2.73 - Note C60 A/C is reqired when WS7 is ordered with 403 and NB2 Calif emissions
L80 403 High Altitude 2.73
Note: WS7 was not available with the W72 400-cid engine or Y84 model Trans Ams"


Hope this helps

[Jim Rotella]

Thanks for the help John, that really clears it up.

Jim