89' Formula LB9/MM5/G80/N10/GM3....ONLY 42....
04-30-2013, 04:54 PM
#101
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Car: '88 GTA, 90 Formula
Engine: 5.7 TPI, fed growth hormones
Transmission: 700r4 4u2?
Axle/Gears: 9bolt
Re: 89' Formula LB9/MM5/G80/N10/GM3....ONLY 42....
Here are a couple sites that help to decode the RPO's:
http://www.c2e.info/rpocodes/
http://www.lesabret-type.com/GMRPOCodes.html
G80 = AXLE, POSITRACTION, LIMITED SLIP
GM3 = AXLE REAR, 3.45 RATIO
If you don't have the 3.45 differential ratio, you've probably got something close to that (like 3.42 = GU6, for example). I don't know if other ratios were available on the '90 Formulas; I thought all the Third-Gen LB9/N10/MM5 cars got a 3.45 ratio...?
http://www.c2e.info/rpocodes/
http://www.lesabret-type.com/GMRPOCodes.html
G80 = AXLE, POSITRACTION, LIMITED SLIP
GM3 = AXLE REAR, 3.45 RATIO
If you don't have the 3.45 differential ratio, you've probably got something close to that (like 3.42 = GU6, for example). I don't know if other ratios were available on the '90 Formulas; I thought all the Third-Gen LB9/N10/MM5 cars got a 3.45 ratio...?
TA
05-01-2013, 07:54 AM
#102
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Car: 87 Formula T-Top, 87 Formula HT
Engine: 5.1L TPI, 5.0L TPI
Transmission: 700R4, M5
Axle/Gears: Sag 3.73, B&W 3.45
Re: 89' Formula LB9/MM5/G80/N10/GM3....ONLY 42....
Starting in 1990, the Borg & Warner (9 Bolt) axle was dropped (some axles remained in stock and some cars have been found to have them for 1990, but there was no RPO on the SPID for it.) Therefore for 1990 - 1992 the SPID RPO would be GU6 which is the Saginaw 7.625 "10 Bolt" axle that has the 3.42 gear instead of 3.45
So US Formulas with the LB9/MM5:
1987 - 1989 - GM3 (3.45) Borg & Warner (9 Bolt) axle
1990 - 1992 - GU6 (3.42) Saginaw (10 Bolt) axle
This was standard fare for the Formula, I have never seen a US Formula with the LB9/MM5 without a GM3 or GU6, if you don't have it and the car was not an export I would be more than interested
Hope that helps.
John
So US Formulas with the LB9/MM5:
1987 - 1989 - GM3 (3.45) Borg & Warner (9 Bolt) axle
1990 - 1992 - GU6 (3.42) Saginaw (10 Bolt) axle
This was standard fare for the Formula, I have never seen a US Formula with the LB9/MM5 without a GM3 or GU6, if you don't have it and the car was not an export I would be more than interested
Hope that helps.
John
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