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'91 Formula WS6 options

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Old 04-29-2005 | 02:26 PM
  #1  
Julie Bergman's Avatar
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From: In the sticks near Woodland,CA, USA
Car: 91 Formula WS6
Engine: 305 TPI
Transmission: five speed
'91 Formula WS6 options

I just picked up a '91 Formula WS6, TPI and five speed. Surprisingly this car has a drum brake year end! I thought RPO GU6 got you four wheel discs? Anyone know if it was possible to get a WS6 LB9 TPI car without four wheel discs? I am wondering if they took out the stock rear end and threw something else in before I bought the car.
Old 04-29-2005 | 02:30 PM
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TAdan's Avatar
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From: NJ,USA
Car: 1984 Trans Am
Engine: GMPP 350 V8
Transmission: 700R4
Axle/Gears: 3.23
Their was a rear disk brake shortage in 91. Drums were used as substitutes.
Old 04-29-2005 | 02:36 PM
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Julie Bergman's Avatar
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From: In the sticks near Woodland,CA, USA
Car: 91 Formula WS6
Engine: 305 TPI
Transmission: five speed
Thank you Dan, that is really interesting! I have ordered the PHS documentation for this car, wonder what it will say if anything about that! I wonder if they reimbursed folks that ordered them?
Old 05-04-2005 | 09:30 AM
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From: Thornton, CO
Car: 1987 GTA 350
Engine: L98
Transmission: 700R4/2400 stall
Axle/Gears: B/W 3:27 posi disc
Do you have the code in the console for the car? That should tell you, but I asume you don't. Thought I'd ask.

Conrad
Old 05-04-2005 | 10:18 AM
  #5  
Julie Bergman's Avatar
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From: In the sticks near Woodland,CA, USA
Car: 91 Formula WS6
Engine: 305 TPI
Transmission: five speed
Hi Conrad, I do have the codes, the sticker is in the rear locked compartment lid. I heard that was a mid year change Either I overlooked it or I could not find the code for drums in back. I also ordered the PHS packet for the car, looking forward to seeing it all decoded.
I have a book that decoded most of it.
Old 05-08-2005 | 03:18 PM
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I have the same car a 91 formula lb9 5 speed with 3:42 posi drum rear.
Like they said some how GM ran out of rear disks
Old 05-09-2005 | 10:29 AM
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GTA Jim's Avatar
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From: Woodlands, MB, Canada
Car: 1990 GTA
Engine: 5.7
Transmission: 4L60
Axle/Gears: 3.27 Posi
FWIW, J41 is the RPO for rear drum brakes.. The RPO for rear disk brakes is J65
Old 05-14-2005 | 12:34 PM
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From: Wichita, KS
Car: 1991 Camaro Z28
Engine: L98
Transmission: 700R4
My 91 Z28, which has G92, has rear drum also. I have seen alot of other 91s like this too so there must be some truth to the "great rear disc brake shortage of '91"
Old 05-14-2005 | 02:16 PM
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From: Doghouse ······································ Car: 1989 Formula 350 Vert Engine: 350 L98 Transmission: 700R4 Axle/Gears: B&W 3.27
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
Correct me if I am wrong, but I thought that most years disk brakes were an option, as was the performance rear axel. Therefore you could order one without the other.

Early T/A's for example with the WS6 got the disk brakes, and WS7 cars were the same suspension but with drum brakes. That changed when the RPO sheet was introduced in 84, then each component got its specific RPO.

I know that for some engine combos, specifically the 350 auto cars, the Disk brakes were manditory, less the times when there was a shortage such as 1991, then you got the Aluminum drums, which are probably as good as Disk brakes for a normal street car.

But I have never heard of a manditory rear disk brake with the 305 TPI 5 speed cars and the performance rear axel, although most of them got it.

John

Last edited by okfoz; 05-14-2005 at 02:19 PM.
Old 05-14-2005 | 02:34 PM
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From: Wichita, KS
Car: 1991 Camaro Z28
Engine: L98
Transmission: 700R4
To my knowledge, when the G92 package was ordered on a camaro (not so sure how it worked on firebirds) from 89 to 92 you got an engine oil cooler, dual cat exaust, rear disc brakes, performance rear axle ratio (3.23 for autos 3.42 for M5s) and the 145mph speedo. I know the L98 required G92 (on 90-92 at least) but G92 was an option on TPI 305 5-speed cars. Oh yeah, and my drums are not aluminum, and I'm almost positive they are the originals. Also my car has all the other G92 options except the disc brakes.
Old 05-14-2005 | 03:52 PM
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From: I won't tell either
Car: 1986 Grand Prix TPI
Engine: 350 TPI
Transmission: 200 4R
82-85 WS6 came with rear discs.
86-89 WS6 the discs were optional or part of another package.
I dont know about 90-92.
Old 05-16-2005 | 07:26 AM
  #12  
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From: Doghouse ······································ Car: 1989 Formula 350 Vert Engine: 350 L98 Transmission: 700R4 Axle/Gears: B&W 3.27
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
Originally posted by injdinjn
82-85 WS6 came with rear discs.
86-89 WS6 the discs were optional or part of another package.
I dont know about 90-92.
same for 90-92...

Colin91Z, I guess I should admit that the aluminum drums is what I was told here on the boards, when you got the 350 in the shortage time.

John
Old 05-16-2005 | 05:21 PM
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From: Wichita, KS
Car: 1991 Camaro Z28
Engine: L98
Transmission: 700R4
Well, I know that I have iron ones right now, but i guess its possible that they were replaced before i owned the car, but they do appear to be the originals. Maybe someone will chime in that knows for sure...
Old 05-16-2005 | 10:23 PM
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From: Batesville, AR 72501 USA
Car: '88 Bright Red GTA
Engine: 5.7L TPI
Transmission: 700R4
Axle/Gears: 3.27:1
Julie, the 1991 Pontiac Firebird Car Order Worksheet says:

"UPC LB9 - 5.0L FI V8 Standard Trans Am - NA Firebird - Optional Formula - (Credit GTA Option)

Requires G80 Limited Slip Differential - Requires R6P Performance Enhancment Group (Engine Oil Cooler, Dual Converter Exhaust, Front Disc - Rear Drum Brakes and 3.42 Axle Ratio) on Formula and GTA with 5-Speed Transmission"

I don't know about the disc brake shortage and I've always heard there was one, but this order sheet was printed in 7/90.... and it already says that all TPI Formulas would get the drum rear brakes, so....?

It also lists the drum brakes for the 5.7L TPI cars.... apparently if your car was built with the R6P group, then you got the rear drum brakes, regardless of the engine used. There is no mention of a GU6 RPO on any of the order sheets from 1987-1992, whereas the R6P group is shown as required with any TPI engine in both '91 and '92.

The 1992 order worksheet shows a reversion back to four-wheel-disc brakes for both TPI engines with the R6P group.

Just an FYI.

Last edited by FrankieRider2; 05-16-2005 at 10:26 PM.
Old 05-16-2005 | 10:47 PM
  #15  
Julie Bergman's Avatar
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From: In the sticks near Woodland,CA, USA
Car: 91 Formula WS6
Engine: 305 TPI
Transmission: five speed
Thanks everyone for all the useful and interesting input! My first mod to the car is a Pro 5.0 shifter. I am liking the LS1 brake conversion idea also....
Old 05-17-2005 | 07:55 AM
  #16  
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From: Doghouse ······································ Car: 1989 Formula 350 Vert Engine: 350 L98 Transmission: 700R4 Axle/Gears: B&W 3.27
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
Originally posted by Julie Bergman
Thanks everyone for all the useful and interesting input! My first mod to the car is a Pro 5.0 shifter. I am liking the LS1 brake conversion idea also....
I got the Baer Brake$, expen$ive, but well worth it. I used to be afraid to drive my car hard, in fear of stopping... not any more

If you want to retain your stock wheels, the you need the 12" on all four corners. The 13's will fit up front ,but you will need to grind down the fins on the calipers, as they rub. I chose to go with 12's.

John
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