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Old 10-29-2008   #1
wildbird
Mustangs can run but birds can fly
 
Join Date: Aug 2006
Location: Raleigh NC
Posts: 365



GTA Year: 1988
GTA Engine: 350 TPI Automatic
gears question

im tryna decide which gears i should go with.. i have the stock 3.27 9 bolt gears in my trans am gta... i have done numerous mods and i wanted to know what gears would be best for my powerange... basically i want low end torque because this will be a fun daily driver with some strip use...but i use it manily for the streets.... a popular guy on thirdgen gave me this advice.....



"Your gonna think that I'm crazy for saying this, but save your $$$ and stay with lower gears.
Tpi's make great torque right? Use that torque to move those gears!!! If you get high gears you'll just spin the crap out of your tires and have a very short powerband, especailly because you already have a 2500 stall converter.

Think about this for a second..... You got a mountain bike right? It's hard to start in 18th / top gear isn't it? But with enough strength you slowly start moving the pedals and can keep it in that gear for a long time before you can't pedal any faster and your flying (speed wise). That's like having a 2.73...... If you make enough torque you can get that gear moving and you have a long powerband.

If you start your mountain bike in first gear you can probably spin the tires right off the bat (literally) but you soon can't pedal any faster and look like a retard pedaling as fast as you can without going anywhere ...... That's like having a 4.56

Now that's the extremes right...... but if your gonna keep the TPI System (made for torque and a shorter powerband) and already have a 2500 stall you should keep the 3.27's or go lower (in my opinion) because the TPI will make great torque to get the tires moving and the higher stall will get the engine into the heart of the power.

In my opinion the more torque/power you make the less you need those 3.73's....... you already spin like crazy with those 3.27 don't cha.....? Keep asking questions, keep reading different books. If you start having too many mismatched parts you'll start hating that Trans am because it won't work up to your expectations


here are my mods as of now....

5.7 350 factory l98 engine
Rebuilt l98 heads
Cranes 2032 cam 452/465 214/220 112lsa
Cranes matching springs
SA performance double timing chain
Cranes Adjustable fuel regulator set at 45psi
Flowmasters 80ís series 3.5 inch catback
Catco High Flow converter
Custom 3 inch built Y-pipe
Heated O2 sensor
Hedman Longtube Street headers
Ported and Siamesed SLP runners
Ported and Siamesed Plenum
Ported Edelbrock High flow Intake
SVO 24lb Injectors
SLP cold air intake with K&N air filter
SLP airfoil
IAT relocated to SLP air box
160 thermostat
Throttlebody Bypass
EGR delete
Heater valve delete
Air/smog delete
LT1 Starter
Heavy duty flywheel
MSD 8.5 super conductor wires
Accel super coil
Performance radiator
Pro built 700r4 rated at 500 horsepower
B&M shift kit
Tranny cooler
2500 converter
High flow water Pump
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My Super L98 lol"

Forged 355 4 bolt, FIRST injected TPI, L98 headed, hotcammed engine

"Completely Assembled and built by My dad and I"

Tuned by PCM4less

dyno numbers and timeslips comming soon

"12 Second daily Driver GTA"

http://www.thirdgen.org/techboard/vb...=view&id=62362
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Old 10-29-2008   #2
FearThisGTA
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Posts: 4,742



GTA Year: 1991
GTA Engine: 350 TPI Automatic
Re: gears question

Stay with the 3.27 grzzz, unless you are goin corner carvin. Otherwise if you are goin drag racin a taller gear will hurt you in the long run, unless you are runnin slicks. hth
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1991 GTA Trans Am
w/305,231 miles
on the original motor!!!!
Time of Death on motor, 4:07pm on 05/29/2010.
Hp:211.2@4200rpms/Tq.328.5@2700rpms
Best et: 13.959@97.05mph
Best mph: 98.3
Best 60' : 1.875 on BFG Comp TA's w/ 32 lbs of air in them
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Old 10-29-2008   #3
Tony89GTA
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Location: Prince George, B.C. Canada
Posts: 334


Re: gears question

Most I would go is 3.45 with your car but with the gears that you have now and the higher stall probably best to stay with your gearing as is unless you change your intake to a short runner type.
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ATI Procharger D1SC, AFR 195 Eliminator heads, Mini Ram, ZZ9 cam, AS&M Mono-blade TB, 60Ibs injectors, Stainless Works LT 1 3/4 headers, Mufflex 4" catback with Magnaflow race muffler, McLeod Street twin clutch, Moser Ford 9" with 3.70, DIY Prom with Code59. Stock short block

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Old 10-30-2008   #4
merc3065
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Re: gears question

3.45s would be the absolute top end you should go with the mods on your car.

You need to be at the top of your power band in 3rd gear when you cross the traps in the 1/4 mile. If you are out of your powerband before or after, you need to change the gears.

The 3.27s will put you easily into the 12s with the right engine mods. Dont swap it out until it breaks. When it breaks, get 3.45s but dont change it until then.
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Old 10-30-2008   #5
wildbird
Mustangs can run but birds can fly
 
Join Date: Aug 2006
Location: Raleigh NC
Posts: 365



GTA Year: 1988
GTA Engine: 350 TPI Automatic
Re: gears question

ok.... but i have never seen any 3.45 gears for a 9 bolt..... i think im just gonna stick with my 3.27 gears.....
__________________
My Super L98 lol"

Forged 355 4 bolt, FIRST injected TPI, L98 headed, hotcammed engine

"Completely Assembled and built by My dad and I"

Tuned by PCM4less

dyno numbers and timeslips comming soon

"12 Second daily Driver GTA"

http://www.thirdgen.org/techboard/vb...=view&id=62362
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Old 10-30-2008   #6
strc09
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Location: Linden, NC
Posts: 1,405



GTA Year: 1988
GTA Engine: Custom
Re: gears question

9-bolt.com sells different gear sets for our cars up to 4.11s or 4.10s. I can't remember off the top of my head. It all depends on what you're trying to do. Stock my car was pretty good with the 3.27s, but I wish that I had upgraded the gears when I put the 383 in. Now that I'm having a T56 installed, I definately had to upgrade or I would have probably never seen sixth gear until around 80 or so if that.
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GTA: Grand Turismo Americano (Grand Touring America)
1 of 930 1988 Gunmetal Metallic GTAs produced (RPO 87U)
Built by Zeus Performance and tuned by Alvin from PCM4Less
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Old 10-30-2008   #7
merc3065
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Re: gears question

http://www.9bolt.com/gearsets.html
Check out the site, its got all the info you could ever want to know on the 9 bolt including the kits to overhaul/modify.
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Old 10-30-2008   #8
merc3065
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Re: gears question

yeah, with a T56, you can go as high as 4.56 and still get good gas mileage.
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Old 10-30-2008   #9
strc09
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GTA Year: 1988
GTA Engine: Custom
Re: gears question

Eventually I may moveup to a 4.11 later on after I can afford to upgrade to the mini-ram. I haven't decided yet. We'll see how the car feels once I get it back.

BTW...thanks for posting the site, Merc. I was being lazy. LOL!
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-Patrick

GTA: Grand Turismo Americano (Grand Touring America)
1 of 930 1988 Gunmetal Metallic GTAs produced (RPO 87U)
Built by Zeus Performance and tuned by Alvin from PCM4Less
Check out my website: Night Vision GraFX
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Old 11-02-2008   #10
brooklyngta
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Posts: 78


Re: gears question

i agree totally.i have the same stock set up.i dont race my car and use it only on the street.the thing i enjoy the most is that with our configuations,the pull in each gear is long and strong.i am not sure if shorter stronger aplication would be better for the street than what you already have.balance of power tru out the band is most important to me.
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