Any source for a 3:08 gearset for a 9 bolt?
#1
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Any source for a 3:08 gearset for a 9 bolt?
My Iroc has a 3:42 5 spd. The 400 sbc has over 500ft/lbs the car buzzes down the hwy too much it's not a drag racer. Normal sources dont have a 3:08 for this rearend. Anyone know of one? thanks
#4
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Re: Any source for a 3:08 gearset for a 9 bolt?
A complete used 2.73 peg leg drum 10-bolt should be an easy find. Put a want-ad on craigslist and I'll bet the offers blow up your inbox. Don't gut a good gear set just because it doesn't match YOUR combo. Starving kids in Kansas dream of doing burnouts and can't find a good gear ratio for a 9-bolt. Just sayin.
#5
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Re: Any source for a 3:08 gearset for a 9 bolt?
A complete used 2.73 peg leg drum 10-bolt should be an easy find. Put a want-ad on craigslist and I'll bet the offers blow up your inbox. Don't gut a good gear set just because it doesn't match YOUR combo. Starving kids in Kansas dream of doing burnouts and can't find a good gear ratio for a 9-bolt. Just sayin.
lol
#6
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Car: 92 Firebird
Engine: 4.8 LR4
Transmission: T56
Axle/Gears: 3.45 9 Bolt
Re: Any source for a 3:08 gearset for a 9 bolt?
Do you have a 3.45 9 bolt in your car now? If you do, it would just be easier to get a complete 9 bolt axle with the gear ratio you need and swap it in, then sell your rear for more money than the one you're buying because the 3.45 is a more desirable ratio. So much so that I would want the pumpkin from your axle with the gears and ship it the the USA because setting up used gears SUCKS.
#7
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Thread Starter
Re: Any source for a 3:08 gearset for a 9 bolt?
Do you have a 3.45 9 bolt in your car now? If you do, it would just be easier to get a complete 9 bolt axle with the gear ratio you need and swap it in, then sell your rear for more money than the one you're buying because the 3.45 is a more desirable ratio. So much so that I would want the pumpkin from your axle with the gears and ship it the the USA because setting up used gears SUCKS.
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#9
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Re: Any source for a 3:08 gearset for a 9 bolt?
3:42 or 3:45 whatever it is. It has stock 4 wh disc and 9 bolts on the cover....I counted. With the stock Iroc wheels and 245 50 16s at 75 mph in 5th Im at 2750 rpm Id like to be around 2000.
#11
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Re: Any source for a 3:08 gearset for a 9 bolt?
And Id pay for your stuff to be shipped to me....and youd pay for my stuff to be shipped to you.
#12
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Re: Any source for a 3:08 gearset for a 9 bolt?
Probably, but if money or honor is changing hands, pop the cover and look for the stamp on the ring gear.
Pics are of a 10-bolt, but the 9-bolts are marked the same way ??:?? divide the two numbers, round to the closest, that's your ratio. Likewise you can count the teeth on the ring and pinion gears and that'll give you the numbers stamped in the ring gear. Sometimes you'll see the ratio stamped as the regular published ratio.
9-bolts are a bit goofy. The ratios are a bit different for GM, 2.77 instead of 2.73 in the 10 bolt, 3.27 v 3.23, 3.45 v 3.42, 3.70 v 3.73. I've heard there is a 3.08 9-bolt gearset that GM used but never had one in hand, same with the 9-bolt with drum brakes.
Generally speaking, a TPI has enough grunt from idle to pull 2.77 gears. A lot more were built with 2.77 gears than 3.27, 3.45, or 3.70 gears.
Pics are of a 10-bolt, but the 9-bolts are marked the same way ??:?? divide the two numbers, round to the closest, that's your ratio. Likewise you can count the teeth on the ring and pinion gears and that'll give you the numbers stamped in the ring gear. Sometimes you'll see the ratio stamped as the regular published ratio.
9-bolts are a bit goofy. The ratios are a bit different for GM, 2.77 instead of 2.73 in the 10 bolt, 3.27 v 3.23, 3.45 v 3.42, 3.70 v 3.73. I've heard there is a 3.08 9-bolt gearset that GM used but never had one in hand, same with the 9-bolt with drum brakes.
Generally speaking, a TPI has enough grunt from idle to pull 2.77 gears. A lot more were built with 2.77 gears than 3.27, 3.45, or 3.70 gears.
#13
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Re: Any source for a 3:08 gearset for a 9 bolt?
You can play around with this one:
https://www.randysworldwide.com/calculators/rpm/
Your tire height is 25.6"
I did and 2.77 won't even get you to 2000 RPM. About 2200 is where you will be from where you are now..... the 2.77 is the highest gear available for the 9 bolt that I'm aware of so if you wanted even taller to get to 2000 in 5th you would probably have to go to an auxiliary over-drive like a Gear Vendors..... though I don't think anyone offers anything that works with the torque arm.
I can pull the cover of course. But it's a 2.77. My daily is the same car, same year. Both have the same 2.77 diff in them. With Delco-Morain iron rear disc's. The 9 bolt diffs have a metal tag with the ratio and the LSD information.
GD
https://www.randysworldwide.com/calculators/rpm/
Your tire height is 25.6"
I did and 2.77 won't even get you to 2000 RPM. About 2200 is where you will be from where you are now..... the 2.77 is the highest gear available for the 9 bolt that I'm aware of so if you wanted even taller to get to 2000 in 5th you would probably have to go to an auxiliary over-drive like a Gear Vendors..... though I don't think anyone offers anything that works with the torque arm.
I can pull the cover of course. But it's a 2.77. My daily is the same car, same year. Both have the same 2.77 diff in them. With Delco-Morain iron rear disc's. The 9 bolt diffs have a metal tag with the ratio and the LSD information.
GD
Last edited by GeneralDisorder; 04-19-2019 at 11:49 AM.
#14
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Thread Starter
Re: Any source for a 3:08 gearset for a 9 bolt?
You can play around with this one:
https://www.randysworldwide.com/calculators/rpm/
Your tire height is 25.6"
I did and 2.77 won't even get you to 2000 RPM. About 2200 is where you will be from where you are now..... the 2.77 is the highest gear available for the 9 bolt that I'm aware of so if you wanted even taller to get to 2000 in 5th you would probably have to go to an auxiliary over-drive like a Gear Vendors..... though I don't think anyone offers anything that works with the torque arm.
I can pull the cover of course. But it's a 2.77. My daily is the same car, same year. Both have the same 2.77 diff in them. With Delco-Morain iron rear disc's. The 9 bolt diffs have a metal tag with the ratio and the LSD information.
GD
https://www.randysworldwide.com/calculators/rpm/
Your tire height is 25.6"
I did and 2.77 won't even get you to 2000 RPM. About 2200 is where you will be from where you are now..... the 2.77 is the highest gear available for the 9 bolt that I'm aware of so if you wanted even taller to get to 2000 in 5th you would probably have to go to an auxiliary over-drive like a Gear Vendors..... though I don't think anyone offers anything that works with the torque arm.
I can pull the cover of course. But it's a 2.77. My daily is the same car, same year. Both have the same 2.77 diff in them. With Delco-Morain iron rear disc's. The 9 bolt diffs have a metal tag with the ratio and the LSD information.
GD
#16
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iTrader: (17)
Re: Any source for a 3:08 gearset for a 9 bolt?
http://www.tremec.com/calculadora.php
Stock tire 25.7 inches
Am I missing something? You should be at 2000 rpm @ 70 mph now.
Stock tire 25.7 inches
Am I missing something? You should be at 2000 rpm @ 70 mph now.
Last edited by TORN; 04-20-2019 at 06:47 AM.
#17
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Thread Starter
Re: Any source for a 3:08 gearset for a 9 bolt?
http://www.tremec.com/calculadora.php
Stock tire 25.7 inches
Am I missing something? You should be at 2000 rpm @ 70 mph now.
Stock tire 25.7 inches
Am I missing something? You should be at 2000 rpm @ 70 mph now.
#18
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#19
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Re: Any source for a 3:08 gearset for a 9 bolt?
I had it up on the lift....def 3:45
#22
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Re: Any source for a 3:08 gearset for a 9 bolt?
Sorry been on holidays with no web access for a couple weeks....I run an Fitech in the car. I could check the tach on the dash against the tach on the Fitech handheld. I dont usually have the handheld hooked up as it sacks the battery over time and the car isnt a DD. Thanks
#23
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Thread Starter
Re: Any source for a 3:08 gearset for a 9 bolt?
Sorry been on holidays with no web access for a couple weeks....I run an Fitech in the car. I could check the tach on the dash against the tach on the Fitech handheld. I dont usually have the handheld hooked up as it sacks the battery over time and the car isnt a DD. Thanks
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