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

Re: Any source for a 3:08 gearset for a 9 bolt?
 

Anything other than 3.70 will be a used set. You'll probably have to get used gears from Australia.

GD

Re: Any source for a 3:08 gearset for a 9 bolt?
 

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.

Re: Any source for a 3:08 gearset for a 9 bolt?
 

lol

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.

Re: Any source for a 3:08 gearset for a 9 bolt?
 

It's a 3:42 sorry....but anyway as far as I know the 9 bolt only came with a 3:42 in a third Gen

Re: Any source for a 3:08 gearset for a 9 bolt?
 

9 bolts came with 2.77, 3.27 and 3.45 gears in 3rd gens. If you have a 3.42, you have a 10 bolt.

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.

Re: Any source for a 3:08 gearset for a 9 bolt?
 

I'll trade you for a 2.77 9 bolt out of my parts Trans Am. You pay shipping.

GD

Re: Any source for a 3:08 gearset for a 9 bolt?
 

Hmmmm....That seems a little tall but isnt there a chart somewhere where you could calculate rpm?

And Id pay for your stuff to be shipped to me....and youd pay for my stuff to be shipped to you.

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.

https://i.imgur.com/Ev2HQvl.jpg

https://i.imgur.com/8E76wiF.jpg

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.

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

Re: Any source for a 3:08 gearset for a 9 bolt?
 

I could live with 2200...I'll be in touch

Re: Any source for a 3:08 gearset for a 9 bolt?
 

Another option, T56. I love my 3.27 9 bolt highway RPM with the 6th gear. I am moving to 3.50 to get the RPM back up a bit.

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.

https://cimg5.ibsrv.net/gimg/www.thi...a126e8901c.png

Re: Any source for a 3:08 gearset for a 9 bolt?
 

Hmmm....I assumed it is a 3:45 because from what I read a 3:45 was the shortest gear that was available with a '89 305 tpi iroc. However that doesnt really stop anyone from swapping in something shorter before I bought the car. Maybe I'll pop the cover off or even rotate the wheel once and count the driveshaft revolutions

Re: Any source for a 3:08 gearset for a 9 bolt?
 

https://photos.smugmug.com/photos/i-...CbwD449-X3.jpg



https://photos.smugmug.com/photos/i-...K7jdGHQ-XL.jpg

Re: Any source for a 3:08 gearset for a 9 bolt?
 

I had it up on the lift....def 3:45

Re: Any source for a 3:08 gearset for a 9 bolt?
 

You have plenty of low end torque for a 2.77 final drive with that 400 small block. Also the 2.77 is stronger due to a much larger diameter pinion head. Because it's a "2 series" carrier.

GD

Re: Any source for a 3:08 gearset for a 9 bolt?
 

https://cimg7.ibsrv.net/gimg/www.thi...78e695be89.png
Well if you confirmed its a 3:45 here are the numbers. I think you have a tach problem not a rearend problem if you ask me. Can you data log the car to check the tach?

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

Re: Any source for a 3:08 gearset for a 9 bolt?
 

Compared the handheld on the Fitech to the tach.....the car's tach reads 275rpm higher than the Fitech handheld.