3.27 gears in rearend
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3.27 gears in rearend
Did the '90 GTA come with a 3.27 rear?
Picked up a 350/TPI and rear end to drop in my '89 305/TPI. The rear end Im replacing is the stock 2.73's that came with my '89. Guy told me they were both pulled from the same car.
Researched the rear differential and its the 9 bolt, Limited Slip and has 3.27 gears.
I'm hearing this is a hard one to find parts for. Fortunatly, the gears in the one I bought are in great shape. All machine marks are clearly visible, no worn spots, no cracks, no endplay and no slop in the rotation. I love the gas mileage I get from the 2.73's but since this is a weekend driver, I'm looking foward to putting in a but smaller gear ratio for the pep factor.
Anyone have this one in their car? Any thoughts.
Picked up a 350/TPI and rear end to drop in my '89 305/TPI. The rear end Im replacing is the stock 2.73's that came with my '89. Guy told me they were both pulled from the same car.
Researched the rear differential and its the 9 bolt, Limited Slip and has 3.27 gears.
I'm hearing this is a hard one to find parts for. Fortunatly, the gears in the one I bought are in great shape. All machine marks are clearly visible, no worn spots, no cracks, no endplay and no slop in the rotation. I love the gas mileage I get from the 2.73's but since this is a weekend driver, I'm looking foward to putting in a but smaller gear ratio for the pep factor.
Anyone have this one in their car? Any thoughts.
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iTrader: (8)
Joined: Jul 2001
Posts: 3,204
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From: New Boston, IL, USA
Car: '90 Formula 350
Engine: 383 SBC
Transmission: ProBuilt S/S 700-R4 & ACT 9" Stall
Axle/Gears: 10 bolt 3.23
Re: 3.27 gears in rearend
I'm not sure about the GTA thing, but my '90 Formula had one.
If you have the cover off it will easy to check for sure. It should be stamped right on the ring gear.
9 bolts are 7.75" size which is little bigger than the 10 bolt. 9 bolts use 4 cross shafts for the spider gears. Limited slip is a friction type setup using cones.
Check that limited slip is working correctly. Overtime the cones wear and move down the inside of the housing and get slop in the middle of the spider cross shafts which then that prevents the "posi" from working correctly. It's easy enough to check as described in this thread: https://www.thirdgen.org/forums/faq-...now-about.html
You can find spare parts on here from time to time. Don't expect corner auto parts stores to have your gaskets and stuff you need for it.
3.27 is an excellent gear for a 350 stock TPI. Some say 3.45s are better but once you figure the cost ($200+ gears), labor ($600+), then an install kit ($150+) IMO it's not worth the swap.
3.27 is the series 3 carrier so you can upgrade gears in the future if needed, but frankly once you start working deep on the 9 bolts it's not that much more to just get an aftermarket setup if you're like myself and too lazy to do it in your garage.
http://9bolt.com/ carries parts but they are expensive.
One nice feature about the 9 bolts besides them being stronger than our 10 bolts is the fact they already have retaining brackets to hold the axles in. That means no C Clips like on the 10 bolts.
If you have the cover off it will easy to check for sure. It should be stamped right on the ring gear.
9 bolts are 7.75" size which is little bigger than the 10 bolt. 9 bolts use 4 cross shafts for the spider gears. Limited slip is a friction type setup using cones.
Check that limited slip is working correctly. Overtime the cones wear and move down the inside of the housing and get slop in the middle of the spider cross shafts which then that prevents the "posi" from working correctly. It's easy enough to check as described in this thread: https://www.thirdgen.org/forums/faq-...now-about.html
You can find spare parts on here from time to time. Don't expect corner auto parts stores to have your gaskets and stuff you need for it.
3.27 is an excellent gear for a 350 stock TPI. Some say 3.45s are better but once you figure the cost ($200+ gears), labor ($600+), then an install kit ($150+) IMO it's not worth the swap.
3.27 is the series 3 carrier so you can upgrade gears in the future if needed, but frankly once you start working deep on the 9 bolts it's not that much more to just get an aftermarket setup if you're like myself and too lazy to do it in your garage.
http://9bolt.com/ carries parts but they are expensive.
One nice feature about the 9 bolts besides them being stronger than our 10 bolts is the fact they already have retaining brackets to hold the axles in. That means no C Clips like on the 10 bolts.
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