Ring and pinion size
Thread Starter
Racer
Joined: Nov 2023
Posts: 292
Likes: 495
From: Vail, AZ
Ring and pinion size
New to the Corvette scene. My 73 has the 454 with an automatic trans and pushing 550 hp. The car has 4.88:1 rear gears which makes it great if your running the quarter mile or stop light to stop light, but not very enjoyable to just drive.The build sheet shows that it had 3.08:1 in it. The owners manual shows that the 3.36:1 was a performance gear option. I'm looking to be able to run 75-80 mph with the engine rpm's around 2200-2500 range. My question is, would the 3.36 gear run the car around that range or would the 3.08 be better? I know the 3.08 would be a good cruising gear, but how much performance would be lost? What size ring gear do I need for the spool? Thanks for any help.
Melting Slicks
Joined: Nov 2006
Posts: 3,402
Likes: 1,814
From: Apple Valley, MN
The ratio of choice for many is a 3.70 (or 3.73). There are many calculators on line for you to enter gear ratio, tire diameter and speed.
The 63-79 Corvette differentials are typically shown as 8.5”.
Word of caution on Ring & Pinions, the “good ones” like USGear are no longer produced so be cautious about what you buy.
The 63-79 Corvette differentials are typically shown as 8.5”.
Word of caution on Ring & Pinions, the “good ones” like USGear are no longer produced so be cautious about what you buy.
Tech Contributor
Joined: Aug 1999
Posts: 15,166
Likes: 3,968
From: Connecticut, USA
488 gears would use a 4 series case. If you go to a 3 series gear, you will need a new 3 series posi case.
No difference per say between the 308 & 336 in terms of performance. I put 336 in my 72 that had 308 only because 308 were backordered at the time. No difference to speak of.
New Chinese Eaton posi's are $760 now, new Chinese gears are cover $400 and I rebuild them, new out of the box.
Market price on a core diff is $250, what vendors pay. Buying used you better ask for pictures, or you may have two diff's needing posi cases. There is a lot of overpriced junk on the market today, a lot think a core diff is worth $500-$1000, or the best is the myth of BB diff's
No difference per say between the 308 & 336 in terms of performance. I put 336 in my 72 that had 308 only because 308 were backordered at the time. No difference to speak of.
New Chinese Eaton posi's are $760 now, new Chinese gears are cover $400 and I rebuild them, new out of the box.
Market price on a core diff is $250, what vendors pay. Buying used you better ask for pictures, or you may have two diff's needing posi cases. There is a lot of overpriced junk on the market today, a lot think a core diff is worth $500-$1000, or the best is the myth of BB diff's
Old Fart Pilot
Joined: Apr 2010
Posts: 1,903
Likes: 978
From: Spokane, WA
Listen to what GTR1999 says! He's the expert on diffs & steering gears as well as alot of other stuff. He does great work and is willing to share his knowledge with us hobbiests and offer advice.
Paul
Paul
Tech Contributor
Joined: Aug 1999
Posts: 14,377
Likes: 6,377
From: At my Bar drinking and wrenching in Lafayette Colorado
New to the Corvette scene. My 73 has the 454 with an automatic trans and pushing 550 hp. The car has 4.88:1 rear gears which makes it great if your running the quarter mile or stop light to stop light, but not very enjoyable to just drive.The build sheet shows that it had 3.08:1 in it. The owners manual shows that the 3.36:1 was a performance gear option. I'm looking to be able to run 75-80 mph with the engine rpm's around 2200-2500 range. My question is, would the 3.36 gear run the car around that range or would the 3.08 be better? I know the 3.08 would be a good cruising gear, but how much performance would be lost? What size ring gear do I need for the spool? Thanks for any help.
Lars
Last edited by lars; Nov 28, 2023 at 12:04 AM.
