4:11 Diff is a problem
Thread Starter
6th Gear
Joined: Nov 2011
Posts: 6
Likes: 0
From: Tampa Florida
4:11 Diff is a problem
Hey guys - Just recently purchased my first Corvette, it is a 1973, 454, 4 speed. It has a 4:11 Diff ratio which gives it plenty of punch but makes it hard to drive over distance. Would appreciate if anyone can give advise on what ratio would be best (I was thinking around 3:7?) and any info on where I can get this as a used or recon component.
Appreciate any help you can give.
Cheers,
Rev.
Appreciate any help you can give.
Cheers,
Rev.
Pro
Joined: Jan 2007
Posts: 646
Likes: 17
From: Hendersonville NC
I had a 71 with a 370 and had lots of get up and go but still ran highway speeds ok. My 71 that I own now has a 355 and I really like the 370 gear better. You may find someone on the Forum that will swap rear ends with you.
Thread Starter
6th Gear
Joined: Nov 2011
Posts: 6
Likes: 0
From: Tampa Florida
Rev.
Melting Slicks
Joined: Apr 2004
Posts: 2,008
Likes: 38
From: Space Coast Gator Territory
This is good advice, going from a 4.11 to a 3.7 will accomplish little. A much better change would be to an OD transmission. You will get the highway cruise gear, without sacrificing get-up and go.
Le Mans Master
Joined: Jan 2004
Posts: 8,295
Likes: 30
From: one night in Bangkok you are never lonely
My 3:73 was a bear on gas and the motor with the 4 speed, now with a 5speed (.80 OD) it still has the getup and scare you plus the enjoyment on the highway trips.
Melting Slicks
Joined: Aug 2008
Posts: 2,200
Likes: 3
From: Lehigh county Pennsylvania
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Safety Car
Joined: Sep 2007
Posts: 4,458
Likes: 331
From: Indy Indiana
4.11 to 3.73 will not drop your rpm that much... less than 10%.. swapping gears costs alot of money and lots of hassle for such a minor incremental.
if you go with a 5 or 6 speed, you will find that 1st gear with a 4.11 will be such a granny gear that you won't use it. you will catch yourself starting off in 2nd.
you might want to consider a philosophy change similar to mine.. I bought my car with a 4.11 and swapped it out with a 2.73. it practically idles down the highway and my 454 has plenty of power to pass when I need it or to get around someone.
it just won't do donuts in the parking lot... but that is not how I treat my cars anyway.
IMHO...
if you go with a 5 or 6 speed, you will find that 1st gear with a 4.11 will be such a granny gear that you won't use it. you will catch yourself starting off in 2nd.
you might want to consider a philosophy change similar to mine.. I bought my car with a 4.11 and swapped it out with a 2.73. it practically idles down the highway and my 454 has plenty of power to pass when I need it or to get around someone.
it just won't do donuts in the parking lot... but that is not how I treat my cars anyway.
IMHO...
Le Mans Master
Joined: Oct 2007
Posts: 7,459
Likes: 978
From: RI, Now Franklin/Nashville TN
Again, I agree that going from 4.11's to 3.70's which I have with my 4 speed is not going to do much for you. I think the best solution is a 5 speed with an overdrive which will give you the best of both worlds BUT it costs to me big money for that luxury! Unless you plan on doing a lot of highway driving, I would not spend the $'s on the 5 speed. The last time I looked the 5 speed was going to cost me about $4,000 to do the conversion myself. I know that many have done it for less but you know how these types of projects can go. If you are not planning to drag race or autocross the car, I think that I would look to beef up the 454 for relatively cheap dollars and would go with the 3.08 gears since the BB has great torque! Personally, I wish I could ditch my 3.70's for the 5 speed since I really have tired of the engine turning 3,500 RPM at 70 mph and close to 4K at 80 MPH after 28 years of owning the car. It gets old especially with a beefy exhaust like I have-maybe I am just getting too old for it anymore?
