4.11 or 3.73 GEARS?
Thread Starter
Intermediate
Joined: Dec 2012
Posts: 30
Likes: 0
4.11 or 3.73 GEARS?
Guys, I need some feedback regarding a new rear differential with new gears:
I have a 68 Vette (327, TH400 transmission w/ stock cam and heads) and was looking to improve acceleration and mid-throttle response. I currently have 3.08 gearing.
My question is: Would a new differential with 4.11 gears be overkill or is 3.73 best? Should I also upgrade the existing torque convertor?
According to Chevy's data, my car currently has 2,100 stall.
P.S. I drive my Vette on the weekends only. Aftermarket aluminum heads and camshaft will follow within a few months.
Thanks for all the input!
I have a 68 Vette (327, TH400 transmission w/ stock cam and heads) and was looking to improve acceleration and mid-throttle response. I currently have 3.08 gearing.
My question is: Would a new differential with 4.11 gears be overkill or is 3.73 best? Should I also upgrade the existing torque convertor?
According to Chevy's data, my car currently has 2,100 stall.
P.S. I drive my Vette on the weekends only. Aftermarket aluminum heads and camshaft will follow within a few months.
Thanks for all the input!
Melting Slicks
Joined: Jul 2010
Posts: 2,503
Likes: 33
From: McGrady NC
St. Jude Donor '15-'16
I would suggest 3.36 as a good all-around gear. More punch off the line and reasonable revs on the road. I had a 3.42 gear in my '78 Z/28 and it was a little buzzy on the road but was a lot of fun around town.
Burning Brakes
Joined: Sep 2008
Posts: 805
Likes: 5
From: Naperville Illinois
I guess it's a matter of personal preference, because I changed the 3.08's in my 1968 to 3.73's and LOVE IT. If you are turning 2400rpm at 60mph with your 3.08's, you'll be right at 2900rpm at 60mph with 3.73s; this didn't bother me at all and the car is a whole lot more fun to drive from 0 to 60!
Yeah, you'll burn more gas, and make more noise, and chirp your tires more, but.....wait--what was the problem again?
Yeah, you'll burn more gas, and make more noise, and chirp your tires more, but.....wait--what was the problem again?
Thread Starter
Intermediate
Joined: Dec 2012
Posts: 30
Likes: 0
What about the torque convertor...do I need to swap out the stock one if I upgrade to 3.73 or 4.11?
Btw, just how uncomfortable would it be say going 100mph on the freeway in either of those gear ratios?
Thanks again guys
Btw, just how uncomfortable would it be say going 100mph on the freeway in either of those gear ratios?
Thanks again guys
Drifting
Joined: Aug 2005
Posts: 1,443
Likes: 65
From: Wauconda IL
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Drifting
Joined: Aug 2005
Posts: 1,443
Likes: 65
From: Wauconda IL
Le Mans Master
Joined: Oct 2010
Posts: 6,914
Likes: 836
From: melbourne florida
2023 C3 of the Year Finalist - Modified
i would say anywhere between 3:36 and 3:55 depending on tire size.
i recommend changing convertors due to cam specs not gears.
i run 3:55-1 with 275-60-15 tires on the rear and it revs a little but not bad.
i recommend changing convertors due to cam specs not gears.
i run 3:55-1 with 275-60-15 tires on the rear and it revs a little but not bad.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,114
From: Crossville TN
A set of 3.55 gears is about as steep as you want to go with an auto tranny. If you go to 3.73 or higher, the gearing and the torque multiplication from the converter from a dead stop will just burn rubber and you'll not get a good launch. Now, if your car will be purely setup for the strip...suspension, slicks, etc...steeper might work OK. But, not for street use.
Safety Car
Joined: Oct 2004
Posts: 3,920
Likes: 731
From: Youngstown Ohio
For that matter, you may also want to wait on the gear change if your new cam is not a "low end torquer".....
Last edited by C3 Stroker; Aug 7, 2013 at 05:26 PM.
Le Mans Master
Joined: Feb 1999
Posts: 8,351
Likes: 75
From: Tampa Bay FL
Driving my L48 with its 3.54 gears, I shift my 700r4 into OD above 50mph. My Silverado with OD and 3.73's turns 2,000rpm at 60mph.
I'd go with 3.31's or 3.42's if my trans were TH350/TH400 and I planned spirited highway driving.
If I were focused on quarter mile only, I'd go 3.73 or 4.11's.
I'd go with 3.31's or 3.42's if my trans were TH350/TH400 and I planned spirited highway driving.
If I were focused on quarter mile only, I'd go 3.73 or 4.11's.
Pro
Joined: Jun 2009
Posts: 613
Likes: 3
From: Fleetwood PA
I have 4.11 in my BB 68. Wish I didn't , but that's what it came with off the factory floor. It's a 4 sp, but 1st gear is almost non-existent, 4th is 2600ish at 60. I wouldn't say uncomfortable, but it sounds and feels like your going 100. If you plan on actually going 100 anywhere but the drag strip, don't go 4.11.
Thread Starter
Intermediate
Joined: Dec 2012
Posts: 30
Likes: 0
This car will be on the street 80% of the time. Based on the advice given so far I am leaning towards 3.73 gears...I hope a cruise on the freeway would not be too uncomfortable.
1) Any ideas at what speed I would reach redline (5,400 rpm) with 3.73 gears?
2) What type of Camshaft would you recommend with 3.73 gears? According to Chevy my 327 has 10.1 compression.
Thanks-
1) Any ideas at what speed I would reach redline (5,400 rpm) with 3.73 gears?
2) What type of Camshaft would you recommend with 3.73 gears? According to Chevy my 327 has 10.1 compression.
Thanks-
Le Mans Master
Joined: Oct 2010
Posts: 6,914
Likes: 836
From: melbourne florida
2023 C3 of the Year Finalist - Modified
the 350 horse 350 chevrolet cam is a good cam, nice idle good power mileage isn't too bad. it was at one time, maybe still is the most used cam for a small block chevy. I'm sure someone will recommend a hydraulic roller cam , compare your prices and decide what is in your budget