4.11 or 3.73 GEARS?
Burning Brakes
Joined: Apr 2013
Posts: 1,194
Likes: 109
From: Las Vegas NV
My '79 with 225/60/15 tires (put on by a previous owner who didn't know what he was doing) and unknown gears spins just over 3,000 rpm at 65 mph. Slow lane on the highway for sure, I don't like spinning at 3,500 for very long. Around town is fine.
I dream of having 4.11s and a 6-speed.
High-numbered gear ratios and high stall converters don't mix for the street. I had a '94 LT1 Z28 that was stock except for a few bolt-ons and a 3,200rpm converter. That thing screamed off the line...LOADS of fun, but if it were not a lock up converter, freeway driving would have been pretty bad.
Can you install a lock-up converter on a TH350 or TH400?
Definitely plan your cam / converter / gear ratio together.
I dream of having 4.11s and a 6-speed.
High-numbered gear ratios and high stall converters don't mix for the street. I had a '94 LT1 Z28 that was stock except for a few bolt-ons and a 3,200rpm converter. That thing screamed off the line...LOADS of fun, but if it were not a lock up converter, freeway driving would have been pretty bad.
Can you install a lock-up converter on a TH350 or TH400?
Definitely plan your cam / converter / gear ratio together.
Racer
Joined: Feb 2013
Posts: 386
Likes: 3
From: Clifton Virginia
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!
BUT it s a blast on back roads and dusting off mustangs and imports on straightways to prove a point. So choose your poison wisely. I am currebtly looking at tremec 600 and with .64 final drive, you can have the best of the both worlds.
Safety Car
Joined: Mar 2007
Posts: 3,518
Likes: 37
I put 4.11 gears on one of the C5s I had. It was a blast to drive, really woke it up. It changes the drive all the time with more power and a much "Quicker" feel all the time.
For your weekend driver definitely go with 4.11 gears. For the money it is the most noticeable performance driving feel option.
For your weekend driver definitely go with 4.11 gears. For the money it is the most noticeable performance driving feel option.
Safety Car
Joined: Mar 2007
Posts: 3,652
Likes: 49
From: Bridgewater nj
I drive 75-80 everyday and my 82 has a 700r4 trans. First gear feels like I have 3:55 and 4th feels like I have 2:05 in the rear! At 80 I'm spinning 2000rpm.
If you're a fuddy duddy crawling in the slow lane with your 500hp car, than 3:73-4:10 are for you because you'll never drive the car anyway.
If you're a fuddy duddy crawling in the slow lane with your 500hp car, than 3:73-4:10 are for you because you'll never drive the car anyway.
Racer
Joined: Feb 2012
Posts: 261
Likes: 3
From: Clawson Michigan
30 years ago in was no big deal to do 80 90 100 on the freeway with that big block chevelle spinning 3.73's or 4.10's. Now we are all used to low revs at freeway speeds and cars capable of top speeds we will never use. The cruise speed on my boat is 32mph at 4600rpm and it will run it all day. 350 merc. I will be swapping my 3.08 for 3.73 this winter and a 383, I cant wait
Burning Brakes
Joined: Apr 2013
Posts: 1,194
Likes: 109
From: Las Vegas NV
30 years ago in was no big deal to do 80 90 100 on the freeway with that big block chevelle spinning 3.73's or 4.10's. Now we are all used to low revs at freeway speeds and cars capable of top speeds we will never use. The cruise speed on my boat is 32mph at 4600rpm and it will run it all day. 350 merc. I will be swapping my 3.08 for 3.73 this winter and a 383, I cant wait
I think to myself....my '79 that I'll drive under 5,000 miles per year, is it really a big deal to drive for an hour on the freeway at 4,000 rpm? Sure it seems like it will wear the engine quicker, but so will the hole shots and 6,500 rpm shifts.
It is uncomfortable to do, no question about that.
Safety Car
Joined: Nov 2008
Posts: 3,726
Likes: 558
From: Seattle Washington
Have You thought about leaving the rear end alone and swaping in a 4 speed Auto Trans ? It will have a lower 1st gear to get what you want, even if you never use the overdrive. But you will have an overdrive to boot. Keep in mind that the late C3's came with the overdrive Trans, and 2.87 or 2.65 Rear end gears with a mild 350. Your 327 might have a bit less torque than the 350, but you will have the 3.08 ratio wich should even this out.
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Melting Slicks
Joined: Aug 2008
Posts: 2,456
Likes: 10
From: Somerdale NJ
St. Jude Donor '11-'12-'13-'14-'15-'16-‘17-‘18
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.
Switched out the 4.11 in my SB for a 3.55 -much better!
Safety Car
Joined: Oct 2004
Posts: 3,926
Likes: 739
From: Youngstown Ohio
The formula is:
RPM = MPH x Ratio x (336/Tire Diameter).
So, MPH = RPM/(Ratio x 336/Tire Diam.)
Using a 27.1" tire (BFG 255/60), you have 5400/(3.73 x 12.4) =116.75 MPH.
As for the type of cam, that is your personal preference.....no effect on gear ratio.
Burning Brakes
Joined: Feb 2006
Posts: 1,223
Likes: 4
From: Regina Saskatchewan
If you want to experience what a steep gear is .... shift the TH400 into 2nd gear and take it out on the highway. With those 3.08 gears , it be like having 4.56 gears. Not far from the 4.11s your thinking about. You can probably install a 700R4 for under $1000 bucks and rule the street and the highway.
Drifting
Joined: Aug 2005
Posts: 1,443
Likes: 65
From: Wauconda IL
30 years ago in was no big deal to do 80 90 100 on the freeway with that big block chevelle spinning 3.73's or 4.10's. Now we are all used to low revs at freeway speeds and cars capable of top speeds we will never use. The cruise speed on my boat is 32mph at 4600rpm and it will run it all day. 350 merc. I will be swapping my 3.08 for 3.73 this winter and a 383, I cant wait
Remember how those 4.10 geared Big Block Chevelles would also be burning oil well before 50,000 miles? I do.
Safety Car
Joined: Mar 2007
Posts: 3,652
Likes: 49
From: Bridgewater nj
30 years ago in was no big deal to do 80 90 100 on the freeway with that big block chevelle spinning 3.73's or 4.10's. Now we are all used to low revs at freeway speeds and cars capable of top speeds we will never use. The cruise speed on my boat is 32mph at 4600rpm and it will run it all day. 350 merc. I will be swapping my 3.08 for 3.73 this winter and a 383, I cant wait
There's a reason why race cars swap out engines every few races or in some cases every race! I you want many miles of cruising you have to do a few things besides building a new motor. First, oil changes at the right time with the best oil. Second, cruise under 3500 rpm and last, make sure it runs cool!
If you can do those 3 things and hit your target cruising speed that you normally cruise at. You'll be happy
Burning Brakes
Joined: Mar 2011
Posts: 969
Likes: 1
From: NJ
I asked a related question about RPMs here.... might be of assistance
http://forums.corvetteforum.com/c3-g...-too-fast.html
http://forums.corvetteforum.com/c3-g...-too-fast.html
Pro
Joined: Oct 2009
Posts: 523
Likes: 4
From: Calgary Alberta
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!
I will be swapping the 4 speed for a Keisler SS700 Wide ratio 5 speed with a .68 final ratio.
That should produce about 2000 rpm at 65 mph in 5th with good gear spacing from 1st to 4th for more spirited driving when desired.
Racer
Joined: Feb 2013
Posts: 386
Likes: 3
From: Clifton Virginia
If you don't have headers and sidepipes, it will be lot better to tolerate the LOUD high revving exhaust noise.
If like 4.11 gears and don't mind the rev/exhaust noise, but love the high rev and quick acceleration go for it. You like quick races in the back straight away roads, go for it.
Only fun I have with my 4.11 gear is that when I turtle in the slow lane and when someone tailgates me, I hit the throttle and leave like 10 car length behind me in seconds so they know my vette is no turtle.
Every time you drive your 4.11 vette without OD, you are going to have like 10 love and hate relationship or 10 smiles and 10 frowns all in the same day.
Here is short video clip of my vette with 4.11 gears with no OD running through all gears with headers and sidepipes shifting around 3K. If you like it, go for it.
If like 4.11 gears and don't mind the rev/exhaust noise, but love the high rev and quick acceleration go for it. You like quick races in the back straight away roads, go for it.
Only fun I have with my 4.11 gear is that when I turtle in the slow lane and when someone tailgates me, I hit the throttle and leave like 10 car length behind me in seconds so they know my vette is no turtle.
Every time you drive your 4.11 vette without OD, you are going to have like 10 love and hate relationship or 10 smiles and 10 frowns all in the same day.
Here is short video clip of my vette with 4.11 gears with no OD running through all gears with headers and sidepipes shifting around 3K. If you like it, go for it.
Last edited by jackwabbit703; Aug 8, 2013 at 12:11 PM.
