Fast66vette

Maybe I should or maybe not. I've been thinking of going to a 4:11 in my 66 big block car with a m20. I currently have 3:70's and thought about having some fun for summer of 2013. Most of my driving is in town and back roads. Just wondering on your guys input and experince with this kind of setup. I know it wont be great on gas but It's not a green machine. I want to have some fun!

MasterDave

Around town 4:11's would be a blast for sure. There's a reason, however, that there aren't many original engines left with 4:11 rear ends installed.

babbah

Mine is - original 4:11 never been touched - Just fluid changes throughout the past 45 years!

Ironcross

my 1968 is a 4.11, I always liked the 4 series gears...

I just realized I`m in the C-1 and 2 and I do have a 396 and 427 early Camaros, both are 4.11`s

and the 62 Vette is a stiffer gear at 4.56





.

BarryK

my '65 SB L76 365hp has 4.11 gears. A blast around town and back roads... LOUSY for the highway. Believe me, a 2 hour trip on the highway becomes torture with that gearing but if you are only doing town and backroads you will have fun with the 4.11's

OldKarz

My 66 BB 427 car has 4.11 gears and it is great running around. I doubt it would be great on a long road trip. I also have the same in my BB 67 396/375 Chevelle SS......same story. Bottom line.....I would not change a thing!

Fast66vette

I always wanted to run a 4:11. The car won't see the highway so I'm not to worried about that. I just hope it wont be a little over board with the m20? I figure I'll go with 4:11's and get rid of the 3:70 cause I figure if I ever want to get back on the highways I'll end up dropping down to atleast a 3:55 gear not the 3:70's.

Matt Gruber

How is the BB not fun now?
If it can't fry the tires w/3.70, i'd fix whatever is wrong.
And there are several things that could be holding it back, especially at low rpm.

DansYellow66

I have to agree with the above. My 4.11 is just fine for around town and backroads driving which is what you described. It sounds and feels right cruising down a backroad at 50 or so.

Overall, a Firebird I once had with a 3:73 gear was probably one of the most flexible rear ratios in my mind if you venture out on the highway once in awhile. Oh wait - that was in the 70s and the speed limit on the interstate was 55.

It works fine with a M20 which I have - I think an M21 would probably be a bit better as it would make for a more flexible 3rd gear for use in slower city street/neighborhood driving where 4th is starting to lug slightly and 3rd seems just a little more wound out than it should be cruising along at 35 mph or so. With a BB and 4:11 gears you don't really notice the gap between 3rd and 4th in acceleration.

Any of the above with a 4 speed is too buzzy for the guys grown use to OD transmissions.

66since71

I'd bet most of the guys reporting in with 4.11's have an M21/22. Your M20 with 3.70's will have very close to the same overall ratios in 1st, 2nd and 3rd as an M21/22 with 4.11's. I think it works out to 4.08... That for blasting around town and a more accommodating overall 4th gear for the highway.

I'd leave it alone.

Harry

DZAUTO

The 56 has 3.08 gears behind a SB400 and wide ratio Muncie (M20). I frequently do some Interstate driving (75-80mph) and a 4.11 would be murder on long drives. In town, to compensate for the 3.08 gears, the tranny is often in 1 or 2 or 3 (BUUUUUUUUUUT, that's why a manual tranny has the ability to select the "right" gear for the speed).

Tom Parsons

sub006

3.70 is PLENTY for a healthy big block anywhere but the drag strip. Back in the day, 4.11 was for light trucks moving heavy loads.

Your 'Vette's rear tires will thank you!

larrywalk

I agree - good analysis!

DucatiDon

3.70 with a .65 OD is perfect.

salty_waders

I love my 4.11's! I dont know about the BB's but my little L79 loves the high revs, thats where it makes power! Twisty roads are a blast!

1974purchase

these cars are not easy to control. not wise to put the pedal to the floor with the amount of rubber that is on the ground.

toddalin

I had 4.11's in the '64 and replaced them with 3.70's with the M20. I prefer the 3.70's.

I now have the TKO-600 and 1st would be almost unusable with the 4.11's.

mrg

Non highway? .. 4:11's would be just right for your intended use. If you get tired of using 1st, 2nd gear starts are a snap with the M20/4:11 combo.

Westlotorn

I keep looking at what gear ratio / tranny option. Curently I am leaning to the 5 speed option. 2.95 first gear and .63 overdrive with a 3.35 rear Diff, I also have a 3.70 rear diff but I wonder if 3.7 is too low with a 2.95 first.
I made the attached excel sheet to help me make decisions, maybe it will help others to.

mickatbp

Wlt,

Fantastic spreadsheet, ............ hey wouldn't it be good if you did the same for the aftermarket boxes offered ie. Keisler, TKO etc ............. just a thought. Also what is your tire size?