rhinz1966

Gear ratio,

Hi guys when driving my 66 vette 427, 4 speed the cars rpm is running around 3600 rpm at hwy speed. I am thinking of changing the gear ratio and from what I have read sound like going with 3:36 or 3:55 gears are good cruising gears. Anyone out there running these gears? How does the car perform of the line and what RPM are you running at on the hwy.

thanks

Vega$Vette

What gears do you have now?

C6Matt

and what rear tire size?

Westlotorn

If you can open this excel sheet it shows RPM and MPH for several gear ratio's with a 26.5 inch tire.

Vega$Vette

Stock 27" tires and 4.11 3600 rpm at 70 mph

3.36 will drop you to about 2900 at 70 mph

With the BB you'll still be OK off the line




http://www.angelfire.com/fl/procrastination/rear.html

x0000rgw

If you have a wide ratio Muncie then a 3.36 ,
close ratio then a 3.55. The 427 has the torque to pull
it.
I use a 3.36 in my small block 355 with a wide ratio.
Get an 11 inch clutch and you will be fine.

2800 rpm at 70 mph.

Ray

isac

I have 3:55 stock gears (AZ) and 27" tire diameter in my 427 L72 and running around 2800 at 100 kph (62mph) and I wouldn't go any lower with a M21 , a little sluggish off the line in city traffic but otherwise ok , but a lower fourth gear ( M21Y) would be nice though. It's a 450 rpm drop in fourth gear.

wmf62

3.36 with .73 OD = 2400 @ 80. 3.09 1st gear helps
Bill

Mark Lovejoy

I'm running 3.55's in our L78 with relatively tall tires (70 series radials), I don't think 3.36's would be a good choice if you want decent acceleration. I considered 3.73's during during the rebuild, but I'm happy with the 3.55's.

tjstarduster

I went to a wide ratio 4 speed and a 3.36 rear on my '66 big block. I'm perfectly happy driving in town in 3rd gear and it runs great on the highway. Acceleration might be slightly less than the 4.11 rear that I originally had, but not enough to make a difference. With the higher gears, my 496 bb can really move. Good luck.

zpletcher

My L36 has 3.36 gears 4 speed 215/70/15 tires..

Probably 2800 rpms at 70 mph... plenty of power in all gears..

I sure did wish for a 5 speed when I was trying to keep up with the new corvettes when I drove from San Antonio to Corpus last September for The Lexington aircraft carrier ...Gave that up quickly! Ha!

too many rpms at 80 mph or more ... It will do it with no problem but don't like to go over 70 for too long a period.. No sense in it...

Car never runs hot... even in 103 degrees in bumper to bumper traffic.... Had it down here for 6 years... (knock on wood)

Cheers, Zale

SLWRNU

I hear ya. Put a 5 spd in my 65 last year and this Jan. drove to Fla. with two C5's. Ran 75-80 mph and they stayed BEHIND me. 70 mph=2000 rpm with 3:73 gears. Lovin it.

DansYellow66

That amazing Qtr mile time that Car and Driver reported in their 66 - 427/425 road test back in 1966 (12.8 sec at 112 mph) was supposedly with a 3.36 rear. Yeah, I know - you can't believe everything you read.

zpletcher

Could be true... probably more gettin' it and less spinning

those skinny tires..... Ha!

Westlotorn

The factory cars provided for test in those days were ringers. I saw the internals of one that had different pistons, cam and carb. Good times in the magazines sold cars.

427Hotrod

A 5 speed would give you the best of both worlds.

JIM

Tampa Jerry

Get a 5 speed and don't look back. Jerry

65 vette dude

I think you will be unhappy going from a 4:11 to a 3:36....especially if you have a close ratio tranny. I think a 3:55 would be a good compromise gear.

mark6669

My 66 427/425 came with 4.11 and close ratio trans. I put a 3.36 in it 12 years ago plenty of power in all gears best improvement ever made to that car.Still have the restored 4.11 if I have to go faster half a days work.
Mark

1974purchase

the 427 has plenty of power. with the narrow tires i never did understand how a 4.11 was a benefit (mine came with a 4.11).