Technical 4:10 Gears with 700R

I am needing to make a decision on my 51 Dodge truck build. It currently has a 4:10 gear with a 700R and a 350 with about 350 HP. I have a 308 rear I could swap out as I mostly just drive. Is there a way to determine the final gear ratio with the 4:10 in over dive.
thanks

 

Looks like the OD ratio is .70 so 4.10x.70=2.87. The 3.08 will be 2.156

 

Perfect. You will be very happy with the 4.10's. Later you could go to a 3.70 but that would be my limit. Good luck

 

try sites that have calculators that take in many factors to help figure this out like project33.com

 

I always Google RPM calculator....first hit is Randy's Ring and Pinion I think...works like a charm. I 2nd the 4.10s with the 700r4...

 

I've got 4.10's in the Dana 70 under my Diamond T, with a 4L60 and 6.0 liter LQ4. It's perfect. I don't think, with stock-ish 350, that you'll be happy with the 3.08 gear. Way to long legged gear.

 

I have a healthy 383 w a 700r4 in my '34, w 3.25 gears. I don't shift into overdrive until at least 60 mph- the motor bogs. It spins about 1700 rpm in OD at 60. Run the 4.10s!

 

I ran a 700R in a '68 chevy pickup with 3.73s and a 292 six. Worked out ok.

 

My old truck has 4.10s and 700R4 with 30ish tall tires. 2000 rpm gets about 55mph. I'm pretty happy with the combo.

 

thanks for the input, I will stay with the 4:10s. I like noise so the lower gears will give a nice tone.

 

Ive got a 700R4 with 3.90 gears and 28 inch tall tires. Just went to 4.30 and Im happier than shit. Don't go lower than the 4.10s

 

my 47 caddy has 3:08s with the 4l60e, works fine and cruises the highway getting 20mpg. Stock 350 makes plenty of torque, no bogging at all. Same combination as 1994-1996 caprice police cars. Use the calculator to figure your highway RPM at 65 mph if you plan on long distance cruising.

 

454/700R4, 3.42 gear 2100 rpm at 70 mph. I've been very happy for over 75,000 mi. I've gotten as high as 19.7 mpg

 

Droptop....is your 47 Caddy fuel injected? With a 3.08 and an overdrive trans its almost mandatory to be efficient. I'd say a highway rpm cruising range of 2200 to 2500 for carburetor engines is sweet. Big blocks can tolerate a taller gear because of their torque. All this assumes the rod in question weighs 3000 lbs plus...lightweight cars can get away with taller gears for sure...

 

Here is a great calculator. It lets you do side by side comparisons and has a ton of transmissions in the database.

http://www.grimmjeeper.com/gears.html

 

Hi, yes I have fuel injection, but i doubt it matters since the cam in that engine is stock and makes plenty of low end torque. 4000 pound car and it moves out just fine.

 

Def. go w the 4.10's - I ran 373's behind a 700 ( MPFI Sm Blk pickup) and the OD rpm was too low. ...and just think how kick ass your first 3 are gonna be!

 

My Henry J with a 700r4 , 4.10 gears and 29x12.50x15 tires runs the same RPM as my Turbo 350 with 3.00 gears and 255-70 15 tires when locked up.

Gary

 

At 70 mph, with 30" tires, you will be turning 2,255 rpm's with a 4:11 rear. Just right, IMHO.

 

I will just add that the earlier 700r4 (pre 89/90ish) had less vanes in the pump and due to very low rpms at highway speeds would suffer from a lack of oil flow and fail prematurely. If the vehicle was equipped with 3.42, 3.73 etc then they tended to last longer due to higher rpm.
Just something to be aware of.