Polo Vert

A friend of mine has some 3.73 gears but wanted to check here before I dropped any cash on them. My car is a stock 94 vert with a 4L60E. What kind of rpm will I see at highway speeds? Car is just a cruiser and I have no intention of modding the motor. I have the 3.07s now.

crowz

Mine with the 700r4 is 1900 rpms at 55 best I remember and 2000 at 60.

Gas mileage flat sucks at 18 mpg. On a plus side with the 383 motor the 3.73's make for some fun take offs

FASTAZU

Can't help with RPM's as I have a ZF6. But I can say I love my 3.73s.

QCVette

Check your RPM now and multiply by 1.215 (3.73/3.07) to get the new RPM.

WVZR-1

I was thinking while you typed it appears. Same/similar results - different way to get there.

Simple math I believe should work without reference to any tire sizes, trans gear ratios or other information required by some of the on-line calculators. It would work for any direct ratio replacement from a "known" ratio in that particular car. Substitute the "known" where I've used 3.07 and multiply by any ratio of your choice.

XXXX/3.07=YYY.YYYY multiplied by 3.73 for the new RPM value. Drive your car in your usual manner and do the math for direct comparisons.

XXXX - any RPM value you choose YYY.YY the results

If you wanted to do some comparisons use this calculator with these:

GEAR RATIOS:
First: 3.06 (rounded up)
Second: 1.63 (rounded up)
Third: 1.00
Fourth: .70 (rounded up)

matching your tire size/diameter and inserting axle ratio where it requests final drive.

http://www.cargister.com/calculator-...l_ratio_teeths

8a8mfh

Around 2400 at 70 rpm.


The calculator I use (is any) the formula is:
Gear ratio x trans ratio x 355 or 336 x mph / tire diameter = rpm.

355 is for an unlocked torque converter with stock stall speed.
336 is with the torque converter locked or a manual trans.

The rpm and mph above was calculated like this:

3.73 x .7 x 336 x 70 / 25.7 (an assumed tire diameter) = 2390 rpm rounded off.

I only use this because it can be used anywhere, no website required. It can be used for everything related- to see what rpm will be with different tires, different gears, different transmission, adjusting shift points, etc, etc, etc. I only need to remember one formula for all...

WVZR-1

I'm very familiar with the math and I generally "do the math". In the OP's post he's maybe only interested in a "quick reference" to his general driving habits so either "QCVette's" or mine is a very quick reference for the OP.

I've done the math several times before ever mentioning the calculator I did in my original post. If you use accurate tire dimensions and provide correct information that calculator "works". I don't ever post a "web-based" solution or comparison unless I've done and understand the math. Wouldn't think of it.

oldpro

you might think about 345s . would keep your rpms around 2000-2100 at 70 which would mess with your gas milage as much

8a8mfh

All I said is "this is what I do"

383vett

Make the switch. I was very happy with my 3.73s and auto when my car was on the street.

Polo Vert

Thanks for the input guys. Was just looking for a general reference. I have a complete 2.59 pumpkin with fairly low miles that I was going to stab the 3.73s into. If I don't like them I can always put the 3.07 unit back in.

pologreen1

They have to be the Thick gears to fit in the 2.59. meaning if they are out of a D44 or were in a 3.07 factory case they won't work.

2.59 is series 2 size carries
3.07+ stock is series 3 size carrier