What is your rear end gear ratio with your 700 R4 ?

[Learpilot]

What rear end gear ratio are you running in your Hot Rod with a 700 R4 ?
Just like to know.
Thanks, Rick Harris.

[Leon]

I'm running 3.50 in the rear of the 54 with 215-75R15s.  I cruise about 2100 rpm at 70mph.

[1FATGMC]

I got a 3.50 also with 275/60 X 15's (28 inch dia.) and usually am running around 2400-2500 at 75 and a little more.  2100 for me is about 65.

According to my spreadsheet for speeds (and Fat Cat's) using. rear gear, tire, etc.. 75 should be 2207 with my combo, so maybe my tach is off  :?  :?  Or maybe I'm running over 75.  I got the speed from timing the mile markers not the speedo.

Well whatever is the correct rpm, I'm pretty happy.  The perfect rear gear with my motor I think would be 3.43's, but the ford rear that I'll be putting in will have 3.50 gears.

Leon's speed and rpm match the calculators almost right on   .

c ya,

Sum

[sal37]

A number of the net calculators I have used tell me that ratios of 3.7 or 3.89 (tires 235/75R15 which are about 28.5") should be right, but have also been told that 3.5's are a better choice.
Steve

[chopped]

4.10 with 295/50x15 About 26 tall. Haven"t changed the trans gears yet so guessing 2000 rpm at 60 mph. I'm more a back road kind of guy so I can live with it.

[1FATGMC]

A number of the net calculators I have used tell me that ratios of 3.7 or 3.89 (tires 235/75R15 which are about 28.5") should be right, but have also been told that 3.5's are a better choice.
Steve

Hi Steve,  I don't think there is a universal "best" choice.  It is going to depend on what speeds you like to drive at and what you drive at the most.  Where I am I do very little city driving and the speed limits are high.  

Your motor combination, mostly the cam.  The weight of your vehicle and if acceleration is important, etc.,

3.50's though do seem to be a pretty good gear for a lot of applications.  Good acceleration and low cruise rpm's.  For most of us I would stay away from gears under 3.25's or over 3.73's.

c ya,

Sum

[Ohio Blue Tip]

Or maybe I'm running over 75.  I got the speed from timing the mile markers not the speedo.

Sum

I've followed you before and you're going OVER 75!  

[Leon]

I thought about going to 3.73s because I'm usually towing but after getting it on the road with the 3.50s I have plenty of power and it cruises nice.  The way my tranny is set up, I do spend a lot of time in third putting around town, but at 30 - 35 mph that works out nice, too.    The total weight without driver or passengers is 4900 pounds.  Without the trailer I'm getting a little over 20 mpg and with the trailer it's about 17-18

[Deuce]

I thought about going to 3.73s because I'm usually towing but after getting it on the road with the 3.50s I have plenty of power and it cruises nice.

I had considered the 3.70 gear but I installed a 3.50 ratio under the 3W. My coupe is fairly light ... so I hope it will be OK ... have not driven it ... YET    :cry:

[enjenjo]

I built a 47 Ford coupe, with a 350 chevy, 700R4, and 2.79 gear. Not my choice, but what he wanted. It actually worked out ok. If I had a choice, I wouldn't do another like that.

[Charlie Chops 1940]

My '40 has a ZZ4 350 and 700R4 with 3.55 gears. Car weighs in at about 3500 and I pull a loaded Mullins trailer and a teardrop. 70 mph is around 2250. I think it's a good compromise gear. Mileage is pretty good and acceleration is fine. The western swing last summer was almost 6000 miles, rode hard and put away wet more than one day and averaged 16.5 for the entire trip. Quite a few tanks in the low 20's and likewise a few in the low teens.

Charlie

[Ed ke6bnl]

3.50's with 275x50x17 tires 700r4 a little to high geared for my 327ci but that is what I had for the 9" I would like 4.10's that about 29" tires

[rumrumm]

I use a 3.89 rear with P285-70RX15 tires. Works fine for me.

[slocrow]

Rick; I too have a 3.5 gear. I roll on 285x70-15's and am doing 2100ish at around 70mph. My mileage sucks but is better then 1 to 1 would be.............Frank

[phat rat]

3.42 gear, 255/60X15 tire, 3700#, 454, runs 2000 rpm at 70mph. I've pulled as high as 19.5 mpg on the highway but usually around 18+.