69 GTX Best GEAR

[Hammer136]

Hello All, whats the best gear for my 69 GTX. I know there were some old discussions. Just rebuilt my motor. Its around 500hp. Some hwy mostly around town. Any suggestions anything new to consider.i read some of the old post just looking for some suggestions no harm.I have a 3.23 in it now considering 3.55. Thanks

 

[hunt2elk]

Depends a whole bunch on the height of your rear tires, but 3.55's will rev about 10% more than your 3.23's while going down the freeway. If you can live with that, go for it. I have 3.23's in 2 of my cars and 3.55's in the other. You really can't go wrong with either on a 500 hp motor.

 

[zyzzyx]

The 3.55 was an option from the factory, I went with a 3.73 because I wanted a little
more Oomph! Anything more would be rough on the highway.

 

[Darter6]

I look at it as the roads in your area. I grew up in small town Southwestern Pa.
Most roads were twisty turn and average speed limits 35-45. Highway was 55 at the time and most never drove over 60 mph.
3.55 was a great gear for the roads. Often we would bump to 3.73. These were street driven cars.
Now that I'm out west my 64 Belvedere 3.55 geared was like I was driving with 5.13's.
3 miles from my home in any direction the speed limits are 75 and the nuts around here drive at 90.
Just my thought.Torquey 440 GTX with 3.55 that doesn't see allot of highway sounds great.

 

[AR67GTX]

I used to be of the opinion that a 3.73 or 3.70 rear was the best all around compromise in a decent HP street car. That was before I owned a 440. I put a 3.55 in my stock GTX a couple years ago with a slightly looser converter. Now I think it’s the best gear for a 440, although I sometimes wish I had stuck with a stock converter. My car is auto with factory air w/ PS & PB so it’s fairly heavy. In first when the tires would finally bite you could feel the engine sag a bit as it tried to wind back up. The 3.55s took care of that and then some. A lighter car with a stock 440 and 4speed might not need more than a 3.23. A car with 500 HP and a bigger cam would probably like at least the 3.55.

edit: failed to recognize 440 - 4 speed cars have Dana’s with 3.54/4.10.

 

[Ceedawg]

Highway gear-2.76 440 HAS torque to move that car. Top end unlimited. Been there.

 

[zyzzyx]

My 68 GTX got 145 MPH with a 3.23 back when it was new! Lifters floated at that speed!

 

[Ceedawg]

My 68 GTX got 145 MPH with a 3.23 back when it was new! Lifters floated at that speed!

A slight friend got a new 67 GTX, daddy-grandfather rich. Got clocked with those tri pod speed detectors running 155 down interstate 95. They set up a road block across the two lanes with lights flashing so he would see and stop. Spent the nite in jail, car got impounded but his granddaddy had money and connections and was out the next day with a fine. Dark blue bench seat auto on the column. He was 17 at that time. I would NOT ride with him to crazy, he’s 71 now but still here.

 

[Cojohnso1]

Both my 440 GTX were 4-speed Dana with the 3.54:1. I know no other? (That is one advantage about 8 3/4"? More gear range to select? I have never known why?)

 

[Net440]

355-391

 

[Cojohnso1]

My 68 GTX got 145 MPH with a 3.23 back when it was new! Lifters floated at that speed!

I buried my speedo with my '69 GTX. (Factory tach was showing 6g.) Thats with 28" tire 15" rim. My first GTX of very similar 440 build (a little more than stock. But still under the hood) same 4-speed Dana 3.54:1 rear. But with shorter and wider 26" 50s on 14" rim was done at about 130 MPH. (With decent drivetrain vibration.) Though not as quick thru the gears? This guy is smooth as silk at high speeds. Only signs and sounds of valve float and my fear of tire performance stopped its climb. This guy can pull away from my 10 sec index drag race Duster if given enough road. A true "Highway Star!"

Now is the stock speedo and tach all that accurate? Unknown. But calculations did put it at 140+ MPH. (If I had to dump one of these cars? Bye bye Duster. Not even a real choice.)

 

[diesel_lv]

3.23 gears, 1:1 final drive ratio, 26" factory height of most tires in the mid/late 60's, 145 was 6100 rpm.

 

[Cojohnso1]

3.23 gears, 1:1 final drive ratio, 26" factory height of most tires in the mid/late 60's, 145 was 6100 rpm.

That sounds right. My taller rear tire does make a difference. (But also a little slower thru the gears.) I bought the car with this setup. The rally rims in the front are 14". 15" on rear. I didn't even notice until I looked at tire size. I guess the guy wanted a little taller rear stance. But didn't want to mess with springs. But I know this. It works.

 

[Ceedawg]

Both my 440 GTX were 4-speed Dana with the 3.54:1. I know no other? (That is one advantage about 8 3/4"? More gear range to select? I have never known why?)

Dana couldn’t make a higher gear. They can’t make pinion with more teeth and bigger and ring gear is to thin at 3.54, Had to make a different housing, the ‘61’ to get a 3.08.

 

[Cojohnso1]

Dana couldn’t make a higher gear. They can’t make pinion with more teeth and bigger and ring gear is to thin at 3.54, Had to make a different housing, the ‘61’ to get a 3.08.

I agree higher. But how come deeper? 3.73? 4:30?

 

[Ceedawg]

I agree higher. But how come deeper? 3.73? 4:30?

It was a truck rear to start, 4.10 was the best all around gear for a pickup. Heavier stuff 4.56 and up. I think they (Dana Spicer) made the 3.54 just for Chrysler cars and Chrysler only used it in cars for 6 years. If going racing the 4.56 4.88 or 5.13 were the choice, street or race

 

[Cranky]

I stuck a 276 in my 383 Challenger and that thing rolled pretty good. It actually surprised me that it still got off the line pretty good.

 

[Hammer136]

I have a few for 3.55. Leaning in that direction.

 

[Cojohnso1]

I have a few for 3.55. Leaning in that direction.

I of course agree. Most with 3.23:1 wish car had more stop light punch. 4:10 folks? Of course complain about highway use. 3.73:1 is a very decent street gear. 355 a tick better on the highway. (And fuel)

 

[hunt2elk]

Dana couldn’t make a higher gear. They can’t make pinion with more teeth and bigger and ring gear is to thin at 3.54, Had to make a different housing, the ‘61’ to get a 3.08.

Until recently. Cass aka Dr Diff got a 3.23 in the works for the Strange 60. I've been running mine for 2 summers now.