Gear ratio suggestions

[RT SE 440]

Hello all i'm just refreshing up my rear Diff it's an 8 3/4 open wheeler thinking of upgrading to an true-trac whatever they call them but at the moment it has 3.23:1 ratio what would be a nice ratio for daily driving both local and open road ? The car is a standard 440 hp with a small cam with a 727 auto i was thinking 3.55:1 or stick with the 3.23:1 what's everyone's thoughts or what are you using thanks ahead .

 

[RemCharger]

True tracs are the cats ***.
As far as ratio, I'd prefer 4.56 , probably not what you're asking

 

[66 Sat]

3.23 all the way. Perfect for your set-up, great compromise ratio. Unless you have huge rear wheel/tire diameter of course.

 

[Runcharger]

3.23 for what you want and if it's nice and quiet right now you'll save a bunch of hassle getting new aftermarket gears setup.

 

[Lefty71]

3.23 is probably fine, in your Prius.
3.91 is and was always the hot street gear. Just my 2 cents....other opinions will vary.

 

[pnora]

You will almost never know the difference between the 3:55 to 3:23.

 

[Black_Sheep]

3.23’s if it’s going to see a lot of highway time…

 

[66 Sat]

3.23 is probably fine, in your Prius.
3.91 is and was always the hot street gear. Just my 2 cents....other opinions will vary.

He's in Australia and wants an open road ratio as well as around town.
Revving the nuts off a stock 440 to keep up with traffic on the motorways here will get tiresome real fast.

 

[Dave6T4]

A stock 440 has gobs of low end torque, and 3.23's is a nice all-around gear.

 

[diesel_lv]

3.23's are a great gear for what you're looking for. My stock 383 2bbl w 727 could smoke the tires w 2.76's. Unless you plan to take it to the track, 3.23's are plenty for around town and decent on the long highway stretches.

 

[33 IMP]

Agree with the above, I would just add the True Trac to your current (hopefully quiet) gears. Avoid the chance of lousy quality noisy new gears. For the use you describe, I think the 3.23s are the better choice, anyway.

 

[Fran Blacker]

If you drive at speeds above 70 mph 3.23's. Ran 3.54's at 68/70 mph 26.5 inch tire on a 350 mile trip no problem after 70 3100rpm.

 

[kramer]

For a limited slip setup I am partial to the factory style 68 and older Powerlok differential that has clutch plates, Dr Diff is who I would get a hold of on part 8 3/4 parts. They can be setup very tight or loose depending on your preference.

Mopar 8 3/4" (8.75) Clutch Type Sure-Grip ("Powr-lok")

 

[Car #4]

Another vote for 3.23s. What's your driving style? If racing everyone and their brother off the street light then you want a taller gear. But if you're just cruising around or down the highway then 3.23s are perfect. They still have enough performance to fun when you want them to be.

 

[RemCharger]

Hello all i'm just refreshing up my rear Diff it's an 8 3/4 open wheeler thinking of upgrading to an true-trac whatever they call them but at the moment it has 3.23:1 ratio what would be a nice ratio for daily driving both local and open road ? The car is a standard 440 hp with a small cam with a 727 auto i was thinking 3.55:1 or stick with the 3.23:1 what's everyone's thoughts or what are you using thanks ahead .

I have run a 2.76 in a decent 440 with headers etc, on a long run into town against my cousin to a car show with his 220 geared 81 imperial .(built up 360)
I know you guys have long straight roads.
If you want some real mph get your phone app and some gears.

 

[66Satellite47]

My daily driver '70 Barracuda had 3.23 gears. Not ideal for the drag strip, but sure worked great for daily driving, both in town and on the highway at 70+ MPH.dif. Both

EDIT: BTW I ran both the open wheel OEM and the OEM limited slip both worked perfectly.

 

[Photon440]

3.23 is probably fine, in your Prius.
3.91 is and was always the hot street gear. Just my 2 cents....other opinions will vary.

The new (2023) Prius has you beat, with a 4.11 differential. (which helps explain its 7.1 second 0-60 times)

But for a mild 440 I'd stay with the 3.23; it worked fine as a standard 383 road runner gear.

 

[Lefty71]

The new (2023) Prius has you beat, with a 4.11 differential

That'll be the day. I'm not out to please the Man Bun crowd.

 

[fj5gtx]

As was said, 3.55 to 3.23 isn't much of a change. I put a 742 limited slip in a 489 case, because I had a spare one. Factory correct when you look under it, but clutches are better performers than the grinder it replaced and you can rebuild it.

Anyone have experience with Dr. Diff's Sure-Trac II ?

Mopar 8 3/4" (8.75) Helical Gear Sure-Grip ("Sure-Trac")

 

[RT SE 440]

Well made a decision today after i pulled the pumpkin out to find the 3.23:1 gears in the diff in perfect condition no damage no wear no metal fillings in the oil so 3.23 it is .I purchased a Eaton Detroit Truetrac LSD center , bearing & seal kit .Has anyone used the Eaton TrueTrac what's your thoughts ?