Rear End Ratio Options for 70 383 Plymouth Barracuda

[Ariovistus]

Hello, It has been awhile. A friend has a 70 Plymouth Barracuda with a 383 automatic. It has a mystery rear axle. He said it came with a 3.23 rear axle with a Limited slip, but someone swappped it for a one wheel wonder. He wants to restore it back to original. A friend says He should put a 2.93 gear ratio rear end so He can have a freeway friendly car, but yet have a good off the line response. Another friend says to put a gear vendor in it and have a 3.55 rear axle. It would give his car a 2.84 final gear ratio at 65 mph on the freeway. He has a a gear vendor system, but is reluctant to have it installed because He wants to keep it simple. And the Purists say to put the 3.23 rear axle in to keep it original. But the car will be turning 3000 rpm at 65 mph on the freeway. He does not want the engine to work too hard and have a limited top end speed. So what is the best option? I look forward to hearing from the Experts on this forum, because He is not sure what the best approach is. Thank You.

 

[moparleo]

You know , life is a compromise sometimes I wish I was shorter and sometimes taller.
There is no "expert answer" The best approach is to figure out what is more important to him and then how much are you willing to spend to get it.
Doesn't want the engine to work too hard and have a limited top speed. Now that is funny.The rear axle is not a mystery if he wants to figure what the gear ratio is. Simple procedure.

Wallace Racing - Calculate Speed for given RPM, Rear Gear Ratio and Trans Gear Ratio

Calculate Speed(MPH Km/H) for given RPM, Rear Gear Ratio and Trans Gear Ratio

www.wallaceracing.com

How to determine rear gear ratio without removing differential - - Video Search Results

The search engine that helps you find exactly what you're looking for. Find the most relevant information, video, images, and answers from all across the Web.

video.search.yahoo.com

 

[Ralph]

I am selling two good OEM sets of 323's if you decide to go that way.

PM me if interested

 

[70chall440]

Absolutely agree with @moparleo, its all about preference. The car most likely came with 3.23 or perhaps 3.55 gears. My "preference" is usually 3.55s, I feel that they are a great all around gear.

 

[Challenger RTA]

Personal preference is what matters.Smiles per mile!

 

[Rapidfire]

Hello, It has been awhile. A friend has a 70 Plymouth Barracuda with a 383 automatic. It has a mystery rear axle. He said it came with a 3.23 rear axle with a Limited slip, but someone swappped it for a one wheel wonder. He wants to restore it back to original. A friend says He should put a 2.93 gear ratio rear end so He can have a freeway friendly car, but yet have a good off the line response. Another friend says to put a gear vendor in it and have a 3.55 rear axle. It would give his car a 2.84 final gear ratio at 65 mph on the freeway. He has a a gear vendor system, but is reluctant to have it installed because He wants to keep it simple. And the Purists say to put the 3.23 rear axle in to keep it original. But the car will be turning 3000 rpm at 65 mph on the freeway. He does not want the engine to work too hard and have a limited top end speed. So what is the best option? I look forward to hearing from the Experts on this forum, because He is not sure what the best approach is. Thank You.

What is the outside diameter of your tires? With a 26 inch diameter tire you will run close to 2600 at 65 with 3.23 gears not 3000!

 

[70chall440]

Ah run a OD, 5 or 6 speed then you can run 3.91s or 4.10s and still cruise...

 

[Ariovistus]

What is the outside diameter of your tires? With a 26 inch diameter tire you will run close to 2600 at 65 with 3.23 gears not 3000!

26 inch diameter. Thank You.

 

[Ariovistus]

Ah run a OD, 5 or 6 speed then you can run 3.91s or 4.10s and still cruise...

Thank You.

 

[Ralph]

I am running a 5speed with 391 and love it. Had an tremec 5 speed in roadrunner and 60 mph at 1800 RPM's.

There can be alot of work involved but liked the outcome

R

 

[Richard T]

Hello, It has been awhile. A friend has a 70 Plymouth Barracuda with a 383 automatic. It has a mystery rear axle. He said it came with a 3.23 rear axle with a Limited slip, but someone swappped it for a one wheel wonder. He wants to restore it back to original. A friend says He should put a 2.93 gear ratio rear end so He can have a freeway friendly car, but yet have a good off the line response. Another friend says to put a gear vendor in it and have a 3.55 rear axle. It would give his car a 2.84 final gear ratio at 65 mph on the freeway. He has a a gear vendor system, but is reluctant to have it installed because He wants to keep it simple. And the Purists say to put the 3.23 rear axle in to keep it original. But the car will be turning 3000 rpm at 65 mph on the freeway. He does not want the engine to work too hard and have a limited top end speed. So what is the best option? I look forward to hearing from the Experts on this forum, because He is not sure what the best approach is. Thank You.

What are your looking to do with the car? Stock original numbers matching, resto-mod, survivor?

I have a low mile numbers matching drive-train '70 383 4-speed Challenger R/T. It was a base R/T with the only option being A/C, even down to the 3-speed manual trans. Over the years, the original owner swapped in a pistol grip 4-speed and a power antenna (why?) in about '72. The next owner did a restoration in the 90's and added the go wing, T/A chin spoilers, and magnum 50 rims. Looks bone stock, but it's not numbers matching on the option list. No I've added FirmFeel power steering, dynoMatted the interior, and will add stock looking power front discs next year. The year after that, I'll probably go with a Tremec 6-speed.

The car looks and drive's great! I think for what you're looking for, just go with the gear vendor unit. You can always take it off later if you don't like it. (but, I think you will like)

 

[fasjac]

Ah run a OD, 5 or 6 speed then you can run 3.91s or 4.10s and still cruise...

Correct, and that’s what I do but, there’s substantial coin involved. and worth it to me.
Again, just how you want to drive/use the car.

 

[70chall440]

What are your looking to do with the car? Stock original numbers matching, resto-mod, survivor?

I have a low mile numbers matching drive-train '70 383 4-speed Challenger R/T. It was a base R/T with the only option being A/C, even down to the 3-speed manual trans. Over the years, the original owner swapped in a pistol grip 4-speed and a power antenna (why?) in about '72. The next owner did a restoration in the 90's and added the go wing, T/A chin spoilers, and magnum 50 rims. Looks bone stock, but it's not numbers matching on the option list. No I've added FirmFeel power steering, dynoMatted the interior, and will add stock looking power front discs next year. The year after that, I'll probably go with a Tremec 6-speed.

The car looks and drive's great! I think for what you're looking for, just go with the gear vendor unit. You can always take it off later if you don't like it. (but, I think you will like)

Hey now, I like power antennas..

 

[Ariovistus]

What are your looking to do with the car? Stock original numbers matching, resto-mod, survivor?

I have a low mile numbers matching drive-train '70 383 4-speed Challenger R/T. It was a base R/T with the only option being A/C, even down to the 3-speed manual trans. Over the years, the original owner swapped in a pistol grip 4-speed and a power antenna (why?) in about '72. The next owner did a restoration in the 90's and added the go wing, T/A chin spoilers, and magnum 50 rims. Looks bone stock, but it's not numbers matching on the option list. No I've added FirmFeel power steering, dynoMatted the interior, and will add stock looking power front discs next year. The year after that, I'll probably go with a Tremec 6-speed.

The car looks and drive's great! I think for what you're looking for, just go with the gear vendor unit. You can always take it off later if you don't like it. (but, I think you will like)

My Friend has an Original numbers Matching Car. He just wants to drive it on the street, but be able to cruise with Traffic on the Highway too. His problem stems from the 741 rear end with a mystery gear ratio, that someone swapped out for the original 489. He is thinking of running the gear vendors with a 3.55 posi unit. I have driven a 70 Challenger with a 383 4 speed and a 3.54 Posi Rear. It's a dog on the Highway, turning High RPMS while traffic passes. He was in the car with Me and that's where He came up with the idea of the Gear Vendors OD. I apprecaite Your Advice. I know He will too. Thank You.

 

[70chall440]

Posi is a Chevy deal, Mopars have Sure Grips.. just saying

 

[cuda joe]

thats a good ideai have 323 in mine cruises down the highway good but won;t hook up from a start

 

[heminut]

thats a good ideai have 323 in mine cruises down the highway good but won;t hook up from a start

I've always dealt with this by having two Sure Grip carriers. For my first Cuda, a 70 340 4 spd., I had a set of 3.54's for the hiway and a set of 4.56's for the track. For my current Cuda, a 5.7 Hemi with a TF 727, I have a set of 3.23's for the hiway and a set of 4.10's for the track. Back in my younger days this was a great solution but these days getting under the car to change carriers is not appealing to me at all! I am seriously considering an overdrive tranny and the lower geared carrier.