Looking for rear gear opinions.

[Roadcuda]

As some of you may recall I'm driving my Road Runner to Carlisle this year. It's a 300 mile trip for me, and with the looming threat of the rising gas prices, I'm thinking of doing a gear swap for the trip. Also some my recall I was getting miserable mpg with my stock 383 but that problem has been resolved and it's now closer to 12 to 13 mpg. My mechanic says he can do a few things to tune it up that should help the mpg, and I have an option for a set of 2:76 gears all set up in a chunk, for a great price, FREE! My question is, do you guys think it will be worth the effort the pull the 3:23s currently in the car and replace them with the 2:76s trying to get a few more mpgs for a long trip? I'm not racing the car at all so the performance lost isn't all that important to me.

 

[69B5]

Good morning, Harry
My drive to Carlisle is about the same as yours, 284 miles
I,ve never had 2:76's in any of my cars, just 3:23 in my RR and 3:55 in the R/T.
So I'm not sure what you would save or exactly what you would be giving up in performance.
I'm concerned about the price of gas as well, but I quess if it was me facing the gear options, if it's not too expencive,I'd put the 2:76's in and drive around abit and see if I like them and what they may save in gas compaired to your 3:23's
I'd hate to give up much performance, after all we are driving one of THE KING OF BEASTS. lol
Hope to see you in Carlisle. Have a safe trip.
69B5

 

[69B5]

Good morning, Harry
My drive to Carlisle is about the same as yours, 284 miles
I,ve never had 2:76's in any of my cars, just 3:23 in my RR and 3:55 in the R/T.
So I'm not sure what you would save or exactly what you would be giving up in performance.
I'm concerned about the price of gas as well, but I quess if it was me facing the gear options, if it's not too expencive,I'd put the 2:76's in and drive around abit and see if I like them and what they may save in gas compaired to your 3:23's
I'd hate to give up much performance, after all we are driving one of THE KING OF BEASTS. lol
Hope to see you in Carlisle. Have a safe trip.
69B5

 

[mcmopar]

Its easy to swap chunks - particularly if you have Green bearings since you won't need to adjust axle end-play after the swap. Just swap chunks and go. If you have the factory rear bearings you'll need to adjust axle end-play. The shop manual can help you with this.

 

[droptop]

Go with the higher gears for the road trip. :cents: If it is a smaller yoke center chunk, they make a 2 size u-joint so it will make it a truly bolt in swap.

 

[roadrunnerh]

I would swap out the 3.23 for the 2.76 if you want a little better mpg on the highway. I don't how much better it would be, but it would improve mpg - especially if the carrier is FREE! :cents:

 

[Roadcuda]

I do have green bearings in the car John so I'm not concerned about doing that. I'm mainly wondering how much better, might the gas mileage be with the 2:76 gears over the 3:23s. If I'm thinking correctly the engine would be turning less rpms therefore using less gas. So the question is how much could I gain? One or two mpg, or could it be more then that? Or would I gain any at all? BTY Fran? My name is Steve!!!!!! :jester:

 

[69hemibeep]

Gas mileage is gained by little changes like your doing, tune up, gears or drive slower. you can also throw some tall tires on it for the road and change them at the hotel, if you have some.

 

[69hemibeep]

Here's another, car pool and split the cost.

 

[ACME A12]

Swapping the chunk is child's play; I say go for it. :cents:

 

[Big John]

Let's do some math.

300 miles x 2 = 600 (round trip)
600 / 13MPG = 46.2 gallons of gas used.
46.2 gallons @ $4 gallon = $185

Let's say you increase your gas mileage to 15 MPG. That's a 15% increase in mileage and that's probably the best you could expect.

600 / 15MPG = 40 gallons of gas used.
40 gallons @ $4 gallon = $160

Savings of $25 based on $4 gas.

Quart of gear lube with sure grip additive will set you back about $12 and the gasket will be about $4.

You'll have to change the speedometer gear (assuming you don't have one). I checked Ebay and they seem to be going for $10 with a couple dollars to ship. Let's say $12.

Total cost to change your gear ratio (without labor) = $28

$25 - $28 = negative $3.

You can make your decision from there....

 

[69hemibeep]

Let's do some math.

300 miles x 2 = 600 (round trip)
600 / 13MPG = 46.2 gallons of gas used.
46.2 gallons @ $4 gallon = $185

Let's say you increase your gas mileage to 15 MPG. That's a 15% increase in mileage and that's probably the best you could expect.

600 / 15MPG = 40 gallons of gas used.
40 gallons @ $4 gallon = $160

Savings of $25 based on $4 gas.

Quart of gear lube with sure grip additive will set you back about $12 and the gasket will be about $4.

You'll have to change the speedometer gear (assuming you don't have one). I checked Ebay and they seem to be going for $10 with a couple dollars to ship. Let's say $12.

Total cost to change your gear ratio (without labor) = $28

$25 - $28 = negative $3.

You can make your decision from there....

The voice of reason I use to do it from 4.10s to 323s for a 2400 mile round trip but that's different

 

[Roadcuda]

Let's do some math.

300 miles x 2 = 600 (round trip)
600 / 13MPG = 46.2 gallons of gas used.
46.2 gallons @ $4 gallon = $185

Let's say you increase your gas mileage to 15 MPG. That's a 15% increase in mileage and that's probably the best you could expect.

600 / 15MPG = 40 gallons of gas used.
40 gallons @ $4 gallon = $160

Savings of $25 based on $4 gas.

Quart of gear lube with sure grip additive will set you back about $12 and the gasket will be about $4.

You'll have to change the speedometer gear (assuming you don't have one). I checked Ebay and they seem to be going for $10 with a couple dollars to ship. Let's say $12.

Total cost to change your gear ratio (without labor) = $28

$25 - $28 = negative $3.

You can make your decision from there....

Thanks John, and everyone else. I had figured the cost of gas, and while I knew about that gasket and lube I hadn't figured that cost in yet. If you think I won't get much better then 15 it may not be worth the effort.

 

[Roadcuda]

Gas mileage is gained by little changes like your doing, tune up, gears or drive slower. you can also throw some tall tires on it for the road and change them at the hotel, if you have some.

Bob, what would the taller tires do? And what size would accomplish it?

 

[69B5]

Forgive me Steve.
I know your name.
Why I typed Harry, I'll never know.
I guess I had a brain fart.
I seem to be getting alot of them.
And whats up with the double post?
I don't know how I did that.
I think I'll lay low for awhile.

 

[moparchris]

I would go through the effort to swap them out. You probably wont recoup the cost and hassle but it might make the drive better for you. I have been guilty of changing out my 4.56s for 2.76s for road trips. For you a change from 3.23 to 2.76 will be a 16% change in RPM at cruise so if you cruise at 3000 with 3.23s then you would cruise at 2520 with 2.76s. I dont usually care about that kind of drop in RPM but when your driving for several hours it makes difference. :cents:

 

[69hemibeep]

Gas mileage is gained by little changes like your doing, tune up, gears or drive slower. you can also throw some tall tires on it for the road and change them at the hotel, if you have some.

Bob, what would the taller tires do? And what size would accomplish it?

Its like changing gears, that's why it messes your speedo up http://www.csgnetwork.com/multirpmtirecalc.html

 

[Basketcase]

l'll go agalnst the graln here and say l'd stay wlth the 3.23s. except for Freeblrd l've always run 3.23s. get good milage. l travel 19 miles one way to work. when gas hlt $4 a couple years ago l parked the Power Wagon l had and drove the runner. never fgured the mpg but lt got me 5 days for a tank. Now lf you had 3.91s l'd say swap'm.

 

[John69RR]

I'm with Dave on this one. Keep the 3.23's. I have the same gear in mine and when I made the trip to Detroit for the Dream Cruise with 225-14 tires I was turning 3000 rpm at 70 and averaging 14 mpg.

 

[dobie]

Someday i swear ill drive mine there, 3.91 gears and all!