RE: {Chrysler 300} Driving Experiences with less than a 3.23 ring and pi

Bob,

I found the Chrysler 1959 Dyno results on the 413 RAM engine. Mine is a single 4. But the percent spread on Brake Specific Fuel Consumption should be about the same for the displacement.

After a bunch of math and using their fuel consumption data what I ended up with is a 13% difference between using a gear set that gives you 2652 RPM at 65 MPH with the 3.23 and gives you 2266 RPM at 65 MPH with the 2.76 ratio.

A round trip from San Francisco to New York City is about 3000 miles or 6000 round trip.

At an assumed 10 miles per gallon, that is 600 gallons of fuel. At todays national average price for premium fuel of $4.10 a gallon that is $2460 dollars. The gear change would save, theoretically , 78 gallons or $319.

So, you are correct that changing the rear end just to change it on a single trip would not pay for itself. Unless fuel prices really spike again. If gas doubled then the savings would be $640.

Now, since I am using this car both for daily driving and for retirement cross country road trips, lets do some math. If we use the annual milage it is about 10K a year in retirement. If we assume 4 cross country trips in the next 10 years then we get a 10 year miles driven of 100,000 miles, plus say 30K in trips. So, 130K miles at 10 MPG is 13,000 gallons of gas. That 13% gear change would equal 1690 gallons. At say $5 a gallon to deal with inflation on average then that comes out to $8450.

The cost to do a complete third member rebuild with good used or new gears so it is as good or better then factory, and adding sure grip, would be about $1500 to $2000. I would still net out about $5K over the next 10 years.

James.

From: Bob Podstawski <bobp8@xxxxxxxxxxxxx>
Sent: Thursday, December 8, 2022 08:57
To: James Douglas <jdd@xxxxxxxxxx>
Subject: Re: {Chrysler 300} Driving Experiences with less than a 3.23 ring and pinion ratio

You’ll never make up the cost of the change with the gas you save…

On Dec 8, 2022, at 11:26 AM, 'James Douglas' via Chrysler 300 Club International <chrysler-300-club-international@xxxxxxxxxxxxxxxx> wrote:

Hi All,

I am thinking of changing out the 3.23 rear end on the 1964 300K.

I would appreciate any driving experiences by folks that may have a 300 with a 413 and auto that has the 2.76 or 2.93. Since this car is going to be a daily driver and I regularly drive it from San Francisco to our place out of town, 160 miles round trip, and we will use it in the next year for a cross country trip….

…I am thinking about gas milage….

Any comments would be appreciated on driving through the mountains with the low gears and on general acceleration like on freeway on ramps and the like.

Thanks, James

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RE: {Chrysler 300} Driving Experiences with less than a 3.23 ring and pinion ratio