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Keith,
Going from a 2.94 up to a 3.23 won’t be much of a noticeable difference. Yes, you will notice the tone of the car will be different at your regular cruising speeds. Depending on how regularly you drive the car, you may not notice any difference in mileage. Do you know what RPM the motor is turning now at 65 MPH? Is everything else bone stock on the car? The ideal condition is to have the motor sitting happily in its powerband at your desired speed. Having the motor sitting below will have it lugging, and above just increases wear, decreases mileage, etc.
How heavy is that trailer you are pulling behind?
I recommend the Sure Grip if you are going to be towing. It will help pulling out in the rain. Yes, you will need to get used to it, but it’s not a difficult transition. My 5-speed ‘96 Dakota has a SG rear. Yes, I can kick it sideways in the fowl weather if I want to.
I have 3.55 gears in my ’68 Barracuda. Previously it had 3.23’s. My highway cruising RPMs are around 3000 RPM. That’s a bit high for my taste. I wouldn’t want the Imperial cruising at that RPM. One of my uncles sold his ’73 Road Runner to another uncle. It has a stock 440 with 3.23 gears. I don’t remember the highway RPM, but I made the delivery run in it. It was 2 ½ hours, and the motor was not complaining. Actually, the car seemed quite happy. And it only took 1/2 tank of gas.
2.76 is my favorite highway gear. I don’t think I’d recommend that for an Imperial though. Tall tires and lots of weight to get moving. I have a 2.76 rear in my wife’s Challenger, but I have a spare 3.23 SG ready to go. I may put it in and see how it feels after I get some of the other work done.
If you are going shopping for a center, you have a few options. I would avoid the 741 case center section. It was intended for lighter weight and lower torque vehicles. A 742 or 489 would be fine. There is a column in the current issue of Mopar Action on how to test a SG center section that is out of a car. I don’t have it in front of me right now, but I can look it up for you if you need the info.
Oh, one more thing.? If you change the gear ratio, you will need to change the drive gear for the speedometer.? It is located in the transmission, and is not difficult to change at all.? The gears are available new at any Chrysler/Dodge/Jeep dealership.? Unless the parts guy is a veteran, tell them it’s for a ’88 Ram or something like that.? The rule of thumb is to match the number of teeth on the speedo gear to the gear ratio in the rear.? For example, a 3.55 rear would use a 35 tooth gear, a 2.94 rear would use a 29, etc.? If the area you live in uses the radar signs to post your approaching speed as warnings in low speed zones, or wherever, as long as it’s not a photo ticket machine, you can use them to check your new gear.? They aren’t always perfect, so you may want to test the radar with a known “good” car first as your control group.? Rounding up another driver would allow that “good” vehicle to lead or follow and you can compare your speeds as well.? A little seat time is more fun than a ticket.? Paul might agree…
Rob McCall ’67 LeBaron
-----Original Message-----
Hey everyone, I have an issue with my rear axle that is tearing me up. I need to replace the bearings ( sounds like a church choir in my trunk ) and I would like to install taller gears and a limited-slip diff while I am in there. Here is my problem: I would like to go from the current 2.94 to a 3.23 for a little extra "go" and better towing capabilities. If my calculations are correct, that would be an increase of approximately 200 rpm at 65 mph. Will that increase make my highway hauler not so highway. My main goal with this car is road trips. And one last question: Is rebuilding an axle difficult? I rebuilt my transmission myself ( with a little help from my brother ) and that was easy.
Keith
P. S. I want to thank everyone for their support. I was asking a few weeks ago if I should keep her or set her up for adoption. As you can see, I am keeping the little @!&^%$(&^........... |
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