Rear-ending a 1968 4 door Satellite!

[dave's not here]

Greetings from CT to all,

What's the consensus for un-dogging the 2.76 open rear on these cars? i've got a streetable 300hp 318 build on a 904 trans, and priorities are affordability and durability . The 15 inch rims are about to go from a 215 tire to a 275/60. Would a gear change to around 3.55 and a limited slip unit be the most bang for the buck? With the taller tires i'm guessing the highway drive will be just fine - i cant imagine these new tires on the 2.76 around town. Thanks!

 

[#41]

It depends on how much highway driving - how fast, and for how long?

3.55's, even with 275/60/15 is too tall of a gear for 70mph+ for hours. 3.23 is the comfortable max in my opinion for long drives. 3.55's are ok for under 70mph or short hops.

 

[Darter6]

I'm running 3.23 with 30'' tires on my 65 Belvedere. Comfortable driving at 65-70.
Now out here speed limits are 65-75 and some places 80,and lots of straight roads. Plenty of knucklehead speeders that don't know what a speed limit is.
I see you have a location of Northeast USA. I lived in the southwestern PA area. Not a straight road to be had and the interstates are 65.Back then I ran 3.55 or 3.73 for those roads.
That being said a 3.55 may be just right for you giving the get up and go and a tolerable highway drive.
The RPM's maybe just fine for you.

 

[Fran Blacker]

I ran 3.54's with a 26 1/4" tire 3100 at 70 mph. 3.55's with a larger tire to get rpm's down to 2800. Doing 75/80 mph in CT. have your check book ready.

 

[Kern Dog]

It depends on how much highway driving - how fast, and for how long?

3.55's, even with 275/60/15 is too tall of a gear for 70mph+ for hours. 3.23 is the comfortable max in my opinion for long drives. 3.55's are ok for under 70mph or short hops.

Not to be rude but conventionally, the term "Tall" in reference to gears means low numerically as in 2.76, 2.94, etc. "Short" gears mean 3.73, 3.91 and higher numerically. This is because taller people with long legs take longer strokes and fewer steps to cover the same distance compared to shorter people.
Long legs= lower rpms at freeway speeds.
Regarding the OP and the topic at hand, There are a few ways to go here.
The 2.76 gears are great for the freeway but do leave you wanting more leverage from a standing start.
You could leave the gears as is and swap in a later 904 trans, known as a A-999. They are essentially the same as a 904 but come with a lower 1st and second gear. The A-999 was phased in around 1980 so just about any 1980 car, truck or van had them.
The stock 904 had a 2.45 1st gear ratio. The A-999 had 2.75. That has the effect of changing your 2.76 gear to a theoretical 3.06 ratio.
The 999 was used as a stopgap for Chrysler until they could develop a real overdrive transmission. Many cars with the 999 had silly tall axle ratios, as tall as a 2.21! The deep first gear offset some of that weak suck axle gear but with cars like the 85-89 Diplomat, Gran Fury and Fifth avenue closing in on 4000 lbs and a 318 making 150 net HP, the cars were slugs!

If swapping the transmission does not interest you, know that the 3.23 gear is a pretty good compromise. I ran a 3.23 for awhile with an automatic in my '70 Charger. I missed the acceleration I felt with the 3.91s but since I was driving the car on a 1000 mile road trip, I just used the 3.23s for that since I had them here on the shelf. I've ran 2.76s too. Holy crap....the car was super smooth on the freeway but disappointing from light to light.

 

[dave's not here]

May just leave well enough alone...although a 3.23 would be an improvement - thanks for all of your well guided input!

View attachment 119732

 

[Darter6]

Good looking car ! I like 4 doors. They can do everything a 2 door can and cost way less.
And it's not GREEN !

 

[RemCharger]

A police road runner

 

[Darter6]

Un-marked 1 Adam 12.

 

[69SatelliteGuy]

Woah, just wanted to pop in and say nice looking car! I've got a '69 myself.