MALIBU Rear gearset selection

Ribbedroof

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Not sure what the speed limit is around your area, or how often, and how you drive. Most people seem to go by the 60mph rpm. If I'm taking my car more than 30 minutes, I'll be on a major interstate, which is 65mph, and of course everyone does 75-80mph.
Well 20mph difference also makes huge rpm difference. So in my case I went 3.73 because I have a double overdrive and 6th is .50. So with a 25.5" tall tire it puts me at 2000 rpm at 80 mph. Worked out awesome for highway cruising 700 miles one way to Kentucky last September.
Long story short. How fast will you be going in your commute, honestly?
I’m past the age of recklessly being a speed demon 99% of the time. Daily commute because it involves some interstate will see 70 mph. That portion of the drive is only about 8 miles. Weekend cruises sometimes involve the toll roads which have an 80 mile an hour speed limit which we usually stay pretty close to. Obviously Okies being what they are the right lanes full of slow pokes in the left is full of people that are in a giant hurry to get nowhere quickly.
 
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Ribbedroof

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In my Regal I am running a 200R4 and it came with a 2.56 gear so when I installed my QP 9" I decided to go with 3.25 gears since this car is mainly a cruiser and I didn't want to lose too much top end, I am very happy with my choice and it feels well balanced between city and highway plus gets decent gas mileage.
What rear tire are you running?
 

Ribbedroof

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Tire diameter also effects engine RPM at a given speed.

There is a formula to help predict your RPMs with different setups.

RPM=(MPH×final ratio×336)÷tire diameter. Final ratio would be the trans gear you want to be in x rear axle gear ratio.
Yes I’ve played around with them quite a bit. That’s how I arrived at the two most likely candidates.
 

Ribbedroof

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I'm kinda in the same position as my Pontiac has the 200-4r with the 2.41's. I had pretty well decided that 3.08's would fit my application best as I see Interstate speeds regularly and don't really need crazy launch ability.

On the upside though, if your motor has above stock levels of power that gear is not terrible. Mine will still do a burnout on command, but is holding 2100 RPM at 90mph
Yes I had concerns about being able to pull that 2.41 in overdrive. Engine is a late Monte Carlo SS 305 converted to throttle body
 

Ribbedroof

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Buick used to pair their 4.1L/200-4rs with 3.08s when these cars were new in 83/84 and they did OK.

Through the years I had half a dozen and EVERY one of them was optioned with the 3.08 limited slip.
That one surprised me a little bit but I guess in the end it’s no worse than that same combination with a 214 gear that some of them got when they were equipped with a three speed automatic
 
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Ribbedroof

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Big thank you to everybody that contributed to this thread. It’s nice to have some real world input. It’ll give me something to think about while I get the powertrain swapped over
 
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565bbchevy

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Rt Jam

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The moment you question gear ratio. You need to consider an overdrive transmission.
There is N O gear that will do both accelerate well and have a comfortable cruising rpm on the highway. You make a choice and the it will suck for the other usage or you go in the middle and both suffer.
 
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Bonnewagon

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65mph, and of course everyone does 75-80mph.
full of people that are in a giant hurry to get nowhere quickly.
I think that is the biggest problem. If you gear for 60mph , you will be like me. I go about 10-20 mph over the limit [55mph] and I am the slowest car on the road. If you gear for 80mph and get stuck behind a slowpoke or a cop, you will be lugging the engine if you don't downshift. Not a problem for me with a manual trans, but an automatic will have a hard time. Another thing is your engine. My Pontiac 400's did not like sustained high revs. But my short stroke Pontiac 301 does not care. It may run out of breath but it stays smooth the whole time. When I had 3:73 gears in my '81 Malibu wagon, the 400 revved at almost 5000 just to keep up with traffic. It took a tank of gas to get to Englishtown from Queens, and a tank to get back. Unsustainable. Changing to the 3:23's was like night and day different. I really could have used an overdrive back then.
 
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BlairC_789

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i had a turbo 350 and 2.41 then switched to a 700r4 (.7 overdrive vs .67 if you got a 200r4) and 3.27 rear gear. I also have 26” tires as well
The new combo dropped my rpms by about 100-200 at crusing speed. Perfect for my daily driver on highways.
Any gear in the 3.08-3.55 would be the perfect. 3.23 would be my choice in your case
 
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