No right answer, opinions only!

I know there is not a right answer to the following question, so I did not post it in the Technical section. I am looking for opinions only. It is related to what differential gearing I should get (I'm waffeling) for my 1971 Maverick Grabber. Here is my situation:

1) I have a new mild rebult 302 with 288 HP (fairly level torque across rpm based on dyno).
2) I have a stock C4 auto transmission (Not changing it)
3) My differential is opened up for inspection and will close up around Oct 1.
4) I am planning on 27 inch diameter tires (28" with new 4 leaf springs are only a bonus)
5) The differentail gears are 3.80:1, putting me at 3200 rpm at highway speed (65 mph).
6) I am 56 years old and retired. I don't really need to burnout, but it would be nice once in awhile.
7) I don't plan to use this on the highway much, but a friend wants to do a 36 hour across country trip with us.
8) Yes, I can afford the gas, but I also want to stay retired!

I am leaning towards a 3.25:1 changeout which will put me closer to 2600 rpm at 65 mph, but that would be a $400+ investment. I would rather spend $400 on other things and this project is way over budget.

Opinions are appreciated!

 

First off Congratulations on being retired at 56 - I envy you - sounds like you are on the right track with the 3.25 gears - I believe they will pay for themselves over a period of time

 

I am assuming this is a stock 8" Maverick rearend? If so, keep the 3.80:1 gearset for you local cruises, etc. It really isn't a big deal to change gear ratios if you have another carrier all set-up. You can practically get 2.79:1 carriers for free, even one out of a 4-lug car will fit. If you were closer, I'd give you one. Swap the 2.79:1 in for your cross country tour and leave the 3.80's in for local cruising. This would cost you pennies compared to your $400 estimate for 3.25's.

 

If you are just looking for something to put in there for the trip, I have a 3.00:1 8" open complete drop in pumpkin out of my old Mustang II with only 10K total miles on it. Send me a PM if interested.

 

Great idea

 

I agree with Paul.

 

An extra setup was also my first though, that's the beauty of the 8 & 9 inch rears, easy ratio swaps!

 

Mee tooo...

I've swapped gears for longer jaunts, go with the 2.79 or no more than 3.00...

 

The other option is to ditch the C4 for an overdriven transmission. Something you don't want to do.

 

What's wrong with the 3.80? I drive mine on the highway and yes, 3000-3200 rpms, but I still pull mpgs in the low (very low) 20s. Like exactly 20!

With my Flowmaster Super44s, it is a touch loud and obnoxious, but when I tap the throttle, I can pass that semi or granny on her way to church without a worry.

And a burnout is just a toe-twitch away, if I want it.

I have driven 4.11 and 4.56 and they are lots of fun, but I would never go that high for any highway driving.

And I drove 2.79 for a while...blech!

Someone might be able to convince me to go 3.55 if they volunteered to loan me the gears, but in all honesty, I really like my 3.80s.

I would drive this cross country for 36 hours, but ONLY if I had A/C!!!

I am running 255/60r15 right at 27" diameter.

This is just my opinion, though, so take it with a grain of salt. Still cheaper than $400!!!

 

i generally recommend 3.25s for cars described like yours.
the suggestions of getting a second 3rd member to swap in for long road trips is a great one. my word of caution is if you have a high stall speed torque converter, you will want to make sure your cruising rpm is above the stall speed. if not, the converter will generate excess heat and shorten the life of the transmission.
while it is possible to drive at over 3000 rpm and get good mileage, i look at it like that is 1000 revolutions every minute more off the life of the engine than if i was cruising at 2000rpm. now i know its not that simple but rod bearing are more likely to spin and oil more likely to brake down at higher rpms.
i find i have a never ending urge to shift when im cruising with rpms over 2800. when i had a c4 i started with the stock 2.79, went to 4.56 (1/8mile drag racing), 4.10s, then 3.89s. ive also played with just about every other ratio under the sun on my other cars and customer cars. if i wasnt using my car as a street strip car i would have had 3.25s. with the c4. i ended up swapping in a t5 and it was perfect with the 3.89s. i could road trip my car anywhere, race it and drive it home in comfort at 80mph at around 2500rpm.

 

I also agree with Paul on having another setup center section and keep the 3.80 gear for local cruising. My other question is why $400 for the 3.25's? I bought a nice 3.25 and 3.40 center section for $50 each. I put an ad on my local Craigslist that I wanted to buy a 3.25, 3.40 or 3.55 8" center section and got a call two days later.

 

Thanks everyone. All the opinions really helped. For now, I will leave the 3.80:1 gears in and enjoy them. If I can get 20 mpg on the highway, I'll be fine with that since I will do only a few long trips. When/if money becomes available later, I think I will try to find an 8" pumpkin with 2.79 or 3.00 gears as suggested for my long trips (at a much lower price!).

 

I'd go with the low ratio as well. Spend the $400.00 once or multiple times in fuel costs with higher gears. Stretch the retired income!

 

If I were using the car for mainly street driving; my choice wud be 3.25. Seeing as u are getting older, how many times will you want to be crawling under a car swapping pigs? I believe 3.25's are a nice set for mostly cruising. If I were to go above anything more, I wud be thinking AOD.