Rear gear choice

[polara71]

For reference, a large portion of modern vehicles come with a final gearing of somewhere between 2.7-3.1 so don’t feel like you have to go too big!

Yeah, in 8th gear

 

[413]

Keep in mind new cars have multi port fuel injection and VVT - variable valve timing and this makes torque at all rpm’s. Plus the 6-8 speed transmissions. You just can’t compare the figures to a old car with a carbureted engine 3 speed non OD trans.

keep the 2.9 gears with that 318. It’s already done right.

 

[Yeahrightgreer]

Sorry when I say new I mean about 2004 before all these 8 and 10 speed automatics and before every car had VVT. Simple NA 4 and 5 speed cars. Anything over 2001 is “new” to me.

 

[polara71]

Sorry when I say new I mean about 2004 before all these 8 and 10 speed automatics and before every car had VVT. Simple NA 4 and 5 speed cars. Anything over 2001 is “new” to me.

I agree with you on the definition of new but new is older than your new.

Still a 4 & 5 speed comparison to a 3 speed auto is a fair comparison. Hell at this point put 373s in and a gear vendors unit then let's compare.

 

[moper]

I always liked a little steeper rear gear. I daily drove my Newport with 3.55s and loved them. It routinely went 125+ on the highway, on 2-300 ,mile round trips (GF was in college so a few times a month it did this). If the engine is in decent shape, and you can tune, the steeper gearing is just more fun. At least to me.
I can't imagine a mildly built big block of any decent tuning that can't get between 15-20mpg in a big car unless you're actively hammering on it.

 

[Snotty]

I always liked a little steeper rear gear. I daily drove my Newport with 3.55s and loved them. It routinely went 125+ on the highway, on 2-300 ,mile round trips (GF was in college so a few times a month it did this). If the engine is in decent shape, and you can tune, the steeper gearing is just more fun. At least to me.
I can't imagine a mildly built big block of any decent tuning that can't get between 15-20mpg in a big car unless you're actively hammering on it.

My folk's '65 Newport with HP 383 got 17 highway. My '62 New Yorker 413 got 18. But I would like to hear some people say they get 15-20 with a 440, in any condition?

 

[polara71]

I always liked a little steeper rear gear. I daily drove my Newport with 3.55s and loved them. It routinely went 125+ on the highway, on 2-300 ,mile round trips (GF was in college so a few times a month it did this). If the engine is in decent shape, and you can tune, the steeper gearing is just more fun. At least to me.
I can't imagine a mildly built big block of any decent tuning that can't get between 15-20mpg in a big car unless you're actively hammering on it.

WHEN , When I was 23 I used 373s in a daily driver Sport Fury convertible. The very worked 440 got 4-5 miles to the gallon on an average week.
I didn't care about the revs or the MPGs as I never feared driving triple digits or burning up the tires.

Now, it all makes sense, 323s

 

[moper]

[QUOTE=" But I would like to hear some people say they get 15-20 with a 440, in any condition?[/QUOTE]

How about a 500” that makes just shy of 600hp that gets 17 with 3:23s? A 422” small block that makes 470hp based on weight and ET that gets 17+.
Mileage isn’t just gearing. It’s good tuning with the right parts, good alignment and tire pressures, it’s staying on top of the tune as the seasons change.
“Your results may vary”...

 

[cbarge]

To be honest,my old 68 NYer 440 got 16.25 highway doing runs to Joisey to visit Steve Hobby average speed 62 65 MPH.
It had a 260/260 Purple shaft cam,23570R15 tires and 3.23 Sure-Grips.TTi exhaust and Pertronix ignition inside a recurved distributor,750 Carter marine carb.

 

[JIM ROPER]

I have a 1969 Plymouth fury 3 and it currently has a 318 and 727 with 2.91 gears. I've put a little work into it and the car runs and drives great right now but my girlfriend's uncle sold me a 1976 crate 440 and a brand new 727 for $500 and I couldn't turn that down. I don't really want to do the engine swap just yet because of how well it runs so my plan now is to run the 318 until it blows up. The car is my daily driver 90% of the year and I beat on her pretty good. It has a 8 3/4 rear end but with the stock open diff. I'm planning on swapping a posi into it at some point but I'm not sure what gear to go with. Currently I'm trying to choose between 3.23 and 3.55. On the one hand I'd like the performance of a 3.55 but I drive on the freeway pretty often and want to be able to drive 80 mph without sitting at the top of the rpms. At the same time I'm going to run whatever gear I choose with the 318 and the 440 so at the end of the day I'm going to need what's best for the 440 even if it isn't really the best choice for the 318. Anyone have any experience with running either of those gears on a daily? I'm basically trying to go with the best middle ground of driveability and low end performance.

Stop Stop Stop worrying about what rear ratio. I'll double your money on the engine and trans. LOL

 

[NewportRbod]

I agree with you on the definition of new but new is older than your new.

Still a 4 & 5 speed comparison to a 3 speed auto is a fair comparison. Hell at this point put 373s in and a gear vendors unit then let's compare.

I was wondering when the Gear Vendors OD/UD would get involved. Gear Vendors would be an ideal choice. There is easy access to Torque Flight tail shaft housings. The switch can be hidden easily. The unit allows you to split the gears, First to First high, Second to Second high, and Third to Third high (if used and set up for Overdrive). The biggest drawback is the cost. You can drive quite a while before you break even on cost. Now if you are rich or just won millions the fuel costs don't matter...All things considered do what is best for you. If anyone should come up with the perfect combination for all driving conditions you'll be famous. Until then it will be a series of compromises.

 

[polara71]

I knew a guy that installed one in a Challenger 15 years ago and swore id be buying one. I'm still eyeing up the GV unit and figure im two years away.
I am in the mindset that it'll be advantageous regardless of fuel money savings. High revs, wear n tear on other components , OD is the way to go.

 

[Turboomni]

What is the ball park money figure of a Gear Vendors OD unit and what does it entail to install? I would guess a custom drive shaft for starters. What rear ratio do most guys use with this OD unit? Would be the best of both worlds I would think.

 

[Snotty]

What is the ball park money figure of a Gear Vendors OD unit and what does it entail to install? I would guess a custom drive shaft for starters. What rear ratio do most guys use with this OD unit? Would be the best of both worlds I would think.

I just looked on the GV site. Since you didn't state what your car is I went with New Yorker, 727 18" tail-shaft, year 1966-78: Price : $2,895.00

​

 

[Turboomni]

Thanks Snotty. That gives me an idea. Not planning on it but was curious.

 

[twostick]

GV is pretty easy to swap. I'd start with a short shaft truck trans to keep the overall length as close to stock if I could. Keeps the driveline angle under control.

Kevin

 

[Turboomni]

Are there floor pan mods to be done with these?

 

[bluefury361]

[QUOTE="m0par0rn0car, I'm planning on swapping a posi into it .[/QUOTE]

OK.... First things first. One does not swap a "posi" into a Mopar. It's a sure grip.

Gears....? I'd leave the 2.70 but a 3:23 offers just a little more response at the sacrifice of fuel mileage.

 

[70bigblockdodge]

Overdrive is not for mileage, it's about 70-75 mph effortless cruising and no drone because the engine is loading at 2300 rpm, and yeah getting high teens for mileage. Getting passed by every grandma in a KIA soul because your car is revving 3500 rpm to go 70 mph is not effortless.

 

[James Romano]

3:23 with Sure-Grip and a stock 383. She got plenty of boogie-woogie out of the hole and on the highway. BUT... my gas mileage does suffer. Also keep in mind your tire size will make a slight difference in RPM as well.

I run 255/60r15's in the back and 215/65r15's up front.