What's you favorite gear ratio for the street?

[RiverRaider]

3:55 for big block and 3:91 for small block with 8 3/4 has worked well in the past for me.

 

[#41]

It used to be 3.55 when I lived in the City. Now I have to jump on the highway to go anywhere so all cars have been geared down one step making 3.23 kind of my go-to gear. My fragile ego can't handle getting passed on the highway by a Kia, Hyundai, minivan, etc.

 

[Coelacanth]

In answering this question, it's important to mention tire height as that affects the all-important RPM-on-the-highway issue.

I also want to move to a stouter gear ratio than my current 3.23's (383 Magnum w/727) and for months I've been torn between choosing 3.55 or 3.73. I bought US Mags Indy 101 slots to put on the car next spring, with 275-60-15's, which are 28" tall...a fair bit taller than the original tire size, so that will play a part in my choice. How do 3.73's feel at highway speeds for RPM on 28" tall tires? I will mostly be driving around town but will do the odd 2-hour highway drive.

 

[hdwrench]

interesting topic . i’ll be having to make this choice soon enough. got a few centers to choose from , they seem to be getting a little hard to find ! ( or able to buy )

 

[33 IMP]

In answering this question, it's important to mention tire height as that affects the all-important RPM-on-the-highway issue.

I also want to move to a stouter gear ratio than my current 3.23's (383 Magnum w/727) and for months I've been torn between choosing 3.55 or 3.73. I bought US Mags Indy 101 slots to put on the car next spring, with 275-60-15's, which are 28" tall...a fair bit taller than the original tire size, so that will play a part in my choice. How do 3.73's feel at highway speeds for RPM on 28" tall tires? I will mostly be driving around town but will do the odd 2-hour highway drive.

Kinda depends on what your "highway speeds" are. Are you comfy at 65? My part of az has speed limits of 75, and everybody is doing 80-85, and 90 is not uncommon. (Roughly 150 kph.)
You can calculate your rpm at a given speed, knowing the gear ratio and tire size. You have to allow for some slippage in the converter.
Your rpm with a 3.73 and 28" tires will be between 3150 and 3300, depending on how sloppy your converter is. 3.55s will run about 200 rpm less at the same speed, same tire.
At one time my daily commute with a 4.10 geared road runner was 25 miles one way, at 70mph and 3700 rpm. I don't think I'd like to do that anymore.

 

[AR67GTX]

With my stock 67 440 GTX auto and 215/75-15 tires, in first the tires would stop spinning and hook before the engine was quite high enough on the torque and HP curves to prevent a bit of sag or slump in acceleration while the rpm’s built back. With the 3.55 I put in it, the tires spin longer and by the time they hook its up, the rpm’s are high enough on the torque curve such that the acceleration just seems to transition and build without any sag or slump. So with that size tire and a stock engine but slightly looser than stock converter, a 3.55 seems to be all the gear the car, motor and transmission needs to run strong and near optimum. Yes, with more gear it would have more snap and acceleration but at the risk of highway capability.

With a stock size 14” wheel and tire, a 3.23 may do just as well. My 2 cents.

 

[Coelacanth]

Thanks 33 IMP, I like that answer. Too many times, I see guys answering this question but neglecting to mention tire height. It's not a meaningful answer if tire height isn't indicated because it directly factors in the acceleration, top speed and RPM equations.

 

[1970Bee]

I have 3.91 with 275 60 15 tires (29” or so?). Brother and I drove it from Denver to Louisville, and I didn’t find it objectionable on the highway.
Everyone will see this differently, but if performance is important to you, I think not enough gear is more frustrating than a bit too much gear.

 

[33 IMP]

Thanks 33 IMP, I like that answer. Too many times, I see guys answering this question but neglecting to mention tire height. It's not a meaningful answer if tire height isn't indicated because it directly factors in the acceleration, top speed and RPM equations.

I learned the hard way to take tire size into account when selecting a gear ratio.
I had 4.56s in a V8 Vega, that would not pull past 6 grand. After I blew it up, I decided to find out why. Took the 1/4 mile speed, 24"tall G60-14s and 4.56s, and found out why it wouldn't pull past 6. The tach was LYING to me.
Speed/rpm calculated to the high side of 7500, while the tach said 6000. Cast pistons don't like 7600 much.
Now my current small block car with 4.57s..... has 32"tires.
And my big block car is gonna get 4.10s...... with 31" tires. (Or maybe the 33s I have too.)

 

[Coelacanth]

I have 3.91 with 275 60 15 tires (29” or so?).

Thanks 1970Bee...just to mention a 275-60-15 tire is ~711 millimeters tall, or a hair under 28". 27.992" to be exact...unless over-inflated.

 

[1970Bee]

Thanks. I’m on my third pint of a nice British ale atm. I’m not mathing well right now. In any case, I didn’t find it objectionable on a long road trip

 

[Coelacanth]

Thanks. I’m on my third pint of a nice British ale atm. I’m not mathing well right now. In any case, I didn’t find it objectionable on a long road trip

No worries. Just when I'm almost ready to settle on 3.55's, someone like you posts that 3.91's are okay on the highway, and makes me want to split the difference and get aftermarket 3.73's for my 275's...

 

[70ChargerRT]

Man I don’t think there is a better gear set combo out there than what I’m running. I’m using a Close Ratio T-56 Magnum with 3.91 gears and that set up is just wicked. The gear set in that close ratio is as follows . 2.66, 1.78, 1.30, 1:1, .80, .62. It was worth cutting my tunnel back in 17.

 

[Detective D]

In BFE WI, where all it is basically is 55mph highways and open roads(if you stay off the main corridors) 3:23 is where it is at. Especially for big blocks, gets off the line acceptably well, and gorgeous power/drivability on the highway. Even small blocks can rip at highway speeds with that ratio, they just suffer from the stop sign a bit more.

Also, Mopar put that in the cop cars, I figure they knew what they were doing

As Kern Dog said, add a gear or two and it alters the whole thing.

 

[Dennis H]

3:54 Dana w/SST TKO 5. 2150 @ 72 MPH. Sweet roll on spot, run with modern traffic, still smoke em on demand.

 

[kiwigtx]

My '70 GTX was great with 4.10:1 and 4-speed was awesome around town. Got a little noisy on a long run, and made the big block rev hard. But around town it made for easy driving and terrific 3rd gear burnouts. Managed 13.5 sec run at around 107mph - enough to help my team win the Club Champs back around 25 years ago.

My '70 Road Runner was kitted out with a 440 and 4-speed....with 3.23:1 rear gears. That was a little hard on the clutch, but made for awesome top speeds on the open road (back in the days when cops had less radar, and not as many speed cameras). I also set a New Zealand land-speed record in this car for towing a BBQ Trailer - reaching 140mph before running out of road.
The RR also did great 3rd gear burnouts when required.....quite hard on the drivetrain, but it worked.
This car was also the one where I did the first & last Full 1/4-mile burnout at the local dragstrip. I have video proof of that day and a neat picture.

Now to my '68 Dodge A100 - these were never built for speed, and I can see why .....all the aerodynamics of a brick (worse than the Space Shuttle ever was) and a loose rear end that needs careful control. Running 3.23:1 gears in it now behind the BluePrint Engines 408 stroked 360 block, it run hard and *****.
Achieved a 13.07 @ 103mph and gave me a boost knowing I was knocking hard on the door of 12's. Initially I had set this truck up with the 4.10:1 ratio out of my GTX, but that proved too hard driving any distance, although I could get through a set of traffic lights and be in top gear before I was across the intersection....lol

The next two photos were taken some 30 years apart at the same location just a few kms from home......

 

[Budnicks]

I had 3.73:1 in a 8.750",
didn't notice any loss of power or difference in the 1/4 mile performance either
from a 3.91:1 gear, barely a difference from a 4.10:1 too...
(like 2,800 rpm w/3.73:1 - 2,900 rpm w/3.91:1 29" tire, freeway at 65)

I preferred to run 'steep gears' in my cars, taller tires/wider too usually,
bigger contact patch...

Back in the day when gas was $99 or less, I ran 5.13:1 in my 68 Charger R/T
nobody beat me 'out of the hole' & as long as you didn't go too far on the freeway
it wasn't as bad as some would think 3,700-3,800rpm at a constant 65,
29.5x10.5w's on the rear, cut them down a bit, with a J converter & 4200 stall,
it was a great gear...
I went back roads mostly, wasn't concerned about milage, I wanted the best performance...

People are 'pussified' today, or just getting old, acting like it too
or whine, want to influence others in what they have & what they want (you) to do (followers),
for you to accept them & their style of builds...
I never did get that ****, I build my cars for me, not by committee
or to appease some other crowd...

Now, I'm not into driving a bunch of freeway miles, in an old muscle car anyway...
Got other cars/trucks for that ****...

I ran anything from 3.23:1, 3.55:1, 3.73:1, 3.90/3.91:1, when mostly street driven/cruising
or 4.10:1, 4.30:1, 4.56:1, 4.88:1, 5.13.1 if I knew I was gonna' race like Friday or Saturday nights
I had the gambit of gears, you name it I had it, with a sure-grip or spool
I got from an old racer clearing out his shed, Bill Stammerjohn, (spell)
a Sacramento guy who was well known for MoPar engine builder, cylinder heads & porting

There's nothing like gear ratio to get a heavy car moving quickly
I always ran big tall rear tires too, 1st was N50/15 were
like 27.5" to 28" depending on what brand or what width or rim etc.
a lot taller than the 14's x 24"- 26" you could get at the time, these cars came with...
Than later when better wide tires, better compounds came out,
I ran the tallest/widest tires I could fit some 30"s mostly 29" or 29.5",
on my many RRs or Chargers'... It helped cut the gear ratio a bit
& for more MPH, less trap RPM" it was always about the 1/4 mile",
not posing by my car at a show or a cruise...

Now I'd go with a lower 1st gear ratio to get that 10:1+ combined gear needed in 1st
& run a milder gear for speed, like a 3.55:1, 3.73:1 or 3.91:1
or an over/under drive like a gear-venders,
But they are expensive, so is a manual OD conversion, 5-6 speed
when I was younger; there's no way I'd have afforded that ever
barely want to even spend that now
IMHFO takes the fun out of it too, these old muscle cars
are supposed to be a lil' obnoxious
unless you are driving nothing but freeway mile,
then why do it ?
You only live once, enjoy it...

MY Pro-gas 49 Ford I ran 4.88:1 w/33"x 18" tires, drove it all over the place
even down the freeway, did many a cruise night in it, many 100+ miles away even...
Concord to either San Jose, Cupertino, Fremont, Fairfield, Modesto or to Sacramento, even Reno
I drove it to Pheonix, from Concord Ca. for
(did it & won it in my 67 Camaro S/C a couple years earlier too)
Super Chevy Sunday "Worlds Fasted Street' Car" race, in 1989-ish 1st
3,100#s 477cid BBC 4.5" bore 3.75" stroke, .880" gvl roller on alcohol injected
(Methanol at the track only) Tunnel-ram with Enderle hat, 80a pump
had gasoline nozzles in it, for the trip down,
so I could get fuel along the way at the pump
then changed to Alky nozzles, at the track
(later & then 1995-ish a 526cid Milodon Hemi, Blown Inj Hemi, didn't drive it down then,
just the 20 mile loop we had to do & restart after it, it was towed, still had the 4.88:1 gear
a lot more heavy hitters showed up in 1995 era, I took 3rd, but I broke a rocker in the semi's
running 7.90's at 180-ish, next guy up/fastest loser, took my place in the finals)
Mikes Transmission Powerglide 4,500 stall/flash to 5,000,
tight converter in high gear for N2O,
but wasn't running any N2O, 16 Gal. cell was a PITA way too many stops
89-ish I won the class too, 8.98 @ 160-ish black-tracking the whole damn way
(it'd run high 7.90s at like 178-ish on 33" x 15" slicks)
I wasn't as bad as some may think, 3,300 rpm on the hi-way going like 65 mph
it got like 13-14 mph if I was being cool, I was surprised...
didn't need no OD ****

Right now my car 68 RR street beast, has a 3.23:1 gear & sure-grip
near 28" rear tire P295/50/15 on a lil' narrower wheel
good for up here driving country roads, not to steep or too high

I do need an overdrive, if I want to drive long distances, not really in my plans
maybe a Gear-venders OD
I'd like to go to a 5-6 speed manual, but not spend $10k
on a trans, clutch, peddle, MC, driveshaft & gears, after all's said & done
or to have to hack the tunnel...

 

[6PKRTSE]

I have 4:11's in two cars, 4:10"s in one car, 4:88's in one car, 3:91's in one car, 4:10's in one truck, 3:54's in another truck. All other cars have 2:XX highway gears.

 

[Black_Sheep]

I answered 4.10’s in a previous post, I would like to add that this is with 295/65R15 Drag Radials which are 29.5” tall. Mathematically it is within 75 rpm of 3.55 gears with the factory F70-14 (26.2” diameter) tire.

In my ‘58 Apache I run a 3.55 gear in an 8 3/4 Mopar rear with 235/70R15 which are 27.95” diameter. It’s a little over 3000 rpm at 70 mph. But in all honesty, an overdrive transmission would be more ideal. The Chevy has a 454 with a RV cam that makes great torque from off idle to 4500 rpm and a stock converter, with OD it would be around 2100 rpm at 70.

The GTX has a 440 with a .509/292 cam and an efficient 9 1/2” converter. The cam starts coming strong around 3300 rpm which coincides with what the converter flashes to. It does just fine on the occasional trip running 70 mph down the interstate because it’s up on the cam, and under part throttle the converter is pretty tight.

My point in all of this is that you need to consider the entire combination and it’s intended use. Personally I’d run a 3.55 gear with a stock or mildly built big block B Body and something like 275/60-15 rear tires. It would be a well mannered street machine that could roast the tires at will. More cam or converter would need more gear. It depends on how far down the page you go…

 

[polywideblock]

3:23 roadrunner
3:54 charger