will a 4.10 ring and pinion really make it that much faster?

Question

everyone's telling me to put either a 3.90 or a 4.10 gear ration in my 99 dodge dakota 3.9L auto. will it really make it that much faster and about how much mpg will i be getting?

Answer 1

It is gonna raise your cruising rpm on the freeway about 900~1000 rpm. somewhere in that range. I had 4.10's in my 01 Dakota 4.7 and didn't realise any significant drop in mileage. Of course my truck with the other mods was much quicker accelerating! Top end speed? You are gonna probably not have to worry about....as I don't believe you are gonna be able to pull 6000 rpm in overdrive anyways..( overdrive is a .69 ratio ) that would math out to something like 165 mph with a 26" tall tire with 4.10 gears...
One more thing..if your gonna rev that motor higher than stock, your gonna need to breath..headers,camshaft, k&n air intake, and I would either find an aftermarket intake manifold or modify the stock one by shortening the runners 2~3 inches.. this will give more power up top.

Answer 2

Actually a 3.90 or 4.10 gear will slow the car down. The lower ratio (higher numerically) will increase acceleration, but you will decrease top end and mileage. The lower gear ratios are more suited for drag racing than for street use, particularly if you're seeking better mileage. I'd stick with whatever ratio the factory installed, unless you're planning on taking your truck to the drag strip.

Answer 3

Your vehicle will accelerate much more quickly from a standing start, as in drag racing where that is, or used to be, a common rear end ration. You will not have as high a top end, however. If you want fast on the bottom, go 4.ll to 1. If you want faster on top, go down in ratios. The closer you get to 1 to 1, the faster on top, the slower on bottom. The 4.11 will also cut your mpg somewhat.

Answer 4

It'll be about like driving around in 2nd gear.

I dunno if your truck has a 2nd gear position on the shift selector?

But take any vehicle that Does,,lock it into 2nd,,,go drive about 50mph and punch the gas.
Thats APPROX the effect of a 4.10 gear

Or in a Standard Trans/Stick Shift,,it's about like cruising down the road in 3rd gear of a 4 speed.

It changes relationship of Engine Speed to Road Speed.
You get More Pulling Power,,QUICKER acceleration..
But Lower Top SPEED.

At any given ROAD speed,,,the Engine is running Faster with a 4.10,,,
than with a Smaller Numbered Gear,,,like 3.50 or 3.00

Fuel mileage will take a beating,,,same as if you drove around in Any gear Lower than Hi Gear.

3.90 and 4.10 is considered a very "LOW" rear axle ratio with an Auto Trans.

Probably Lower than your current gear.

By switching to the Lower Ratio/Higher Number rear-end gear
You can expect better acceleration,but Lower Top Speed,,,
and worse fuel mileage due to engine turning MORE TIMES per given distance.

The Difference in Fuel mileage is tuff to say,,,
but it is somewhat proportional to the percentage increase in engine speed.

ROUGH,approximate Example:
Say your truck Now cruises at 60mph at 2500 engine rpms.
To Lower the Rear End Ratio 20% would raise rpm about 20% to around 3000 RPMs.
That's gonna yield APPROX a 20% Drop in gas mileage.

At $2.50/Gal,,,
EACH MILE you drive would cost you about 5 Cents More per MILE

IF you were getting 20MPG,,,it would drop to about 15~16mpg
5 Gals per 100 Miles= $12.50
12.5 Cents per Mile
Drops to about
7 Gals per 100 Miles= $17.50
17.5 cents per mile

A 2 Gallon/ $5 Loss per 100 miles

** The Mileage Example I used,,is The Very Roughest Approx.
Just to illustrate the RELATIONSHIP between the 2 different rear end ratios.
OFTEN,,the results are far Worse.
Sometimes,,it's actually not so bad.
There's a bunch of other details & variables involved.

But a Lower Rear End Gear can safely be considered to ALWAYS hurt overall fuel mileage

Hope that helps.

Answer 5

it will make the cars accelration climb dramatically you would lose a little top end speed but you will never see this unless you drive your truck up to its maximum speed all the time, your normal free way top end will be fine....the steeper gear is a torque multiplier and will get you into the powerband quicker, the only way you will lose any fuel mileage is 1. if you drive on the freeway ALOT you would lose like 1 mpg thats it or if your driving around and launching hard everywhere you drive

Answer 6

if you put taller tires on the truck a 4.10 will bring it close to stock

if you run stock size tires, a 4.10 will give you a quicker start but lower your top speed, it will also cause your engine to run at a higher rpm during normal driving, decreasing your gas mileage and causing more wear on you engine

Answer 7

everyone else explained how gear ratios work, if you want a faster ride, get something other than a V-6 Dakota.

Answer 8

Not faster --Quicker

0-whatever gets quicker --top end speed lower

Gas mileage decrease dramatically

Answer 9

The larger ring gear will not make it faster, however it will make it llaunch from teh line easier. It will also drop your mileage

Answer 10

radar examine it first the speedo kit is interior the trans and available from the exterior of the trans/you dont could the touch speedo itself because of the fact the form of tooth on the trans cable resets the speedo