3.27 rear end gear

[87_ltd]

So I have recently found out that my car has the 3.27 gear ratio...
I was wandering if anybody could tell me the pros and cons of the different gear ratios...as i know nothing about them

[1987cp]

I have two cars with 3.27 rears, and I honestly like them pretty well. I find that they generally give a decent blend of putting the power to the road, so to speak, and keeping engine RPMs down at cruising speeds.

In a nutshell, going to a "lower" (numerically higher) gear ratio such as 3.73:1 or 4.10:1 will give your engine more mechanical advantage and therefore more effective torque at the wheels. This can be a big benefit in any heavy car, or if you want to have good acceleration with a small engine (as in a lot of FWD imports that have little low-end torque), or if you choose to build an engine that makes lots of power at high RPM. It's also common for trucks of various descriptions to use fairly low rear-end gears to increase hauling capacity.

Cons of lower gears include higher engine RPM at cruising speeds (you can calculate a theoretical new cruising RPM pretty easily), lower theoretical top speed, and the fact that you may experience traction problems in a light car with lots of torque.

A "taller" gear will lower your effective torque at the wheels. Its main benefit is that it's good for having lower engine RPMs at a given road speed, as with my old '79 wagon with a 2.26:1 gear that made highway cruising at low RPM very comfortable with a non-overdrive C4 transmission (it could actually go 70mph in First gear at only 5000 RPM), or if you have a light vehicle, an engine that makes power only at very low RPMs, need to remedy traction problems at low vehicle speeds (again, as with a light car with lots of torque), or want a higher theoretical top speed. Lower engine RPM per wheel speed, of course, also means, aside from the fact that the vehicle won't be going anywhere in any great hurry due to decreased effective torque at the wheels (said wagon was quite the slug off the line), that the wheels spin faster for a given engine speed, as I was reminded of when I got stuck in the snow in that same car with the 2.26 gear and found I had tremendous difficulty controlling wheelspin compared to the 3.27 gear I was used to.

All that said, 3.55:1 rear gears are a fairly popular swap among Panther-body owners, with 3.73:1 gears a little ways behind. I know of a smaller number of cars with 4.10:1 gears, but I'm pretty certain those cars are no longer driven daily.

[packman]

3.27s would be my choice of gear ratio over that of the stock 2.73s. With a conservatively built or more efficiently running engine with 3.27s, I would think that accelaration would be better than a lopo with 2.73s and MPGs wouldn't be too far down. It all depends on the kind of driving that you do.


Packman

[87_ltd]

thanks 1987cp, you sound like you know what your talking about...

[1987cp]

Nah, I just sound like it ... :p The real guys with knowledge on this stuff are the ones who've actually swapped their own rear gears at home. But Packman is correct, stock "lowpo" engines are about worthless above 4000rpm, and once you decide how to build your engine (if/when that's in the works), check your vehicle's weight (typically between 3600 and 4000 lbs.), and decide what if any transmission mods you want and how you intend to use the car, you can pick the gear ratio that'll be best for you.

[crown vic muscle]

i swapped out a 2.73 for a 3.73 and still get around 25 in my 90 cv.

[1987cp]

i swapped out a 2.73 for a 3.73 and still get around 25 in my 90 cv.

You have an odor. I still get about 16 max in both my cars!

[87DeuceVic]

Thread Jack, sorry, will the internals from the rear end of a fox body Stang fit in a Vic?

[gadget73]

Internals, yes. Its the same 8.8 rear in the middle. Axle shafts and the housing is different, but the guts work.

1987cp: EFI baby.

[Southern_Pride]

I did my 4.10 swap at home, and my car is not driven daily, but I have major tranny issues. Once I get all the bugs worked out and the car like I want it it will be.

[1987cp]

Internals, yes. Its the same 8.8 rear in the middle. Axle shafts and the housing is different, but the guts work.

+1, provided one gets only carriers designed for 28-spline axles. Stock Vic axles are 28-spline, as are stock Mustang axles (so far as I know, exceptions being wilder applications such as the '03 Cobra-R with the super-heavy-duty IRS), but Explorer centers I've seen on eBay are listed as 31-spline, and some Lincoln limo axles are also said to have been 31-spline, so if you get one of those you'll have to upgrade your axles to match.

1987cp: EFI baby.

Yeah, yeah, yeah .... :p

Maybe one of these days I'll build me a Quadrabog to see how it works ....

[mrltd]

+1, provided one gets only carriers designed for 28-spline axles. Stock Vic axles are 28-spline, as are stock Mustang axles (so far as I know, exceptions being wilder applications such as the '03 Cobra-R with the super-heavy-duty IRS), but Explorer centers I've seen on eBay are listed as 31-spline, and some Lincoln limo axles are also said to have been 31-spline, so if you get one of those you'll have to upgrade your axles to match.



Yeah, yeah, yeah .... :p

Maybe one of these days I'll build me a Quadrabog to see how it works ....

and by "upgrade" he means get some custom made

[87DeuceVic]

Oh, ok thanks guys

[82LTDQS]

Ok I have a Low Po 5.0 for now. Im planning on a high Pow with carb conversion Blah Blah Blah, The usual. I have the stock 3.08 rear end and I want to put in 3.73's now just so I wont have to do it later. How will my low po drive with the 3.73's?? Should I wait?? I dont do any highway driving. Will it be unbarable?

[gadget73]

it'll run its ass off with a 3.73. Its not bad on the highway either if you've got an AOD.