Gman13

Is the 4:10 ratio the one most recommended for the 05 manual GT and what are the advantages and disadvantages?

GMAN

CrazyAl

Yep, 4.10s are the recommended ones for the manual. (BTW, thats 4.10 : 1, not 4:10 in case you care -- as in the pinion makes 4.1 revs for every 1 rev of the ring)

Advantage: 15.5% more torque to the wheels through all the gears.

Disadvantage: engine revs go up by the same amount (15.5%), which means your gas mileage will suffer somewhat. Most guys report a fairly minor drop in mileage--maybe 1 MPG. It would be less of an issue in city driving, and more pronounced on the highway.

rerun

How are 4:10's on the highway, lets say a 6 hour trip?

Gman13

Thanks Al,
What would be a good or avereage price to have them done... parts and labor?

CrazyAl

Stick with the FORD brand gears becasue other brands are known to whine. They are about $180-190 most places.

The most basic parts required beyond that is a new pinion nut, crush sleeve, and some shims. Figure about $25 for that stuff, or if you want to do it right you need new pinion bearings in addition to those parts. Pinion bearings will add another $30 or so to that total.

The only other thing is gear lube. I understand it's fairly expensive from Ford. I used Royal Purple Max-Gear, which cost me less than $30 from OReily. If I remember right someone else had posted here that the stuff from Ford comes out to $50-60.

It's about a 3 hour job, so labor should cost you about $200. I'd say that anything under $250 for labor is reasonable. Above that, and something is up. I've heard of guys getting charged as much as $400 for the labor alone and that's just plain nuts IMHO.

That being said, I'd figure about $500-600 total, for everything.


4.10s work fine on the highway. The "issue" is just that your RPMs will be up a bit higher, so your mileage won't be as good as it would be with stock gears, but there's nothing wrong with highway driving.

rerun

Good post! So if one was in 5th gear crusing at lets say 90, what kinda RPMs are we looking at?

CrazyAl

Exactly 15.5% more than what you'd be doing with stock gears.


Stock tires are 27" diameter, so that's about 745 revs per mile.

At 90 MPH the axle is therefore turning 1118 RPM. Times 4.10, that puts the driveshaft RPM at 4582. Stock 6th gear is .68:1, so you're looking at about 3100 RPM

jerseystang07

the 4.10s are good for non-modified engines. when you start to modify your engine, the torque will increase and spin your wheels more, plus as someone said earlier, they will make you mpg go down. if youn plan on modifying your engine, just go with 3.73s but if you are going to keep it pretty much stock but with a little more of an edge then go with the 4.10s.

Timmay!!!

4.10s all the way!! At 80 I'm turning about 2700 RPM, 90 should be around 3000-3100. But I really haven't noticed any diff in gas mileage. Heck some guys who do nothing but city driving are running 4.30s but thats a little extreme for me and the mostly hwy driving I do. FRPP gears or nothing. And try to stick to a reputable or respected shop if you can for the install. Although I have no whine everything does seem a little louder since I had mine installed, but I can live with that. And take her easy on the break in. I went with 5 heat cycles and basically took it easy for 500 miles. After that I changed the gear oil again just to get any metal shavings (which there wasn't much of) out and swap in some royal purple.

CrazyAl

Keep in mind that suspension plays a big factor too. A properly set up rear suspension will go a long way to letting you run those 4.10s with a blower/turbo/etc. I wouldn't hesitate to use 4.10s on a modded motor--just do your homework and make sure that everything else is up to snuff: the diff, tires, rear sway bar, UCA/LCA, panhard, etc...