05 Mustang

good information!

cedarmn

I am more confused then ever. I found the sticker but mine shows "CD" under axle. Any idea what gears I would have now?

OSUTX440

BG — 3.31 — non-limited slip
CD — 3.55 — limited slip
CG — 3.31 — limited slip

I found these just by google.

cedarmn

Sweet, good find OSUTX440. Now that I know this I'm thinking 4.10's are in my future. I do not think I would notice 3.73 enough to warrent the change.

Now I worry about the gear wine. Which brand have you guys had success with?

drewsky

Ford racing is the ONLY brand to use via the differential specialist that installs them on mustangs on a daily, all other brands are subject to whine. They made a big deal if saying the fords are some of the toughest gear installs there are, they have to be pin point perfect or they whine and click. From 3:55 to 3:73 you will not notice any difference at all and just wish u went 4:10!! Fact! The sticker in the door will say "CD" for 3:55's from the factory. I only dropped about 1 mpg overall 50/50 city and freeway, and for the bang for your buck it's totally worth it! Gas in the city improves a little due to keeping the engine in the correct rpm without having to downshift.. I believe (and this is strictly my own theory) that it's better for the engine due to it not bogging down from time to time, it gets a few extra revs however it's "easier" on the motor to move the car...Again this is just my own theory!!! But it seems to make sense if you think about it. Get some good tires and never look back. Totally worth it and you won't regret it for a second. Kinda ranting on but I hope this helps out.

OSUTX440

Agree with Drewsky on the FFRP gears.

But my question would be what do you want to do with the car? Track it, auto cross, and DD.

IMO, 3.73's are strong enough and will put you in your seat.

cedarmn

Thanks for the question. My car is nothing more than my toy to cruise around on sunny days. I only insure it 4 months a year and put 3000 miles on a big year. I can't resist linning up with some guy in their ricer car when it is available though. Mostly I like to drop the top and take the wife for a spin.

no track or auto cross for me.

The way I'm thinking is 4:10 is like having a blower. You may not need it or use it regularly but when you want it they are there and you are glad you have them...

Am I out to lunch? Any advice is wanted

wcgman

I've done 4.10's in 3 mustangs. It's a very large difference. You will need a new tune. Only use FRPP gears and make sure you have the mechanics put friction modifier in. 4.10's aren't quite as impressive as a blower, but they do make a huge difference. I'd say ignore the naysayers of 4.10's. Totally driveable. Took my '10 that was M90'd as well from Denver to L.A. running 110 on cruise control across the empty open stretches of Utah and back and it was fine even with muffler deletes. I think I have my wife sold on 4.10's for her 'vert but I think in the snake it would be unusable because Im breaking traction thru 3rd. Until I get that figured out, no gears in the Shelby. I also used all my stangs with 4.10's as daily drivers.

drewsky

If you go 3:73's you will drive home from the shop wishing you went 4:10's.. The deffierence is hardly noticeable from a 3:55. I'll add on what I said about the ford racing gears also, the diff shop uses Yukon and are a licensed dealer. HOWEVER in all fords they use FRPP gears, that should tell you something haha. I'll take their advice, had mine in for almost two years trouble free!

CPTCO

I did 4:10s a while back. I find that my car is a lot more driver friendly in town and on the highway. Even after supercharging, I don't regret the choice.