How much does it cost to change a gear set? I have 3.31s and Im buying 3.73s.. How much would a shop charge to do this? I have been told I shouldnt attempt it.

 

If it's not done correctly the gears will whine, so depends on how mechanically skilled you are. From what I've read, it seems like ~$400 is a pretty good median price

 

whew that is a ton... of $$$ that is just for install not parts?

 

If you've ever installed gears yourself. (And I've done them a few times) $400 isn't a ton. Believe me.

 

Yeah I found that out haha. I called around. Ford wants $900 for just labor. A tranny and axle shop wants $1400 with parts. That is ridiculous. I guess I will do it with my buddy. I will get the kit from Late Model...

http://www.latemodelrestoration.com/...r-End-Gear-Kit

$259.99 for everything I need... I think this will be okay haha.. Just got nice and slow...

 

I just put 3.73's in my '05 on Friday. Well worth the change as it drives harder down low and through the midrange, but you lose a little top end speed.

Gears will cost the better part of $200, 3 Quarts good quality Diff Oil close to $50, If you do the bearings & racers add another $80-$90 for the kit, and the labour will run at about 4hrs so dependent on hourly rate if paying a shop.

 

Your right, a car will always quarter mile faster the steeper the gear ratio. But, gears will do a car with lots of torque less good than a car with less torque. Just from my own experience I had an A body Buick with a 455 which was factory rated at 505 foot pounds of torque. I changed it from 342s to 256s and picked up 5 mpg and only slowed down .04 in the quarter.

 

And that should be an axiom of rear gear diffs:
The deeper (numerically higher) the rear gear ratio, the faster potential acceleration but you sacrifice MPG and top speed.
The less steep (numerically lower) the rear gear ratio, the slower the potential acceleration but you gain a potentially faster top speed and get better MPG.

Potential top speed for a given rear gear can be calculated. All you need to know is the tire diameter, your overdive tranny gear ratio, and your engine's redline

I use the word "potential" everywhere because what I said above is NOT a guaranty.

Also, another thing one should consider is the tires and the suspension set-up and his torque at take-off at the line form a dead stop. If you go too deep of a rear gear and your engine is making crazy torque at take-off, you could very well hurt your runtime, namely by your suspension being overwhelmed and your car begins rapidly hump up and down from wheel hop like a hamster in heat. Or, the torque in 1st gear with such a deep rear gear could put so much torque at the wheels that your tires will break free and burn-out instead of grip.

 

I've also had thoughts of putting in the 3.73. I just don't know if the price is worth it (juice is worth the squeez.