NewEdgeStang00

Ordered 4.10s and extras today, but just read that some owners with 4.10s on an auto gt have experienced very jerky shifts.

My car on stock 3.27 is already jerky but when the ford tech drove it they said it's just because the gears are incredibly worn and need to be replaced (which is why I'm taking this opportunity for a rebuild and 4.10 upgrade)

Anyone else have good experience with there auto+ 4.10 rear?

My1stGT

have had 4.10s in my auto for a couple years now and have never had "jerky" shifts. only thing that changed my shifts was when i got a tune and tuner and changed my shiftline pressure

TRUEBLUE3934

I find it nearly impossible to believe that the gears are "incredibly worn."
Gears generally DON'T wear out. How exactly did this tech reach this conclusion? Did he open the differential and inspect the gears?

That being said, it doesn't matter much since you are planning to install new 4.10s anyway. It could be a factor in deciding whether to let that tech perform the gear installation and clutch pack rebuild.

The jerky shifting is far more likely related to the transmission and not the gears in the differential.

GOOD LUCK and enjoy the new gears!!!

zanypunk

Where did you get the idea that gears don't wear out? lol :P Well they do. The problem he's having has to do with clearance. The only way to find out is to take the pan off though, though the diff plug will tell how much metal piece it has been collected.
Note: 4:10 is horrible on the highway. Stick with the 3.73

NewEdgeStang00

Yeah he took the diff cover off and inspected the gears, said that's what's causing a howling whirring noise when I'm driving. Yeah I had originally thought 373 but so many people pushed me to 410 saying that it's OK on the highway. I figured just to go 65 mph my revs would be close to 2.5k revs, but everyone kept saying it's not noticeable so I chose 4.10.

How's your acceleration feel with 373? So many people on the forums kept saying they wish they did 410s so it's been like flipping quarters between the two..

TRUEBLUE3934

Agreed that any gear interaction will cause some degree of wear, but for the factory gears to be "incredibly worn" sounds highly suspicious unless the diff was either run with low fluid, or if the gears were removed in the past and re-installed incorrectly. This statement assumes that he doesn't have 200k miles on his GT.

The factory set-up will run 200K miles without problems if fluid is maintained.

OP,
Unless you plan to go for some boost later, I would get the 4.10 ratio and not look back. Your estimate of rpm at 65mph is about right. The only chances that you will dislike the 4.10 ratio is if you do a lot of highway driving (75mph+) or if they move your cruising rpm into a band where your exhaust drones.

You will LOVE the gears!

My1stGT

glad i went 4.10s. At 70 on the freeway im about 2700 rpm .

piledriver

I have 373's on my '03 Vert; ya can see my sig., Lots of $$$$ dumped into her since new in April 2003. About $18,000, not including the purchase price of 28K. That's around $46,000, still less then a Roush or Saleen, and there is only one like it , mine. The only solace I get is when I see the sticker price on 2012 'Verts; $42,000.00! Needless to say, I won't be selling her, I will just make her faster and faster, lol! I am 58 years old, it's my toy; I deserve it after putting 3 kids through College, those ungrateful bastards! But sorry, I degress. My acceleration is great with my 373's, I have a $1200.00 GPS unit, and when properly adjusted, I hit 60mph in 4.33, if I don't spin the tires....... and 100mph in 9.79. I have run the 1/4 in 11.94, but only once; I usually run in the 12.3's if I pay attention. I only use street tires, so with my 5 speed I'd have to shift into 5th gear running the 1/4, I don't want to do that! Redline in 4th is about 122-124mph, perfect for me right now, because I trap out @ around 116-118. If I increase the power output like I plan, I probably will have to go with 390's.When I shift into 5th at that speed, 124, she still pulls. I don't know about autos, but I do know that you WILL F-UP your tranny if you don't make the proper adjustments. I am a Dinosaur, so I don't know how to upload pics on this site. If you want to see my ride, go to Facebook and look up Ronald Thomas in Pawleys Island , SC. I have about 30 pics there; My profile pic is my Mustang. I will befriend you so you can take a gander.

WannaBeGearHead

Make sure you have a handheld tuner when you install the gears. Your shift points are going to need adjusted.

zanypunk

4:10 are great if you're going to drag race but as a daily 3:73 are pretty good on the highway. I would not flip a quarter, because that's assuming and I don't like to assume.