Hello All,

I am somewhat new here and I can use some help. I've had my 2004 Mustang GT for 4 years now and so far the only thing I've done was a K&N CAI. Basically it's all stock and also an automatic.

I want to do some mods and the first thing that comes to mind and within budget is a 3.73 rear and my first cosmetic mod I want is to lower it by 1.5".

I raced it once at ATCO in NJ and my fastest time is 13.9 at 99mph.

My questions are...

What are the positives and negative of installing a 3.73 gears in an auto?

The only neg that comes to my mind is losing top end speed. I rarely go near 120 mph so I am not bothered by losing top end, or should I be?

A buddy of mine actually told me my car would be slower all around with 3.73s. Correct or incorrect?

My final question is, if you had 2K and your car was stock what would you do?

I am not mechanically savy with cars, the only things I can do are...basic tune-ups, brakes, and detailing.

Thanks for your help

Here's a pic.

 

Use that 2k and start shopping for a used supercharger kit. The best thing to do with that 2k.

Your buddy probably doesnt know what he is talking about. You have come to the right place.

I have 3.73's in my auto mustang and have gone 118 in the 1/4 mile

You will pick up about 2-3th's in the 1/4 mile with 3.73 gears IF you can get the car to hook up on launch.

At 75 mph you will be around 2500 rpms but my car is more quiet at that rpm.

I have taken my mustang to 173 mph on the autobahn...You shouldnt be worried about top end.

Should cost around 200-350 for a shop to install the gears.

 

Thanks, looks like gears FTW.

I never believed my friend but he swears on this because he had new gears installed on his Caprice and the shop IMO did a bad job. Like I said I am not very knowledgable on this stuff and feel this forum is the right place to answer my questions. Plus this sticky here on this forum also confirms that I want the gears. https://mustangboards.com/general-te...ification.html

I am going to wait on the SC though as I want it brand new and I think (not sure) I should also upgrade the top end of the motor ( heads, cams, etc..) first before the SC.

Should I tune it to 93 octane with the new gears or does it not matter?

 

Your car looks nice and the lowering springs would definitely be on my list. I will say that while 3.73 gears would be a nice upgrade the majority of auto guys go with 4.10's. And since you asked for negatives as well, it will have some effect on fuel mileage.

 

^Thanks and nice car. Looks familiar

One other cosmetic mod I thought about was changing the hood (I hate the fake hood scoop), but that can wait.

Now I don't know if this is true or not but I've heard people say that cars with automatics are better off with 3.73s and only because of the lack of that one gear (5th), because at higher speeds with the 4.10s we get a loud whirring noise coming out the rear from the gears spinning way too fast

 

Will be in the shop next week for the following

Ford Racing 3.73 ring and pinion

Eibach Pro Spring Set 1.5" w/ alignment

Thinking about the next MOD 70mm throttle body and under pullies.

Question: do I need a new MAF sensor with the 70mm throttle body?

 

No.

 

I`ve just bought 4.10s today. They`re not installed yet but I`ll give my honest impressions/opinions when they are.

 

Very nice! Take it from me (I have Eibach Pro's) you will need caster camber plates to get back into alignment. If you don't you will be driving on the inside of your tires. I got a whopping 15k miles out of a brand new set of Nitto NT555's by running with -1.8 degrees of camber.

 

Well the car is in the shop today...already looking forward to getting it back. I told them at the last minute about the caster plates and said, whatever it needs to ride right with the new springs, do it.

Thanks everyone for all your help.

 

Make sure you get some before and after shots of the lowering springs, please.

 

A few cheap cosmetic mods are fun too. It made my car a little different from the other ones in my area, but there aren't many mustangs here compared to down south

Ideas: mach 1 chin/ grill delete, rear blackout, tail tint, new headlights (fairly cheap on ebay)

 

SO the car is 90% done. They need to order the castor camber plates and then Tuesday I take it back for the alignment and the installation of the plates. Oh and I am having them tune it to 93 octane

I do have her back and I have to say two things...

I feel a slight significant change in the pull and shift points and I barely noticed that it was lowered until I am next to it looking at it. In the future I can lower it again or just get 18" rims

What I need to do now it take it to the track and see if I can beat my fastest time.

 

Have you done any mods yet? Have you lowered it? Coilovers?

 

Thats from 3.27s to 3.73s? I`m going 4.10s so hopefully it`ll be more than slight for me

Stick a pic up mate

 

I have always heard you feel the most from 4.10's...

but for a daily driver 3.73's seem to be the best for hwy