gt gears 3:31 and 3:55

nyers · Sep 4, 2007

Hi
I'm looking in to buying a GT manual trans. There is the option to get 3:55 in stead of the standard 3:31 gears.
Any body really know what this does in terms of MpG and acceleration is it worth the extra buck. My car will be a daily driver with some mods later ( down the line a year or two)

partsbill · Sep 4, 2007

the difference in MPG from 3.31 to 3.55 is hardly noticable, I do alot of highway driving and I like the 3.55 ratio, it's a good all around gear for a manual trans,
if you don't do alot of highway driving and most of your driving is in the city then save your money and go with a 4.10, the acceleration is alot more noticeable.

05wolfkiller · Sep 4, 2007

it also depends on your mods in the future. if you plan on keeping your car n/a, and you dont do a lot of highway driving 4.10 would be great. i have 4.10s now but plan on adding a s/c in the future. i will then go w/ 3.55s. but if you have an option b4 you buy the car i would go with 3.73s or 4.10s. you wont see much of a difference by going from 3.31 to 3.55. good luck

stang8urimport · Sep 4, 2007

Save the money for the 3.55s and have 4.10s put in. 3.55s sound good, but these cars like to rev, and they are dogs even with the optional 3.55s.

gt06 · Sep 4, 2007

What was the option code for the 3.55"s?

87fcoupe · Sep 4, 2007

PoopDawg said:
Save the money for the 3.55s and have 4.10s put in. 3.55s sound good, but these cars like to rev, and they are dogs even with the optional 3.55s.

+1

Gearbanger 101 · Sep 4, 2007

05wolfkiller said:
i have 4.10s now but plan on adding a s/c in the future. i will then go w/ 3.55s.

Don't bother....stick with the 4.10's and don't look back. The only time you should ever considering gearing back is if you 're stringent about fuel economy, or running out of usable gear at the end of the quarter mile.

MM&FF's project car MILF (Mustang I’d Like to Flog) makes over 500hp with the intercooled version of the FRPP blower kit, and runs mid-11’s with 4.10 gears. They stated that under normal driving, it’s completely docile for street use.

4.10's and XCal tune will probably be my first mod when I get mine.

kooldawg6 · Sep 4, 2007

I have the auto and the 4.10s. They are great for DD I have nearly 13K miles on mine since March and I've only dropped about 1 MPG on average(went from 3.31 to 4.10).

Gearbanger 101
4.10's and XCal tune will probably be my first mod when I get mine.

Will run you about $900, but WILL be a huge perfomance gain you will feel for sure

Bikerdrumr · Sep 5, 2007

Seinfeld fans?...

Mr. Costanza to George... "So you got the 3.31's, ...3.55's, ....3.73's, ...and the 4.10's. THAT'S the biggest."

Sorry, but I couldn't resist.

Seriously, you can get the 3.31 or the 3.55 from the factory. The others (I'm assuming) you can only get aftermarket. Now, my car will be ordered in a couple of months, and I'm thinking 3.55's or I'll get 3.73 if it's reasonable in cost and install. For MPG I'm staying away from 4.10's. (I drive at least 80 miles a day.) So the question I have is how easy is it to install yourself? I do basic stuff around the garage, oil & trans fluids, tire rotations, brake jobs and such.

Thanks.

gashog · Sep 5, 2007

Bikerdrumr said:
Mr. Costanza to George... "So you got the 3.31's, ...3.55's, ....3.73's, ...and the 4.10's. THAT'S the biggest."

Sorry, but I couldn't resist.

Seriously, you can get the 3.31 or the 3.55 from the factory. The others (I'm assuming) you can only get aftermarket. Now, my car will be ordered in a couple of months, and I'm thinking 3.55's or I'll get 3.73 if it's reasonable in cost and install. For MPG I'm staying away from 4.10's. (I drive at least 80 miles a day.) So the question I have is how easy is it to install yourself? I do basic stuff around the garage, oil & trans fluids, tire rotations, brake jobs and such.

Thanks.

Mr. Costanza: You know about the... cups?

I would take it to someone. It is a pretty involved procedure.

Casey4s · Sep 5, 2007

kooldawg6 said:
I have the auto and the 4.10s. They are great for DD I have nearly 13K miles on mine since March and I've only dropped about 1 MPG on average(went from 3.31 to 4.10).

QUOTE]

That is good news for me to hear, I also have the Auto Trans and was thinking about 3:73 gears with a Posi unit but was afraid it would be too low for an automatic and kill gas milage. How do the 4:10's do on the open highway, at 65+ MPH? You don't feel over-reved?

kooldawg6 · Sep 5, 2007

At 70 MPH it revs just under 2500 RPM.
I drive 64 miles roundtrip to and from work(14 days/month). When I drive up to MD(about 3 times/week) it's almost 140 miles roundtrip. I'm glad I didn't do the 3.73s.

MikeysOTP · Sep 5, 2007

Y ou might want to try negotiating with the dealer to install the gears for you. When I bought mine I paid the dealer for parts only and they put them in before I took delivery of the vehicle. It saves you a couple hundred in labor costs and the dealer is able to absorb the cost a lot easier since they are just paying the mechanic. FWIW, I have 3.73 with a stick shift and 18" wheels. I think I would have been happier with 4.10s but at least if I ever get a supercharger these will probably be just right. I drove the same car with 3.55s and 17s and it seemed much quicker, I think the 18s slow you down (heavier?? bigger?? don't know for sure) so keep that in mind also in case you go that route.

Casey4s · Sep 5, 2007

kooldawg6 said:
I'm glad I didn't do the 3.73s.

You are? Why?...

I am still thinking 3:73's, the 4:10's still seem awful low to me. There is also a 3:90 available for the 8.8 rear end, maybe that would be a good compromise. At a parts dealer I was just looking at it says that the 4:10 is not for sale or the be used on smog controled vehicles go figure...

kooldawg6 · Sep 5, 2007

Casey4s said:
You are? Why?...

I am still thinking 3:73's, the 4:10's still seem awful low to me. There is also a 3:90 available for the 8.8 rear end, maybe that would be a good compromise. At a parts dealer I was just looking at it says that the 4:10 is not for sale or the be used on smog controled vehicles go figure...

I will be stepping up my rear tire diameter 1" so that will affect the ratio a bit. It will effectively make the ratio <4.10 compared to the stock sized tire.

Funny about the 4.10s not to be used on smog controled vehicles You can get them in the Ranger, Explorer and F Series right off the lot.

Casey4s · Sep 5, 2007

kooldawg6 said:
I will be stepping up my rear tire diameter 1" so that will affect the ratio a bit. It will effectively make the ratio <4.10 compared to the stock sized tire.

Funny about the 4.10s not to be used on smog controled vehicles You can get them in the Ranger, Explorer and F Series right off the lot.

Hmmm.... well I am going to 18" wheels this week myself, I am just waiting for the tires to arrive. But my diameter will actually shrink by about 1/2" I am going from stock 235-55x17 to 285-35x18 in the rear, so the 3:90 might be a good choice. Geeze .... the more I think about this the more confused I get LOL I made the mistake of too low of rear gears once before, I had 4:88's in an Automatic '69 RoadRunner, it ran great on the strip but was a tough daily driver. I don't want to get in that kind of predicument again LOl

kooldawg6 · Sep 5, 2007

Don't think you will have that problem with anything between 3.73-4.10 in the auto Stang.
So if you are going shorter, then the 3.90 may work great. I know I can still hit 130 MPH(she was still pulling, but I never glanced at the tach to see how close she was to redline-only the speedo and wisely backed it down) so that is definitely more than fine by me

Gearbanger 101 · Sep 5, 2007

Casey4s said:
Hmmm.... well I am going to 18" wheels this week myself, I am just waiting for the tires to arrive. But my diameter will actually shrink by about 1/2" I am going from stock 235-55x17 to 285-35x18 in the rear, so the 3:90 might be a good choice. Geeze .... the more I think about this the more confused I get LOL I made the mistake of too low of rear gears once before, I had 4:88's in an Automatic '69 RoadRunner, it ran great on the strip but was a tough daily driver. I don't want to get in that kind of predicument again LOl

Don't beat yourself up over it. The difference between 3.73-3.90-4.10 is all of about 125-150RPM between each gear set at cruising speed. It’s nothing to get excited about. Personally, the 4.10's are probably the best gear for an Auto. For the ever so slight amount you might loose on the highway, you’ll gain it back in the city. The only thing that’s really going to affect your fuel economy from that point is your inability to keep your right foot out of the oil pan after the swap.

Look at it this way, you'll feel a lot better about over gearing it ever so slightly, than you will about under gearing it. So many people I know have gone too conservative with their gearing, only to find themselves regretting it and paying to have it done over again with the lower gears they should have gone with in the first place.

And besides, there's a big difference between a '69 Road Runner with a 1:1 high gear ratio and 4.88 gears out back and a S197 Mustang with a .68 O/D (or whatever the ratio is) and a much smaller set of 4.10's out back. Again, don't sweat it.

fartingchicken · Sep 14, 2007

I have an automatic. I read somewhere where 4.10 gears were discouraged for autos, but don't know what to think. I think the complaint was the hardship on the transmission from the demands of a lower gear.
Where do you recommend buying the gear? How do you find somebody who won't botch the job?
Thanks.

SpartaPerformance · Sep 14, 2007

For the $100 that they charge to upgrade to 3.55's it's worth it. I would have done it however I got a great deal on mine off the the lot and the rest is history.

gt gears 3:31 and 3:55

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