1998 Mustang GT Auto

tuned · Sep 5, 2004

I was curious on what my current rear end ratio is, the car is 100% stock as of right now. Is it a 3.27 or 3.73 or what?

What woudl you suggest for a rear end ratio, I see many suggest the 4.10's but generally that seemed to be when they were talking about the 99+ Mustangs... So whats the best for a 98 GT auto?

If 4.10's are suggested how slow will the car be when starting off, slower than the current or faster?

Also can ou suggest an intake and exhaust for a 98 auto GT?

Thanks.

1tirefire · Sep 5, 2004

3 gear ratios were available. stock 2.7x, my old one had the 3.08 and then the 3.27. Go with 3.73 or 4.10

kboy262 · Sep 5, 2004

Definetly get some 4.10s for your auto. It will help a lot. Go with a PI intake and some cams. If not do the good old headswap.
As for exhaust that is up to you. I say go with a o/r midpipe and mufflers that have the sound you are looking for.

BlackenedSVT · Sep 5, 2004

1tirefire said:
3 gear ratios were available. stock 2.7x, my old one had the 3.08 and then the 3.27. Go with 3.73 or 4.10

He's right, 2.70, 3.08 and 3.27 were the options to get for the rear end in 1998. The manuals came in 2.70 with the option of going to 3.08 or 3.27 if you ordered the car from ford.

However, all 98 GT Automatic transmissions came with 3.27.
(FYI: I had a 98GT auto and when i swapped them out, the stock gear in there was 3.27...i did some research on this)

BlackenedSVT · Sep 5, 2004

Oh and like i said with someone else's post about "2004 Mustang GT Gears", i would not put gears in an auto car.

I did 4.10s in mine, and they were fun, made the exhaust sound cooler with the higher RPMs. but in the end, i didn't really feel a difference unless i raced someone, and in the auto (since its only a 4spd) it takes your top end WAY down....your top end will be like 115 if you go with 4.10s...

tuned · Sep 5, 2004

normally i wouldn't mess with the car at all but it just so happens it sounds like the read end is baout to go at any minute so i figure if im going to go thru the trouble of oreplacing them i mid as well get the ratio i want.

you say the top end will drop down to 115!? this kind of go against what the article says on stangnet regarding gear ratios.

btw, will it feel a considerable amount faster or no? how bad is it going to kill my fuel economy?

i have posi i think, does it make a difference?

BlackenedSVT · Sep 5, 2004

1st, you have a Limited Slip Differential, its similar to posi. With posi, both wheels turn while accelerating,and with a LS Differential the rear passenger wheel turns when u accelerate, but if you "power brake", "brake stand" or launch the car you'll notice both wheels spinning because the other wheel kicks in when you lose traction.

Ok anyway,
- DONT WORRY about Fuel Economy, its really not an issue.
- What articles were you reading about the rear end gears? With an Automatic, you only have 4 gears, not 5...so your top end drops a lot, because you can't go into that 5th gear.
- IF you are changing your whole rear end, you COULD get a posi-rear differential (EATON makes them and a few other companies) They even have this one out now that is a limted slip, and you can push a button and it switches to posi Very cool.

Also, after the 4.10 gear swap i needed to balance my driveshaft, correct the speedo, and needed to replace my rear end axel and carrier bearings (only because they went bad). JUST an FYI, you probably wont need to do the bearings thing, just something i personally went through.

EDIT: As for the "faster feel" to the car. I really didn't FEEL faster. Maybe its just me When i would race people and launch of the line, you could clearly see i had gears done, because i would jump ahead right away. So THEN i would feel faster. And on the highway you can jump a head of cars with ease as well I just REALLY wasn't a fan of losing all that top end. Not that i race a lot, but when i did, if the race went above like 110mph i just instantly lost because by that time my RPMS were at like 5grand, and i wasn't going to take it to 6grand just to go 120mph. I mean, not many people on here go 120, but i like my car to be a highway car, beacuse im on it all the time, and to lose THAT much top end was kinda much Even though i've only gone like 140 once, and 125 a hand full of times.

tuned · Sep 5, 2004

whats the point of posi?

one question you missed, will the car be a considerable amount quicker?

since you know so much about this specific car and year and stuff, maybe when i get home (currently away because of frances) perhaps we can exchange contacts. thanks

BlackenedSVT · Sep 5, 2004

I edited my response

but EDIT #2: The gears made the car a bit louder with a meaner sound with my exhaust because the RPMS were always cruisin higher. And when i got WOT and on it, it sounded sick so that was a plus with the 4.10s.

And i live in North Jersey, and if you want my mechanic to check it out (he works for Ford) he can check out your rear and prob and do your swap if you want. E-mai me anytime.

BlackenedSVT · Sep 5, 2004

The point of Posi = two wheels spinning which = more traction

But posi in the rain on a turn =

BlackenedSVT · Sep 5, 2004

MORE STUFF FOR YA:
I just seem to keep posting here.

Anyway, if you DO do the gear swap, i HEAR that the 'speed-cal' for automatics does not work. So i guess you'd be forced to get a performance chip (diablo, etc). I tried the plastic $15 speed chip from STEEDA but since my speedo was all messed up when i originally got the car, it kinda of just made things a LITTLE better, still far off from correct. So i can't help you at all there. Goodluck correcting the speedo Maybe ask other 98GT guys or any auto trans owner on the forum here.

EXHAUST:
I had stock manifolds/shorty headers and a MAC H-pipe with cats and Flowmaster Catback exhaust. The car was cool sounding at full throttle and a nice rumble at idle. A LOT of people loved the sound of the car, i thought it was kinda quiet, but i was used to it i guess. I even had one guy chase me through traffic, and i didn't even know he was following me, until we got to the next light a few miles down and he pulls up next to me and goes "that car is SICK man! I had a 5.0 i hooked up just like that, nice car man!" (light turns green) we both leave

I would recommend a PI (power improved) headswap for your car with a PI intake. www.karkraft.com used to sell kits, or you can get them from www.parkwayfordga.com (a bit pricey though since its from ford - but its complete). This will basically swap your heads/cams/intake for 99+ GT equipment that has bigger ports for the air to flow through. It wil instantly add 60hp to your car, since the 98GT compression is lower, it is a GREAT mod for non-pi cars like yours. If you DONT want to do that, because it can be pricey to get that all installed (my mechanic would do it for $500 ) you could always just do a Mid pipe and catback. And if you DEF aren't doing the PI thing, then get a 90 MM F-150 Lightning MAF (mass air flow meter) and ACCUFAB throttle body and plenum.

WRXracer · Sep 5, 2004

um the over drive in the 5 speed and the auto is the same.. if your saying an auto would get 115 top speed then so would a stick..

BlackenedSVT · Sep 5, 2004

Nah the 4.10s mess up the OD. And the OD doesn't work like the 5th gear does in a 5spd.

And IF it does...my AODE trans 4spd with OD did NOT do the same as the 5th gear in my 02 GT now

WRXracer · Sep 5, 2004

sounds like your OD doesnt work.. my 5 speed 02 GT when was stock was the same on the freeway as my 01 GT auto is right now..

WRXracer · Sep 5, 2004

im not going to put gears in my 01 auto.. just needs a kenne bell..

MyEarsHurt · Sep 5, 2004

UDTBadkarma said:
He's right, 2.70, 3.08 and 3.27 were the options to get for the rear end in 1998. The manuals came in 2.70 with the option of going to 3.08 or 3.27 if you ordered the car from ford.

However, all 98 GT Automatic transmissions came with 3.27.
(FYI: I had a 98GT auto and when i swapped them out, the stock gear in there was 3.27...i did some research on this)

Um, okay, so when going from a 3.27 to a 4.10 how much e.t. am I really gonna lose when going to a 4.10 in my 98 auto. Gears were going to be my next mod, but after the gears, the installation cost, and the hypertech programmer (for the speedo) I could manage to get used parts for the PI swap and do that instead for probably the same price. Which mod would lower my E.T. more?

BlackenedSVT · Sep 7, 2004

I never brought my car to the track, so i dont know how much the gears improved the ET.

The 4.10 Gears cost me about $140, then $80 in extra parts (oil etc) for the gear install, then $200 to install the gears. $420 all said and done, then you can add about $300 for a Diablo chip to correct the speedo. So THAT all said and done you're looking at $700+. I would NOT get a chip if i were you until you had a lot of other mods. It would be a waste to get a chip JUST for the gear swap, because when u do more mods you will need to reburn it for about $50-100. Just not worth it if you ask me

But now looking at the other mod option...
The PI Headswap (Heads, Cams and Intake) will net you around 60+hp and will be the best bang for your buck mod on a 'non-pi' (96-98) GTs. My mechanic said he would do the headswao for me for $500, and used parts on the net here cost around $500-600. New PI Parts (from parkway ford, GA) is around $1300.

OOOOOOR you can do what i did, and decided against the mods, and traded in my car for a 99+ GT

BlackenedSVT · Sep 7, 2004

WRXracer said:
sounds like your OD doesnt work.. my 5 speed 02 GT when was stock was the same on the freeway as my 01 GT auto is right now..

Yeah, you're right, my OD *DIDN'T* Work. However, only AFTER i installed the gears.

Before the gear swap, the OD worked the same as my 02 GT manual now and my car could go 150mph with the OD on. AFTER the gear swap it MUST have thrown off the OD because my top end was 115-120mph. And i know 5spd cars that have 4.10 rear ends can still go 150mph because of the 5th gear. So the 4.10s in the auto must have messed up the OD.

So im just saying i wouldn't do gears in an automatic car anymore. My opinion. And if i did, i wouldn't go over 3.73s.

joestang98 · Sep 7, 2004

somethings wrong with your OD...I have never heard of gears messing up your OD??? I have 4:10 and wouldn't go with anything less. Get the gears!
and UDTBadkarma get your tranny looked at!

TopDeadCenter · Sep 8, 2004

if you 98 came is an auto and came with the 17 inch alloy wheels its a 3.27 w/ posy

1998 Mustang GT Auto

New Member

New Member

Active Member

Active Member

Active Member

New Member

Active Member

New Member

Active Member

Active Member

Active Member

New Member

Active Member

New Member

New Member

New Member

Active Member

Active Member

New Member

New Member

Similar threads

Privacy & Transparency

Privacy & Transparency