Hey can anyone tell me if switching from 327s to 373s will mess up the automatic transmission? I heard it will mess up the shift points. And how can i correct the speedometer? some people say to use a speedcal, and some say i need some gear thats inside the transmission. Its a 98.

 

It will not harm your car. It will also not change the shift points as that's controlled by the computer and a gear swap doesn't change that. Because you have a 98 you do not have to get a speedcal or tuner both of which would change the single sent out by the trannys speed sensor and correct it for the gear swap. But like I said because you have a 98 all you have to do is change the speedo gear in the tranny with a different one this will correct the speedo for the gear swap.

You can get the different speedo gears here:
http://www.steeda.com/products/speed...tion_gears.php

Also I would get a steeper gear set like 4.10's for an auto car. If you search we have many posts and lots of info on what gears to get.

 

alright thanks man. Ill look into that speedo gear. The reason i chose 373s are cuz i plan to swap out the auto, for a manuel. And ive heard 373s would be good for a manuel. And plus, i dont want to kill the gas mileage on it either.
The only other question i got, is how do i know if i have posi trac or not? As far as my understanding, "posi trac" is when both axles spin, moving the whole car. And "single posi" is when only 1 axle spins, moving the whole car. I thot GTs have posi, and V6s have single. And is that speedo gear difficult to install?

 

your swapping your transmission for a mexican named Manuel?? or did you mean a manual transmission?? lol, just busting chops.

rule of thumb, 3.73s for manual, 4.10s for auto. however, i'd do the tranny swap first, because you never know how it'll affect other parts of your drivetrain. shouldn't be a problem, but still, i tend to lean on the side of caution.

what kind of car do you have? V6 or GT?? if you have a V6, then you have a one wheeler, and only one wheel spins.

it kind sounds that you are building up your car. if you have a V6, then i'd consider looking for an 8.8" rear from a 94-04 GT. you can even find one with a higher gear ratio already in them.

 

LOL hell no man, i would never buy a V6 mustang. No offense if u have one. But ya its a 98 GT auto. And i dont have $2700 right now for the transmission swap. So i kinda decided to rebuild the rear end alil cuz its an auto. For right now, i bought some mosar spline axles, the gears, and complete bearing kit. The cars got other bolt ons, but i figured changing out the rear gears will make some what of a difference. Hopefully they will. But I had heard recently that changing out to 373s from 327s can mess up the automatic. Like the shift points. I had never heard of that. And what u mean affect other parts of the drivetrain? Like what?

 

when you register on the forums it should say please do not post about gears.

 

it should.

 

my first stang was a sixer. it was a 94 5-speed, and i now have a 2002 GT, also 5-speed. if you have a GT, then you have a positraction, and both tires should spin when you burnout. if they don't then you need a new one because its shot. and no, changing gears will not mess up your automatic. i know plenty of guys who can't drive a stick that get 4.10s or 3.73s in their ride. changing the gear ratio will definetly make a huge difference in your acceleration. for some more horsepower, i recomend getting PI heads. the heads on yours are non-pi, and restrictive.


and as for affecting other parts of the drivetrain, like i said, probably nothing, but you just never know.

 

The speedo gear swap is a very simple swap to do.

 

alright thanks man. I already bought the speedo gear. Hopefully it'll be somewhat accurate.

 

As long as you got the correct one for your year tranny and gears you will be good to go.