3.73 or 3.55 also upgrade to 8.8?

L

lex2lo

New Member

Nov 1, 2008

14

0

1

Apr 19, 2009

#1

• Apr 19, 2009

• #1

ok so my 91 gt is in the shop getting full exhaust and new clutch installed. i also
purchased the complete rear end rebuild. the one for 650 bucks and 3.73 gears.

Revolution Performance - Check Out Our Specials!!!

does anyone know if the 91 came with 8.8?

my question is if i have a 7.5 rear is it worth doing the rebuild or should i just wait and upgrade to a 8.8 and get the gears then. can the 7.5 handle the 3.73's or do i have to worry about the axle twisting off if i launch it too hard? i am on street tires and pony rims right now. and if i upgrade to a new 8.8 which one should i go with and what other parts will i need to get with them also whats the difference with 28 or 31 or 33 spline? im a newbie so im still learning

 

tannerc91gt

This last 25% is foreign territory at this point

Founding Member

Nov 29, 1999

4,392

2,967

234

Indiana

Apr 19, 2009

#2

• Apr 19, 2009

• #2

You already have an 8.8 rear end. And 3.73s won't be a problem I run 4.10s on my 91GT and haven't had a problem

 

9

90stang5speed

Member

Jan 19, 2009

582

2

19

Columbus Ga

Apr 19, 2009

#3

• Apr 19, 2009

• #3

I just put 3.73's in my 90 with a full spool and upgraded to 5 lug 31 spline axles. I think it is a BIG improvement over the stock gears. I also added 275 50 R15 mt drag radials too. This is my first project build too. My car was intended to be mainly a track car but with my wifes car down right now, it has become my DD. Some would say that you cant drive a spooled car on the street but i cant tell much difference. parking lots kind of suck put then again I dont have power steering anymore either so im fitting both ends. Had to drive to work today in a rain storm. the drag radials didnt like that. I can still cruise the intersate at about 2500 rpm in 5th too. good luck with your build.

 

Maryland Stang

Active Member

Aug 21, 2002

1,656

30

39

Greenville, NC

Apr 20, 2009

#4

• Apr 20, 2009

• #4

Those "special" prices are crap. You can get the same stuff here:

Buy Ford Racing Parts!

for $250.

 

Maryland Stang

Active Member

Aug 21, 2002

1,656

30

39

Greenville, NC

Apr 20, 2009

#5

• Apr 20, 2009

• #5

Oppss.. My bad. I didn't see that their prices included installation. Carry on.

 

skunk21

Active Member

May 22, 2007

1,203

3

36

Taxachusetts

Apr 20, 2009

#6

• Apr 20, 2009

• #6

Like the others stated you have an 8.8 rear. 3:73 are a really nice gear, really wakes the car up of the line vs the stock gear set. The often over looked item is the speedo gear, you will need to change to a red ( really looks a wine color) 21 tooth speedo gear, the other thing is you will have to have them remove the tail housing on your T5 to change the driven gear, the 1990-95 T5's have a 8 tooth driven and need to be swapped to a 7 tooth driven gear. enjoy your new gears!!

 

NIKwoaC

中國製造

15 Year Member

Oct 31, 2006

5,525

943

214

Chengdu Province

Apr 20, 2009

#7

• Apr 20, 2009

• #7

Stock axles (which are 28 spline) are notorious for failing during hard launches on sticky tires. Good aftermarket (Moser, Yukon, etc) 28 splines should hold up better, but its always a good idea to upgrade to 31s or better. More splines=bigger diameter=more durable.

You can always reuse gear sets on upgraded (higher spline count) differential carriers down the road, so don't feel like you're going to have to throw those 3.73s away later on if you don't upgrade your axles right away.


P.S. 500th Tech post! Woo hoo! :SNSign: