I have an 88gt with a 5-speed and a basically stock motor. I currently have 3.08 gears, but I want to switch. I "think" I want to go with 3.55's but I may consider 3.73's. The car is driven on the highway a fair amount but I intend to do some auto-x as well as some HPDE driving. What gear ratio would work best for an "average" auto-x course? For anyone who has swapped from 3.08 to 3.55, was it "enough" of an improvement, or did you wish you went taller. Thanks.
A 3.55 will be fine with a stock engine and also keeps you in a street prepared class (ESP). The 3.73 knocks you up to street mod (SM), a place you don't really want to be in a Mustang. I still have the 3.55 in my ESP 95 Cobra and with good tires I can do rather well with it.
Get the gears. My 3.55s were one of my best mods. I liked them when I was near stock and when I got heads, cam, and intake. I think they would be ok if I put a supercharger on the motor. I am going to 3.27s and a Tru-Trac (or Torsen) once I get my turbo installed.
Thanks for the replies guys, please keep them coming! I actually do have a plan. So far the engine has limited bolt on mods. Down the road I plan to do H/C/I, with the goal being around 300rwh. So far I have done a fair amount of suspension work. Now I'm getting ready to do a rear disc conversion(with fronts coming later), so with the axles coming out I figure that now is the time to change my gears; I just have to decide on a ratio. So far it sounds like going with 3.55's is the best compromise for street/highway driving, while 3.73 might be a little tall for an auto-x course. Any other opinions? Thanks.
I had 3.08's and went 3.55's and love it. I'm doing everything you said you do with the 3.55's and still keep low RPM's. 3.73 are to much on the freeway and on the track you well your limiter.
My vote is 3.55
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I had stock 2.97's at first. Changed them too 3.73's and didn't like the power band once I started doing the H/C/I and exhaust. Went too 3.55's and loved it. This was all done with a stock 87 T-5 tranny.
Tried to use the 3.55's in my Viper tranny, but first gear is way to steep. Had to go with 4.10's and love it now.
I went with 3.55's back in 91, I wish I went with 3.27's with my 5spd. On long straights like TWS I run out of gear in 4th. I either have to stay at red line or bog in 5th. Now if I had a .8 5th gear, 3.55 might be better. Also it seems to me that with 3.55's I am either to low a gear or to high a gear. YRMV.
I'm using 3.73 gears and with the 2.87 1st and .82 5th in my TKO it all comes together rather nicely. The car pulls away well in 1st without having to immediatley upshift to 2nd and on long straights I can shift into 5th without the engine bogging.