top speed in fourth gear....?????help

[hotstanggt]

my buddy has 96 gt with a 5 speed and 3.73s...he just bought a new tranny out of a cobra tha had 4.10 gears and now at 5500 rpm his speedo is at 90 mph in fourth gear his speedo was never fixed when he had the gears installed so he doesnt know what it should be any help would be appreciated

 

[BlackenedSVT]

I got 4.10s on my AODE 98GT. Man...my speedo is not only ALL messed up now. But since ihave an auto, and it only goes to 4thgear and O/D. My top end is like 110mph. I need to get a 5speed to get the extra gear in there.

I'm confused though...the tranny wouldn't have anything to do with the 4.10's...Does your friend have 4.10s in his car??? Or the OTHER car had the 4.10s? Because the tranny is a tranny. Shouldn't affect your speedo...UNLESS the kid with the 4.10's changed the speedo gear IN the tranny. In THAT case, that tranny has the 4.10 speedo gears. And you'll need to change them BACK to whatever rearend gears your friend has. OR just get a speedcal (which i hear is the only way to fix the speedo anyway). Dallas Mustang sells them. They are like $100.

 

[hotstanggt]

he has 3.73s in his car...hes sayong that his speedo was reading over 100 mph at 5500 rpms in fourth gear before he put that tranny in, by the way how does your car run with 4.10s....i have a 98 aod and im really thinking about getting 4.10s for mine what rpms are you doing at 70 mph?????

 

[HogStang]

He did get a SpeedCal or Chipped I'm assuming right?

 

[hotstanggt]

yeah hes got a bbk off-road x-pipe, JET chip, cold air, and 3.73s

 

[red98_gt]

the guy in the cobra has changed the gear in the tranny to compinsate for the gear..so: if ur buddy that has 3:73's has already gotten a chip or tune to recalibrate for the gear, he needs to get a factory tranny gear. If he doenst have a chip or tune to do so, then he jus needs the gear for 3:73 gears since he will have to change it anyway....

 

[hotstanggt]

so do you guys think itll just be best that he swap the 3.73s for a set of 4.10s ..?

 

[todd4566]

so do you guys think itll just be best that he swap the 3.73s for a set of 4.10s ..?

That is and option, but a rather expensive one. As said before, best way to fix it would to to either:
a. make sure the speedo gear is stock (if the chip is tuned for the 3.73)
b. replace the speedo gear w/ the 3.73 gear
c. put on a speedcal