Quote:
Originally Posted by GjC
I have a CCX with the 4 speed Top Loader and I'm considering swapping out the tranny for a Tremec 5 speed (.82 OD) or the Richmond Super Street OD
(.77 OD), with either transmission is it possible to swap out 5th gear for higher ratio such as .91 for 5th gear? The rear end is a 2.88 and I have 26.5" diameter tires the car revs at 2450 at 60 MPH, I know that is probably a good RPM but I would like to drop it. The car has a 428 CJ and HP peaks at 5800 rpm's, if my calculations are correct with the rear end gears and tire diameter with a .91 OD the motor will be turning at 2000 rpm's at 60 MPH. Either tranny will give me good acceleration in 1st 4th gear it's the cruise ability on the highway I'm looking for (I do mostly highway driving), the .82 and .77 OD are to low with the 2.88 gears.

You need to do your maths again.
2450 at 60mph x .82 = 2009 rpm
2450 at 60mph x .91 = 2229 rpm
Can you see .91 as 5th gear would not be useful, since the drop in rpm from 4th gear is insignificant.
Gary