View Full Version : Gear change question in an 01

02-03-2005, 09:39 PM
I was considering a gear change and I am curious if anyone knowa how or where I can get an idea of where my rpms will be say at 75 with different gear ratios. I have found that I travel alot right at 75. However when I travel at distance in the 85 and 90 mph I seem to get better gas mileage. I am curious what gear ratio would duplicate the higher rpm at 75 that I get at around 90. Any ideas? It has been suggested that I go to a 4.10 or even 4.30ish. Still haven't decided on na or forced induction.

John in Va. Beach

02-04-2005, 07:41 AM
Right now, your stock 3.27 gears will probably put you at 2150 rpm @ 75, and 2580 rpm @ 90 mph.

3.73 gears will put your car @ 79 mph @ 2580 rpm
4.10 gears will put your car @ 72 mph @ 2580 rpm

hope that helps

02-04-2005, 08:49 AM
Thanks a bunch. I think I will go ahead and get the gears. Awesome.


02-04-2005, 09:00 AM
I have the FRPP 4.10 in my cobra and it's great. My car is a daily driver
(in nice weather). Big improvement in acceleration. Both city and highway
driving are fine. City driving is better because you can cruise in 5th at
a lower speed before having to downshift to 4th. Less shifts in the city.
I have no experience with 4.30, but many people like them. Try searching
the SCMC site for Gears. I know that this topic has been dicussed at great
lengths in the past two years.

02-04-2005, 11:38 PM
4:10's or bust for everyday driving! If I still had my 99 Cobra, it would have 4:10's in it. :)

03-05-2005, 06:18 PM
I know this thread is old...but I had to post this link

microsoft excel gear calculator (http://www.mustangworld.com/forums/showthread.php?t=274278)

03-06-2005, 03:23 PM
Thanks for the sheet, it is cool. Helps alot even for those of us that have trouble with that higher math.


04-01-2005, 02:37 PM
If you have experience with the 2001 3.27 rear end I can use some help. My car has only 6000 miles and I brought the car in to the dealer at 3000 miles when it was under warranty for noise from the rear end. I put the car up on ramps last week and with the transmission in neural, I could move the drive shaft about 10 degrees. When I brought it back to the dealer this week they said 1" of play( equal to about 10 degrees of motion) is normal and within factor spec.From my past experice with other high performance rear ends the lash should be minimal. The amount of play between the pinion and ring also results in a clunk ( no surprise) if I am in 3rd gear at say 2000 rpm and then accelerate. The final symptom is that when under hard acceleration I get a loud rhythmic groan in third and fourth starting at about 3000 rpm to red line again seeming to come from the rear end.. Do you have any of the same symptoms or sounds or is the dealer just giving me the typical "it's within Spec" answer to make me go away. thanks.