3.31 gear ratio sucks
03-30-2015, 08:48 PM
#11
2nd Gear Member
Join Date: Jul 2013
Location: Shenandoah Valley of Virginia
Posts: 406
Our '08 has 3.31 rear gears ..... and we like them. 
With the 3.38:1 first in trans, that comes out to about 11.188:1 overall ..... which is same as an old M-22 rock crushe's 2.20 low with a 5.08 rear axle and many late '60s z-28s with 302s lived quite happily with that 2.20 first and just 4.10 or 4.56 gearing.
My Chevelle and GTO both had a 2.56 low wide ratio trans, to get to that same overall I'ld have had to put 4.37 gears in their 12 bolts .... but I got close with the 4.10s in the GTO for awhile.
My old Dart Swinger 340 lived with a 2.66 low in it's A833 trans and while the 3.91s were a blast and good for a best et of 13.01 on some street tires, it lived quite happily on 3.23 rear gears most of it's days. To get to 11.188 I'd have needed 4.20 rear gears.
With the 3.38:1 first in trans, that comes out to about 11.188:1 overall ..... which is same as an old M-22 rock crushe's 2.20 low with a 5.08 rear axle and many late '60s z-28s with 302s lived quite happily with that 2.20 first and just 4.10 or 4.56 gearing.
My Chevelle and GTO both had a 2.56 low wide ratio trans, to get to that same overall I'ld have had to put 4.37 gears in their 12 bolts .... but I got close with the 4.10s in the GTO for awhile.
My old Dart Swinger 340 lived with a 2.66 low in it's A833 trans and while the 3.91s were a blast and good for a best et of 13.01 on some street tires, it lived quite happily on 3.23 rear gears most of it's days. To get to 11.188 I'd have needed 4.20 rear gears.
03-31-2015, 01:32 AM
#12
I'm lucky enough to have 3.55s as stock gears and I wouldn't swap them for anything else. I presume that Ford decided to go with 3.31s in manual models from 2007 to increase highway gas mileage and ever-tightening CAFE standards, but those gears are too tall for optimum performance unless you have small twin turbos or a positive displacement supercharger that can generate plenty of boost at low rpm.
03-31-2015, 02:07 AM
#13
5th Gear Member
Join Date: Oct 2008
Location: CA
Posts: 2,073
I'm lucky enough to have 3.55s as stock gears and I wouldn't swap them for anything else. I presume that Ford decided to go with 3.31s in manual models from 2007 to increase highway gas mileage and ever-tightening CAFE standards, but those gears are too tall for optimum performance unless you have small twin turbos or a positive displacement supercharger that can generate plenty of boost at low rpm.
so you can maintain traction in 3rd gear.
03-31-2015, 11:06 AM
#16
5th Gear Member
Join Date: Oct 2008
Location: CA
Posts: 2,073
Yeah, hitting 63 in 1st gear and 193 before shifting to 5th would be pretty crazy... but it would require crazy power to even wind out 4th in that case, probably something like 3 times the power that a Mustang GT came with from the factory.
03-31-2015, 01:27 PM
#17
700fwhp should be just about enough
04-01-2015, 03:30 PM
#19
2nd Gear Member
Join Date: Jun 2012
Location: CA
Posts: 202
I have the 3:31s and for the FRPP Pro-Cal tune was a nice improvement. Throttle response is much better and the added torque (+60 ft. lb.) down at 1500 RPM really helps with getting off the line. You will have to switch to 91 or higher octane with the Ford Pro-Cal tune though.
if you've been using 87, have you tried premium fuel? That might help quite a bit all by itself!
if you've been using 87, have you tried premium fuel? That might help quite a bit all by itself!
04-01-2015, 04:29 PM
#20
I have the 3:31s and for the FRPP Pro-Cal tune was a nice improvement. Throttle response is much better and the added torque (+60 ft. lb.) down at 1500 RPM really helps with getting off the line. You will have to switch to 91 or higher octane with the Ford Pro-Cal tune though.
if you've been using 87, have you tried premium fuel? That might help quite a bit all by itself!
if you've been using 87, have you tried premium fuel? That might help quite a bit all by itself!