3.90 Gears Who Has Them

[03TrchRedCobra]

i'm lookin to instal some 3.90 gears when i do the solid swap & i would like to know if anyone here has them & what do you think about them.

 

[unit213]

I have 3.90's.

Is your car a daily driver? Are you on the highway much?
It's a great gear for a street car, but they suck ass IMO for highway
driving. RPMs are way to high in 6th gear. Cruising in the left lane
with traffic is annoying at 3,000rpm. I need the Viper spec tranny.

You should be fine at the track with a 26" in tire though in terms of
having enough rpm to cross the finish line in 4th. I'm going with a 28"
tire.

Based on your sig, we have a similar setup. I'm running the stock
manifolds and Bassani exhaust though.

Consider traction gone on the street. I run a 17" MT ET drag radial
for my daily driver tire and it's absolutely worthless in 1st and 2nd gear.

 

[03dsgsnake]

3.90s

:rockon: love them!the stock 3.55s werent torquey enough and 4.10s were too steep, but the 3.90s are perfect! They get your car right in the powewrband at 3500-3800 where our cars need to be and real driveable around town and highways are fine perfect gear for the terminator just make sure you get a reputable installer or youll open a can o f headaches:??:

 

[AzSonicSnake]

i have them, and other than being a little noisy, i love them. perfect mix of torque, and cruising speed.

 

[03TrchRedCobra]

thanks for the replies guys. my car is a daily driver right now but i only live about 5 miles from work. i was thinking of running a 275-40-17 MT et drag which i read in the same in size as a 26x11.5x17 tire. what rpm are you at when crossing the line in 4th gear.

thanks again
Greg

 

[svtnos1011]

i love the 390s! :coolman:

 

[03TrchRedCobra]

how noticable is the change to 3.90's from like a 40 roll. cause my care is already nasty with the stock gears. so i'm gathering that there is no cons to this swap what so ever. looks like i'm aobut to place an order.

 

[BuffDigits]

id have to say it depends on how much power your putting to the ground.
if you like me with 580~600rwhp gears don't help, especially on the street with street tires. makes things worse in fact. if you have any traction problems now with whatever power you have, gears will exaggerate the problem.

now if your talking about the strip, and your running slicks or good DR's then gears combined with the right sized tire and improve your track times.

so like i said it depends what your trying to do and what kind of power your putting down. it appears that if you in the 400+rwhp it seems to help a lot
but get that above 500 or 600 and forget about it, even with DR's I do not get any real traction in first or second, adding gear would certainly not help that at all.

but some say dont fear the gear, but if you have enough power you dont need it ;p

 

[svtnos1011]

buffdigits is correct, if you are making tons of power, traction will be a problem on the street

 

[03TrchRedCobra]

i figured that much when my car started to go sideways in 3rd one night while playin around. i just thouhgt i'd put some MT, Hoosier or BFG's on it

 

[unit213]

i just thouhgt i'd put some MT, Hoosier or BFG's on it

That still won't matter if you're making 600rwhp. I run MT ET drag radials
as my daily driver tire and I roast them just by blipping the throttle.
WOT is a joke in 1st, 2nd, and some of third on the street. I'm changing
to a 15" wheel with plenty of sidewall. :rockon:

 

[Trick Pony]

IMO if you plan on making a lot of power 3.90s are a little too steep. I have 4.10s in mine right now and I have to go to 5th gear in the 1/4 and 4th gear in the 1/8th. I'm only making 465/473 right now and plan on doing some more power mods so I am going to switch to 3.73s.
Mine actually makes great traction all around with the 4.10s, but I have a solid axle and a torque arm/panhard setup..