373's or 390's? cant descide pick for me.

**william SS** · 08-24-2007, 03:31 AM

Im going insane here. Ive got 323 in my 01 SS A4 and am either gonna go with a 373 or 390. I will not go higher than a 390. I keep going back and forth telling myself im going with this gear than i change my mind and then i change my mind back again and this is driving me nuts. Im buying a ford 9" tru track with one those 2 types of gears and a 3400 stall today and I can't descide. Im making a poll and and going with the one with the most votes. I will be taking this car to the strip just as much as i will be cruising on the streets and the highway on the weekend and only during the weekend.

**5.7literMustangEater** · 08-24-2007, 12:10 PM

Originally Posted by william SS

Im going insane here. Ive got 323 in my 01 SS A4 and am either gonna go with a 373 or 390. I will not go higher than a 390. I keep going back and forth telling myself im going with this gear than i change my mind and then i change my mind back again and this is driving me nuts. Im buying a ford 9" tru track with one those 2 types of gears and a 3400 stall today and I can't descide. Im making a poll and and going with the one with the most votes. I will be taking this car to the strip just as much as i will be cruising on the streets and the highway on the weekend and only during the weekend.

I'd go 390's if your just going to use it as a weekend driver nad going to the track. Might as well get as much power to the wheels as you can.

**ATCharming** · 08-24-2007, 12:12 PM

tough call... if ur worried about mpg, go with 373s. also im sure 390s are going to limit ur top speed alot, so if you expect to be racing at real high speeds id say 373

**b.lee** · 08-24-2007, 12:19 PM

3.73

**william SS** · 08-24-2007, 02:11 PM

Well im also gonna be spraying 125 or a 150 shot so with this being said would it be better to go a lower gear like 373 or would it not matter?

**ATCharming** · 08-24-2007, 06:36 PM

Originally Posted by william SS

Well im also gonna be spraying 125 or a 150 shot so with this being said would it be better to go a lower gear like 373 or would it not matter?

as far as i know that wouldnt make a difference in gear selection...

other than, theres no reason to go too high like 3.90 if you could just get more power to the ground with a bigger shot of nitrous

**Jays00ss** · 08-24-2007, 07:07 PM

I have 3.90's but I have a M6 Love the gears and I have the Motive performance

**silverz28camaro** · 08-24-2007, 08:01 PM

i say 3.73 cause' i have them and love them. if you go 3.90 you will see probably another .1 or so, I almost went 3.90 when i ordered my 12-bolt, but i do drive 60 miles to the track so i needed the highway gear more, nitrous loves gears, if you nitrous the 3.73 vs the 3.90, the 3.90 will net you about a 2-3 tenth gain over the 3.73

all in all you will be happy with either choice, and if you are still undecided just throw t peices of paper in a hat and randomly draw.

good luck

**SSwt00SS** · 08-24-2007, 09:16 PM

Originally Posted by william SS

Well im also gonna be spraying 125 or a 150 shot so with this being said would it be better to go a lower gear like 373 or would it not matter?

Originally Posted by ATCharming

as far as i know that wouldnt make a difference in gear selection...

other than, theres no reason to go too high like 3.90 if you could just get more power to the ground with a bigger shot of nitrous

just to help correct the both of you, even though i know what it is you mean. when it comes to gear ratios, a LOW gear ratio, the higher the number is (IE: 3.90 is a lower "deeper" gear than 3.42)...

a HIGH gear ratio the lower the number (IE: 2.73 is a higher gear than 3.23)...get it, got it...good!

**ATCharming** · 08-24-2007, 09:16 PM

Originally Posted by SSwt00SS

just to help correct the both of you, even though i know what it is you mean. when it comes to gear ratios, a LOW gear ratio, the higher the number is (IE: 3.90 is a lower "deeper" gear than 3.42)...

a HIGH gear ratio the lower the number (IE: 2.73 is a higher gear than 3.23)...

hahahaha i swear i knew that!!! its just such a habit to say 4.10 is a higher gear ratio than 273 cuz its a higher number lol.

thanks tho

**LS2Tuner** · 08-24-2007, 11:51 PM

It all depends on what tire your going to run......If your going to blow that thing remember your adding more tq than hp so unless your doing major work to get it to hook including putting V-6 rear springs from the boneyard all you will do is blow the tires off. Those stock SS springs are hard as a rock for corners they could care less about the dragstrip handeling.
Are you going to be running a real tire at all times (M&H or a Mickey) or are you going to have Nittos on it.
That would be the determining factor for me.......

**william SS** · 08-27-2007, 04:16 AM

I talked a guy at a place that does rearends and gears about what I was planing on doing and he told me 390's. Then I mentioned nitrous and he said 373 and that he couldn't recomend 390's because I would rap up my rps too high to quick and I would run out of gear. Is this true? Also with or without using nitrous how much gain would I see in the 1/4 mile using 390's over 373's?

**Spaz** · 08-27-2007, 04:55 AM

373s... if you take a highway, i doubt you will like it with the 393's...

**LS2Tuner** · 08-28-2007, 09:23 PM

Originally Posted by william SS

I talked a guy at a place that does rearends and gears about what I was planing on doing and he told me 390's. Then I mentioned nitrous and he said 373 and that he couldn't recomend 390's because I would rap up my rps too high to quick and I would run out of gear. Is this true? Also with or without using nitrous how much gain would I see in the 1/4 mile using 390's over 373's?

It all depends on if your hollshot can handle the added torque. I have had it go both ways. Gain can be alot... I have had cars pick up a .10 just in 60' times. Then again I had cars that spin after trthe swap to.

**william SS** · 08-29-2007, 03:03 AM

Well ive done ordered them the 390's that is. I had originally orderd 373's. While my dad was the one that placed the order for me. The next day he called them back and told them he wanted 390's instead so so they said ok. He tells me this later the next day I think and im surprised. I couldn't make up my mind and he thought I truly had my heart set on the 390's. So this is what im getting and i figured ill try it out for a while and if its too much ill order some 373's or go with bigger tires and be done with it. But if I can get my tires to hook I really dont think ill have too much of a problem with this setup. One more thing I know my top speed will no longer be 160. So does anyone have an idea of what I will drop down to, my top speed that is?

**slims00ls1z28** · 08-30-2007, 07:00 AM

Only problem with the 3.90's is that if you have the stock RPM range you will more than likely be bumping into OD at the end of the 1/4. I have 4.11's and even with my limiter reset to 6800 the max I get out of second is 70 MPH (haven't really ran third out yet to see where the max is). Theres a calculator somewhere on the web the will tell you but that is the only drawback I see on the 3.90's. Now add a cam and beef up the valvetrain and let that puppy spin and its a whole different ballgame.