Thinking about going down from 3.73 to 3.31, anyone have done that???

[MADRUSSIAN]

Long story short: car makes around 830rwhp on blower and a bit over 900 on spray. Car is 2011 with factory 6 speed and 3.73 rear gear. Curently sits on 28x13.5 qtp hoosier tire. Don't care about the track, want this thing to work well on hwy, especially from 40 roll. Curently it will spin of 40 hit, even if it somewhat hooks, I have to shift almost instantly into 3rd. Gears seem way to short. I do like the kick that 3.73 have, but if it barely hooks and I have to go through 4 gears while other guy goes through 2 or 3.....idk. was thinking about going down to 3.31. Would it be to tall? I don't know if 3.55 will do any difference. ...please chime in if you got any useful info or personal experience

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[2000GTSTANG]

My car is no where near your power level but I went from 3.73 to 3.31 and the change was great. I can still spin 1st and 2nd, but im running M/T Street Comps.

I make half your power so I would suggest you go even higher for a gear, maybe 3.08s or 3.15. Youve got the power to make up the big gap.

 

[jazz]

I think 3:31 would be perfect for your setup also depends on what rpm you shift at... Im thinking about switching mine to 3:31s too and im not even at your power level. I feel like running the same setup on my shebly as yours but dont think i would have the same luck as you on the stock motor lol

 

[MADRUSSIAN]

I think 3:31 would be perfect for your setup also depends on what rpm you shift at... Im thinking about switching mine to 3:31s too and im not even at your power level. I feel like running the same setup on my shebly as yours but dont think i would have the same luck as you on the stock motor lol

Yeah, I'm willing to accept the fact that motor will let go at any moment now, although there are no indicators of that right now..... good fuel, cooling mods and solid tune are the foundation. I do try to shift at 6300-6400 although some times rpms climb so fast in lower gears that by the time I react car is near 6600 rpms....I'm trying to shift at 6000 now lol

My car is no where near your power level but I went from 3.73 to 3.31 and the change was great. I can still spin 1st and 2nd, but im running M/T Street Comps.

I make half your power so I would suggest you go even higher for a gear, maybe 3.08s or 3.15. Youve got the power to make up the big gap.

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[jazz]

What size belt are you running with 2.5 pulley?

 

[marsh2o]

I have 2007 and went from the stock 3.31 to 3.73 -- which was a big mistake. I now have to shift so quickly into 2nd, that 1st gear is just wasted time -- and that's at my stock power level. So I think, for you, 3.31 or lower would be a good move -- but get the FRPP gears, as I haven't heard of a single aftermarket install that hasn't resulted in whine.

 

[Derek@Lethal]

It all depends on what your use for the car is. Sounds like to prefer to do highway racing which start from a roll, so a 3.31 would probably work better for you. We've gone both ways in our project cars. Got rid of 3.31's for 3.73's and in our 2008 GT500 and picked up some solid ET. Got rid of 3.73's for 3.27's in our 2011 GT which helped us make 1 less gear change and we picked up ET and MPH. With the TQ your car is making, I'm sure the 3.31 would work best for you.

 

[Speedboosted]

3.55 are IMO the best compromise between the street and track. It's not great at anything, but it doesn't suck at anything either. I'm happy with them at just under 700 whp. Top of 4th is like 155 or so, not sure how fast you like to go on the highway but that's usually good enough for me.

 

[Joewee500]

3.55s here with 700whp. I'd like 3.31 but I am much happier with these than the 4.10s that someone put in the car before I got it.

 

[MADRUSSIAN]

Thanks for all the input guys. I did some calculations and looked at couple of different gear ratios. With frpp 3.27 gears, 28" tall tire and 6400 rpm top of 4th goes to 162 mph. Second gear goes farther, but power band no is at 48 mph, so I guess no 40 roll. 3.08 goes to 168 mph in fourth and second becomes more useful as well but power band now is at 50 in second. Although numbers look really good I wounder if it going to bogg down of the hit.

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