Am I going the wrong way?

[BadPiggy]

With my ring & pinion gear selection, that is!

RJ (W3bb3r) and I were talking about my gear choice a couple days ago and he brought something to my attention that I hadn't thought of.

Currently the car has the stock 3.55 gear. I have a TruTrac and a 3.90 gear ready to install.

RJ reminded me with my current engine build, putting a 3.90 in is going to render my 1st gear pretty much useless. That I'd bang the rev limiter no sooner than I hit the throttle.

So my question is...am I going the wrong way?
Should I stick with my 3.55...or go higher to like a 3.31...or what?

 

[skwerl]

IMO hold off on the gear change until after you get the engine completed. Try it out with your new power level and decide from there.

 

[Riptide]

^^ Seconded

 

[GallopingFord]

Thirded.

 

[BruceH]

With my ring & pinion gear selection, that is!

RJ (W3bb3r) and I were talking about my gear choice a couple days ago and he brought something to my attention that I hadn't thought of.

Currently the car has the stock 3.55 gear. I have a TruTrac and a 3.90 gear ready to install.

RJ reminded me with my current engine build, putting a 3.90 in is going to render my 1st gear pretty much useless. That I'd bang the rev limiter no sooner than I hit the throttle.

So my question is...am I going the wrong way?
Should I stick with my 3.55...or go higher to like a 3.31...or what?

Not true. Plenty of people have run 4.10 and even 4.56 with forced induction.

 

[BlueDevil]

I have 4.10 gears with my KB, and I sometimes wish I had 4.30s. I also run a fairly tall tire (305/45-18).

 

[FAST3V]

whaaattt????

On my setup (the one you bought) I ran a 325x50x15 tire. I had 3.55's and I wanted a TALLER gear.

3.90s/4.10s.....its going to be too much gear....IMO.

With the setup..I think 3.31 or 3.55 will be the BEST choice. If you do want a shorter gear, I wouldn't go past 3.73....however, since you already have the 3.90s...I wouldnt spend money on 3.73.

I would either:

1. See how you like the 3.55s...they're already in the car.
2. Put the TruTrac & 3.90s in, and if it's too short, put 3.55s or 3.31s in.

In any event..gears and gear swaps are pretty painless and cheap.

 

[skwerl]

What transmission do you have? The 3650 has a nice short first gear so the 3.55's will be about right IMO. However the 3650 isn't going to hold up with your planned power levels. I think I would just install the Trutrack now, then the 3.90 gears when you install the T56 Magnum. The T56 has a tall first gear (2.97 I think).

 

[BruceH]

How many people in this thread have had or have forced induction and 4.10+ gears in a 4.6 3v? I've had the combination with a 3650 and 6060 transmission. I do like a tall tire and I'm sure that has something to do with it. Comparing a 29" tire with 4.10 gears to a 26" tire with 3.55 gears results in less than 4mph difference at 6000 rpm in 4th.

Change those gears to 3.73 with a 26" tire and the 4.10/29" combo is 2mph higher at 6k.

Tire size plays a very big part in what a gear change will do. With 4.10+ you can always go to a larger or smaller tire to fine tune. With 3.55 you can only go smaller and imo 26" is already too small for the car.

See where I'm going with this?

 

[skwerl]

Bruce, I agree. With the Bullitt I had 3.73 gears and ran a stock height tire, about 27". With the tall first gear in my trans I would have needed 4.10 gears to run a taller tire.

 

[stkjock]

All about the tire!

 

[MassMustang]

I agree with the taller tire/shorter gear combo. I haven't swapped yet, but with 27" tires (stock) and 3.55s, it rips. With 28" tires (technically 295/45/18s) the 3.55s kinda suck and I want 4.10s or better. I'll bite the bullet (or bullitt) next week and buy a 4.10 kit and get it installed soon.

From all the research I've done (yes, I use the search function) plenty with forced induction have 4.10-4.56 gears and love it. It's a quick shift in 1st but it works with taller tires as they reduce the overall gear ratio. Again, that is the knowledge passed down from those wiser than me. I'd go 4.30s but too cheap to spend the extra $$ when the 4.10 kit with everything is only $260 or less (edited price).

 

[Doug M]

^^Where did you find a price that cheap for a kit?

 

[MassMustang]

^^Where did you find a price that cheap for a kit?

Oops! I meant $260 for the 4.10 kit. Edited...

 

[firestang70]

My 06 ran a whipple, 3650, 4.10,28" bias ply. Car would hook hard shifted to second pretty quick. I would not go shorter than a 28" tire. I trapped low 120s and finish near the top of fourth.

 

[Bingo]

I still have 3.55s with a T-56 Magnum (2.97 first, I believe?). It makes first gear much more usable. Even at relatively low power levels, with 27" tires, the 3.55s with the TR-3650 made first gear useless.

 

[Five Oh Brian]

With the 4.6L 3V and the associated 5 speed trans ratios, my opinion is that a positive displacement blower (like in the OP's 427R) can get away with much less gear than a centrifugal blower (i.e. Vortech, Paxton, Procharger) since it makes so much torque down low versus the the centri's needing to rev before making torque. With a PD blower, I'd keep the rear gears in the 3.55 to 3.90 range, while with a centrifugal blower, I'd go with 4.10's or more.

As for my own 3V, I had an '07 with a Vortech V2 S-trim and I found that 4.10's worked great for my combo. That was with a 26" tall drag radial, so with a 28" tall DR, I would have gone with even steeper gearing.

 

[Dark_horse]

My 2 cents... 4.10, 3650, turbo setup on the 4.6... car was right at 500whp and 1st was useless even on 275/60/15 ET Streets... Now with the 326ci motor and more boost second gear is useless and so is the top end of 3rd... I cant wait to get them out lol...

 

[AbdullaGT500]

I ran 4.10's on my 06 GT with a 324 stroker and Whipple with 18 lbs of boost. With the right tire it was perfectly fine. 1st gear was definitely not useless.

 

[MassMustang]

With my ring & pinion gear selection, that is!

RJ (W3bb3r) and I were talking about my gear choice a couple days ago and he brought something to my attention that I hadn't thought of.

Currently the car has the stock 3.55 gear. I have a TruTrac and a 3.90 gear ready to install.

RJ reminded me with my current engine build, putting a 3.90 in is going to render my 1st gear pretty much useless. That I'd bang the rev limiter no sooner than I hit the throttle.

So my question is...am I going the wrong way?
Should I stick with my 3.55...or go higher to like a 3.31...or what?

Chris

What did you decide? 3.90, 4.10, 3.31or 4.56?!

I'm gonna buy some 4.10 gears from AM shortly.

Scott T.