Rear gears high(er) power centri

[Slick4.6]

Looking for other 650+ whp centri guys to chime in. I have a D1sc at 18-19 psi going through a tr6060. Currently running 3.55s and they are a bit long to say the least. What rear gears are you running with same trans combo? Car is 90% street car so ideally being able to get traction in 2nd would be nice.

Also have a Detroit locker in there that’s coming out when I do the gear change if anyone with a truetrac might be interested in a swap.

 

[Midlife Crises]

I don’t run a centri but 3-73s are pretty common. 4-10s might be just fine with the 6 speed.

 

[Wild White Pony]

Centri blower needs the 4:10s, they don't have a lot of umph coming out of the hole unlike a turbo the have less torq down low and build linear power as you get going. I found that running 10-15% overdrive on the crank and a smaller pulley on the blower helps the spool up quicker out of the hole.

 

[1ohiostang]

Don't fear the gear!
I'm running 410s with the 3650. Helps with the soft bottom end with centrifical blowers

 

[Slick4.6]

Centri blower needs the 4:10s, they don't have a lot of umph coming out of the hole unlike a turbo the have less torq down low and build linear power as you get going. I found that running 10-15% overdrive on the crank and a smaller pulley on the blower helps the spool up quicker out of the hole.

my blower is maxed out by 6800rpm so can’t do much more pulley wise lol

Don't fear the gear!
I'm running 410s with the 3650. Helps with the soft bottom end with centrifical blowers

what kind of power are you making? 4.10s on a 3650 are a lot more aggressive than the 6060 so if you’re pulling that off 4.10s would be good for me lol

 

[Dino Dino Bambino]

Looking for other 650+ whp centri guys to chime in. I have a D1sc at 18-19 psi going through a tr6060. Currently running 3.55s and they are a bit long to say the least. What rear gears are you running with same trans combo? Car is 90% street car so ideally being able to get traction in 2nd would be nice.

Also have a Detroit locker in there that’s coming out when I do the gear change if anyone with a truetrac might be interested in a swap.

Which TR6060 transmission do you have? The ratios differed between model years except for 3rd & 4th gear:

07-10 GT500
2.97 1.78 1.30 1.00 0.80 0.63

11-12 GT500
2.97 1.78 1.30 1.00 0.74 0.50

13 GT500
2.66 1.82 1.30 1.00 0.77 0.50

With 650+rwhp I hope you've built the 4.6 short block with forged rods/pistons and upgraded the oil pump with billet gears.
You should hit the 1/4 mile trap at ~138mph and ideally you'd want to be near the top of 4th gear. Assuming your rear tire circumference is near stock and rated at roughly 770 revolutions per mile, a 3.73 axle ratio would have the engine spinning at 6600rpm at 138mph which is right where it needs to be if your rev limit is 6800rpm.
If you swap in a 4.10 ratio axle gear, you'd need to shift into 5th before the 1/4 mile trap unless you have bigger tires.

 

[Slick4.6]

Which TR6060 transmission do you have? The ratios differed between model years except for 3rd & 4th gear:

07-10 GT500
2.97 1.78 1.30 1.00 0.80 0.63

11-12 GT500
2.97 1.78 1.30 1.00 0.74 0.50

13 GT500
2.66 1.82 1.30 1.00 0.77 0.50

With 650+rwhp I hope you've built the 4.6 short block with forged rods/pistons and upgraded the oil pump with billet gears.
You should hit the 1/4 mile trap at ~138mph and ideally you'd want to be near the top of 4th gear. Assuming your rear tire circumference is near stock and rated at roughly 770 revolutions per mile, a 3.73 axle ratio would have the engine spinning at 6600rpm at 138mph which is right where it needs to be if your rev limit is 6800rpm.
If you swap in a 4.10 ratio axle gear, you'd need to shift into 5th before the 1/4 mile trap unless you have bigger tires.

2.97 first gear tr6060, I wouldn’t try to make this much power on a stock engine... Not as worried about what rpm and what not I might go through the trap being the car only sees a strip maybe once a year if at all, but that is something to take into consideration. Might give 3.90s a try even though they’re noisy, that kinda stuff never bothered me.

 

[1ohiostang]

my blower is maxed out by 6800rpm so can’t do much more pulley wise lol




what kind of power are you making? 4.10s on a 3650 are a lot more aggressive than the 6060 so if you’re pulling that off 4.10s would be good for me lol

I'm putting 580 to the wheels first gear is a little short with the 3650. Over all it runs out good.

 

[Slick4.6]

I'm putting 580 to the wheels first gear is a little short with the 3650. Over all it runs out good.

I appreciate the input

 

[GlassTop09]

Might give 3.90s a try even though they’re noisy, that kinda stuff never bothered me.

Just making a suggestion here...............

If you do decide to go w\ a 3.90 gear set for this Ford 8.8", do not get the 3.89 actual ratio Ford 9" OE 9 pinion\35 ring tooth count pattern (this is the noisy 3.90 gear set as it is a non-hunting set) gear set, only get the 3.91 actual ratio aftermarket 11 pinion\43 ring tooth count pattern (this is the quieter 3.90 gear set as it is a full-hunting set) gear set.

The only 2 brands I've found that offer this quieter set of 3.90 gears (3.91 actual ratio) is Motive Gear & Nitro Gear. Richmond Gear & Yukon Gear offer the noisy 3.90 gear set based off the Ford OE 9" 9 pinion\35 ring tooth count 3.89 ratio (these are the 1's to not get even though they'll be the cheaper sets).

These are the only 4 brands that I've found to date that offer a 3.90 ratio gear set for Ford 8.8" axles.

1 more thing. All these 3.90 gear sets are made using the 5-cut face milled gear tooth cutting process so make sure that you use the matching gear checking pattern when setting them up using gear marking compound.
Not all gear sets made for Ford 8.8" axles are cut using the same gear tooth cutting process so be aware. There are 2 cutting processes used (5-cut face milled, 2-cut face hobbed) which are geometrically different & the pattern moves different between them when moving away from center so make sure that you're using the right checking patterns that match the tooth cutting process used to make the gears you buy.

 

[RED09GT]

The 3.55's aren't going to give you any traction advantage over 4.10's with 650 rwhp.
I found it easier to walk the line with 4.10's than 3.55's-you spin the 3.55, lift and the car bogs, with the 4.10’s you lift and you can keep the heat on and salvage your run.

I'm running 4.10's with a 2.97 TR6060 with similar power. The 3.55's made me shift just before the stripe in the 1/8th mile and just felt lazy on the street out of boost.

 

[Slick4.6]

Just making a suggestion here...............

If you do decide to go w\ a 3.90 gear set for this Ford 8.8", do not get the 3.89 actual ratio Ford 9" OE 9 pinion\35 ring tooth count pattern (this is the noisy 3.90 gear set as it is a non-hunting set) gear set, only get the 3.91 actual ratio aftermarket 11 pinion\43 ring tooth count pattern (this is the quieter 3.90 gear set as it is a full-hunting set) gear set.

The only 2 brands I've found that offer this quieter set of 3.90 gears (3.91 actual ratio) is Motive Gear & Nitro Gear. Richmond Gear & Yukon Gear offer the noisy 3.90 gear set based off the Ford OE 9" 9 pinion\35 ring tooth count 3.89 ratio (these are the 1's to not get even though they'll be the cheaper sets).

These are the only 4 brands that I've found to date that offer a 3.90 ratio gear set for Ford 8.8" axles.

1 more thing. All these 3.90 gear sets are made using the 5-cut face milled gear tooth cutting process so make sure that you use the matching gear checking pattern when setting them up using gear marking compound.
Not all gear sets made for Ford 8.8" axles are cut using the same gear tooth cutting process so be aware. There are 2 cutting processes used (5-cut face milled, 2-cut face hobbed) which are geometrically different & the pattern moves different between them when moving away from center so make sure that you're using the right checking patterns that match the tooth cutting process used to make the gears you buy.

thats good info. Thank you for sharing

The 3.55's aren't going to give you any traction advantage over 4.10's with 650 rwhp.
I found it easier to walk the line with 4.10's than 3.55's-you spin the 3.55, lift and the car bogs, with the 4.10’s you lift and you can keep the heat on and salvage your run.

I'm running 4.10's with a 2.97 TR6060 with similar power. The 3.55's made me shift just before the stripe in the 1/8th mile and just felt lazy on the street out of boost.

I’ve really been going back and forth between 3.90s and 4.10s. Seems like 4.10s might be the more popular choice even at higher power. Thanks for the input.

 

[FrancoGT]

I’m running 4:10 with 550hp and 460torque in rebuilt 07 ‘vert with Paxton 2200 at 12 lbs and magnum trans.
Love the 4:10 feel (like low-end power). My hardest thing is learning how to keep my non-sticky tires on the road.

ps I don’t race - all street and show. So discount accordingly. Good luck, and have fun!