Gears?

[vistablueFTW]

410s or 430s? Discuss....

Don-

 

[MTAS]

I had FRPP 4.10's installed more than 2 years ago and have never regretted anything about them. Had I known that 6 months after they were installed that I'd be putting 295/45/18's in the back, I'd have gone with 4.30's from the beginning to maintain an over all 4.10 ratio with the taller tires.

 

[ucfstang]

While we're on the subject of gears...I've heard a couple different opinions I'd like to discuss.

Do you want higher gears (4.10+) with power adders? I've heard that for Superchargers it is helpful, but with something like a turbo that builds boost slower, you'll want to stay with the lower gears (3.55-3.73s). That doesn't make much sense to me...Some explanations here would be helpful.

Thanks!

 

[tom281]

I would do 4.10s because they're perfect IMO when you're NA and they still work well after you go to FI and get blown. I have had them both before and after the blower and love them.

 

[94tbird]

i have 4.11(9" rear) and with my tire diameter i have aproximately 4.25's. i would recommend 4.10s because a 4.30 combined with a slightly smaller tire diameter (if thats what you have) is nightmare on the highway

 

[S197 GT]

I too have had my 4.10's before and after I got blown, and I love my gears!

I run 285/40/18 in the rear.

 

[marcspaz]

Go with 4.10's. 4.30's are too low unless you plan on getting bigger tires. If you get bigger tires and want good street manners, numerically increase your gear ratio about .25 revs to every inch of extra tire dia.

I spent decades 4-wheeling and racing. tried every combo you can think of. for streetable DD, this has worked the best for me.

Building a track car with an auto trans? get a 9" with 4.56's and keep a tire smaller than 28" on it.

 

[ChevyKiller]

i have 4.11(9" rear) and with my tire diameter i have aproximately 4.25's. i would recommend 4.10s because a 4.30 combined with a slightly smaller tire diameter (if thats what you have) is nightmare on the highway

I would be willing to bet you drop down some when you get your car back in the spring. With a 28" tire, you are out of gear with 4.10's at the 1000' if you are running in the 129+ range

 

[marcspaz]

I would be willing to bet you drop down some when you get your car back in the spring. With a 28" tire, you are out of gear with 4.10's at the 1000' if you are running in the 129+ range

Looks like you're right. (did i really just say that?) My recommendation is only good for 1/8th mile tracks.


I got a cool formula way back when. these are est. only TQ, HP and other factor will play in too.

(RPM x tire dia) / (r&p ratio x trans gear ratio x 336) = speed in MPH

ex... (6750 x 28) / (4.56 x .75 x 336) = 164 MPH (in OD)

(6750 x 28) / (4.56 x 1 x 336) = 123 MPH (no OD)

My car (stick) = (6750 x 26) / (4.1 x .71 x 336) = 179 in 5th (est)

My car (stick) = (6750 x 26) / (4.1 x 1 x 336) = 127 in 4th (confirmed)



This is good for figuring tq convert lockup rpms...

http://www.summitracing.com/landing/mustang/article_pages/tz_02torque_converter2.htm

 

[2oo5GT]

I had 4.30's and liked them but now i have 3.90's. I would shift at 6Krpms if i'm in 4th and that's at 108mph back on stock rims and tires with a 75 shot in the quarter mile. If i would of had my 100 shot installed, i would of had to back off before the trap or shift into 5th or took it to 6500rpms on stock springs. Now with cams and springs, i could have kept the gears and shifted around 6500-6700rpms and would have been fine. I would go with the 4.10's unless you stay N/A. Also 4.10's would be good for a centri SC since it takes some time to build the power, and not to bad for a roots style since it makes instant power. With my 3.90's i can take 4th to 130mph in the quarter mile if i shift at 6500rpms, now if i can just go that fast to see.