Dragaholic

iTrader: (180)

I plan on buying a rear soon and Im having a hard time deciding on the gear. I definately want to at least go with a 3.90 gear. I thought about going with a 3.90 just in case I ever wanted to spray the car. But now that I think about it, I want to go all out naturally aspirated. I think I would get more props running a good time with no nitrous rather than with a power adder. Plus, I want to see how far I can go with a cam only and then maybe down the road slap on some heads. So Im thinking of doing away with the 3.90s since I probably wont spray on it and go 4.10s. But then as I thought about it some more and I plan to go all out naturally aspirated, why not go with more gear, but would I be ok to do this in an auto.? I know that Ill have to up the tire size, but I dont know what size, and how far I can go. Basically, I want a gear and tire combo that I wont have to make huge modifications to the wheel well. Ive actually seen a 30" tall non-expanding tire on a F-body with no modifications. Do the non-expandable hook less than ones that do? Anyways, do you think I should just do 4.10s or go bigger since Im staying naturally aspirated? Thanks.

SMOKIN01TA

iTrader: (10)

after you get done thinking with you key board
run a 4.10 gear and a 26" or 27"tire. you could also run a 4.56 and a 28" tire.
coach is running like a 5.13 gear with a 30" tire. im sure he'll correct me shortly if im mistaken

Coach 02 A3 Z/28

iTrader: (10)

Yes, I run a 5.13 gear with a 30x9x15 Goodyear slick. the slicks have a 94 inch rollout.

If I were you and want a all out race set up. I would go with 4.56 gears and a 28x10.5x15 slick.

Coach

Tom the roofer

iTrader: (9)

4.86 gear with a 29.9" tire

PewterZ28

iTrader: (1)

For real? I'm a drag strip only guy so I'd consider that when I go to a 12 bolt but what is the maximum trap speed you can get at 6700 rpm with that set up? Would you suggest that even with a 346? I know George C used 4.30 gears but he had a 383.

gator's 99TA

iTrader: (2)

gearing has everything to do with engine rpm (shift point), tire size, and trap speeds in your final gear. the faster you go, the LESS gearing you need. with the right convertor, gearing wont help that much honestly. also, there is no reason to put a big tire on a car just becuase you want to run a big gear. vice versa.

havent you asked this question before?

SMOKIN01TA

iTrader: (10)

im traping 121 at 6500 so you should be good for 125 or better, my rev is at 7200 so i need a 27" tire or some more power.

gator's 99TA

iTrader: (2)

an A4 given the same powerband and same gearing wont be able to run as fast before hitting the limitor due to tranny gearing and convertor slippage.

SMOKIN01TA

iTrader: (10)

true, but thunders car that i went to the sbso with had 28's and 4.56's with a th350 and huge stall traping in the 125 range. but that was at like almost 7000rpms. and th350 are geared a lil diff also right.

Navy David SS

iTrader: (13)

I have a stock bottom end 346, with H/C. Have a TH400 w/4000 stall. Red line is 6800, with shift light at 6700. I have 4.30 and run with 26x10x15. As I cross the traps the shift light comes on. Just about perfect. I recently broke the 4.30's again, and ran the numbers wether or not to bump to 4.56's. If I was to run nitrous (like I plan to) I would have to run some huge tires (that I figured would only cause more problems). So on engine with the 4.30's 26x10x15, on nitrous 28x10.5x15. Numbers came to 122mph on engine; 132 on nitrous.

Go with the 4.30's for engine only runs on 26's; 4.56 on 28's would work if you have no intentions on running any power adder.

David

Dragaholic

iTrader: (180)

Wow...this is more complicated than I thought! I had no idea how many other factors were involved in order to choose the right gear. I figured that I would want to go a little more since my gearing was a little higher (numerically lower) than the 4L60E. I want to pick the right gear the first time because I have no experience whatsoever in gear installs and I dont think I have all the tools to do it. Thats why when I order my rear, I want to order it with the gear that I plan on using for good...well at least for a while. i know for sure that its going to be at least a 4.10, but I wanted to get opinions on whether to go more or not. From what I know, the order goes: 4.10, 4.30, 4.56, 4.88, and 5.13. I dont think I want to go 5.13 though. Also, with an auto. do you want to pass the traps in 3rd or 4th? Ive heard its ok to pass them in 4th, but for maximum times, to pass in 3rd almost shifting into 4th. So having the 200-4R in mind, wanting to go all out naturally aspirated, what do you think? I thought Id throw in a bit more info to narrow it down. I plan on getting rid of my SS4000 and going with a more race oriented converter with more stall and Im also going with a bigger cam. I hope to have all this figured out and in the car when it starts getting cool again. Help me decide guys/gals!

next

iTrader: (9)

There's a decent gear calculator on the prestage website, give it a try.

gator's 99TA

iTrader: (2)

why are you so concerned about rearend gearing having to be so big?

http://www.f-body.org/gears/ - and remember that you want to look at top rpm in 3rd gear, not 4th (overdrive). also remember to subtract easily 3-5 mph minimum for convertor slipage.

Dragaholic

iTrader: (180)

I just used the calculator, but what is it that Im looking for? With my current setup running 3.42s, I pass the traps around 5700. I want to pass the traps at 6500/6600 because that is where my shiftpoints are. So I put the info that I already have into an equation to see what gear it will take to get me to pass at 6500/6600.

3.42 5700
---------- = 3.96
X 6600

However, if I was to switch the numbers around, Id be able to estimate what RPMs I will passing the traps at with a given gear.

3.42 5700
----------- = 6833
4.10 X

3.42 5700
----------- =7166
4.30 X

All I know is that these 3.42s arent cutting it, especially with my 2.75 1st gear. Ive got a 4000 stall and I plan to go bigger, so even now, I need more gear. I dont have the power or enough converter, so I want to go with more gear. Whatever I decide, Im not going with anything less than a 4.10. I just wanted to get opinions on whether jump up to a 4.30, 4.56, etc. I plan to stay all motor for now, so that is why I want to go with more gear. I want to try and get as far as I can with cam only, then once Ive reached that point, throw some heads on it. I want a gear thats going to get me out of the hole quick and get me down the track the fastest. Does more converter require more gear or is it better that way? Anyways, I personally dont have the knowledge in this field, so that is why Im asking. My 26x11.5x15s are almost gone, so I will be needing more tires and I wanted to go with a 28". More tire, more traction. The reason I say that I would need more tire is if I run out of motor in 3rd gear. I would make it up with tire. I just thought that I would need to go a little more gear than most using a 4L60E since I dont have the gearing that it does. I figured that I would need to jump up to the next gear size to stay in the game. (2.75 vs. 3.06)

bad2000ss

iTrader: (6)

This might help you a bit.

http://www.race-cars.net/calculators...alculator.html

Coach 02 A3 Z/28

iTrader: (10)

Hey, I just ran my numbers and I go across the finish line at 7016.01 rpms.

MPH 123
Tire 30
Gears 5.13
Trans 1 to 1

Cool! That is right at the sweet spot.

Coach

Navy David SS

iTrader: (13)

Did the same

MPH 122
Tire 26
Gears 4.30
tans 1 to 1

6785 rpm at finish line

Right at red line. Just right

gator's 99TA

iTrader: (2)

this calculator still doesnt adjust for any kind of convertor slipage does it?

PewterZ28

iTrader: (1)

Nope, it appears not to. Coach and Navy David, I wouldn't rely on that number. It claims I should be crossing the line at 6215 but I really go through the traps somewhere around 6550.

Navy David SS

iTrader: (13)

I track tested mine. Almost dead on. Just before I cross the finish line my shift light (which is set at 6600) comes on. I have also Atap'd it, it showed 6700+ as I lifted. I would guess the calculator is a little off but not 2 much.

David