brewski4u1

all Rigth guys i'm looking to put in 3.73 gears in my car and i'm wondering what kinda gains i'm looking at in the 1/4 mile time. i was goign to go w/ 4.11 but people say that you lose a lot of top end speed is this tru? and will this affect my gass mileage or what. Basicly what are the pros and cons of 3.73 and the 4.11 gears??

thanks

Black01_Z

Well since you have an M6, I would say go with 4.10s. You have 3.42s stocks so if you go with 3.73 you wont see much difference. I have an A4 with 2.73 stock gears and went up to 3.73s which was a huge jump, but 4.10s is really overdoing it on an A4 considering u may hafta by a new rear end with 4.10s on the A4. With the M6 you will see a lower top speed. Im not sure how much though and expect your gas mileage to suffer. When I switched I could barely get 150 miles to a tank till I learned to contain my enthusiasm with the punch the gears provide. They will get you a few tenths in the 1/4 but they will make the car feel alot faster than they actually did.

Generally accepeted principle with gears on F-Bodies

Automatic - 3.73
Manual - 4.10

afterimage ss

from what i understand, if you go w/ 4.10's, you're gonna be hitting 5th gear when you finish the 1/4 mile... and you really dont have that much power in 5th gear, so thats why ppl stay w/ 3.73's... that, and it's better to spray on an m6 w/ 3.73's. this is from what i've heard from my friends who race their cars... could be wrong, but it kinda makes sense, you're reaching the gears faster w/ 4.10's, 5th gear isnt that great for power... the gears are so quick that if you're spraying and you hit the limiter, you're FOOKED! you can spray for a longer time w/ 3.73's ... ehh, im sticking to 3.73's, 4.10's are too short for me. that, and 4.10's suck for top end

AGAIN, this is from what i've heard from my friends... they really know their stuff about cars, but one of them told me it was illegal to put a roll cage in your car, and i found out that it's not. oh well

91Firecrow305TBI

I've got 4.10's and I don't see 5th gear at the end. As I'm crossing the traps, I'm right at 6000 rpm trapping at 110. My top speed went up from 106ish to 110, but this was also in November. My only other mods are a lid and some free mods. I'm going to swap cams in a few months but I'm also raising my rev limiter to 6700, so I'm not worried about shifting into 5th gear still

I love the 4.10's, It really rips through the gears and you can feel the power difference off the line. I picked up quite a lot of time with them as well.

Go 4.10's

For more info you can look at my website. It has my timeslips, etc

Clint

afterimage ss

hmm... i think you're shifting too late... there's not that much power at 6700. thats just MHO...

91Firecrow305TBI

If you look at thunderracing.com there is a cam 224/224 .563/.563 112LSA (mine is 218/229 .560/.560 113LSA) that is pretty similar to the one that is going in to mine and the powerband is advertised as 1700-6600. There is a picture of a dyno graph, before and after and the horsepower lasts all the way up there. I don't plan on shifting that high, probably 6400-6500, myself.

That's the Dyno's Opinion.

afterimage ss

lol my bad man i didn't know you had a better cam on your car... alright, that would explain why you shift later than 5200, hehe

saw your homepage btw, nice car

91Firecrow305TBI

Thanks for the compliments.

The cam isn't in there yet, and I'm not shifting that high yet either . I've still got to buy the LS6 manifold, SLP Double Roller adjustable timing set, Comp Cams Springs, Titanium Retainers, Chromemoly Pushrods, and a new knock sensor and a gasket set.

This will be knocked out by my Tax return, as my commitment to a healthy economy .

afterimage ss

lol

i always thought 4.10's were horrible for driving around on the streets and they waste gas like crazy.... and i guess it would make sense to puit 4.10's if you have a newer head+cam set (or just cam) that would push more power to the upper band of the rpm range... makes sense to me, lol

still though... you'd do pretty bad top end since you'd finish the gears before the other guy, wouldn't you? lol, hopefull you're beating the shiet out of him before you run through the gears but yet i dont think it matters since you're getting a newer and better cam

91Firecrow305TBI

I wouldn't have changed the gearing if there was anywhere around here I could race for a mile legally. I recently successfully fought a reckless 100 in a 55 ticket (reduced to defective equipment) and boy that takes the fun out of going fast on the freeways. My 5th gear isn't as powerful by any stretch of the imagination, but it's better than 5th gear with 3.42's as the ratio is 3.116 instead of 2.599 to 1. 6th gear is more useable as well. I rarely need to downshift on the freeway and 2000 rpms is a reasonable 75 mph instead of the 90 mph it was. If I start spraying along with the cam, etc I will be ditching the 10 bolt when it breaks in favor of a 9" with gears in the range of 3.73 to 4.10, working my way down as my trap speed increases.

afterimage ss

thats what i was thinking... if you wanted to spray, you'd get more juice w/ 3.73's cuz you'd be spraying longer.

everyone's got a dream of having the fastest car in the world... i just want to have a car that makes ppl so jealous that they'd go out of their way to find someone to try and beat me.

btw, why are you going with a FORD 9"? :\ go w/ the 12 man, lol, i've heard they're both equally as good

91Firecrow305TBI

I think all the NASCAR guys use the 9"... Either way I've got to do more research before I spend that kind of money. I like the idea of gear swaps in a matter of 30 minutes.

stone4779

I dont know why a lot of people mention losing top speed when going with 4.11's

I ran mine up till it pegged the speedo...still in 5th gear. must have been doing 150+ since the speedo says 150...I could have gone faster but the passenger asked me to slow down because he reminded me that I didnt have much tread left on my front tires(fixed now)

Havent done it again, and dont see the need to. I will eventually find out if 6th still pulls at those speeds eventually...the road I chose is like 250 mi from here as its perfect for top speed runs, and NOBODY is ever out there....nothing but flat deserted land.(aaw how responsible...NOT)

I dont recommend anyone trying this, just stating fact.

4.11's and an M6 will still peg the speedo in 5th

Gas mileage is unaffected, maybe even better in the city...i still get like 25 mpg plus on the freeway on road trips....doing the speed limit the whole way with occasional small towns with lights to stop at

and 6th is actually usable now, but only about twice a month as I never even see the freeway here in Houston....mainly city driving

in the city I havent guesstimated but 3 gallons take me to work and back for three days (20 mi round trip each time) and I still have another 20 mi trip left in the tank before going below E

Thats not stomping on it though...I usually drive to save gas, shifting at 2K rpms or so, keeping it above 1500 after each shift.

When I play around on the way...it cuts that extra 20 mi trip off, so after 3 trips im right at E (sunny days i like to drive a little spirited)

I wouldnt go with 3.73's but thats just me.....after having driven 4.11's its worth the tradeoff of mileage(which is the only loss IMO)

It feels as though Im putting less strain/wear on the engine though

BUT I have enver had 3.73's in an M6 so I couldnt speak on that

now, 3.73's in an A4 is killer! no more than that! 4.11's on an auto is usually too much for most people unless you dont drive it anywhere but the track or around town.

My '84 has 3.73's form the factory and it burns'em in 1st,2nd, and chirps third sometimes if I want it to (and its a 305 ). Not much traction though as I have NO suspension mods on my '84 because I want it like that...just for fun driving, not a daily driver

Had it since junior high...learned to drive with it (not my first car, just learned to control wheelspin in that car)

MORAL: 3.73's for A4 and 3.73's-4.11's for M6

if you have 3.42's already (M6) then I dont think you will notice a whole lot unless you are spraying or modded already if you swap in 3.73's

Ill say it again...4.11's dont sacrifice top end speed...maybe top end acceleratioon, but not top speed. But from 0-100 it definately kicks ***, and 100+ it STILL feels faster,but I cant be for sure

Capn Pete

And why's that?
Not unless you're running well over 110 mph, in which case the motor is likely cammed, so the redline is higher, and you can then pull ~120 mph in 4th gear!

For 1/4 mile racing, I think that 4.10's / 4.11's are probably the perfect gear, whether stock or modded. For a relatively stock car, where you won't be going over ~110, then the car will still be in 3rd (A4) or 4th (M6). If you're spraying, or want/need to go faster, put taller tires on (27" or 28") which will allow for another 5 - 10 mph at the top of 3rd/4th (1:1 gear), and at that point, if you're making more power (especially via a cam) then raise the redline to ~6500 or higher, which will allow for a lot more speed again.

Play with some #'s using this gear calculator if you don't believe me.

And whoever says 4.10's with an A4 is a no-no .....

..... .

stone4779

yeah 4.10 isnt exactly a no-no in an A4 but most people might not like it as your highway rpms are gonna go up a bit

Didnt ever have them in a A4 but I ridden in a couple and just too high an rpm for road trips for me (makes me nervous) 2600 @ 70 is crazy to me ...but the engine can take it, im just not used to it lol isnt it normally at about 2000 at 70 stock? I bet that sucker gets up and goes with 4.10's