Im going to buy a rear end off a 2002 SS with 3.42s for $250.. which is much cheaper than buying gears and having them installed professionaly.... How much do you think my ET will improve with the gear swap... I'll also probably get some nittos for track use a little later on...

thanks!

 

I have no idea, maybe .3....but a decrease in gas mlg as well, but who cares! I am very interested in this as well, so TTT please.

 

Get 3.73's right off the bat. You will be much happier!

 

Sounds like an excellent plan. I too swapped the whole rear out instead of paying to have gears set up. I think you'll be happy with the 3.42s, they will be a huge step up from the 2.73s although i have a manual and don't know what gain to tell you. A step up even from 3.23s and just a hair lighter than 3.73, for the cost i don't agree with going with the 3.73s. I always suggest 3.42s for A4s if your on a budget. One thing to check though. Make sure both cars have traction control or don't have it. I lost my ABS (no big deal) due to getting a rear out of a traction equipped car while my car was only 3channel ABS. Because i didn't fully understand what i was getting into i always warn people about the rear compatability. You can either search for some of my old posts or just ask here if you're unsure and think this might be a problem for you.

 

This is an old thread I though I would revive for some debate, heres the deal, after running a 13.69 and pretty consistant 13.7-13.9 I went back to the track after 2.73---->3.42's and no cats this time, elec WP, opti, wires, plugs, etc tune up crap, car is running great - and actually saw a descrease in ET and MPH to a 13.90-14.10 with similar 60' nearly exactly. Now I should have seen a decent increase from thoose mods...so wtf? Now granted this was a year, maybe 2 yrs later and alot of miles, but its VERY well maintained, so I was kinda disappointed......both variations in times are over about 12 or so passes each, pretty consistant really for that many passes.

Now heres my theory, with 2.73s I could run a 13.70 @ 102 crossing the 1/4 at redline in 2nd gear, just perfect. Now with the 3.42s I cross at mid 3rd, think this could be the problem with ET decrease? cuz the car is stronger, SOTP wise, now its 13.90-14.00 @ 101-101.50 wtf?

 

Did you have computer reprogrammed for gears/shift points other mods on the dyno, or just an off the shelf email tune? Also, imho, the airfoil is a waste of time. Also, if by !tb you mean descreen the MAF, that is a BAD idea.

 

ya of course, like I said, car was running better than ever this last time @ the track, just going throught the gears flawlessly, trans felt like new, but slower

 

IF ya think about it the car in second gear out the back has more overall gear pulling it than with 1-1 in third.
To equal it in third ya would have to get in the 5 to 1 range in the rear gear.
A 4.10 will make it quicker but doesn't last long in a factory rear but a 3.73 will and be a whole lot better.

 

Yes, the car will feel quicker due to the increase in torque multiplication, but that does not guarantee a lower E.T.

Your engine has to be able to take advantage of the increased breathing that the gears allow (ability to get to redline quicker). If it cannot, there will be no improvement. It's the sum of the parts, not just one thing, that makes the car faster.

 

im not doing gears till i do a cam... which may not happen.. idk.... 2.73s arent bad

 

Yup, well said, this is exactly what I was thinking, everytime you read of perfect setups, etc, the fastest cars in their classes always cross the 1/4 @ redline in their highest gear.

So anotherwords, from now on its really stupid to recommend 3.42s to anyone with an auto without at least ALL the bolt-ons. They actually made my car slower =( until I get some more serious mods that is, IMO 3.42s are trash for a bolt on car, I thought they would be perfect for performance/MPG compramise, but no go. Do people with the stock 3.23s see lower ETs than 2.73 cars???? I think 3.73s would be just enough to allow you the 4-6k pull of 3rd before the redline, not sure if a bolt on car would max 3rd, anyone with a4/3.73s wanna chime in on their bolt-on mph/gear range in the 1/4?

 

to answer the 2.73/3.23 question...yes, i noted a .2 60-foot time increase and over-all about .5 in the quarter. but i had also added an exhaust, intake and 17*9 wheels when i went back...so take it into consideration.

before i did all the other mods i did mess around a bit and did notice a big difference in my "pull". the car seemed to be faster, and i burnt up tires easier...but once i put on all the other bolt ons i hooked like crazy. i think 3.23 are best for minor mods...and 3.42 for the absolute highest of street cars. 3.73 only if you're charged or nos'd.

 

2.73s do have good topend pull... ive pulled on equal cars with mods, because of my 2.73s.... i think there not that bad... 3.23s im considering... I dont want like 3.73, maybe 3.42s.. but ya know... i just wanna work on complete suspension at the moment...

 

wow, you are/were getting 102 out of your 2.73 gears?

stock shift point is about 94, and i dont see the computer tune raising your rev limiter on an LT1 over 6200. mine is raised to nearly 6000 and i am still only getting 95 or so out of it.

on motor, i'm shifting into 3rd right as i enter the traps. running 13.9-14.1 with 96-99mph trap speeds with 2.0 60's

on the bottle i am shifting into 3rd with about 200 or so feet left running 12.2 at 105-108 trap speeds with 1.5-1.6 60's

i just dont see how you're crossing the finish line with a trap of 102 and still in 2nd gear.

 

this is one smart man