Cap'n Pete

iTrader: (2)

Do you KNOW that, or do you THINK that?? Just curious. Most people seem to say stop at 3.73's for the A4, but they've never had 4.10's.

You're only talking a difference of about ~250 RPM between 3.73's to 4.10's for cruising speeds (even upwards of ~80 mph). For comparison's sake, look at this:

@ 80 MPH

2.73's = 2000 RPM
3.73's = 2750 RPM
4.10's = 3000 RPM

Obviously the biggest jump is from 2.73's to 3.73's. That little bit extra upto 4.10's? Not so bad!

When I went from 2.73's to 4.10's in my car, my 100% highway mileage dropped from about ~24 MPG to ~20 MPG. What would 3.73's have offered? Maybe ~1 MPG better?

MattIROC

iTrader: (19)

I'm at 2900 at 80 and I have 3.73's.

If I remember correctly, 2.73's at 80 was 2200 rpm.

I have a stock stall also. Just FYI on your reply.

Irocem99

Did you go from 2:73 to 3:73..I want to do that myself..How does the car feel now? I bet it was a substantial difference..Is it like having a new car now?

Cap'n Pete

iTrader: (2)

Double check it, dude - http://www.f-body.org/gears

I've had 2.73's, 3.23's, 3.73's, 3.90's and 4.10's in my car (don't ask! ) and every one of them have matched up to that gear calculator with ~99.9% accuracy!

I'm guessing your tach must read a little on the high side?

MattIROC

iTrader: (19)

It's like driving a different car. It feels great. Gas mileage didn't suffer at all. I picked up half a second from the swap (actually 7 tenths, but I consider 2 tenths from weather change). PM me if you want me to email you some vids I took yesterday for Rick (guy who made this thread).


I know of the website, but it's not completely accurate vs my numbers.

I've had 2.73's, 3.42's, 3.73's, and 4.10's also. My tach might read a little high, I'm not sure. It shifts at 6k by itself and I have stock internals.

I've driven next to people on the highway and my speedo is exactly on to theirs, and these are new model vehicles. I've pulled next to 2 of the new civic's because they have the digital speedometer and it's clearly dead on vs mine.

60 mph is 2200 rpm in OD
70 mph is 2600 rpm in OD
80 mph is 2900 rpm in OD

any of those dead-on on your car?

Do you know where your car ends in 3rd at 6k?

02silvaZ

iTrader: (12)

^ i think he was just saying your tach might be a little off not the speedo, its possible, hell the more i deal with these cars the more i know anything is friggin' possible

MattIROC

iTrader: (19)

the tach could be off. I hope he chimes back in, and lets me know on my numbers.

rickssz

Hey Matt- the videos were great. They somewhat gave me a feel for how the gears behave in a semi stocker. I assumed when the tach jumped too quick thats where there was some wheel spin, but it didnt seem crazy or to hold you back. The one where you shifted around 6k to 110 mph was that 3rd to 4th? Thanks for putting so much thought into your reply. Buy the way if your tires arent 25.66 your RPM/MPH could vary from the charts.

MattIROC

iTrader: (19)

Yeah, there is some wheel spin thats expected though. I was in 3rd at 112, thats where 6k was. I have stock 245/50's all around.

Cap'n Pete

iTrader: (2)

Yeah, my #'s have been pretty much bang-on compared to the f-body.org gear calculator. One that I always remember specifically was 80 @ 3000 RPM w/4.10's.

Also, you just said "...I was in 3rd at 112, thats where 6k was." ... was that with 3.73's?! Dude, that is definitely WAY OFF!! That's the exact same RPM for 112 mph as having 4.10's!!

If that's really what your TACH is reading? I'd say it's DEFINITELY reading way too high!

And like someone pointed out, I'm not disputing what your speedo says (esp. with so many comparisons to other cars).

Unless your transmission is slipping all to hell?!

rickssz

Isnt there a difference between 6k at WOT and easing up to 6k? What about converter loss? Now youre makin me curious!

MattIROC

iTrader: (19)

Yes, 112 is where 6k is in 3rd. I will find the box I got my gears from, and get the part number off it and look it up just to make sure. I did order the Motive 2 series 3.73's from a local speed shop. If they are 4.10's, that changes everything. But, I don't think they are.

Can you confirm the 1-2, 2-3 mph's at 6k also? Are they exactly the same as the 4.10's also? 1-2 is 38-40, 2-3 is 70.

How can I find out if the tach reads high? When my tuner recalibrated my speedo for me, he also had another program where he checked a few things, and the idle rpm was exactly what it showed. I've heard the rpms can be off as they get higher. Maybe this is the case? He set it as 3.73's on my pcm, I can tell you that much.

My transmission shifts hard and precise in every gear, so I don't think its slipping one bit.

Thanks for the help so far, maybe we can pinpoint this down.

SREETRACEGUY

iTrader: (13)

your welcome and that was in my 4L60E ...... A4 and like i said well worth it to me

rickssz

STREETRACEGUY---How much difference in revs, SOP torque from a roll, traction or lack of off the line and RPM at the finish line in 3rd if you have it.Thanks.

Top Fuel

iTrader: (8)

If the converter is locked the F-Body.org calculator is dead on, if its unlocked all bets are off. I just dont see any normal situation being at 6K rpm with the converter locked.

To the OP, What do you do with your car? drag race? road race? enjoy high speed highway runs? whats your long term or even short term mod goals for the car? whats the tallest tire that you're willing to put under the car eventually? These answers will determine more what gear you want to go with rather than experiences. Going from a 2.73 to anything you'll see an improvement in performance as long as there is traction. Right now it looks like you're mostly concerned with traction and staying on a street tire. Without knowing anything else I would say stay with the 2.73 and spend the money elsewhere.

sixvi6-camaro

iTrader: (9)

I have to agree with that.. sound like you are concerned with traction on street tires and top speed then don't change to a 3.73. For roll racing I'd get a 3.23 to keep a healthy top speed in 3rd then get more Pure HP engine mods...

I went from 2.73's to 3.73s though myself but I really can't compare because I have a vig 3600 stall which makes the car into a completely different animal. Its setup more for the track on sticky tires so I have poor traction on street tires at best.

rickssz

Top Fuel--I didnt understand the 1st part. Its a stock converter and you say 3rd gear @ 6k @112 with 3.73 isnt happening. If I am the OP then track occasionally and enjoy being thrown back in my seat locally at 25 or highway at 50. I just like SOP torque. Tires 275/40/17 BFG with an occasional switch to ET Street (I think mine are like 26.1 app) I wont go 27 etc because I dont want to replace fronts again. Short term Hooker headers Y and cat back, lid, minor free mods, gears and stat and tune. Long term dont know depends how I feel after the short term changes. If it came with 3.23 instead of 2.73 I may have spent the money elsewhere but my last car was M6 and all I know is I dont like the 2.73 in my A4.

rickssz

I dont care about top speed. I think 0 to 60 is more impressive and I have 3 sets of rear tires. And I agree you cant compare your car to my situation. Thanks.

Top Fuel

iTrader: (8)

112 at 6K can happen, just not with a locked converter. The calculator is based on 100% efficiency. Meaning, you're either using a manual or your converter is locked up. The calculator is great for manuals or cruising rpms with autos. Once you're on the throttle in the upper rpms with an auto (converter unlocked) that calculator doesnt mean jack.

Yes you're the OP= original poster

Based on staying with a 26" tire, I'd suggest a 3.73. It'll take you to around 130mph in the 1/4 before needing more tire. Set up well, a 3.73 10 bolt will last a long time as long as its not hit too hard off of the line. A 3.42 is even better insurance with not too big of a hit in performance compared to a 3.73

sixvi6-camaro

iTrader: (9)

the majority of your posts on this thread is about what top speed you can hit and how well the car moves form a roll. Which is the complete opposite of this statement. good luck with your decision.