Gears & Axles - 3.73's vs 3.42's

I want to put a 4000 stall in, and I know that gas mileage wont really be hurt on highway once it locks up. As for the gearing though, i wanted to do 3.73's but i don't want my car at 2500 rpms on the highway. So how much difference in E.T. would there be between 3.73's and 3.42's?? and how much difference in RPMS on the highway?

I just went from 3.23s to 3.73s a few weeks ago. 3.23s went 12.4 at 111 mph, 3.73s went 12.2 at 114 mph. The 12.4 was ran in -1000' DA on a 1.87 60', the 12.2 was ran at -500 DA on a 1.89 60'. The rest of my mods are in my sig. I did the the FRA mod in addition to the gear swap fwiw.

gears will help minimally. your car will only turn slightly higher with 3.73s over 3.42s. about 300 RPMs.



i do enjoy the SOTP feel my 3.73s gave me so it was worth it for me.

With a 4000 stall you won't see more that about 1 tenth of ET improvement with 3.73s (maybe a bit more coming from a 2.73 though). 3.42s would be even less. Track gains will be minimal and not a good return on your money (if that is a concern) once you have a 3500+ stall in an LS1/4L60E application.

I would only change the gears if you are bothered by the looseness of your stall on the street. If you want to squeeze every last tenth out of your current setup though, then gears might be worth it.

I really don't understand why so many people say gears don't help much. I made solid gains from my gear change. My 1/8th didn't change as much as my 1/4 did. Reason being is that the 3.73s put my car at a way better RPM crossing the line in 3rd compared to the 3.23s. The stall will drop your ET the most, no argument there, but the gears will help you all the way across. I would do both the stall and gear swap depending on your budget.

I really just feel like the car is a dog getting off the line, and i've heard 3.73's will really liven it up and break those tires loose non stop. That's what I want, but i'm really afraid of gas mileage, so i was hoping 3.42's would have almost the same effect? I want the car to ultimately be a beast of a machine ha, but without losing too much streetability

I'm sitting at 2400 RPM at 70 MPH. No noticeable change in mileage at all. Car feels ten times better, still hooks good relatively speaking, and showed a nice improvement on the track.

FWIW, 3.23s or 3.42s are both way better than those 2.73s, so any is going to make a big difference. My 3.23s were anything but a dog off the line....or below 40 mph, lol.

I really don't understand why so many people say gears don't help much.

Because once you have a 3500+ stall, they really don't help much in terms of 1/4 mile performance. People that do gears first don't realize this because the gains can be pretty noticeable with the stock stall, especially if you're going from 2.73 to 3.73. But if you do a 3500-4000 stall first, and then add gears later, you'll be lucky to drop anything more than a tenth. This has been proven time and again. The improved launch and raised shift extension of a proper stall upgrade overlaps much of what the gear swap would give you with a stock stall on an LS1/4L60E setup.

I really just feel like the car is a dog getting off the line, and i've heard 3.73's will really liven it up and break those tires loose non stop. That's what I want, but i'm really afraid of gas mileage, so i was hoping 3.42's would have almost the same effect? I want the car to ultimately be a beast of a machine ha, but without losing too much streetability

If you want to come off the line HARD, but still maintain stock cruising rpms above 45mph and stock MPG on the highway, then I'd recommend that you look at getting a stall first. You can drop your 60-foot times into the 1.6 range or better with stock gears and a 3500+ stall on sticky tires. Gears alone will not give you that (well maybe 4.56s would :lol: ).

So should i just return my gears all together? stay with the 2.73's and get my planned stall? If i do that though, are the 2.73's hurting my take off performance at all? I don't know anyone who kept 2.73's with a good stall

Which gears did you buy? You didn't mention that you already had them, I thought that's why you were asking about 3.42 vs 3.73?

I've known some guys with 2.73s and big stalls that have launched in the 1.5x 60-foot range. A lot of people don't like how "loose" a 4000 stall would feel with a 2.73 gear, so that's a primary reason why you may still want to do a gear swap with the stall. Just don't expect any big gains at the track from 3.42/3.73 swap once you have a stall.

hmm okay, i bought some richmond 3.73's. I don't really understand the looseness people talk about with stalls, i tried reading up on it, but didn't really get the concept ha. What i'm gathering from reading this right now, is to do a 3500-4000 stall with 3.42's is going to be best for hard launches, and still decent gas mileage

If you're interested in the most improvement possibile in track performance for the least amount of money spent, and don't want to add an N2O bottle, then the best thing you can do for your A4 car is a 3500+ stall. If you have the money to do both gears and a stall together, then by all means go for it....but if you want to maintain stock cruising rpms and mpg on the highway, then you may want to skip the 3.73s.

I agree with what RPM is saying regarding the gear after stall thing. But, you may want to consider something else. Although a stall will indeed get you off the line harder, you're going to need tires to hold it, and if you're pulling 1.6s then you might as bank on replacing that rear too. One other drawback is the heat that stalls produce. I promise you that stock 4l60 isn't going to last very long. My current stock trans just took a dump at 17k miles on the stock converter. My 98 also burned up a trans within 3 months. I am now in the process of doing an RPM trans and stall. Just saying the cost vs gain thing will add up more than just the initial cost. I can leave off idle with the 3.73s, street tires, and pull 1.8s consistently. There's a low 1.7 in her with some DRs. Again, I am not arguing what anyone is saying in this thread, everyone has posted good info. I just want to get across the pros and cons of both routes.

and if you're pulling 1.6s then you might as bank on replacing that rear too.

I did my share of 1.6s with a stock 10 bolt with zero problems, and there are people that have gone all the way to the 1.4 range on a stock rear without breaking it (auto cars). If you can keep wheel hop away (and not let it run low on fluid due to pinion seal leaks, etc.) then the 10 bolt should last a pretty long time behind an A4. You'll find dozens of people with A4s and a bunch of miles on their stock rear and still cutting 1.6x or better 60-foots.....especially rears that haven't been messed with and still retain their stock gears (sometimes a poor gear install will result in shorter lifespan).

One other drawback is the heat that stalls produce. I promise you that stock 4l60 isn't going to last very long. My current stock trans just took a dump at 17k miles on the stock converter. My 98 also burned up a trans within 3 months.

Depends on the condition of the stock trans. I've owned several of these cars, and been involved with builds on many others. I've known guys that have put a stall in at 70-100k miles on their stock trans and not break it for another ~30-40k miles (although, the higher the mileage, the more likely it will be to fail of course). It's very rare to blow up a 4L60E with a stock engine and stock stall at just 17k miles....that is definitely not the norm, unless it was just a poor/flawed rebuild, or unless all 17k miles were done at WOT a quarter mile at a time. ;)

But I do agree that heat becomes an even bigger issue once you do a stall, and for that you'll want an aftermarket cooler.

Good points, RPM. I've heard of plenty of rears lasting a long time on quick short times, but I've heard of just as many letting go. Like you said, it all depends. Same goes for the transmissions. The first 10k miles of my car's life was spent mostly in a garage and bone stock. Never saw a track until 12k or so miles along with a few mods (in my sig). I make 2-6 passes a month in her, so it hasn't been abused. It hasn't totally let go yet, but 3rd gear is slipping pretty bad under WOT. I'm just going to go ahead and swap it out for a built trans that I know will hold a bigger stall.

Same goes for the transmissions. The first 10k miles of my car's life was spent mostly in a garage and bone stock. Never saw a track until 12k or so miles along with a few mods (in my sig). I make 2-6 passes a month in her, so it hasn't been abused. It hasn't totally let go yet, but 3rd gear is slipping pretty bad under WOT.

It seems that you were the unfortunate victim of a factory flawed trans....sometimes a flawed component makes it to the assembly line and into an unlucky car. But in general, any 4L60E should have lasted much longer than 5k miles of occasional track use and 17k miles total behind a stock internal, non-power adder engine. My '02 car has 102k miles on the stock trans, and it's been driven pretty aggressively, but the engine is stock and the shift points have always been kept within the stock limiter. I keep the fluid changed, and the trans has never failed.

If you want the best milage I would leave the 3.42s

You bought the gears; install them. It's not always about squeezing every last hundredth out on the track; it's about day to day driveability.

I went from A4 LT1/3.23 to A4 LS1/2.73, and from the first day I test drove the LS1 car, I said, "If I buy this car I'm going to do gears." Got 3.42's, installed them, loved them, and have never looked back.

For the same reason, no way would I want to daily drive my 3600 stall with 2.73's: driveability. If it's just a track car, then it wouldn't make a difference. Regular use on the street makes for a whole other perspective.

Go to www.fbody.org/gears and you can do a comparison of how your engine will be turning with the different gear ratios.

Send the gears back, I'm not a big fan of Richmond gears.

Try the stall first, if its where you want to be stay there. If you still want a little more grunt for the street I would go with the American Axle 3.42"s

Here's a question, what is everybody's favorite stall for street and strip?

For the same reason, no way would I want to daily drive my 3600 stall with 2.73's: driveability. If it's just a track car, then it wouldn't make a difference. Regular use on the street makes for a whole other perspective.

Completely subjective. My car isn't a DD, but I could easily drive it daily with the Yank SS4000. Even with stock gears the looseness doesn't bother me and is a BLAST to drive! Took me 10 minutes after I picked it up from Speed Inc to get used to it and I've never driven a stall or even been in a car with a stall.

OP, go SS4k and don't look back. If you go lower, once you get used to it you'll wish you went bigger. My .02

Wish I had known this before putting money into gears :/ I kinda miss my 2:73's mileage lol.

I'm going with a SS4000/373s I'm gonna install them at the same time I want to get rid of my shitty 273 gears. OP When you buy a stall I would get a 4000 Stall like said above. I got the biggest B&M trans cooler they make.

I have a friend running 1.68 60' With 2.73 gears and 110 in the 1/4 put in the converter run it and then decide on the gears his was a 98 formula with SS4000 with bolt ons