I searched but did not see an A6 specific answer. So, I have a 2006 base coupe with an A6. I was thinking of adding gears, maybe 3:42, but I am concerned that it will be too tall and I will lose alot of top speed and have high RPM's. I dona wanna do 90 and be at 4k. Any suggestions or thoughts would be appreciated.

 

You might not see or feel much of a difference at all going from a 2:56 to a 3:42 set up. You should probably go with a 3:90 or 4:10 diff if you really want to feel the difference. There are 6 gears in an A6 so I wouldn't worry too much about high rpm's at highway speed.

 

Do a search, and please don't put anything more than 3.42's. If you go with 3.90's or 4.10's you basically get rid of first gear and now you can start out in 2nd gear (same as your first gear with your stock gears). So essentially you just turned a 6 speed into a 5 speed. That would be a huge waste of money.

I've explained this before, but most people just can't think clearly when they've had years of experience with 3.42's, 3.73's, 3.90's, and 4.10 gears. The A6 is a different animal. It has a 1.53 third gear instead of the 1.00 third gear in the A4. So the A6 with the stock 2.56 rear gears is the same as an A4 with 3.92 rearend gears.

I personally like the 2.56 gears. They act like an A4 with 3.90 gears when you run the quarter, but it acts like a manual 6 speed when you are cruising. One of the few cases where you can have your cake and eat it too.

Good luck.

 

What about 3:15's? would there be a difference from the 2:56's to justify the cost? What kind of RMPs' are the 3:15's at going 80mph?

I agree that going too high would be a waste of 1st gear, not what I am looking to do.

 

Hey Takeman, since Glen just put things into perspective, maybe the 2:56 is better off left alone and other mods should be taken into consideration... Staying in 3rd gear through the quarter-mile sounds really nice. My A6 is still under warranty and I am happy with it for now.

I have seen plenty of forum members claim a big difference in how the car feels under throttle from this mod, but not much of any concrete drop in quarter-mile times from swapping 2:56 gears with a 3:42

Maybe Glen can help shed a light as to how much or little of a drop to expect in your quarter-mile time from this single upgrade.

Thanks!

 

CorvetteHulk, I am kinda thinking what you are thinking. I dont want a beast. I already have that in another car (Supercharged 96 Cobra). Just wanna make some simple performance mods but dont want to suffer any driveability or get a drone headache

Thanks for the replies guys..

 

There is another thread going on that a guy put a decently high stall convertor in his A6 and made a world of difference with the stock 2.56 gears. So a stall might be what you could look into. It all kinda depends on what kinda driving you do and if you take it to the strip at all or just a street/highway cruiser. Plus what other mods do you plan on doing to the car.

 

I was the guy who installed the converter and even I was surprised at the results.

I've had 2.56's, 3.15's and 3.42's in my car and can tell you that going from 2.56 to 3.15 makes for a huge SOTP improvement but not a whole lot at the track.

There wasn't a lot of difference between the 3.15 and 3.42's either at the track or driving around town. The only noticeable difference was on the freeway as the 3.42’s revved noticeably higher but the upside is that 6th gear isn’t sluggish anymore and you can actually pass people or accelerate pretty quickly without having to downshift.

Here’s a thread I posted a while back with some highway RPM numbers:

http://forums.corvetteforum.com/c6-t...-42-gears.html

 

If a 2.56 with A6 acts like an A4 with 3.90. Maybe a higher stall & tires will get you what your looking for........Joe

 

I say the stall is the biggest bang for the buck. The car is the best of both worlds. 2.56 gears can cruise at 90mph at 2k and still cut a 1.5x 60 ft time at the track.

 

You would know!!!! Congrats on that rocket. 1.5 60' my god

 

subfloor, I was following your thread. Good info there and your thread with the rpm numbers. I have never owned an automatic, so whats a 3200 or 3600 stall converter run? Any downside?

I'll do a cold air intake, NPP mufflers, a tune....nothing crazy. I just want to make it a little quicker, but not lose any driveability.

 

ONLY go by a recomendation of a guy with the actual gears you are asking about and not a guy with a calculator or one with 3.15's commenting on 3.42's. Like 4.10's on the manual trans the VAST majority of people love them and the A6 with 3.42's is the same. I havent seen anyone with 3.42's want them out and I sent about 30 of them to get them in. On the other hand, I persoanlly have 4 friends with the A6 and 3.15's that regretted not getting the 3.42's citing that they cant really feel much difference with the 3.15's.

The guy with a calculator is often the one that is most surprised when he gets a ride with the gear set that mathematically to him looked too steep but drove awesome without the wheel spin he expected. Steep gears spin less rotations and then hook faster because they slow the rate of rotation down so the car gets to the speed the tires are rotating at. So 3.73's on a A6 will hook way faster than 3.15's in this respect.

Hiway rpm's for the A6 and 3.42's is about 75mph at just under 2k rpms and 2250 rpms with 80mph.....so 90 at 4k rpms isnt realistic.

Gears dont lose top speed. All cars from the factory are actually way to steep geared and if they had the power they are geared for 250mph.

Usiung the above factual rpm for a 75mph cruise at about 2000rpm's then even with 3.42's the car would still have enough gear for 225mph at 6000rpms if you had the sick power to do it. So gearing isnt going to limit top end. It gets you nearer your HP peak and actually helps it.

If you ever cam your car, know that most cams will have 2k-6600 power bands and as such they dont like being under 2000rpms so its best to target a cam that will keep you inside that power band. If you drive at 75 or so on the hiway then 3.42's are great in this respect. Economy for cammed cars is best around 2k rpms for this reason.

 

Both the 3200 and 3600 are $775 plus shipping from Yank.

You might lose a little gas mileage around town but it should stay the same on the freeway since the converter eventually locks up like the stock one does. You’ll need to install a transmission cooler as they do tend to make it run a little hotter but other than that there really aren’t any drawbacks.

 

With the A6 and the known limited power handling capabilities of it. Do you think the addition of a good converter triple disc or so help it hold anymore or is it the actual hardparts inside that cannot handle the torque? Which I know a tune does wonders for the A6 but I want to know what parts are the weak link.

 

Continuing on the converter and heat control will be your best option to extending the life of the A4/A6. I have had all kinds of converters and they make one of the biggest performance gains for the money. Since the Vette is a light vehicles, the Yank SS3600 would be an excellent choice. The SS Series from Yank drives better than the older series converters and act much tighter on the street. When it comes to converters, Yank and Precision Industries are the best. After some tweaks to the PCM/TCM, the Vette will be a whole different animal. One car that I have is a 1998 TA with a SS4000 and just topped 148,000 miles on a stock, untouched 4L60E. I installed a transmission temp gauge and stop racing it at 190 degrees.

 

Thanks !

 

I am just guessing but do All A6 transmissions have the provision for lines to be hooked up for a Tranny cooler, Or do they all have lines running up to the raditor for cooling?

 

Glenn & Chris have pretty much covered the important points. If I may add from my experience, a higher stall speed converter for a auto is the best bang for the buck, (the cost of the converter, installation & tuning costs approximately the same as a new gear set with axles installed) and the improvment in 1/4 mile times is not even close!

In addition, the trans can be tuned to your liking. Gears while accelerating faster bleed off horsepower. I would suggest that you speak with Chris (thesubfloor), Tony (TonyB4), Marc (LS1LT1) & Mike (Mikeg4572) they all have converters & the A6 some with gears and some without and get it straight from the horses mouth as you will get the straight poop

 

The stock setup has the lines running to the trans cooler in the radiator.
The best way to install the cooler is to bypass the stock trans cooler in the radiator and install the coolant lines directly to the new cooler