This may be a stupid question but how much difference could there be in going from a 273 rear end to a 342 rear end or just driving around in 3rd gear? Is that a stupid question?

 

I have a 273 and always drive in 3rd around town. The only thing a 342 gear will get you is a little more pop off the line.

 

Not a stupid question, but....3rd gear is 1:1 on an A4, so.....2.73 at 1:1 vs. 3.42's at 1:1. The 3.42's make the vette finally feel and act like a vette! "A little more pop off the line" is an understatement.

 

Two weeks ago I had installed a 3.42 (z06) differential and a 3000 Yank converter..... unbelievable increase in acceleration (from a stop or roll).
Add a converter if possible.
Local dealership service manager and two techs are allowed to use shop on off time to add mods to corvettes. Great price & great work.

 

Two weeks ago I had installed a 3.42 (z06) differential and a 3000 Yank converter..... unbelievable increase in acceleration (from a stop or roll) from 2.73.
Add a converter if possible.
Local dealership service manager and two techs are allowed to use shop on off time to add mods to corvettes. Great price & great work.

 

This may be a stupid question but how much difference could there be in going from a 273 rear end to a 342 rear end or just driving around in 3rd gear? Is that a stupid question?


Where do you like to play? I like to play from 0-100 mph. That's where your going to feel the difference. At WOT you will come out of 1st at around 30-35 2nd around 80 and 3rd somewhere around 125. Rolling under 25mph nail her she will drop into 1st scratch and scratch again coming out. I have done the swap and you get more than a "little" more pop off the line. The car is more responsive at many levels. When I had my 2.73s and doing the twisties in the mountains I used to leave the tranny in 2nd any higher gear and I always felt like I was coasting around the corners. With the 3.42s I leave her in 4th and can feel the engine pulling her back during deceleration plus I get the added benifit of the tranny down shifting 1 or 2 gears if I want it coming out of the turns just by pushing down a little or a little more on the gas. Gas milage improved 2 MPG around town from 19 to 21. Highway MPG no noticeable difference. IMHO Best mod you can do to the A4 with 2.73s.

 

I agree this IS a great mod for A4 (2.73), but whats up with the gas milage thing? How's your car getting better milage, after switching to 3.42 ???? Milage is supposed to drop by 2-4 Mpg. THAT IS a fact!

 

I agree on the best mod for A4s. GM should offer the 3.42s as an option instead of the 3.15s. I have done the gear change to my older vette and the SOTP difference was apparent immediately. Do a TC swap at the same time to get the most benefit.

 

I had a dyno tune and Vararam done at the same time as the rearend. I don't have to give it as much gas to get her rolling. I'm just going by what the computer said before and after and I am getting better milage around town and no noticeable change in hwy driving that's the facts maam just the facts

 

I don't have all the technical details, but it is my understanding that engines operate more efficiently at higher RPM, so such a gear change likely allows the engine to operate in a more efficient rev range most of the time. I changed my MN6 from 3.42 to 4.10 and have noticed no drop off in mileage - again, the 3.42's had the car 'lugging' around at 1500 rpm or less in many situations - but no longer!

 

I think it depends how you drive more than anything.

Its like increasing BHP with intake and exhaust mods. If driven hard it WILL use more fuel. But it will also offer the same performance as before for less effort so when not at WOT many people will drive or sedatley allowing for better mpg.

The same goes for gears, if you always where flooring it and forcing the box to kick down it would not have been economical but with more pep in the higher gears you'll probably find you won't force it to kick down as much.

On the highway at a constant speed it may be a different story as to achieve the same speed you will have to run at higher rpms.

 

What size gearing do you have to change out the case? I have a A4 2.73 1998 and was wanting to just swap the ring and pinion for one that is 3.42. I heard they wont fit in the casing. Is this true?