fatboytc88

I Am Looking At 2 Verts Automatic Trans, One Has The 3.15 Ratio And The Other The 3.42 Ratio. Has Anyone Changed From 3.15 To 3.42 . How Much Of A Difference Did It Make, Do You Think It Was Worth It?. Does It Change Speedometer & Odometer Readings? Thanks Steve

steves red vette

i had 273 gears and changed to 342 you can feel a difference. not sure about the other set up.

VETTEWIZZ

I Have The 3.15 Upgraded Tranny In My C6; It Provides Better Of The Mark Pickup - The Difference Is Noticeable. Take The Option If Available, The Gears Themselves Are Also Beefed Up To Handle The Increased Torque And Power Of The C6.

CORTVET

Keep this in mind. No autos were made with 3.42's from the factory. So the auto with those gears is not stock.

That aside. I had a 2.73 and went to a 3.42 on my first C5. My current C5 came with the 3.15. But, I just put in a 3.73. I love it. Some say the 3.42 is the perfect auto rear gear. Now I have 3.73's, I think they are the better than 3.42's

I will be posting an in-depth review of the 3.73's in the next day or 2.


Have Fun,

AZC5

Mitch C

I have had 3.15s 3.42s and now 3.73 gears. IMO there isn't enough of a difference between 3.15s and 3.42 gears to warrant the swap. If you are going to keep the stock converter go with 3.73 gears. However if you really want great performance you should consider a high stall T/C. A high stall T/C will give a much bigger performance increase than just gears.

Target Chaser

Mitch, what stall do you have? I too am pondering the gear swap (3.42 vs. 3.73). But still want to maintain streetablilty. TIA

JadeDragon

I too am planning a change of gearing. I have a stock 2.73 right now...and I was about to start a new thread asking if I should go either 3.42 OR 3.73.

Is there a price difference? As long as I am switching to a better performing gear, shouldnt I go ahead and get more serious with the 3.73's? Or is there a downside to that (Besides the top end, which I very much doubt I will ever experience)?

Also, Im not all that clear on what a Torque Converter does, and is that a necessity (or highly recommended) when doing this kind of improvement?

My ideal is to generate the quickest acceleration to 60MPH or 1/4 mile that my Auto can achieve. Without getting TOO crazy or affecting daily driving to work in some bad way.

I have a good window to get in the shop next Monday to do this (on vacation till then)...so any speedy advice would be MUCHO appreciated!!

Thanks!~~~JadeDragon

JadeDragon

Good info, Mitch!

Is there any down side to the 3.73's?

Excellent! Any chance of posting that soon? Im nearly ready to bite on the 3.73...unless there is some downside or huge price difference.

Looking forward to that review!!!~~~JadeDragon

gmosley

corect me if im wrong but
2.73 s have a different carrier than the 3.15 and 3.42s
so price depending on where you buy should be the same for whatever gears you choose since they (3.15 3.42 3.73 3.90 ) all use the same carrier
the bad thing about 2.73s is most places wont give you a refundable core charge for the 2.73 carrier for the new 3.42 or 3.73 carrier

Mitch C

I currently have a 4200 stall with 3.73 gears, I have also had a PT2400 with 3.42s and a ST3500 with 3.73 gears.

Once you have a good high stall T/C gears don't give you as much extra performance as they do with the stock converter. However going to a numerically bigger gear makes a high stall T/C feel tighter (more like stock).

A nice street combo would be the Yank SS3200 with 3.42 gears. This combo will give a big increase in performance without hurting your cars driveability.

There isn't a huge difference between 3.42 and 3.73 gears. The main reason I upgraded from 3.42s to 3.73s was for better driveability with my 3500 stall. However the ST3500 would have also had very good driveability with 3.42 gears. The disadvantage of 3.73s compared to 3.42s are you will lose 1-2 MPG on the highway. Your RPM at 70 MPH is 200 rpm higher than it is with 3.42 gears. In most cases 3.73 or 3.90 gears will cost you more than 3.42 gears.

3.15 gears and bigger use the same carrier. 2.73s use a differennt carrier. However forum sponsor DTE can convert the 2.73 carrier into any gear ratio you want. You can sometimes find 3.15s or 3.42s used for about $500.00-$600.00. It is much more difficult to find 3.73s or 3.90s used. The bigger gears will normally cost you more than 3.42s.

The stock T/C stalls at only 1600 RPM. Your engine makes alot more HP at 3500 RPM(assuming 3500 stall) than it does at just 1600 RPM. A high stall T/C allows your engine to instantly spool up much higher in the power band where your engine is making more power. The more power that is available when you go WOT the faster your car will accelerate. You also get higher shift extensions with a high stall T/C. Meaning when your tranny shifts at WOT the RPM of your engine does not drop back as low as it does with the stock converter. Your engine stays higher in the power band where the sweet spot of the power band is giving you much better acceleration.

Bluevet2006

I am going from the stock 2.56 ratio to 2.73 ratio next week. I wish I would have read this before I bought the 2.73. I would have bought the 3.42 ratio. I was told the 2.73 was a good one because of the gear reduction in my automatic panel shift. What do you think? Sorry guys, your right I have a C6 new to the site. Take care

CactusCat

Why not drive both and make your decision based on how each of them feels to you? Several have chimed in but the final decision is yours. You can feel a difference between 3.15 and 3.42. The 3.42 will be a bit quicker but won't get as good gas mileage as the 3.15. And as stated, the 3.42 was not available on any A4 C5s from GM so it has to have been changed by a PO. Both are good streetable options and both get decent gas mileage. RPMs at highway speeds are a few hundred rpms higher on the 3.42s. Speedo readings are negligible and can be tuned to read the new 3.42s properly as well. No biggie there.

grantv

Wait... what? No C5 came with 2.56 gears. Some autos came with 2.73, some 3.15, all sticks with 3.42

Bluevet2006

Mine came from the factory with a 2.56 ratio in the Z51 package. I was told the 2.73 would be a good match for more torque and still have good top speed & gas mileage. Anyone do this yet? I am doing it next weekend. My drag time now is 12.6 @ 111.00 I am hoping to get that lower. I just installed 1.82 rockers and porting the intake and now doing the gear change. With all the rest I have done I hope I can get into the 12.4 maybe 12.3 range

Bluevet2006

I must tell you guys I love the way my car runs with the 1.82 rocker arms. When it is comp mode it is running better and you can feel the difference. There are many claims of the power difference, I am going to dyno it after I get the rest done. May 7 th getting it tuned with all the things I have done. Should be interesting what it all adds up to.

phoneman91

If you have a C6-then you are in the wrong forum. This forum is just for C5s.

Manual transmission C5s should have been offered a factory "performance ratio"-just like the factory auto transmission C5s. The 3.42 is great if you live in Kansas and have long distance highway commutes. But it would have been nice to have the factory offer a 3.73 or 3.90 also for those living in hills and mountains--or for those who just like the increased acceleration .One of my first impressions of a manual 3.42-the car is way undergeared for it's horsepower.(But surprisingly still a very low 13 second car.)

CactusCat

I do believe that according to his nick, he's driving a C6, not a C5. And the C6s did come with 2.56 gears. The "performance" gears on the C6s were 2.73 for the A6s. I think the poster accidently posted this in the C5 section instead of the C6 section. But all is good... no harm, no foul.

grantv

Ahh if you're driving a C6 you posted in the wrong forum like another said. No biggie, but that explains your incorrect (for a C5) gear comment.

sloopdawg

So to get a little more pep, all I need to do is change the rear end gears from what I have now (not sure what I have but know its stock 2001) to a 3.42? Not going to race it and don't want to break the bank, just a little more pep.

grantv

Easy to do on a phone...