3.42 Differ QUESTION?
Thread Starter
Pro
Joined: Mar 2004
Posts: 627
Likes: 0
From: Pittsburgh PA
3.42 Differ QUESTION?
I have a 99 auto coupe with 26K miles on it with a 2.73. I saw online a GM 3.42 differ on sale for $1,100 from one of the forum sponsors. The only mods I have on my car right now are a intake and cat-back exhaust. Is that Diff a worthy mod at this point and time? How much of a 1/4 diff will I see? Is that a good price?
Safety Car
Joined: Dec 2004
Posts: 3,730
Likes: 217
From: Arizona AZ
I have seen them at lower prices, so shop around. There is also a difference in the ZO6 3:42 and the 3:42 that comes on the MN6 6 speed. I had an automatic and was going to do the swapout. Mine was a 2003 and I needed to get a handheld programmer to make the changes so the management system wouldn't thin there was slippage. Contact Mike Mercury, he did a write up that I followed. I never did the swap but Mike has a lot of the answers.
Safety Car
Joined: Jun 2004
Posts: 4,353
Likes: 22
From: Bella Vista Ca
you will be very happy with the 3.42's. You also have to get your shift points changed. Make sure you have torque management removed when the shift points are adjusted. My first real mod..... money well spent 
Instructor
Joined: Jul 2004
Posts: 168
Likes: 0
From: Metairie La.
Great mod. It will feel like you added 50 HP. Gas mileage may drop... but only 1-2 MPG.
If you can't find a used one, one of the forum sponsors (can't remember which one) sells Z06 differentials (shot peened) for $1,000.00 +/-.
Good Luck
If you can't find a used one, one of the forum sponsors (can't remember which one) sells Z06 differentials (shot peened) for $1,000.00 +/-.
Good Luck
Drifting
Joined: Mar 1999
Posts: 1,250
Likes: 1
From: Greensboro NC
You will be very glad you did the change. I would not go with a higher ratio than the 3.42, but I would make ABSOLUTELY SURE to put in a mild converter (2800 to 3000 stall) while in there (Do it! Don't make the mistake to disassemble all of it and not put the converter in there!!!). With these two mods you will not recognize the performance of your car again and shave 3/4 of a second off your quarter mile, while retaining full every day driveability.
Originally Posted by Ward1
I have a 99 auto coupe with 26K miles on it with a 2.73. I saw online a GM 3.42 differ on sale for $1,100 from one of the forum sponsors. The only mods I have on my car right now are a intake and cat-back exhaust. Is that Diff a worthy mod at this point and time? How much of a 1/4 diff will I see? Is that a good price?
Burning Brakes
Joined: Nov 2004
Posts: 1,028
Likes: 0
From: Fort Worth Texas
3.42's are a great mod. Be sure to have the car re-programmed for 3.42's in the rear, or you will throw a transmission slippage code. Also as someone already stated, the shift points should be changed to match the 3.42's. You'll love it....nothing like breaking the tires loose at will! 
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Team Owner
Joined: Apr 2001
Posts: 54,204
Likes: 179
From: S.W. Ohio. . . . . . NRA Life Member
Originally Posted by mperl93
ECS... Who's differential do they use?
Motive Gear (an offshore company, who I've been told made the gears in the factory Getrag carriers) decided to make the 3.73, 3.90, and 4.10 gear sets and sell the gears alone as upgrade parts.
So, there's only the original Getrag carrier case, and there's only gear sets from Motive. The only difference would be - who does the physical labor.
Le Mans Master
Joined: Aug 2000
Posts: 5,294
Likes: 2
From: Suffolk, Long Island NY
Originally Posted by mperl93
Where in Jersey is ECS? Who's differential do they use?
Drifting
Joined: Oct 2005
Posts: 1,943
Likes: 18
From: Henderson NV
Just remember, you cant swap a set of 3:42 into a 2:73, the carriesrs are different and other mods need to be made,(check other posts on this), best bet if your going to spend 1k or more is to just throw a whole new cased 3:42 in, I wish I did that instead of just getting resealed, but I didnt have the extra mooola at the time for that, Live and Learn I guess.
Drifting
Joined: Oct 2004
Posts: 1,345
Likes: 3
From: Mesa Arizona
I had Xtreme Motorsports install my 3:42's and a Protorque 2800 stall converter. Got a lot of vibration from the new TC at 22-2400 rpm's. And I really didn't like the feel of it anyway- too loose for me. Xtreme sent back the TC to Protorque (a brand I would NOT recommend if you are in the market) and re-installed the stock TC. Nice and smooth again!
I love the 3.42's. You will not be disappointed! Don't like High stall TC's around town. Now if I raced, that would be a whole different story.
My .02's
P.S. Yes, you must have someone adjust the shift points for you with the gear change.
I love the 3.42's. You will not be disappointed! Don't like High stall TC's around town. Now if I raced, that would be a whole different story.
My .02's
P.S. Yes, you must have someone adjust the shift points for you with the gear change.
Last edited by bcseitz; Feb 5, 2006 at 05:04 PM.
Drifting
Joined: Mar 1999
Posts: 1,250
Likes: 1
From: Greensboro NC
Get a Vigilante and you never have a problem. 2800 to 3000 is alright.
Originally Posted by bcseitz
I had Xtreme Motorsports install my 3:42's and a Protorque 2800 stall converter. Got a lot of vibration from the new TC at 22-2400 rpm's. And I really didn't like the feel of it anyway- too loose for me. Xtreme sent back the TC to Protorque (a brand I would NOT recommend if you are in the market) and re-installed the stock TC. Nice and smooth again!
I love the 3.42's. You will not be disappointed! Don't like High stall TC's around town. Now if I raced, that would be a whole different story.
My .02's
P.S. Yes, you must have someone adjust the shift points for you with the gear change.
I love the 3.42's. You will not be disappointed! Don't like High stall TC's around town. Now if I raced, that would be a whole different story.
My .02's
P.S. Yes, you must have someone adjust the shift points for you with the gear change.
Team Owner
Joined: Apr 2001
Posts: 54,204
Likes: 179
From: S.W. Ohio. . . . . . NRA Life Member
Originally Posted by Pizzano
Just remember, you cant swap a set of 3:42 into a 2:73, the carriesrs are different and other mods need to be made
you can swap a set of 3:42 into a 2:73; but since the carriers are different... other mods need be made, and it's a good idea to allow a pro to do the work.
