rear gears 93 convertable
Thread Starter
Cruising
Joined: Aug 2004
Posts: 10
Likes: 0
From: St. Peters Mo.
rear gears 93 convertable
i'm interested in a rear gear change for my 93 auto vette. definately will go with the 3:42, however i'm considering the 3:55 or 3:73. the rest of the car is stock with no other planned changes than the air box, thermostat, and computer. does anyone have any first hand experience with the 3:55 or 3:73 with an otherwise stock vette? i'm interested in changes in fuel economy and rpm on the highway.
your input will be greatly appreciated.
jeff
your input will be greatly appreciated.
jeff
Le Mans Master
Joined: Jan 2002
Posts: 5,556
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From: Jenison MI
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St. Jude Donor '06
I went fro 2.59's to 3.73's I love the gears and how quick the car is but I went from 28mpg down to 19mpg on the highway I also run about 3000 rpm at 80. If I had to do it again I would look more at the 3.42's. but who knows. The 3.73's are great in town but on the highway with no cats and corsa's it's a little loud. Either gear you go with I'm sure you will love. I would only say that if you change gears to also step up to a D44 rearend. 
Melting Slicks
Joined: Apr 2004
Posts: 3,287
Likes: 7
From: n/a SC
Well what gears do you have now and how do they suit you? You probably have the 2.59's I don't think the 3.07's was an option in the lt1 until 94. Personally if I changed my 3.07's for something more I would go with the 3.54s, this will be a good bit of difference without going overboard.
Melting Slicks
Joined: Nov 2002
Posts: 2,471
Likes: 2
From: 1993 Quasar Blue 'vert Scottsdale AZ
I also have a 93 auto vert and last week, I replaced my 2.59's with 3.54's. I've only put 100 miles on it, so I haven't been able to really get on it yet but I can still tell that there is going to be a big difference. I was told to take it real easy for 200 miles and not to hammer it until about 500 miles. IMHO, 3.73 might be a little too much for the Dana 36.
Melting Slicks
Joined: Jul 2004
Posts: 2,695
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From: Chicago Illinois
Im also about to put in a 3.73 in my 93 vette. It now has a 3.07 and the tranny is a 4L60, which is a big concern of mine in terms of correcting the speedo. I wish it was the 4L60E which is electronic and could be easily corrected with a programmer. So how do you adjust the speedo?
Melting Slicks
Joined: Oct 2001
Posts: 2,786
Likes: 22
From: Cary NC
From my past experience...
Converting a 92 auto, 700R4, from 2.59 to 3.54 gears requires all 3 parts in the speedometer gears to be changed. The 2 gears, both drive and driven. Also the speed sensor because the original gears were 2.59 the sensor is for a 2-Series. Now I put in 3.54 gears so I need a sensor for a 3-Series. If you had 3.07 to start with then you can skip the Speed Sensor and save $50.
10456089 - Speed Sensor (3-series)
8642620 - Drive gear, 15-tooth (grey)
25513050 - Driven gear, 43-tooth (purple)
If you were to look up these parts you would find that the sensor actually fits auto and 6sp with 3.x rear gears in 92. Now the 2 gears actually are listed for an 89 with 6sp. Because the 89 6sp had a 3.54 rear axle. Exactly the gear ratio I chose.
So the speed should calibrate properly and the gears will mate properly. This matching is important. If you don't get the right pair not only will your speedo be off but you may chew up one of the speedo gears. Don't ask me how I know...
Graham
Converting a 92 auto, 700R4, from 2.59 to 3.54 gears requires all 3 parts in the speedometer gears to be changed. The 2 gears, both drive and driven. Also the speed sensor because the original gears were 2.59 the sensor is for a 2-Series. Now I put in 3.54 gears so I need a sensor for a 3-Series. If you had 3.07 to start with then you can skip the Speed Sensor and save $50.
10456089 - Speed Sensor (3-series)
8642620 - Drive gear, 15-tooth (grey)
25513050 - Driven gear, 43-tooth (purple)
If you were to look up these parts you would find that the sensor actually fits auto and 6sp with 3.x rear gears in 92. Now the 2 gears actually are listed for an 89 with 6sp. Because the 89 6sp had a 3.54 rear axle. Exactly the gear ratio I chose.
So the speed should calibrate properly and the gears will mate properly. This matching is important. If you don't get the right pair not only will your speedo be off but you may chew up one of the speedo gears. Don't ask me how I know...
Graham
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Team Owner
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From: Former NCM Drag Racing coordinator, National director Corvette Challenge Spring Hill, Tennessee: Whiting, New Jersey
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I like 3.73 for that application, they are very streetable.
Bench Racer
Joined: Feb 2003
Posts: 4,201
Likes: 15
From: Palm Beach Gardens FL
St. Jude '03 thru 14,'25
Originally Posted by Darkgh0st
I also have a '93 with 2.59. Whats the ballpark cost for having the gears changed?
Bench Racer
Joined: Feb 2003
Posts: 4,201
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From: Palm Beach Gardens FL
St. Jude '03 thru 14,'25
If you're up to R&Ring the diff yourself and then just taking it to the gear setup guy, you could probably save yourself around $400. There's an illustrated Tech Tip on on swapping out a Dana 36 for a Dana 44 but it would be the same...