Getting a new diff
Thread Starter
Race Director
Joined: Aug 2001
Posts: 18,236
Likes: 36
From: Haymarket VA
St. Jude Donor '05-'06-'07-'08-'09-'10
Getting a new diff
so my differential is shot on my 02Z. Annoyed about it but after doing a fluid change and seeing all the metal flakes I guess at 70k miles I’m going to be changed.
The car has basic bolt ons. I take and long tubes, along with a tune. Should I just stick with the 3.42 or look to go up to 3.73. The car is a daily driver for the most part with a lot of time on highways and in traffic.
Looking for for some opinions since I don’t know much about differentials
The car has basic bolt ons. I take and long tubes, along with a tune. Should I just stick with the 3.42 or look to go up to 3.73. The car is a daily driver for the most part with a lot of time on highways and in traffic.
Looking for for some opinions since I don’t know much about differentials
Drifting
Joined: Jun 2000
Posts: 1,340
Likes: 233
From: Placitas NM
St. Jude Contributor '03 & '04
I disagree based on my personal experience - my daily driver has 250,000 on it since I drove it off the show room floor, 100,000 with the 4.11 diff. The ‘modern’ 6 speed makes the 4.11 very drivable - AND FUN.
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Safety Car
Joined: Mar 2016
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From: Atlantic Beach FL.
IMO, as long as you are changing the gears anyway, then 3.73's aren't a bad choice. It is a 9% change.
It will require a special tune by someone that knows what the heck they are doing because that gear ratio is not in the map codes of, and was not built in to the existing factory software in your PCM. Therefore, any new information has to be rewritten by a programmer you trust.
It will require a special tune by someone that knows what the heck they are doing because that gear ratio is not in the map codes of, and was not built in to the existing factory software in your PCM. Therefore, any new information has to be rewritten by a programmer you trust.
Safety Car
Joined: Feb 2013
Posts: 4,346
Likes: 755
From: Greensboro Nc
IMO, as long as you are changing the gears anyway, then 3.73's aren't a bad choice. It is a 9% change.
It will require a special tune by someone that knows what the heck they are doing because that gear ratio is not in the map codes of, and was not built in to the existing factory software in your PCM. Therefore, any new information has to be rewritten by a programmer you trust.
It will require a special tune by someone that knows what the heck they are doing because that gear ratio is not in the map codes of, and was not built in to the existing factory software in your PCM. Therefore, any new information has to be rewritten by a programmer you trust.
Pro
Joined: Jul 2008
Posts: 612
Likes: 17
From: Coatesville PA
Gear ratio change on a manual car does not require a new tune. I have had 4.10s in my 02z since I have been cam only and love them but they are definitely not something I would want in a DD. 3.73 would be a nice little bump since you’re already in the rear! 3.73 won’t hurt your gas mileage that much either and if you eventually upgrade your cam they will help get you in its powerband quicker.
Acct Suspended APR 2026 by request
Joined: Dec 2010
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2020 Corvette of the Year Finalist (performance mods)
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if you ever plan to boost the car stick with 3.42's and maybe even 3.15's if you want to make big power with the z06 trans and it's shorter gears... the base t56 trans has better ratios for boosted cars and would work better with 3.42's... just throwing that in the mix in case forced induction is a consideration
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Burning Brakes
Joined: Oct 2014
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From: Detroit MI
4.10's were the best mod I've ever done to my car, hands down. Mine's also a base, so you'd probably want to stick to 3.73's or the like in a Z. Still, it's not as aggressive as you'd think, and an excellent upgrade.
Drifting
Joined: Apr 1999
Posts: 1,667
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From: Brisbane CA
Let me test my understanding here! With a blower car, you will need less gearing? I have a p1SC-1 with a A4 with 3.15 gears. I was thinking about updating the gears when I rebuild the rear end with C6 components and taller gears. What gears I go with? I also have a 3000 RPM high stall torque converter