Which gears to go with (3:42's or 3:73's)?
03-29-2010, 11:58 PM
#1
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Which gears to go with (3:42's or 3:73's)? I am currently rebuilding my 10 Bolt (due to half the bearings taken a crap). The car is an 1998 Z-28 with an A4, and a few bolt on's. The rear end had 2:73's before this rebuild. I drag race the car almost every weekend and am running drag radials on the car this season. I have a set of Alloy axles, Detroit True-Trac (series 3 carrier), and a complete rebuild kit. I would like to upgrade to either a 3:42 or a 3:73 gear. I see that the general consensus is to go with 3:73's,but i have heard some ***** story's of people breaking rearends with 3:73's. Your input is greatly appreciated! Thanks in advance!
Last edited by Chubbz155; 03-30-2010 at 10:29 PM.
03-30-2010, 12:23 AM
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i recently bought a rear with 3.73's the performance was night and day compared to my current 3.42 but i broke 3-4 teeth off the pinion gear im not sure if it was due to a crappy rebuild or me beatin on it but it did happen. now sayin that i am still going to rebuild it and this time i am putting 4.10's in it and keep my 3.42 as a spare just incase
03-30-2010, 12:49 AM
#3
342s... The difference between 342s and 373s in an A4 car are minimal to non existent. In an M6 car it makes MUCH more of a difference.
People say all the time with their A4 cars "I went from XXX gear to 373s and it was a different animal, picked it up a TON".. In reality, it is all SOTP feeling. Ask them for track times, none of them have proof... Meaning DA to go along with it and no other mods done. I have seen many times people swap gears in with no gain.
Stock gearing (especially 342s) in an A4 will take you a LONG way.
People say all the time with their A4 cars "I went from XXX gear to 373s and it was a different animal, picked it up a TON".. In reality, it is all SOTP feeling. Ask them for track times, none of them have proof... Meaning DA to go along with it and no other mods done. I have seen many times people swap gears in with no gain.
Stock gearing (especially 342s) in an A4 will take you a LONG way.
03-30-2010, 10:04 AM
#6
Not being an *** by saying this at all.....
Can any of you guys saying to go 373s because he will gain so much show any proof?
The main thing 373s do is weaken the rear and worse gas mileage. There are plenty of threads around (with DA to prove) to show that people don't always pick up from gears.
The main proof there is that you don't have to have gears to run quick is the "fastest" lists. Check out the SI/cam only/H/C lists..
Can any of you guys saying to go 373s because he will gain so much show any proof?
The main thing 373s do is weaken the rear and worse gas mileage. There are plenty of threads around (with DA to prove) to show that people don't always pick up from gears.
The main proof there is that you don't have to have gears to run quick is the "fastest" lists. Check out the SI/cam only/H/C lists..
03-30-2010, 03:00 PM
#7
Not being an *** by saying this at all.....
Can any of you guys saying to go 373s because he will gain so much show any proof?
The main thing 373s do is weaken the rear and worse gas mileage. There are plenty of threads around (with DA to prove) to show that people don't always pick up from gears.
The main proof there is that you don't have to have gears to run quick is the "fastest" lists. Check out the SI/cam only/H/C lists..
Can any of you guys saying to go 373s because he will gain so much show any proof?
The main thing 373s do is weaken the rear and worse gas mileage. There are plenty of threads around (with DA to prove) to show that people don't always pick up from gears.
The main proof there is that you don't have to have gears to run quick is the "fastest" lists. Check out the SI/cam only/H/C lists..
Gears aren't NEEDED to go fast, and you can still make a fast car with factory gears, but it's ignorant to say that gears don't do anything...
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03-30-2010, 03:54 PM
#8
No it isn't.. There have been MANY MANY MANY people that have documented before/after that have shown absolutely no gain. A typical gain with gears is around .1.. I would rather spend money elsewhere and make my rear last longer.
03-30-2010, 07:31 PM
#9
I'd like to see some of these MANY MANY MANY people that have changed their gears in nearly stock cars, done back to back testing using the factory gears vs. aftermarket gears, recorded the DA, and had no gains whatsoever...
and I do not have the DA's exact numbers handy, but did at one time, they where very close, the testing was done in the same weekend over last summer.
and I do not have the DA's exact numbers handy, but did at one time, they where very close, the testing was done in the same weekend over last summer.
03-30-2010, 08:39 PM
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You are comparing 3.23s to 3.73s. OP was talking about 3.42s to 3.73s. I have ran both in the same car and there is not much difference even with a stock converter (but no I do not have track times with the 3.42s yet). Put a stall in the picture and there wouldn't be enough to justify the waste in mileage and wear on the motor. I picked up 2 mpg swapping 3.42s.
OP, if you do race the car every weekend then 3.73s would be my choice. I dont drag mine that much so I went with 3.42s.
03-30-2010, 09:05 PM
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Well he had just got the rear end rebuilt and got some used 3.42's but they whin like a mother f*cker so he is going to buy new gears and wants to know if he should stay with the 3.42's or jump higher to 3.73's. He had 2.73's before this and has driven the car like 2 miles so he doesnt know how it feels either way. We dont race every weekend but at least 1 or 2 weekends a month.
03-30-2010, 10:33 PM
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So you raced the car one night, then rebuilt the differential and raced it again the same weekend???
You are comparing 3.23s to 3.73s. OP was talking about 3.42s to 3.73s. I have ran both in the same car and there is not much difference even with a stock converter (but no I do not have track times with the 3.42s yet). Put a stall in the picture and there wouldn't be enough to justify the waste in mileage and wear on the motor. I picked up 2 mpg swapping 3.42s.
OP, if you do race the car every weekend then 3.73s would be my choice. I dont drag mine that much so I went with 3.42s.
You are comparing 3.23s to 3.73s. OP was talking about 3.42s to 3.73s. I have ran both in the same car and there is not much difference even with a stock converter (but no I do not have track times with the 3.42s yet). Put a stall in the picture and there wouldn't be enough to justify the waste in mileage and wear on the motor. I picked up 2 mpg swapping 3.42s.
OP, if you do race the car every weekend then 3.73s would be my choice. I dont drag mine that much so I went with 3.42s.
I am not to worried about gas mileage, as this is my toy and not my DD. I am more worried about possibly breaking the rear end with 3:73's.
Well he had just got the rear end rebuilt and got some used 3.42's but they whin like a mother f*cker so he is going to buy new gears and wants to know if he should stay with the 3.42's or jump higher to 3.73's. He had 2.73's before this and has driven the car like 2 miles so he doesnt know how it feels either way. We dont race every weekend but at least 1 or 2 weekends a month.
Thanks Josh for adding some more info to this.
Also i wasn't trying to start a debate over this but just a little insight on pro/cons of 3:73's vs. 3:42's.
What gears have you guys had good luck with/not a lot of noise or whin?
03-31-2010, 02:20 PM
#14
I'd like to see some of these MANY MANY MANY people that have changed their gears in nearly stock cars, done back to back testing using the factory gears vs. aftermarket gears, recorded the DA, and had no gains whatsoever...
and I do not have the DA's exact numbers handy, but did at one time, they where very close, the testing was done in the same weekend over last summer.
and I do not have the DA's exact numbers handy, but did at one time, they where very close, the testing was done in the same weekend over last summer.
I have ran in 2300+DA one weekend and went back the next weekend and it was around 1400+DA. That is around 1-2 tenths difference.
04-01-2010, 12:26 AM
#15
So you raced the car one night, then rebuilt the differential and raced it again the same weekend???
You are comparing 3.23s to 3.73s. OP was talking about 3.42s to 3.73s. I have ran both in the same car and there is not much difference even with a stock converter (but no I do not have track times with the 3.42s yet). Put a stall in the picture and there wouldn't be enough to justify the waste in mileage and wear on the motor. I picked up 2 mpg swapping 3.42s.
OP, if you do race the car every weekend then 3.73s would be my choice. I dont drag mine that much so I went with 3.42s.
You are comparing 3.23s to 3.73s. OP was talking about 3.42s to 3.73s. I have ran both in the same car and there is not much difference even with a stock converter (but no I do not have track times with the 3.42s yet). Put a stall in the picture and there wouldn't be enough to justify the waste in mileage and wear on the motor. I picked up 2 mpg swapping 3.42s.
OP, if you do race the car every weekend then 3.73s would be my choice. I dont drag mine that much so I went with 3.42s.
04-01-2010, 11:26 AM
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Never seen 3.55s for a 7.5 gm.
04-01-2010, 11:43 AM
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I went from 3.23s to 3.42s, and if I had it to over I wouldn't.
I couldn't hook up before, and even less now, even ET Streets
couldn't get me below a 1.9 60' spinning most of the way through
2nd.
I drove a 2.73 Z/28 when shopping, and you definitely want to
change that. But I'd stick with one of the factory ratios and
unless you have slicks & suspension, may as well not go too
nuts.
I couldn't hook up before, and even less now, even ET Streets
couldn't get me below a 1.9 60' spinning most of the way through
2nd.
I drove a 2.73 Z/28 when shopping, and you definitely want to
change that. But I'd stick with one of the factory ratios and
unless you have slicks & suspension, may as well not go too
nuts.
04-01-2010, 01:24 PM
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OP says drag racing almost every weekend and running drag radials. The track is night and day compared to the street when it comes to traction. A gear ads more than just a good 60', it'll keep you in the power when you shift going down the track. Go w/ 3.73's and move on to your next mod. IMO
Last edited by WizardofDetailing; 04-01-2010 at 01:31 PM.