Differential swap questions.
Thread Starter
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1st Gear Member
Joined: Apr 2015
Posts: 163
From: Ocala, FL
Differential swap questions.
So my 93 has the 2.73 gears. Theres a local craigslist ad that has the 3.73 differential for 75 bucks however the case has a crack. can i use the existing case and just swap out the innards? i also believe that this is a bigger gearing than some prefer. can anyone tell me why people would prefer the 3.43 instead of this one? what benefits does this have compared to the others as well as its shortcomings?
I know the rear end is going to need work here soon.. im not even sure whats making this noise but every so often while driving or at idle I hear a 3-4 second long "hummmmmm" coming from the rear end. usually after the car has been running for a little bit. its not a grinding noise.. almost sounds like something is turning on or priming. Its also covered in grime and I wouldnt be surprised if its leaking.
heres the ad if you want to take a look: 10 bolt gen 4 rear end parts Camaro/Firebird
I know the rear end is going to need work here soon.. im not even sure whats making this noise but every so often while driving or at idle I hear a 3-4 second long "hummmmmm" coming from the rear end. usually after the car has been running for a little bit. its not a grinding noise.. almost sounds like something is turning on or priming. Its also covered in grime and I wouldnt be surprised if its leaking.
heres the ad if you want to take a look: 10 bolt gen 4 rear end parts Camaro/Firebird
Last edited by ztwentyate; Jun 24, 2015 at 11:06 PM.
Unfortunately, you can not reuse your current differential carrier, without buying (if they make them) a spacer. The GM 7.5 carrier is split into two series, 3.08 and down (numerically, series 2) and 3.23 and up (numerically, series 3). A gear swap requires some special tools as well as some practice to get it right. Do some research and you'll know what I mean.
Gear choice will depend on what you do with the car. If you plan on leaving it stock, 3.42 gears will be more than enough, you can find this in (as far as I know) all 6 speed equipped cars. Auto V8s came with 2.73 or 3.23, auto V6 came 2.73 (rare) or 3.08, may be 3.23 too. Most sixxers will be an open carrier though, so keep that in mind.
Now, if you plan on upping the car with a cam and such, 3.73s may not be a bad choice.
Advantages
-quicker off the line (assume no wheel spin)
-less throttle needed to get the car up a hill
Disadvantages
-less fuel mileage (how much varies) I didn't notice a difference in fuel mileage going from 2.73 to 3.42s
Loosen the fill hold on the passenger side front of the case, and check the level. If all is good, physically look at the fluid you get on your pinky. If it's questionable, go get your favorite brand 75W-90 gear oil, some LSD additive if the bottle doesn't come with it, pop the cover, drain the old fluid, inspect the magnet and fluid, as well as the guts, clean the gasket area and stick a new gasket on there and refill. You can check your wheel bearings too while you're in there.
Gear choice will depend on what you do with the car. If you plan on leaving it stock, 3.42 gears will be more than enough, you can find this in (as far as I know) all 6 speed equipped cars. Auto V8s came with 2.73 or 3.23, auto V6 came 2.73 (rare) or 3.08, may be 3.23 too. Most sixxers will be an open carrier though, so keep that in mind.
Now, if you plan on upping the car with a cam and such, 3.73s may not be a bad choice.
Advantages
-quicker off the line (assume no wheel spin)
-less throttle needed to get the car up a hill
Disadvantages
-less fuel mileage (how much varies) I didn't notice a difference in fuel mileage going from 2.73 to 3.42s
Loosen the fill hold on the passenger side front of the case, and check the level. If all is good, physically look at the fluid you get on your pinky. If it's questionable, go get your favorite brand 75W-90 gear oil, some LSD additive if the bottle doesn't come with it, pop the cover, drain the old fluid, inspect the magnet and fluid, as well as the guts, clean the gasket area and stick a new gasket on there and refill. You can check your wheel bearings too while you're in there.
Thread Starter
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1st Gear Member
Joined: Apr 2015
Posts: 163
From: Ocala, FL
Alright great info man. This is why I love you guys. The 98 I just bought I believe is the GU5 RPO so it would be the 3.23 and the 93 is the GU2. Also, could the differential be the cause of a 3-4 second long hum? Maybe its the fuel pump? Ill have to let the car idle and record the sound and see if any of yall recognize it after I finish putting things back together in the morning. Now that I think about it.. when I first began to notice the sound was a REALLY hot day and I had been driving for a good 3-4 hours and then pulled into a parking lot to try to get a better idea of the sound. wwhen I got out of the car to hear it.. it kind of smelled like fuel. edit: the sound was mechanical.. not like something going wrong but something turning on or some device adjusting itself.
I imagine the gasket probably isnt too expensive so ill check that out here this weekend and give her a nice *** cleaning lol
I imagine the gasket probably isnt too expensive so ill check that out here this weekend and give her a nice *** cleaning lol
Last edited by ztwentyate; Jun 25, 2015 at 12:26 AM.
Gasket is only a few bucks. A lot of people will say to use RTV instead, but I don't like that method unless it came factory that way, or you're really in a pinch.
Are swapping the whole axle out or just the internals? Doing the whole axle isn't hard. Actually, getting it out is quite easy, but expect to replace some suspension bolts, as I'm sure yours will be like mine and rusted to crap. Getting it back in with one person is a little more difficult, but doable. Remember, you'll need to switch all your braking over from your axle to the new one, unless you want to go with later style brakes, but that requires different brake cables. You can swap them over without disconnecting any lines.
See if you can get a video of your noise. Would seem weird for the diff to only do it for a few seconds if everything remained constant (speed, direction).
Are swapping the whole axle out or just the internals? Doing the whole axle isn't hard. Actually, getting it out is quite easy, but expect to replace some suspension bolts, as I'm sure yours will be like mine and rusted to crap. Getting it back in with one person is a little more difficult, but doable. Remember, you'll need to switch all your braking over from your axle to the new one, unless you want to go with later style brakes, but that requires different brake cables. You can swap them over without disconnecting any lines.
See if you can get a video of your noise. Would seem weird for the diff to only do it for a few seconds if everything remained constant (speed, direction).
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93 F-body with (M28) 6 speed Torque rating 360 lbs-ft. Has 2.73's - GU2
93 F-body with (M29) 6 speed Torque rating 400 lbs-ft. Has 3.23's - GU5
94+ F-body with (MN6) 6 speed Torque rating 450 lbs-ft. Has 3.42's - GU6
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Unfortunately, you can not reuse your current differential carrier, without buying (if they make them) a spacer. The GM 7.5 carrier is split into two series, 3.08 and down (numerically, series 2) and 3.23 and up (numerically, series 3). A gear swap requires some special tools as well as some practice to get it right. Do some research and you'll know what I mean.
Gear choice will depend on what you do with the car. If you plan on leaving it stock, 3.42 gears will be more than enough, you can find this in (as far as I know) all 6 speed equipped cars. Auto V8s came with 2.73 or 3.23, auto V6 came 2.73 (rare) or 3.08, may be 3.23 too. Most sixxers will be an open carrier though, so keep that in mind.
Now, if you plan on upping the car with a cam and such, 3.73s may not be a bad choice.
Advantages
-quicker off the line (assume no wheel spin)
-less throttle needed to get the car up a hill
Disadvantages
-less fuel mileage (how much varies) I didn't notice a difference in fuel mileage going from 2.73 to 3.42s
Loosen the fill hold on the passenger side front of the case, and check the level. If all is good, physically look at the fluid you get on your pinky. If it's questionable, go get your favorite brand 75W-90 gear oil, some LSD additive if the bottle doesn't come with it, pop the cover, drain the old fluid, inspect the magnet and fluid, as well as the guts, clean the gasket area and stick a new gasket on there and refill. You can check your wheel bearings too while you're in there.
Gear choice will depend on what you do with the car. If you plan on leaving it stock, 3.42 gears will be more than enough, you can find this in (as far as I know) all 6 speed equipped cars. Auto V8s came with 2.73 or 3.23, auto V6 came 2.73 (rare) or 3.08, may be 3.23 too. Most sixxers will be an open carrier though, so keep that in mind.
Now, if you plan on upping the car with a cam and such, 3.73s may not be a bad choice.
Advantages
-quicker off the line (assume no wheel spin)
-less throttle needed to get the car up a hill
Disadvantages
-less fuel mileage (how much varies) I didn't notice a difference in fuel mileage going from 2.73 to 3.42s
Loosen the fill hold on the passenger side front of the case, and check the level. If all is good, physically look at the fluid you get on your pinky. If it's questionable, go get your favorite brand 75W-90 gear oil, some LSD additive if the bottle doesn't come with it, pop the cover, drain the old fluid, inspect the magnet and fluid, as well as the guts, clean the gasket area and stick a new gasket on there and refill. You can check your wheel bearings too while you're in there.
MPG wise, I haven't noticed a difference. It cost a little more to put gas in my car this last fill up, but the price had also gone up $0.10. I use my trip meter and reset every fill up and I get about 215-220 miles or so out of a tank, but I also never let it get too low. My tune leans the car out at idle and light throttle so I use a little less fuel than stock.