C7 3:90 & 4:10 Gears
03-08-2019, 06:55 PM
#242
Burning Brakes
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FYREANT (03-08-2019)
03-08-2019, 09:41 PM
#244
Burning Brakes
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phantom1 (03-09-2019)
03-12-2019, 09:55 PM
#247
Burning Brakes
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The 3.90 gears are installed and they work flawless. I drove 20 miles from the shop, and no noise, vibration or any issues. I immediately notice the difference when I accelerate, and shift from 1st to 2nd & 3rd. It feels like a totally different car. I prefer the 3.90 gears, they're definitely more on par with the M7, than the 3.42s. Can't wait til break-in is over.
Last edited by phantom1; 03-12-2019 at 09:59 PM.
03-13-2019, 09:01 PM
#250
Burning Brakes
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That's cool. I chose the 3.90 because I don't plan on changing the stock cam, and I want to trap closer to my power band. You might be shifting near red line with 4.10, especially if you have a Z51.
03-14-2019, 10:46 AM
#251
Drifting
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So phantom1, what was the total price you paid to have the gears swapped? Including purchasing them and the install cost?
And some people have mentioned tuning, what needs to be tuned on a gear swap? (Mine is an M7, Z51 with ELSD)
And some people have mentioned tuning, what needs to be tuned on a gear swap? (Mine is an M7, Z51 with ELSD)
03-14-2019, 11:51 AM
#252
Burning Brakes
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I haven't data log with gears yet, but I will after the break-in.
It was well worth it. I knew something was missing coming out of my C6 with 4.10s, and this is exactly what it was. You won't be disappointed.
729.99 3.90 Gears
750.00 Gear swap
650.00 labor remove & reinstall rear
80.00 GM Diff fluid
The total cost so far $2209.
Last edited by phantom1; 03-14-2019 at 04:31 PM.
03-14-2019, 03:01 PM
#253
Le Mans Master
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I remember when I started modding my C5 M6 the 3:73 rear diff upgrade was one of the best mods to do going from 3:42. 3:90 on M7 would work on cars < 800hp not so sure it makes sense on higher horsepower cars. Especially M7.
03-14-2019, 03:04 PM
#254
Drifting
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The initial quote for labor was $350 over the phone, then they added $300 when I got there. A little disappointed, although I thought $350 was low.
If I remember correctly, I read the C7 M7 ECM calibrates the gear ratio, no tune needed for calibration. I'm not sure how it effects torque management. I haven't log with gears yet, but I will after the break-in.
It was well worth it. I knew something was missing coming out of my C6 with 4.10s, and this is exactly what it was. You won't be disappointed.
729.99 3.90 Gears
750.00 Gear swap
650.00 labor remove & reinstall rear
80.00 GM Diff fluid
The total cost so far $2209.
If I remember correctly, I read the C7 M7 ECM calibrates the gear ratio, no tune needed for calibration. I'm not sure how it effects torque management. I haven't log with gears yet, but I will after the break-in.
It was well worth it. I knew something was missing coming out of my C6 with 4.10s, and this is exactly what it was. You won't be disappointed.
729.99 3.90 Gears
750.00 Gear swap
650.00 labor remove & reinstall rear
80.00 GM Diff fluid
The total cost so far $2209.
03-14-2019, 03:23 PM
#255
Drifting
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I am very interested in hearing your guys' thoughts after you've driven with the new gear sets. I might be ordering up a set next week as my rear end is already dropping out of the car...
Any performance data before/after with a dragy or track times would be super helpful.
Any performance data before/after with a dragy or track times would be super helpful.
Last edited by blue_bomber697; 03-14-2019 at 03:24 PM.
03-14-2019, 04:51 PM
#256
Burning Brakes
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As far is tuning goes, I need to do more research. It will likely need calibrated for the gears, and I don't know how it effects torque management, until I data log it.
Last edited by phantom1; 03-14-2019 at 05:49 PM.
03-14-2019, 04:57 PM
#257
Burning Brakes
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[QUOTE=blue_bomber697;1599045056]I am very interested in hearing your guys' thoughts after you've driven with the new gear sets. I might be ordering up a set next week as my rear end is already dropping out of the car...
Did you drop the rear yourself? if not, this would be the perfect time to change your gears, otherwise you'll be paying to drop the rear again. I did a muffler mod, and AFM delete while the rear was off.
Did you drop the rear yourself? if not, this would be the perfect time to change your gears, otherwise you'll be paying to drop the rear again. I did a muffler mod, and AFM delete while the rear was off.
03-14-2019, 07:27 PM
#258
Safety Car
I don't have electronic Limited Slip Diff.I just purchased 4.10 from RPM.Will there be a problem installing this without the
ELSD.
ELSD.
Last edited by thrilled; 03-16-2019 at 08:48 AM.
03-14-2019, 07:54 PM
#259
Burning Brakes
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03-14-2019, 08:54 PM
#260
Drifting
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[QUOTE=phantom1;1599045623]
Not myself no, its at my shop getting the clutch rebuilt/upgraded and so they dropped the rear for that. So now the diff is lying on the floor all off the car so it would be the perfect time to do gears.
I am very interested in hearing your guys' thoughts after you've driven with the new gear sets. I might be ordering up a set next week as my rear end is already dropping out of the car...
Did you drop the rear yourself? if not, this would be the perfect time to change your gears, otherwise you'll be paying to drop the rear again. I did a muffler mod, and AFM delete while the rear was off.
Did you drop the rear yourself? if not, this would be the perfect time to change your gears, otherwise you'll be paying to drop the rear again. I did a muffler mod, and AFM delete while the rear was off.