3.90 gears
Burning Brakes
Joined: Jan 2008
Posts: 905
Likes: 0
From: BURTON MI
I began to think my installer might be at fault with the gear install, but then I began researching and discovered that many members throughout the country are running into this problem, and their installers have been confiming the story about the Italian gear manufacturer.
I also can't understand why no American firms are making gears. If I owned a factory, I'd be looking to jump all over this opportunity. Go figure.
I also can't understand why no American firms are making gears. If I owned a factory, I'd be looking to jump all over this opportunity. Go figure.
Melting Slicks
Joined: Nov 2004
Posts: 2,408
Likes: 145
From: Northcentral, Pennsylvania
St. Jude Donor '09-'11
My first 4.10 ring & pinion install lasted 500 miles. Horrific whine. Needed ear plugs. They were defective and replaced N/C by the installer about 14 months ago. I really like the 4.10 gears, but it's interesting others have had the same problem.
Burning Brakes
Joined: Jan 2008
Posts: 905
Likes: 0
From: BURTON MI
Mine were also replaced n/c but 3 installs tied my car up for 4 months. Drove it a total of 2 1/2 weeks for the whole summer. Needless to say I was not a happy camper.
Tech Contributor
Joined: Mar 2003
Posts: 12,094
Likes: 197
From: Colorado Springs, CO
St. Jude Donor '08-'09-'10-'11
To do the diff alone requires the cradle to be removed and the exhaust dropped.....its 1/3 of the way in.
Burning Brakes
Joined: Apr 2008
Posts: 891
Likes: 1
From: NY NY
Melting Slicks
Joined: Nov 2004
Posts: 2,408
Likes: 145
From: Northcentral, Pennsylvania
St. Jude Donor '09-'11
Gee...I hope the QuickSilver Mod God doesn't post in this thread and say "I told you so".
Former Vendor
Joined: Oct 2006
Posts: 2,050
Likes: 33
From: Cumming Georgia
Bob, glad you are happy sir!!! After reading this thread I made a quick call to RPM Transmissions to get the real story on this situation.
RPM Transmission says they use Motive Gear (An Italian made piece). They also said that they have had virtually zero issues with 3:90/4:10 gears. They said they have had some issues with 3:73s, but every one of those were installed in C5s, not C6s.
Spin had an absolutely spot on suggestion above... Get your parts/gears/diff from the same shop doing your install. This takes all of the "finger pointing" out of the equation.
RPM Transmission says they use Motive Gear (An Italian made piece). They also said that they have had virtually zero issues with 3:90/4:10 gears. They said they have had some issues with 3:73s, but every one of those were installed in C5s, not C6s.
Spin had an absolutely spot on suggestion above... Get your parts/gears/diff from the same shop doing your install. This takes all of the "finger pointing" out of the equation.
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Burning Brakes
Joined: Jan 2008
Posts: 905
Likes: 0
From: BURTON MI
Bob, glad you are happy sir!!! After reading this thread I made a quick call to RPM Transmissions to get the real story on this situation.
RPM Transmission says they use Motive Gear (An Italian made piece). They also said that they have had virtually zero issues with 3:90/4:10 gears. They said they have had some issues with 3:73s, but every one of those were installed in C5s, not C6s.
Spin had an absolutely spot on suggestion above... Get your parts/gears/diff from the same shop doing your install. This takes all of the "finger pointing" out of the equation.
RPM Transmission says they use Motive Gear (An Italian made piece). They also said that they have had virtually zero issues with 3:90/4:10 gears. They said they have had some issues with 3:73s, but every one of those were installed in C5s, not C6s.
Spin had an absolutely spot on suggestion above... Get your parts/gears/diff from the same shop doing your install. This takes all of the "finger pointing" out of the equation.
Burning Brakes
Joined: Jan 2008
Posts: 905
Likes: 0
From: BURTON MI
Ron. I'm also a Bob, think your quote was to another Bob. We all appreciate you chiming in, as you can see, a lot of members are having trouble with these gears sets. Also learned last week, Chubbs77 just got 390's, from the same place I did, and they are whinning at 500 miles?????
Team Owner
Joined: Mar 2005
Posts: 20,933
Likes: 905
From: salem OR
Ron. I'm also a Bob, think your quote was to another Bob. We all appreciate you chiming in, as you can see, a lot of members are having trouble with these gears sets. Also learned last week, Chubbs77 just got 390's, from the same place I did, and they are whinning at 500 miles?????
too low but they are perfect even S/C'd!
Burning Brakes
Joined: Jan 2008
Posts: 905
Likes: 0
From: BURTON MI
I do like the 390 as they took care of the slow startups. Didn't get too many miles on the 410's but the results were similar. I believe the 390's increase the ratio by 15% and the 410's by 20%. Currently have 5000 on the 390's, so far so good.
Drifting
Joined: May 2008
Posts: 1,621
Likes: 2
From: Petal Ms
St. Jude Donor '08-'11
My second set of 3.73's recently went out. Got just over 600 miles on each set before they started whining real bad. This is in a 2005 c6. Luckily the shop that got the gears did the install and everything in the rear. I am still out of a lot of labor and a lot of $$$$$ in shipping though to get the rear back to them and from them back to me every time. Sucks that I have to pay for them to send it back to me when it is not even my fault though. I am switching to a 3.42 GM gear this time though (a4 trans) so hopefully they won't slow me down too much and won't start whining. I paid to have 3.73's in the car, not 3.42's, but I would rather have them last...
Instructor
Joined: May 2007
Posts: 104
Likes: 0
From: Whitehall PA
What is the break in process of new gears? I'm suppose to be getting 4.10s installed thursday and i'm getting scared cuz of all the problems people are having.By the way i have an 01z06 and was thinking of maybe just going with 3.90s.Any advise is appreaciated. Thanks
Burning Brakes
Joined: Jan 2008
Posts: 905
Likes: 0
From: BURTON MI
If you track the car 4.10's will cause you to shift into 5th before the end of the quarter mile. Don't have those numbers handy. On the 3.90's, you will be at 140 mph at 7000 rpm in 4th. Ask your installer what their recomended break in procedure is so that there is no misunderstanding between you and them. Good luck. OOPS. See you have an 01 Z06. Don't know about those numbers at all. Being in the c6 section I assumed???????? The breakin procedure use the comment above.
Last edited by BOB EAGAN; Jun 16, 2009 at 09:38 PM.
Pro
Joined: May 2007
Posts: 585
Likes: 0
From: Ocean County NJ
Anyone doing a clutch has to have the entire TQ tube/trans/diff removed from the car so the overlap there is a no brainer. The amount of time it takes to bolt on the new diff and fill it with fluid is 15 minutes so the labor would be free on the diff install. With clutch installs running from 600 to 1000 in labor it makes sense to upgrade these two together.
To do the diff alone requires the cradle to be removed and the exhaust dropped.....its 1/3 of the way in.
To do the diff alone requires the cradle to be removed and the exhaust dropped.....its 1/3 of the way in.
Possibly stupid question - how much mph increase in trap speed should I see, if any. I already trap 120 mph with 385 rwhp, runcraps, manual trans and the stock rear 3:42 ratio.
Sorry for the detour and quasi hijack, I am now returning you to your regularly scheduled program..............