rearend? Speed and performance? rmp

[johnny]

Did someone changes his rearend to a different ratio? What will happen? And in what gear is topspeed driven? In 6th? or in 5th, but slower?

I have a sixspeed coupe, with stock rearend (3.42 I think) I have bought myself a Magna charger, but is it wise to change my rearend? According to LPE my vette should run 3.6 till 60mph and 200 mph topspeed......

Hwo knows more?

thx,
John

 

[P-ColaVette]

Gear changes...

Hi Johnny !

Last year I installed a DTE 4.10 ratio assembly into my '99 FRC, and there were NO driveability issues what-so-ever ! In fact, the same day I picked the car up from the installation, I departed on a 1,500 mile round trip to south Florida ! I will say, if you are installing a Magna Charger, 3.42 gearing would be pretty much optimal for that set up. The reason being, a supercharger produces tons of low end power, or torque. If you go to a lower numerical ratio, (3.73,4.10 etc.) you would encounter severe traction problems due to giving the increased power an increased mechcanical advantage over the tires ! It has been my experience that supercharged vehicles perform best with a rear end ratio close to 3.50, which if you have the 3.42, puts you right in the sweet spot ! Just my answer to your question, at 70mph, my car is turning approximately 1800 rpms. Since I went with a 4.10 ratio, my car now pulls all the way thru 6th gear. I have seen all the posts that state max. top speed is achieved in 5th gear, however, I went at it with a viper, top speed, and my car pulled a little over 150, maybe 160mph, and that was in 6th gear.



Steve.

 

[johnny]

re:

Thanks Steve. This info helps me a lot.

What about strenght? Do I have to replace some parts of the rearend?

John.

 

[SLICKMAN]

I was thinking about this mod (4:10's).. What was the cost and did include the gears?

Hi Johnny !

Last year I installed a DTE 4.10 ratio assembly into my '99 FRC, and there were NO driveability issues what-so-ever ! In fact, the same day I picked the car up from the installation, I departed on a 1,500 mile round trip to south Florida ! I will say, if you are installing a Magna Charger, 3.42 gearing would be pretty much optimal for that set up. The reason being, a supercharger produces tons of low end power, or torque. If you go to a lower numerical ratio, (3.73,4.10 etc.) you would encounter severe traction problems due to giving the increased power an increased mechcanical advantage over the tires ! It has been my experience that supercharged vehicles perform best with a rear end ratio close to 3.50, which if you have the 3.42, puts you right in the sweet spot ! Just my answer to your question, at 70mph, my car is turning approximately 1800 rpms. Since I went with a 4.10 ratio, my car now pulls all the way thru 6th gear. I have seen all the posts that state max. top speed is achieved in 5th gear, however, I went at it with a viper, top speed, and my car pulled a little over 150, maybe 160mph, and that was in 6th gear.



Steve.

 

[P-ColaVette]

Possible Gear change...

Hi Johnny & Slickman,

Johnny, unless you plan on drag racing, or launching your car from a standing start at 4000 RPM or higher, your stock rearend will do fine. DTE ( Dyno Tech Engineering) does offer a hardened output shaft that is capable of handling mega horsepower and severe driving. They also have recently released a rearend girdle, which I would highly recomend. Slickman, I purchased my rearend as a complete unit from DTE thru a group purchase on the Corvette Forum. What I did was purchase a "Core" rearend, shipped it to Phil at DTE, they installed all new components, and then shipped to me. My price was considerably cheaper than what an individual's price would be because if I am not mistaken, there was about twenty of us that combined for the group purchase. Purchasing a core unit and sending that to DTE enabled me to continue driving my car until it was time to actually install the upgraded rear end gearing. DTE does/will install the finished unit, if you want to drive to FT Wayne, Indianna for their service ! Hope this answered all questions, if not just post some more, and I will try to answer !



Steve.

 

[SLICKMAN]

Thanks!! I have been thinking about upgrading to the 4:10's. I have been told the seat of the pants change is out of this world.. Your bang for the buck is best by investing in the 4:10 rear.. Would you agree?

Hi Johnny & Slickman,

Johnny, unless you plan on drag racing, or launching your car from a standing start at 4000 RPM or higher, your stock rearend will do fine. DTE ( Dyno Tech Engineering) does offer a hardened output shaft that is capable of handling mega horsepower and severe driving. They also have recently released a rearend girdle, which I would highly recomend. Slickman, I purchased my rearend as a complete unit from DTE thru a group purchase on the Corvette Forum. What I did was purchase a "Core" rearend, shipped it to Phil at DTE, they installed all new components, and then shipped to me. My price was considerably cheaper than what an individual's price would be because if I am not mistaken, there was about twenty of us that combined for the group purchase. Purchasing a core unit and sending that to DTE enabled me to continue driving my car until it was time to actually install the upgraded rear end gearing. DTE does/will install the finished unit, if you want to drive to FT Wayne, Indianna for their service ! Hope this answered all questions, if not just post some more, and I will try to answer !



Steve.

 

[JBsC5]

Stock driveline parts with magnusum supercharger is best ...


plus you can with the magnuson get the extended 36k/36 month drivetrain warranty for 200 bucks...

I would stay stock drivetrain with torque of supercharger ..

 

[P-ColaVette]

Bang for the buck !

Hi SlickMan !

Yes, I will say that hands down, over all my mods, except for the Borla exhaust, the 4.10's were some of the best money spent. Unquestionably, the LS1 in our vette's should have been geared this way from the factory ! Hope you don't wait to long to do it, because it is definitely one of those items which will have you saying..." Why did I wait so long to do this?"



Steve.

 

[SLICKMAN]

Yep, I have plans to get the car to the shop by the second week in Aug.. Having the trans re-built and the gears changed to 4:10's...

Hi SlickMan !

Yes, I will say that hands down, over all my mods, except for the Borla exhaust, the 4.10's were some of the best money spent. Unquestionably, the LS1 in our vette's should have been geared this way from the factory ! Hope you don't wait to long to do it, because it is definitely one of those items which will have you saying..." Why did I wait so long to do this?"



Steve.

 

[P-ColaVette]

Trans Rebuild ?

Hi Slickman !

Is your car a six speed ? If not, 4.10's may be too much !



Steve.

 

[SLICKMAN]

Yep, its a six speed

Hi Slickman !

Is your car a six speed ? If not, 4.10's may be too much !



Steve.

 

[C5Richard]

Hi Johnny !

Last year I installed a DTE 4.10 ratio assembly into my '99 FRC, and there were NO driveability issues what-so-ever ! In fact, the same day I picked the car up from the installation, I departed on a 1,500 mile round trip to south Florida ! I will say, if you are installing a Magna Charger, 3.42 gearing would be pretty much optimal for that set up. The reason being, a supercharger produces tons of low end power, or torque. If you go to a lower numerical ratio, (3.73,4.10 etc.) you would encounter severe traction problems due to giving the increased power an increased mechcanical advantage over the tires ! It has been my experience that supercharged vehicles perform best with a rear end ratio close to 3.50, which if you have the 3.42, puts you right in the sweet spot ! Just my answer to your question, at 70mph, my car is turning approximately 1800 rpms. Since I went with a 4.10 ratio, my car now pulls all the way thru 6th gear. I have seen all the posts that state max. top speed is achieved in 5th gear, however, I went at it with a viper, top speed, and my car pulled a little over 150, maybe 160mph, and that was in 6th gear.



Steve.

I've been thinking about this but have some reservations. The housing has to be modified to accept 4.10 gears. I'm being warned that after the modification the diff makes grinding noise on accelleration and decelleration. Notably so. And howls while driving. Is that pretty accurate?

Richard.

 

[SLICKMAN]

I've been thinking about this but have some reservations. The housing has to be modified to accept 4.10 gears. I'm being warned that after the modification the diff makes grinding noise on accelleration and decelleration. Notably so. And howls while driving. Is that pretty accurate?

Richard.

Humm, I have not heard anything about this...:confused In fact, anyone I have talked to all say the same thing, there were no issues.. Anyone else out there heard of this??? I would like to know seeing that I'm in the process of having this done in a few weeks.

 

[C5Richard]

Humm, I have not heard anything about this...:confused In fact, anyone I have talked to all say the same thing, there were no issues.. Anyone else out there heard of this??? I would like to know seeing that I'm in the process of having this done in a few weeks.

I too was in process of making arrangments for this. The facts I found so far is: The 3:42 and the next one up from that which is something like a 3:60 do not require modifying the case. The 3:73 and 4:10 require that the inside of the casing be ground out to make room for the gears. Apparently there are few places in the US willing to tackle replacing the ring and pinion so it's handled by exchange. With exchange it's about $1100 for the diff and 7 hours labor to change it out. Totals out near 2k. Both the 3:73 and 4:10 ratios are noisy. Enough so that there's slap back no trade backs on the noise issue. Though I would like to hear more about this.
21 Century does a cam change for $1600 with no issues. I may opt for that instead.

Richard.

 

[P-ColaVette]

No Grinding....

Hello Everybody !

As far as any type of noise goes, let me start by saying that the "core" differential that I sent to DTE for the 4.10 upgrade was a "2" series carrier. Meaning that the diff. I sent to them was a 2.73 ratio. A close friend of mine also sent a 2 series carrier, and also had the 4.10 installation done. I believe that there are a lot of "Urban Rumors" floating around about this particular upgrade, however, if done by a competent shop/mechanic, there should be no noise/problems/longevity issues. DTE was very upfront about the extent of thier warranty, and unless you Drag Race your car and Launch it at 4 grand, DTE's worksmanship will stand up. Phil is such a technical person, that the supplier he used for the ring gear bolts had sent him a batch that was mm's too long, and as with everything coming into his shop, he checked them, caught the problem before it went out his door, and his vendor eventually supplied the correct bolts, after several heated conversations with Phil. I don't mean to sound like an infomercial, however, I do not have unlimited resources, and to find someone who is true to thier word, and actually knows what they are talking about from an engineering standpoint, is somebody whom I will be loyal to with all my business ! As I stated in an earlier post in this thread, I P/U my car the same day the 4.10 install was finished, put 1,500 miles on it, and to date, no noise whatsoever, except for the funny noise the tires make every time I hammer the throttle ! Of course there is also smoke associated with this action as well !



Steve.