I just wanted to share my opinion on 410 gears for a c5 zo6. I have had them for about 2 months now, and I love them. I started thinking of doing it after talking with Chuck of Corvettes of Westchester.
I had LT's and cai and then went with 410's. If you don't want to go into the engine 410's will be a great mod, the car felt like it gained about 60 hp. 6th gear now pulls. The only downside is you are running at a higher rpm, so gas milage on the highway will go down. Around town it stays about the same as long as you are not driving it hard. If I want to from a stop I could start in 2nd than 4th than 6th. Now driving it hard you do have to shift sooner, and fster, but you get used to it. When you put your foot into the throttle it will put you back into the seat.
I than did a cam package. I think a big cam and 410's are perfect together. I went with TSP 233/239 cam with UD pulley, made 418 rwhp and 380rwtq. There is now lag anywhere in the rpm range. With a big cam you lose some hp down bellow 4k rpms, not with 410's.
I have not made any high speed runs yet, but I wont to see how 6 gear will pull after topping out 5th.
I know a lot of guys say 390's for m12, I have no exp, with 390's but I can tell you I have no regrets with the 410's. Also I am very happy with how well this think hooks up even with street tires, it does take some throttle control though.
I know some are going to say no way stock gears are perfect for this car, but for me and the way I use the car the 410's are the best think I did for it.
If anyone wants to know more or have any questions on 410 gears get in touch with Chuck at Corvettes of Westchester, he is very helpfull and loves 410's for a c5 zo6, or if anyone is a Las Vegas I would be happy to show you what 410's fell like.
Brian....

 

Isn't WOT in 6th gear supposed to be a big stress on the transmission???

Glad you're happy with your new gears!

 

I have been lightly thinking of gears. I need to get the trans seal fixed, so I figure nail it at once.

What mph and rpms are you seing on the hwy? I usually cruise in the higher mph.
how bad has your gas milage gone down?

 

lower gears will take some of that load off.

 

A buddy of mine had 4.10's in his and I didn't like it at all, nothing but tire spin from any kind of roll in 2nd. We put the stock gear back in his.

 

i have 4.10 gears,and if i remember(bad weather) 70 mph is about 2000 rpm.love 'em.
as far as what mph i'm seeing,that all has to do with my right foot and traffic.the gears don't affect the speed that i drive.

 

My gas millage has gone down a little on the highway, maybe 2 or 3 mpg.

 

what kind of rpms are you seeing at 85 ish?
70 mph is slow lane.
I currently average 15 mpg. mostly city BS killing it. I was getting 20 when I was mostly HWY, would I expect to see 12 with 4:10's.

 

Installing 4.10's will not impact your mileage. If you install them and then change your driving habits from what they are now, to driving around in 4th burning the tires (which for some of us can not be helped after driving my 4.10 Diff.. )

With 4.10's...
RPM's @ 70 with Z51 are 2,050.
RPM's @ 70 w/o Z51 are 1,950.

It'sa net change of like 400 something rpms which is nothing and requires much less throttle to drive the car because of the load change.

Mileage usually remains the same and sometimes even goes up depending on driving. Guys who SUDDENLY change their driving habits for the (he he) better can expect nothing less than 1.5 mpg loss. overall.

Not sure, but 85 mph should only be slightly higher.

Chuck CoW

 

What is the horsepower limit to where your rear end can't take it and you are always having to rebuild rear ends???

 

I think you are right about the gas mileage, mine has gone down because I can't stay out of the throttle.

 

You can NOT break these rears. The gears most especially as they have been tested in the quickest and fastest Vettes around going 9 seconds and faster in the quarter.

The only thing that has been known to break is the housing...usually linked to wheel hop.

While guys have broken the diffs....it is very unlikely or damn near impossible especially when it is used on the street.

Give it a try....You'll love it!
Chuck CoW

 

I just might have to, thanks

 

Sweet im actually pullin the tranny out of the z and changing from the t56 to the c5 tranny. Also was thinkin about the 4;10's also. Glad to here it works great. Im also in vegas id like to check it out some time.

 

Send me a PM and we will meet up. I am in Southern Highlands. Brian..

 

I have spoken with Chuck and I am going to also have the 4:10's installed in the spring and hti two birds with one stone (rear leak and new gears).

Chuck we will be in touch in the spring.