I am looking into changing my 2008 z51 6 speed manual with 3.42 rear to a 4.10. Can I just change the ring and pinion or is in necessary to change the differential case and everything else. Will the stock case and clutch packs hold up. I have about 18000 miles on them. Any advice as to which way to go would be appreciated. I believe the ring and pinion would be about $400 and swaping out the whole diffirential would be $1700 plus labor. Its a big diffence. Also to note that i track to car at driving events 5-6 times a year. I dont believe i will have any problems on the top end because i could use 6th gear now. Any thought with that in mind? Thanks

 

Your stock case is fine, but I'd get new clutch packs while its apart. I would find someone who'll swap the gears in your own case rather than trade in the whole diff built on an unknown case. I know that ECS has a really good price on doing these diffs while you wait. This isn't really a DIY R&P swap since it supposedly requires special tools.

 

Just a suggestion for you, the Z51 gearing is a little to steep for a 4.10 in my opinion. With a stock tire you cannot run out the 1/4 mile in forth with them, and first gear is to short.
We recommend, and have swapped others from 4.10's, to 3.90's.

We can do this while you wait, using your carrier, and replacing any parts necessary. Clutch packs, hardened shafts if necessary and so on.

Our standard price for the gear swap is $1,395, all labor included, and takes roughly four to five hours.

Thanks, Doug


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yea the rates on this are OUTRAGOUS. corvette tax for sure.

a normal gear swap is 400-500 bucks. but becasue most dont haev the tool that make it easier they charge a **** load. no offince vendors.

 

i would go 4.10 with my z51. too. its only 100 rpms at 80mph.

just play inthe 1/8mile down here in the south. and street stuff

 

I am not looking at the 1/4 mile. I am more concerned about road course events. As far as I can see the 4.10 gears wont change the rpm's by that much as compared to 3.90's. Its a 5% difference. I will redline 5th gear at 160 mph. I still have 6th. Am I wrong in thinking this? Your opinions are appreciated. Thanks

 

Tell ya what....While tire sizes do figure in, I would imagine that our normal (very safe and reliable cause we've done it a few thousand times) 500 rpm bump in the rev limiter would get ya across the line in 4th if you were at the drags.

Listen, if you're a really serious drag guy, you'll just have to do the math or test it out with your combo.

If you're a street guy wanting the best bang for the buck, I don't think that you'll find a shop that has installed more 4.10s in ALL year vettes than us....

So much so that our competitors like to make fun of us for it!

What the heck! It WORKS and makes the customers SMILE!

Chuck CoW

 

The difference is the Corvette rears cost around that much just for parts alone. We take a set of Gears, then send them out to be polished and hardened, prior to installation. (micronighted-SP?)

Most installers do not do that, along with the specific tools needed, and the removal of the entire rear cradle compared to a std straight axle which just removes a cover and your started. There's a big difference between the Vette rear and most others. Especially someone coming from older car experience.

Being educated on this, I take no offense at all to it.


As a shop with plenty of road course experience, I then even more so strongly suggest against 4.10's. You end up running out of gear more often in turns, have to shift to often, and it makes the car unsettled more often.

Be careful taking advice from shops that do not have any track experience, you will regret it in the long run. Being in the area, take a run down to NJ Motorsport Park tomorrow if your available, we have an ECS sponsored track day for our customers going on there. You can get sound advice on the subject from those who know best, the ones that are there doing it regularly if thats the direction you would like to go.

btw, Raising the rev limiter to 7100 on a stock engine/springs will absolutely cause you a failed engine at the road course, be careful...

 

Considering you’re going to be hitting the track you might want to look at the quality of the components used and workmanship…are the gears from a well known company with years of proven miles or something from China? Does the shop/installer use the same gears in their racecars and give you the same workmanship as they put into their own cars and proven on the track?
You can get your gears from whomever but what are you really getting besides a quote?

 

For road course events I wouldn't even go as steep as 3.90s. It's not 5th and 6th gear you need to worry about, its 2nd thru 4th. I'd stick with 3.42s or consider 3.73s. For fun street driving or drag racing 3.90s.

 

The problem I was having was coming off a turn onto a straight away in third and shifting to fourth. My rpm's drop down into the low 4000's and i get pulled away from by lamborghinis. I have no problems keeping up in the turns. I thought by changing the rear i would be in the powerband more often, albeit by shifting more but in the powerband nonetheless. I would then use 6th for the first time at 155-160mph if i can get there. I see your point though about having to shift more in the turns and running out of gear at the lower speeds. very confused about what would be the best compromise. I dont see the value to go from 3.42 to 3.90's. 4.10's at least seem to give me much more pulling ability going from 3rd to 4th and 4th to 5th.

 

It might, but with 4.10s you also might find yourself coming out of that corner in 4th not 3rd since 3rd might become too low.

 

I've been driving roadcourse events for 7yrs now and have always had 3:42's for gearing. We have a lot of road course experience, and have had guys change from 4:10's and 3:90's to 3:42's witout any regrets. Do your homework, go to the roadracing section of this forum, and I'm sure you'll see the 3:42's are what is most common among the racers. Call a couple of proven race shops and see what they have to say. I'm an ECS guy, and we run with Vette Dr cars, and a lot of other race proven shops, we all have 3:42's.

 

Glad you brought this up. I started out doing 1/4 mile racing and switched over to RR after I alrady had H/C with 460 rwhp and 4.10 gears. After a few days RR I realize 4.10s were not the right gears for me. I then went to 3.73s which kept me in the powerband and also allowed me to stretch the gears. Speeds increased and lap times decreased at the tracks which I frequent most.

I can show you a video with Doug and I at VIR. He has a 402 running over 500rwhp/rwtq with 3.42s, but with MN12 while I was running the 3.73s MN6 with 460rwhp/401rwtq. There are places in the video where you see me actually pull away from Doug because he cannot utilize the lower gears (remember a mn12 with 3.42s is like a mn6 with 3.90s gears 1-3) and I can. On the back straight where he now has 3.42s and I have 3.73s he pulls pretty easily, but of course this is when he can get all the power down to the ground.

So back to me - I loved 3.73s with my h/c and it wasnt until I put in a LS7 with 570 rwhp/ 540 rwtq where I found 3.73 not to work for me anymore. In the middle of the uphill esses at WGI I had to make a shift change otherwise I was hovering around redline. I was able to make the shift, but I knew each time I did if I made a mistake and disrupted the balance of the car there was a chance I could end up in a wall. It wasnt until after VIR that I decided 3.73s no longer worked for me. I still loved them on the street and if my car was mostly street driven I would have dealt with the 3.73s, but since my car sees 15-20 track days per year I moved to 3.42s. Now coming through the uphill esses at WGI I can be in 4th gear and whine the car out focusing on driving not trying to figure out where to shift. Honestly I barely hit 160s on the back of WGI with the 3.73s, but with the 3.42s I can do it and I am still only in 5th so a single downshift to 4th for the bus stop (or if I am adventurous I rev the **** out of the car and jump from 5th to 3rd).

BTW - years ago I added up the additional shifts I needed per lap and then calculated how many laps I would do in 4x30 min sessions. The amount of extra shifts needed with 4.10s was incredible.

Again I am not saying 3.42s are the best gear for every track, but most of us do not have the ability to change gears for each track so I found the gearing that I liked for the tracks that I go to most. For the tracks I visit less I make do. I am telling you this from my own first hand experience (check out some other tuners who never been to a RR track with their car and as matter of fact dont even own a vette ) so take it for what you feel it is worth.

any help feel free to ask.

 

I'm doing 3.73s on my Z51 HC LS2, mostly street driven, rare track days if I ever have the time and canyon runs once a month. I can see from running in the canyons that anything lower with an MZ12 wouldn't be so much fun on a track.

I also agree that the extra shifts on a track would eat up too much time, especially so in my case because I still suck at shifting this car smoothly.

 

Thank you for the reply. Very helpful.Thanks for sharing the track experience with the different gears. Is it even worth it to go to 3.90's or would I not see a big enough difference? Should i look elsewhere for improvements to the car. I do only track the car 5-6 times a year. I am putting down 478 rwhp right now with bolt ons and a mild cam. Dont really want to go the f/i route. I was hoping the gear change would be what I needed but not if it is going to ruin my fun on the track days. So the opinion of the masses is definately not 4.10 for the track. So 3.73, 3.90 or stay with the 3.42's and stay in the rearview mirror of the lambo superleggera on the straights... thanks again for all of the feedback, its very helpful..

 

All of our RR cars are NA. We do have a few guys who come out a few days per year with FI but we don't recommend FI for RR.

as far as ruin your fun on the track I doubt that could happen but I didn't want you to think your lap times will decrease because you have 410s. Yes 410 have helped many decrease ETs in the 1/4 but we know there is much more to putting together a fast lap for RR than one straight away.

So are there other things you can do to make yourself faster well that depends on your current mods and your ability but I can say from what I have seen all of us on a RR track has room to go faster just finding those areas is the challenge.

I personally just bought traqmate data acquisition system to find my areas which need improvement (I am done modifying my car at this time so it has to come from me improving). Modifying your car might not improve track times It might just come down to you needing more track time.

As am example a friend of mine has same power and basically same setup I have. On the front straight of WGI he asked why was I able to catch him and pass so quickly. I said because I am exiting the turn onto the front 10 mph quicker. So you see having power doesn't mean you will be the fastest car (it does help though).

If you haven't yet venture over to autos/road race section of corvette forum. Post your mods and your skill level. There are plenty of guys over there much better than me who can help direct you in the right direction.

 

all good advice. thanks again for all of your input.

 

Can you list out your exact mods? Perhaps there is some more power and torque available to get you closer to where you want to be....maybe a different cam, intake, FAST manifold, unsprung weight (lightweight clutch/flywheel, lighter rims), better tires....there are so many variables the tuners need to know about before advising on how to dial you in better.