CTZoom

Hi Guys, debuted my car last weekend (C6 Z06) and the factory LSD is clearly not up to slicks and 640hp as I could feel it unlocking in the slow corners. My Car is a track only full race car - only runs slicks. Talking to Shane at RPM the choices are the wavetrac and the quaife ATB. I have previously used Kaaz and Cusco MZ race LSDs which I really liked - both setup 1.5 way.

What are the racers using - thoughts on either choice?

clip of my car

RX-Ben

OS Giken is another option and RPM has experience installing those.

63Corvette

I would AT LEAST investigate the new C7 electronic limited slip differential. It is supposed to be magic on the track

RX-Ben

I'm nearly certain the bolt pattern on a C7 diff might be off, and adopting the electronics will probably be quite difficult unless someone like Motec develops a standalone controller (they did for the Evo Active Center Diff, but C7s are a smaller market).
The "magic" diff also comes on a car with ~420hp and the OP has 640hp. I'm guessing he might run into similar issues.
I'd recommend a clutch-type diff (like the OS Giken) as they should run cooler than a Quaife, which runs quite hot around OEM power levels.

Werks

I have similar HP as you and run an OS Giken lsd and love it. You might want to call the people that did my install which is Unitrax in Anaheim CA at PHONE: (714) 630-4327. They sell all of the major brands of LSD's and do most of the high hp vipers in the area along with a slew of race cars and most of the LA based drift guys.

CTZoom

No magic electronic diffs for my racer, mechanical stuff is far easier and more reliable on a race car thanks all the same. The OS Giken is very similar to the Cusco I used to run, thanks for the suggestion. Kind of surprised that there has been so few responses - unless LSD choice is a such a big secret. Anyone know what the C6Rs used or what the Trans Am guys are currently using in the Camaros and Vettes?

RX-Ben

I think many people stick with OEM with quaife a distant second.
You don't want to know what the C5/6/7Rs run. I think it is north of $75k for the diff. And then the axles are like $15k. Don't remember if that was for a pair or each. I think you'll need different spindles as well. And you'll need a different trans to match the diff, I think. And then a different torque tube/driveshaft. And probably a different bellhousing. Probably some other stuff as well.
Trans Am cars use solid rears.

Werks

I don't think that it is realy a big secret I just think that there are not too many people that modify so much stuff that they ultimately get to replacing their diff lol and/or not a lot of people take the time to realy research things and just stick a Quaife in it thinking that's the only option.

6SPEEDZ

The C6R/C7R use a true transaxle from Xtrac. Yes it's different axles and uprights and everything else is different too. Engine has to be lower to use the transaxle. There is no torque tube etc etc

el es tu

The best Torsen carrier is supposed to be the Torvec unit
http://www.torvec.com/products/isotorque

Z06VENOM

I was in the same boat last year... The clutches just did not hold up go me. So I went with the Torvec...Very nice unit that's for sure...

RX-Ben

How can you say they are the best? They just started shipping them.
They've been telling me for the last ~2 years that they will be shipping them "soon" but it looks like they finally did so.
Hopefully they worked out the reliability issues (total hearsay on that, but the person that told me that was in a good position to know).

RX-Ben

forget the hearsay, below is an excerpt from their CEO's letter to investors. Obviously every company goes through testing issues with their products, so it wouldn't be fair to make negative conclusions. And I grew up in Rochester, and it would great if this is top notch.

During 2012 and 2013, we have focused our IsoTorque differential development efforts on a rear-wheel drive differential for two model platforms (for certain Corvette and Camaro models) that can be marketed and sold initially into the aftermarket. During the fourth quarter of 2012, the test results of our design were still not satisfactory to us, so we determined that we needed to make further design modifications to improve the IsoTorque’s high-impact durability. Although we were at a point where we felt there would be no problems under “normal” use, we were not the best we needed to be. We feel that if we are going to be a world class company, our product has to be world class in every way. For that reason, we decided not to begin to ship our differentials until we are completely satisfied with the product. During the first half of 2013, we modified the design characteristics and built prototypes, and in June 2013 we conducted a series of tests under our stringent testing protocol, specifically for the Corvette model platform. These tests were successful and we determined that we that we were technically ready to conclude our design phase for a limited release of the IsoTorque for the Corvette model platform and to initiate the production process to build units for sale into the aftermarket. During the third quarter of 2013, we continued to work on improving the product’s durability in order to minimize any limitations in its use with customers. As a result, we have made some additional modifications to the Corvette differential design to provide incremental strength to the product under abusive conditions. We are in the final stage of determining the most robust design and we are working with our supply chain to establish timetables for deliveries of component parts. We have begun to procure component inventory for a limited release of the product, which we are targeting to begin in the latter part of the fourth quarter of 2013 or early 2014.

We are confident that there is nothing in the marketplace that can compete with the IsoTorque’s performance, safety and dependability. With a very limited effort to sell the IsoTorque differential into the automobile aftermarket during 2012, we received orders for dozens of units for high powered Corvettes. This activity, along with feedback we have received, makes us confident that we have a very saleable product.



Our broad strategy for the automotive market is to develop numerous IsoTorque differentials for various vehicle platforms, selling initially into the aftermarket to demonstrate our product’s technical and functional capabilities, followed up by marketing to OEMs for being designed into full vehicle production runs. During the fourth quarter of 2013, we intend to begin actively marketing the IsoTorque to Model C5 and C6 Corvette owners who are interested in upgrading their vehicles, and to engage with distributors and installers of Corvette aftermarket products. Also, now that we expect to have a product ready for sale, we will continue discussions with OEM product engineers to market our technology to them. We continue to have a great deal of interest from many companies. During the fourth quarter of 2012, we sent two IsoTorques to a large OEM for internal functional model development, and in April 2013 they conducted some initial testing. We are expecting to receive testing characteristics pertaining to our differential by the end of 2013 that will aid us in better understanding its capabilities. We have also recently provided prototype differentials to select race car teams, and the feedback we have received from them has been extremely favorable with respect to the improved handling, reduced lap times and other functions.

Z06VENOM

To the OP...
Do you know which type of LSD design you want and the pros and cons of each? That was my biggest problem... Lol
Very interesting articles on the web on how they all work
The clutch types (Kaaz, OS Ginken) or gear types like the type1 (torvec) and type2 (Quaife, Wavetrac)

CTZoom

I know the differences having raced with both torsen style and clutch styles. My preference is to replicate the Cusco MZ 1.5 way setup as I found it suited my driving style in a 400hp Miata. The 1.5 way gives great stability under braking and allows trail braking and exceptional power down out of corners. They are also brilliant in the wet. Thanks again to Shane at RPM for his advice. I am leaning towards a Giken but am considering the ATB and Wavetrac still. Car is getting a holinger sequential box as well. Lots to evaluate so I appreciate the thoughts from those with experience. We don't have too many racing corvettes in Australia!

msracing

Hey Ctzoom ,, i have a C6 track car with a Holinger 6sp sequential ,, i am running the stock lsd and seems to be working just great.. .. the problem that i have been having is that i have broken the Diff case twice... I now am putting in a brand new diff case and using a trans diff cradle to stiffing up those components..The first time it failed we thought it was a freak that,,, we installed a new diff with new everything .. and after 2.5 hrs we started finding a leak .. Now we found a hairline crack on the opposite side of the first crack on the first Housing but not as bad of the one in the picts... Not sure if this was part of the culprit but i did find my Diff case bolts a little loose ... This time i will be installing a new case and diff and all new AN locking Hardware plus a new trans / Diff brace.... I really love my Sequential Trans and judging from your Video you will Also

Cheers Manny
[IMG][/IMG]

RX-Ben

mo money mo problems. You were using the OEM soft rubber diff mount?

0Anthony @ LGMotorsports

Switch to a ZR1 case and make sure it has solid engine and trans mounts on it.

We changed diffs in the race cars every 30-35hrs of run time approx.

0Anthony @ LGMotorsports

As for which diff to use, or which diff is best........


That is going to depend on the setup of the car, and also the driver.

Reason I say that? They all are going to act differently in different area's on track. I will say this though, a Quaffe unit is the only one that is not really going to wear out.

Most drivers might find a clutch style diff easier to work with and more predictable but it will wear, and as the clutches wear away the more it starts to act like an open diff and will do so in corner exit typically first.

What can throw off some drivers is making the switch from a clutch style diff to a gear style is how the car will act on throttle off and throttle on in the corners. Generally speaking the rear bar and spring setup will have to change to get the car to act the same. This can catch some off guard with no other changes having it want to come around on them when you go throttle off going into a corner.

The OS Giken units we started running in the Camaro, once it is tuned right, is one of the better ones we have had in the cars.....again ONCE IT IS TUNED RIGHT. So you are going to have to spend some time setting it up for your car and your tracks.

CTZoom

Thanks for the info guys. I'm leaning towards the OS Giken....not a fan of torsen and gear type LSDs though the wavetrac had me interested.