Recently, Superlite has been able to provide new transaxles from Graziano, a well-known supplier to several supercar makers. These transaxles are brand new, capable of supporting 1000 HP in road applications, are designed for mid-engined applications (so they don't need to be modified to run inverted as all the Porsche 911-based units do) and are even lighter than the previous gold standard transaxle (the Ricardo). Best of all, they are priced to SL-C buyers at the time of kit order at about the same cost as a rebuilt Porsche transaxle. With all-new technology, designed for mid-engined applications, OEM-levels of refinement and durability, these are a great solution to the transaxle dilemma.
These transaxles are sourced from the Audi R8 and certain Lamborghini products, so they are built to strict OEM specs, and are capable of handling a prodigious amount of torque. We have seen OEM cars with aftermarket turbos with over 1000 HP and commensurate levels of torque with no problems so far.
The Graziano transaxles are available direct from Superlite, or may alternatively be sourced from an Audi or Lamborghini dealer. Superlite offers them at a discount when purchased from them, with a kit, as well as offering a warranty. They are not available from Superlite for Audi or Lamborghini cars. Some builders have found theirs used from specialty wrecking yards, or from sources like eBay.
Because these are essentially OEM units, the Audi R8 manuals cover them in some detail.
The transaxles are available in two variants, identical except for gearing. The V8 version has shorter gears, while the V10 version has slightly longer gears, and is marginally better suited for American V8s, but costs noticeably more. See the gearing spreadsheet in the general transaxles page.
The factory can supply the necessary adapters for the LS engine series, as well as clutch, flywheel and other needed parts to work in the SL-C.
The Graziano, when mated with the LS series of engines, requires some modification to fit. Either the forward output shaft needs to be trimmed (not recommended) or some small grinding is needed on the engine (the preferred solution). See the PDF discussed in the next paragraph for more details.
Allan U has created this PDF that shows pretty much everything you need to install the transaxle, with all the key parts labelled.
There is a great writeup on how to change the transaxle oil in a Graziano from a Lamborghini forum (the Graziano is used in both the Audi R8 and Lamborghini). Check it out here.
Black Coating on Rear Cover
The transaxle ships with a black coating on the back end of the transaxle. This is factory-applied for sound deadening purposes. Some builders have removed it with various strong solvents, wire wheels, scrapers (!), solvents and brushing, etc. If the coating is removed, the rear cover may be able to be polished, but in any case, the builder should be careful to avoid scratching the relatively soft aluminum. It's not clear what removing the coating means in terms of a warranty problem later.
The gearing of the stock Graziano transaxles may be a little low for some owners with comparatively low-revving American V8s. The transaxle gearing was selected by Audi and Lamborghini for their relatively high-revving V8 and V10 engines. If you are building an 8500 RPM engine for your car, the existing gearing may be just right. However, if you are building your SL-C or GT-R with top speed in mind, just want a more relaxed cruising RPM, or plan to run 1/2 mile events, taller gears will be very useful. In fact, the original purpose of the taller gear sets now available (and discussed next) were to assist Audi and (mostly) Lamboghini cars run these high-speed events.
Recently "drop gears" have become available for this transaxle that have the same effect as a longer final drive. These drop gears don't change any of the actual gear ratios on the shafts, nor do they change the actual final drive ratio; instead, they are inserted "in the middle", and have a similar effect to changing to a longer final drive gear.
None of the gearsets are simple to install, and both of the drop gears (as far as we know) require small modifications to the case, and thus are not targeted at DIY installers.
At present, there are three known options for this transaxle.
The first set we became aware of is made by HP Gear, who also makes new ZF transaxles for the GT40 and Pantera crowd. These are sold by a couple of people, including DeLynn Mason and Erik Johnson at Raceline (see the note about Raceline below). These are apparently the tallest gears available, and some people who have installed them on street cars believe they are too tall.
The second set is just being developed on a limited basis, and is targeted to be in the middle of the original drop gearset and the stock gearing. More information is available at this thread on the GT40s site. The thread also has links to gear charts showing the stock ratios, the HP Gear set referenced above, and the newer set, and is very informative. These are now available from HCF Parts in Texas, and are made from a higher grade steel alloy (EN36A). The gears are also shot-peened and heat-treated.
The third set is from Australia. Check out the page at this link. It is apparently different from the drop gears above in that the gears on the shafts are actually changed. A key difference in this set is that the maker claims that no case modifications are required, and that the gears are able to handle up to 1500 HP. Here's a picture of the gear set:
If you are driving your SL-C on the street, any of these gears may be just the ticket to get a relaxed engine speed on the highway. For road racing, you probably want the shorter gears to aid in acceleration, though you may find that engines need to rev higher than expected to reach top speeds possible on American road race tracks.
These new gears give ratios that are closer to the previous gold standard, the Ricardo. The gears are available from the sources listed above. However, the installation of these gears is not trivial, and should be attempted only by a knowledgeable shop. The gears are near the diff, so the entire gearset has to be removed to get to them, which is completely different from the quick-change Winters rear gears familiar to many.
Here’s a great video showing the gears in a Graziano:
Recently, several owners have ordered sets of the tall-option drop gears from Raceline. Their experiences have not always been good, and we no longer recommend Raceline as a vendor. Reported problems include being misled about the relative ease of installation, unexpected pricing variations, poor communications, and delays (with some still unresolved) in getting gears and/or transaxles shipped, even after more than a year. If you do elect to use Raceline, let us know so we can report on your experience.
At this writing, the Superlite factory is working to provide a solution that makes transaxles available with these or similar gears already installed at the Graziano factory. That would make the updated Graziano transaxle a pretty much perfect solution for domestic V8-powered cars like the SL-C.
Standard Audi R8 parts are used, which helps ensure availability, and ready access, if not low prices. Clutches are also available from places like Spec, who say they have clutches for up to 1300 HP in a stock-weight Gallardo, so presumably a light car like the SL-C could run even more power through it.
The Audi or Lamborghini starter is expensive, but there is a Bosch interchange available from Summit for under $150.
As of 2018, when a builder buys the Graziano and a transaxle completion kit together with a full SLC or GTR kit, the kit will include a new billet shifter that is an original Superlite/RCR design.
In the past, the kit shipped with the regular Cableshift shifters. The new billet shifter uses the original Audi R8 geometry, though in a much more compact unit. The new shifter also includes a reverse lockout, as well as a gated lever like the R8. The new shifter is shipped complete with everything you need except a knob.
Some builders have sourced the original Audi R8 shifter and report that although it is expensive, it has a much better feel than the previous Cableshift unit. The R8 shifter is a bulky unit, and is too wide to fit an unmodified console using either of the tub options (and probably the original SL-C console as well, though no one has reported trying that yet).
Part of the reason for the size of the R8 shifter is that it is a gated design, meaning that there are mechanical fingers, or gates, that guide the shift lever to specific positions. This is a sort of a throwback from the early days of sports cars, and has a certain visual appeal, though it is probably a bit slower to shift gears with such a design compared to modern manual shifters.
Because of it's heritage as a part of the Volkswagen Group, the transaxle uses some parts from more pedestrian cars in a few cases to reduce costs. One such part is the axle shield package which helps protect the CV joints on the axle from heat generated by nearby exhaust pipes. The shields look like this:
The shields can be obtained new from any VW or Audi dealer (and probably Lamborghini as well) but they are readily available on eBay for reasonable prices. You'll probably want to hit used ones with a sand- or soda-blaster to clear up the crud, and then powdercoat, paint or otherwise protect the finish to keep them looking good. The shields attach to the transaxle as shown below.
For many people, paddle-shifted transaxles are the holy grail, and part of the Supercar experience. Recently, we have been made aware that a company in Europe has available a system to convert the traditional H pattern shifter to a true paddle shifter for the Graziano transaxle. As we learn more, we'll update it here and on the Superlite FB and web pages.
Here is one company that does paddle shift conversions that are in use with many different drivetrain combos in races throughout the world. It's not known if they have done a Graziano yet, but here is the link.
The Graziano comes with a reverse switch. It's easy to use this to switch a 12V output from the rear Powercell. The switch uses a popular connector which can be found in a pigtail form as VW part number 1J0 973 702. This pigtail is available everywhere, including eBay.
The switch has capacity to carry normal lamp loads, but a relay could be used if you are doing something exotic. Those using LEDs won't have to worry- just let the switch carry the load.
You could use the switch to control an input to the Mastercell, but that's probably a bit more work than needed, unless you have another use for the reverse light lamps.
Click here to view a PDF of the transaxle manual.