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Lamborghini Gallardo transaxle (Graziano) and the GTM

38K views 39 replies 10 participants last post by  jawerner 
#1 · (Edited)
I thought I would create a new post in the interest of sharing the information with others about my journey of getting the Graziano transaxle into the GTM. Much of this information is thanks for Fran over at RCR as they have put several of these into the SL-C, and he was kind enough to provide the parts needed for the conversion.

Long story short, there are only a few custom things you need for the GTM/Graziano application. I'll revise this post as necessary as I discover things.

Custom adapter plate and flywheel (source: Fran Hall - RCR: $1200)
Flywheel custom machining (source: SPEC: $257)
Custom axles (source: Crash @ MyRaceShop.com: $2300 so far, but still need to buy the actual axle shafts.)
Custom Subframe (source: self)
Modified rear diffuser (source: self)
Cable shifter (source: Cable Shift/Jim Brandwood or original Lamborghini shifter - my cost $2500, but Jim Brandwood's would be significantly cheaper)

The other parts that I know of are available off the shelf.

Transaxle (my source: Ebay: my cost: $5000)
Clutch (my source: SPEC Clutches: $2250)
Pilot bearing (my source: Ebay, 43mm OD/15mm ID bearing: $30)
Slave cylinder (my source: Exotic Clutch Technologies-Ebay, $710)
Starter (source: Summit - http://www.summitracing.com/parts/bch-sr0408x - Thanks to PSB for posting this: $145)

===============================================
Ok. So now for the details of it all:

TRANSAXLE:



The 6 speed gearbox that I am using is out of a 2005 Lamborghini Gallardo. It's manufactured by Graziano, who happens to also manufacture for many other exotics such as Ferrari, Maserati, etc.

There are two flavors of the transaxle: 6-speed manual and E-Gear (paddle shift)

From my research , the transaxles are essentially the same except for the E-Gear has a mechanical/hydraulic unit on top of the transaxle where you can see the ball ends and where it says "NO OIL" in the picture.

ADAPTER PLATE:



The stock adapter plate provided from RCR has a couple extra mounting points towards the bottom on either side of the mount. These could be used in our application, but custom tabs would need to be made.



You can see that it clears, just as the Porsche adapter. You do need to use hex-socket head bolts as they are recessed into the adapter plate unlike the KEP setup.

OILPAN MODIFICATION:



In this pic, the Graziano is on the left, and on the lower left you can see the AWD shaft. This protrudes quite a bit and you need to make room for it in this application.



Although not very cleanly, I took some of the webbing material away from the oilpan to make room for the AWD shaft of the Graziano. Could you cut the shaft? Possibly, but being hardened steel, that may be difficult. Could it be removed/replaced with a blank? Possibly, but it is a whole lot easier to just remove the oilpan material. On the left side of the material being removed, there was a long bolt that ran through there. It needs to be replaced with a shorter bolt (pics to follow)

FLYWHEEL:

As you can see in the above picture, I received a blank flywheel from Fran due to the need for an 8 bolt pattern on my LSX crank. He normally has put them into 6-bolt crank applications, so he left it up to me to get the bolt pattern machined into the piece.

I decided to tackle and reverse engineer the pattern since I had the 8 bolt flywheel from KEP. No one seems to have the bolt circle pattern available. If they do, they seem to think that it's some super secret information and claiming it to be "proprietary information". Well, it's GM's pattern. So since places like KEP wouldn't even help me with that bolt pattern, here ya go.

Starting with bolt #1 at the 12 o'clock position, going clockwise:

Bolt circle diameter: 3.11" (standard for 6 bolt cranks as well)

Bolt 1: 0 degrees
Bolt 2: 45 degrees
Bolt 3: 87 degrees
Bolt 4: 135 degrees
Bolt 5: 180 degrees
Bolt 6: 225 degrees
Bolt 7: 270 degrees
Bolt 8: 312 degrees

So you can see that is it NOT symmetrical when it comes to 2 out of the 8 bolts. Bolt #3 and #8 are 3 degrees out of phase (in the counterclockwise direction) than the other bolts.

Due to the design of the flywheel, you also have to pocket the bolt holes to make room for the flange on the bolts. I'm personally using 11mm x 1.5 ARP 12-point bolts. I'll post pics of the machined flywheel when I receive it back.

The lip on the crankshaft (where the pilot bearing resides in the G50 application) is 2.072" in diameter and 0.340" deep. So there is a pocket being cut in the back so that the flywheel rests against the crankshaft with no spacing. According to Fran over at RCR, this is the proper application.

UPDATE: In addition to the machining locally for the bolt circle, I also had to send the flywheel back to SPEC for adaptation to their billet clutch system. This added an additional $257 onto the cost, but now the flywheel can be rebuilt and serviced with replaceable friction plates.

PILOT BEARING:

Unlike in the G50 application, where the bearing sits in the crankshaft itself, with the Graziano, the pilot bearing needs to be in the flywheel itself (you can see the picture of the pocket where the bearing will reside)

Update: I have confirmed that the Audi stock pilot bearing is not the correct size. It took a while, but I found a 43mm OD 15mm ID bearing that works with the RCR flywheel. Most bearings seem to be available in 42mm OD, but the 43 is the right fit.


CLUTCH:

The clutch can be just a standard Lamborghini clutch with Fran's flywheel. After browsing the forums, people have had shortened life with the stock clutches, especially with the E-Gear (paddle shift version of the transaxle). After speaking with Fran, he brought up the point that the stock Lamborghini Gallardo is much heavier than our cars, so it shouldn't be as much of a problem. However, with the price ($2000+), you might want to just get a Kevlar (expensive) or carbon (insanely expensive) clutch, which have been reported to have significant longer life.

One of the problems with the clutch is that if you buy a stock clutch from Audi/Lamborghini, it comes WITH the flywheel. Obviously you do not need this. Fran has the clutches available with just the clutch disk(s) and pressure plate assembly. These are using the stock spec friction materials. I am not sure what Fran charges for these clutches.

My clutch is being sourced from David Norton at SPEC clutches. SPEC has stated they will sell the clutch assembly minus the flywheel for the custom application and have trims available for all the way up to 1300 lb-ft of torque in a stock weight Gallardo. Obviously you'd be rocketship status with anything approaching it I'm still trying to get David on the phone, as we've just had email dialogue, but not getting the flywheel cuts the cost down significantly.

Update: I got the clutch from SPEC. Their clutch does not work "out of the box" with Fran's flywheel. There are some spacing issues. I'm reasonably confident that this is due to SPEC using a replaceable "friction plate" on their flywheels. I am in communication with David from SPEC and working this out. I may have to add that friction plate to the flywheel to give me that thickness I'm missing. This actually would be a good thing as the flywheel then would not need resurfacing with the clutch replacement and can just swap out the friction plate. Fingers crossed. I also ordered a stock Lamborghini clutch (although used, but was only $700 as opposed to $2500 for a new one). That way I have the original to take measurements from.

UPDATE: David Norton had me send the flywheel and pressure plate to him so he could do a few things. First, the flywheel was machined to accept replaceable friction plates, so the flywheel can be rebuilt along with the clutch instead of being replaced. Second, he machined the flywheel so the geometry was correct with the SPEC billet clutch. On the stock Lamborghini flywheel there is a lip on the outer edge, which Fran's flywheel also has so you can use a stock Lamborghini clutch. I have not received the clutch yet, but it is to my understanding that this lip required machining to make everything work together.

I also got confirmation to relay the costs involved in case anyone else wants to go this route:

SPEC E-trim Lamborghini clutch without flywheel: $2000 plus shipping
Custom flywheel machining from SPEC (not including the cost of the original flywheel): $257 shipped

So the total is essentially $2257. The cheapest stock Lamborghini clutch I could find was $2000, which included the flywheel and is not rated for much over the stock 500 ft-lbs of torque in the Gallardo. That means that it was only $257 more to get a 1300 ft-lb capable clutch setup (for a car that weighs a lot more than the GTM) that can be rebuilt instead of replaced. That's a HELL of a deal. Some of the higher torque rating clutches from other companies run as much as $7000 for a similar rating. This system also allows for different friction disks to be swapped out if you don't like the clutch feel/grip.

It is in transit and I will post pictures when I receive it.

CABLE SHIFTER:

As for the cable shifter, I just got off the phone with Jim Brandwood from Cable Shift (I already have the cable shifter setup for the G50) and he is confident that if I get him the transaxle, he can get the setup to work with the GTM in case the existing setup from an SL-C will not.

UPDATE: I just came across a genuine shifter box out of the Lamborghini and ordered it. It was about half price from an OEM part. I figured that would be the best way to determine the travel and gate needed for the shifting itself. I hope that it will fit. If it doesn't, I'm sure there's a way to modify it or reproduce the part to make it work with the GTM. I also ordered the stock Lamborghini cables to see if they will work. Obviously the CPP cables that Jim Brandwood uses are better, but I wanted to see if there was an off-the-shelf option for research purposes. I have not received my cables as of 1/3/15.



UPDATE: I am still waiting on the second shifter cable from Lamborghini (due tomorrow), but preliminary test fitting indicates that the shift assembly does fit, as do the cables. The cables actually are a tad on the long side. In order to fit the Lamborghini shift box into the center console, part of the welded bracket for the FF shifter needs to be removed because the shift box is actually wider than the FF and Jim Brandwood boxes. I need to fab up a bracket to hold this unit in place, but that shouldn't be too difficult at all. I'm going to give Jim Brandwood a call and see if he wants to take a look at the units before I install them into the car. So that way, he can make a box that will for sure work with the GTM in the future if he decides to do so.

UPDATE: I received the second cable from Lamborghini and I was able to go through all the gears, including reverse with ease. This was expected, but I was worried about cable length and interference with the frame and the shift levers. This does not appear to be a problem. The cables are a tad bit long, but that can be worked with easily enough. The cable shift box DOES fit into the center console of the GTM, but the original shift bracket and ignition switch bracket had to be removed. I'm confident though that if you needed the ignition switch in the stock location, you could remove some material from the Lamborghini shifter enough to clear it. Considering the price of the shift box, I personally would rather relocate the ignition switch.

AXLES:

The transaxle is wider by 8 inches and favors the passenger side, meaning the axle is shorter on the passenger side than it is on the driver's. Fore-aft seems to be nothing different than the G50. While the thread is different for the axle bolts, it is the same bolt pattern and the axle ends will work, but obviously not at the length they are now.

Update: Thread pitch for the axle/cv bolt is M10 x 1.25, so it's more of a fine pitch than the G50.

Update: I received the CV joints and upgraded cages/stars from Crash @ MyRaceShop.com:

(2) 300M Stub Axles
(2) 930 CV Kit - Includes Bolts, Boots, Grease, etc. Two 930 CVs per kit
(4) 300M CV Stars
(4) 300M Cages
(2) 930 Polishing Stones

I'm in the process of taking measurements.

STARTER:

PSB posted about the starter, a Bosch SR0408X. I received mine and confirmed that it fits perfectly. MUCH better option than the $750 pricetag if it were sold under the application of the Lamborghini.





I purchased it through Summit.

http://www.summitracing.com/parts/bch-sr0408x


SUB FRAME:



You can see where the passenger side mount for the subframe on the GTM is in a location where the support beam that goes up at an angle to the back of the subrame itself. As stated before, the transaxle is wider on the passenger side. This will require a rework or just a complete replacement of the subframe itself. This is not too complex of a piece and I'll post pics as I discover what will work.

TEST FIT:





So the initial test fit was very tight. I had to remove the subframe (obviously) and with the combination of a transmission jack and an engine hoist with a load balancer, I was able to get the transmission up through the bottom as you would install a transaxle with the GTM body already on. Again, this was VERY tight. I actually had to manually lift up the body slightly for all of it to clear. Then because of the overall size increase, it required a lot of "massaging" to get it past everything.

As I have more information here, I'll post it. :weight_lift:
 
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#37 ·
Ok, well I had to take the transaxle out again in order to complete the subframe. I decided to weld on some new tabs to the frame, but located farther to the outside of the frame to allow for clearance of the bigger trans.

I also opted for the use of heim joints to allow for adjustment and tweaking of the rear of the body/subframe for alignment purposes.

All in all, it fits perfectly and I just need to add provisions for mounting the transaxle, which should be done tonight.

The flash doesn't show, but the tubing is actually relatively thick here.


Clamped to the old subframe for reference. (the 2x1 piece towards the front is directly above the stock trans mounts on the Lamborghini unit)


Old vs. new (you can see how it's wider and I used a 2"x1" 11ga steel instead of the 1"x1" next to each other on the old unit)


Added a 2"x1" piece at the back instead to accommodate for 2" wide mounting tabs










End Result:


Once I weld on the tabs for the trans mounts, I'll take everything to get powdercoated and then moving on to the turbos again. :evil:
 
#38 ·
And here is the subframe done with the trans mounts welded in. I found some urethane mounts which will work nicely and also give some ability for adjustment as needed. The threaded ends of the chromoly tubes mount to the stock Lamborghini trans brackets. Now I'm actually back to the point of fabbing the turbo setup again. :weight_lift:

 
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