http://en.wikipedia.org/wiki/Transax...ive_transaxles

I have been toying around this idea for quite a while and figured I would take it to the forums.

Below is the picture of a Ferrari 599GTB with a transaxle. Considering that the new Hewland LWS weighs 139LBS (would fully replacing the stock differential and transmission while not really throwing 50/50 balance), would something like this be viable?

 

Now you are thinking outside the box.

But should be able to get by with the smaller LLS 450ft-lbs for most installs.

The 139 lbs is for a magnesium gear box; $$$$ ; more practical would be the aluminum at 152 Lbs or the LLS at 146 lbs

 

For track applications where rear weight distribution is king, it's very interesting. It also handles the issue of fitting heavier duty transmissions to the rotary rear face. With a dry sump and custom front subframe maybe the engine could be further lowered and moved rearward.

Of course you'll need a nicely upgraded driveshaft that can spin at 9000rpm but that's achievable. You'll need to resolve fitment of the transaxle into the tunnel. There is also a lot of equipment behind the rear axle that would not fit with the stock FD rear subframe and gas tank, but that can be managed.

There is a part of me that wonders whether it's worth it or not. There are plenty of things to reduce frontal weight, and the 50/50 of the stock car is hardly a bad place to start from. But then again people have wasted far more resources for much less benefit *cough*2jz swap*cough*

What kind of transaxle are you thinking of? (I can only imagine the cost and impossibility to service a Ferrari transaxle)

David

 

Fitment will be someones nightmare and must built a new engine mount system, shifter linkage and drive shaft, high spinning but low torque; maybe mod a Porsche 928 shaft.

As these model transaxels are squential shifter, they may be very pricey. When purchasing my Lotus Evora, I looked into the race traxsaxle that they offer but it is $45K for the gear box factory.

Alos this series taxle has limited "rear end' gear ratios not going into to the 4:1 ranges and top gear trans ratios not going below 1.08 or so

 

Fabricating parts is not a problem. One of the benefits of doing this is reducing a lot of weight and also creating a lot of room for a bigger exhaust. Since the transmission sits predominantly in the middle, and the $20k transaxle taking place of the weight of the differential, 50/50 weight should not be affected too much. And titanium driveshafts do exist (http://www.diversifiedracing.com/driveshafts.asp) and can handle the RPMs.

You also took the words right out of my mouth with going with a dry sump and lowing the engine. My thoughts are to have the sump plate *BE* the subframe for a lower center of gravity; after all, that was the whole point in what I did with my alternator. And if you have a well balanced engine, vibration would not be a problem. Also, by lowering it, it would be mandatory to move the engine back (if 20B) to clear the steering rack. Give me 10 years, I *WILL* make this happen.

Anyways, it seems a lot of build is outside of the box anyway.
https://www.rx7club.com/build-threads-292/pimp-my-ride-batmobile-edition-590192/page3/

 

Id say if your going to invest all that time and $$, why wouldn't you just make the car mid engine?

 

Because it already is a 50:50 mid engine (front mount)

 

The car is already a front-midship design.... moving the weight of the transmission to the rear would net better traction, and a more perfect 50/50 weight distribution.


I love this idea!!!

 

Another option would be the late model Corvette rear transaxle. Lower cost, many gear ratios, 6 speed, able to withstand gobs of torque and even available in a 6 speed automatic. I would like to hear thoughts on this.

Joe

 

The stock transmission location is nice because it helps centralize mass at the center of the car and provides for a lower polar moment of inertia.

FCs have a super heavy rear subframe/suspension/differential housing to get 50/50 weight and you can really tell it doesn't rotate like an FD.

Plus when you simplify an FC engine bay you end up with more than 50% in the rear and start getting that pesky rear weight bias understeer.

Rear transaxle would enable you to push the motor way back or go with a 4 rotor without hanging the motor way out front.

Looks like you would be doing a bunch of unibody cutting since the FD was set up for rear seats, but the stock interior could hide it all.

Instead of this, you could simply cut up the unibody to install the gas tank ahead of the differential for an even lower polar moment of inertia than stock FD (like RX-8) and save a bunch of money.

Then use the resulting cavity left by the missing gas tank for some rear under body aero.

 

OK it's been 10 years, how is the transaxle FD doing?

 

I had this idea long ago, but I think the toughest part is it would likely require a non-factory fuel tank and/or location. Most transaxles stick pretty far back behind the axle line.

 

Not really a stock FD, one was running around with a DG300 well before that in the late 90s - proper torque tube. Instead of the PPF snapping like in the adjacent thread, it chews through the gears occasionally, torque limited.

Current owner of that car is building another with an A1GP box to address that shortcoming.

 

Easier said than done. That's a MAJOR technical challenge that, short of the Lexus LFA and a few FR Ferraris, hasn't really been done successfully. Most transaxle cars don't rev over 7K rpm.

I'd guess a 150lb transaxle would shift the bias 5-10% rearward. With that kind of weight distribution, you'll need a much larger rear tire to carry the load.

Overall, I don't really think it's worth the effort. FDs can be easily made rear-heavy with the stock transmission location. The transaxle will have clearance issues with the fuel tank (which might need to be modified) and/or the unibody in the rear seat area that would need to be "tubbed" for clearance, but if you want the different packaging of it, go for it. It would be cool to see.