ALFAGTV6.COM

[Duk]

I thought I'd start this so as not to pollute CChans topic. It's also something I'd thought about.

I know everyone thinks that once a certain HP is reached, the rear transaxel will blow, well actually it will, but how has corvette managed to hold nearly 600hp with the gearbox in the back..? I know its had a hell of alot more engineering than our gtv6's, but i'd rather spend the cash modifying my transaxel than having a gearbox up the front..

The 'vette answer is a simple 1. They are a Borg Warner/Tremec T56 based gearbox with a differential housing bolted on the back. Simple, big solid transmission design.

Would love to know what can/could be done to hold more hp for the transaxel...maybe a borg warner could fit in the back...?

That would come down to coin.

The Borge Warner 'box looks the easiest (compared to say a Toyota W58 or a Nissan 'box) to adopt a cable shift mechanism to. I figured that would be the easiest way to sort out shift issues.

The biggest problem that I see is the gearbox output is at the top where the Alfa gearbox output is at the bottom.
Chev got around this by having the pinion shaft go right across the top of the diff and actually engage the crown wheel at the rear of the diff housing. The only real problem I see is that of lubricating the bearings, so I'm guessing they used a pump of some kind.

As for building a diff housing, it could simply be fabricated out of either steel or aluminium and the machined as required for bearings. That's how most/all of the big industrial gearbox housings are made.

I'd base the diff on a common, strong well supported in the aftermarket IRS based diff like the Nissan R200. If they survive behind 1000hp drag cars, then they would be good enough for 99.999% of any Alfa's ever built.
I'd only ever make the housing like the Nissan design with 2 big main bearing caps that hold the diff in place and an end plate, deffinately nothing like the Alfa transaxle design.

[Mats]

I've been deeply involved in development of diff-casings and to tell you the truth I would never attempt to do that without the backup of OEM development teams.
There are so many ways to f**k up a case design you wouldn't believe.

Buy something existing and be done with it, it's driving you wan't to do right?

[Duk]

Mats can you be a bit more specific?
I know it's a hell of a comparison, but I see small, medium, large and huge gearbox housings that have been fabricated from steel and then machined as needed.
1 of those gearboxes is attached to a 5000hp DC motor for the 1st stand at the rolling mill that we have where I work (we make steel from ore to some finished products like rail (for train tracks) and structural steel for buildings aswell as about 200 specialised grades ).
I would love to see a practicle means of adressing the transmission strength issues of the transaxle Alfa's, without having to try and get a Corvette unit.

[Mats]

Well, first of all, if you want something that is even remotely light enough to attach to a car you need to know how to dimension all the parts like bearings, housing wall thickness and stiffness, gears, bolts and such. You also need to know how to design a final drive, assuming you use an existing hypoid gearset you would have to reverse engineer the axle/bearing positions and they are very sensitive to any errors. You would also need to know how to design the lubing system to ger the right amount to all bearings and seals and to keep the breather out of the oil flow.
The breather position is usually something that keeps changing all the way up to start of production and sometimes even after! Not easy.

How do you intend to analyze housing stiffness btw? Bearing preload changes due to material heat elongation? Not intuitive at all and usually needs a well trained team of engineers that only do these types of calcs to get it even remotely corresponding to what will happen in real life.

So, how were you intending to do it?

[GarthW]

Damn me, i never knew so much went into this...there's a guy from an engineering company here in Melbourne who said he would do the work for me, like putting a BW Box in, but damn it sounds like its a big job...but hey loving this thread cheers guys.

Mats and Duk you both know your stuff, i'm loving reading this!!!

[Duk]

Mats and Duk you both know your stuff, i'm loving reading this!!!

Haha I'm just a Fitter and Machinist who is also a total petrol head .
I get to see lots of interesting industrial stuff (you should see the molten metal carriers and the big 6 wheeled stradle carriers that move around here! And that 5000HP DC motor I mentioned, in the old Bloom Mill days (before me) they had 2 of them!!!) and I often think how some of those things/methods/techniques could be applied to cars.
We rely on Mats, Jim K, Greg and Baz to bring the technical engineering type of info.

Now if we could just find a supply of Corvette Borg Warner/Tremec diff housings that bolted onto the back of a conventional T5/T56, Mats would be happy and Alfa Romeo transaxle cars will rule the world

[GarthW]

Duk, may you find a way!!! May the car gods look down opon you with such wisdom that in our time you will find a way!!

But just imagine, mmmm nice..

[Mats]

Now if we could just find a supply of Corvette Borg Warner/Tremec diff housings that bolted onto the back of a conventional T5/T56.

Like this?

[GarthW]

Where to go on that link Mats..?

[Mats]

Call you local GM rep and order a Corvette transaxle, easy.

[GarthW]

Damn ok, Duk what you think about that, could you make it work..?

But Mats, how much would that sucker weigh.? Are they aluminum cased..?

[Mats]

They are about 1/3 of the weight any one of us would be able to make it.

Alu cased, naturally.

[GarthW]

Nice ok...wonder if anyone will end up doing this...well i hope they do, all comes down to the cost i suppose...really gonna look into this thanks Mats.

[Mats]

np. Just remember, the GM way of designing transmission parts makes for a very strong product -> it won't be "light" in the way that it's the same weight as the Alfa unit...
But it's definetly durable, just check the ZR-1 specs and you know it will take a beating.