[Duk]

The other benefit that has not been highlighted too much is the gain in torsional rigidity---the Alfa unibody is pretty flimsy and needs all of the help it can get. A torque tube that ties the front and rear sections of the chassis together will go a long way towards mitigating this!

I'm not sure how you think the torque tube will add to the structural integrity, especially the torsional rigidity of the chassis???
The torque tube is attached to the engine and the transaxle. And they are attched to the chassis via rubber mounts..............

Obviously any added weight has a negative effect on performance. But the added weight is about as low and as central as it can be added. And if you transmission is broken, then there is NO performance! :grin2:

 

[junglejustice]

Pete, you have lost me! The total gain is ONLY 107 pounds TOTAL - about 48kgs.

The bottom left-hand corner number in each corner scale picture clearly shows the total weight for that associated collection of parts!

Anyway, while the pictures of the various components on the scales were cropped to fit the associated scale shots, the full shot of the entire Corvette rear setup CLEARLY shows that the Corvette rear brakes ARE included - another benefit here (gaining outboard brakes which in this case are a gain because of the better serviceability and better performance and easily available upgrades such as the GiroDisc brake upgrade!)

I had to do a double-take myself on the numbers... The first picture in my series of replies clearly shows the totals - the Corvette setup will only add about 107 pounds TOTAL. While 107 pounds may be a lot in race car terms, for a street-track car (considering the gains in ALL other areas such as engine-transaxle alignment, gear-ratio selections, final drive ratios, a 6-th gear, maintaining the TA layout etc etc), it's a small sacrifice.

53 pounds OFF the 107 pound total gain lays inside the tunnel - at the center of the car, low to the ground, and BETWEEN the front and rear axles! The other 54 pounds sits AHEAD of the rear axles - again at the center of the car - and LOW!

And yes, eliminating the twist between the engine and the transaxle is a definite gain!

As far as power; for now she's getting a street-track trim, naturally aspirated, 3.45 litre 24 valve V6 with about 300 horses. The planned future power will be from a twin turbo plant with upwards of 700+ horses! So, yes - the modifications are all being made with the future in mind.

 

[pushrod]

As far as power; for now she's getting a street-track trim, naturally aspirated, 3.45 litre 24 valve V6 with about 300 horses. The planned future power will be from a twin turbo plant with upwards of 700+ horses! So, yes - the modifications are all being made with the future in mind.

You could always simplify your torque tube mounting, further improve weight distribution, and make even more power by going with a 6.2L V-8. They make ones that bolt right up...

 

[jarrington]

You could always simplify your torque tube mounting, further improve weight distribution, and make even more power by going with a 6.2L V-8. They make ones that bolt right up...

I've heard you can even get a chassis that these parts will bolt right into, with a lightweight fiberglass body that will mount on top.

:grin2:

 

[PSk]

Pete, you have lost me! The total gain is ONLY 107 pounds TOTAL - about 48kgs.

Referencing you photos and weights:

53 GM torque tube
198 GM transaxle
186 GM rear suspension and brakes
437 total

149 Alfa transaxle and brakes
111 Alfa rear suspension and axles
70 Alfa driveshaft and roll bar and dedion
330 total

Yep difference is 107. As I am not living in the dark ages, my standard weight reference is kgs, hence why I thought we were carrying around an extra heavy person
Pete

 

[Gabor K.]

Actually why the debate over +50kg, which would matter at 160 Hp but not at all at 700 Hp! Then you would have the extra weight on the rear Wheels!

Myself being used at the dead stiffness of my GTV6 racer with safety Cage, I think this roadcar will be just as flimsy with torque tube as with the original setup compared to the track car! Probably at lot of strenghtening will be necessary.

With regards to the engine I would not mind to have an evolution version of that one from SA!

G.

 

[PSk]

Has anybody tried to stiffen the Alfa casing as surely that is the problem, ie. torque pushing the gears apart. You could cut a series of aluminium plates that fitted around the casing and weld them, basically adding ribbing and therefore strengthening the casing considerably.

But in this case, yes Gabor is right ... please continue and chuck this GM transaxle in
Pete

 

[Duk]

Has anybody tried to stiffen the Alfa casing as surely that is the problem, ie. torque pushing the gears apart. You could cut a series of aluminium plates that fitted around the casing and weld them, basically adding ribbing and therefore strengthening the casing considerably.

But in this case, yes Gabor is right ... please continue and chuck this GM transaxle in
Pete

ALFAGTV6.COM ? View topic - transaxle upgrade's
The week point of the TA has been identified as flex in the centre bearing plate. Tis distorts and reduces contact with the ring gear and pinion.
Naturally there will be something else that will then cause problems.

 

[PSk]

ALFAGTV6.COM ? View topic - transaxle upgrade's
The week point of the TA has been identified as flex in the centre bearing plate. Tis distorts and reduces contact with the ring gear and pinion.
Naturally there will be something else that will then cause problems.

Thanks. Very interesting. A steel plate would be the next step IMO.
Pete

 

[Duk]

Thanks. Very interesting. A steel plate would be the next step IMO.
Pete

I was looking at some of the numbers for the aluminium that the OP used (6068), for his new plate. To get any meaningfull improvement in stiffness over the aluminium, you'd be wanting to go for something like 4140 alloy steel.
As the OP pointed out, regardless of the grade aluminium just isn't that stiff (resistant to flexing) the way the component needs to be.

With an alloy steel bearing plate, a pumped and cooled oil supply for the gears (mainly the ring and pinion) and a reinforced clutch housing, the capacity of the little Alfa transaxle does seam to have been raised considerably.
If a dog ring engagement gear set that uses wider straight cut gears could be implimented along with a thicker input shaft, the level would be raised again. But it's really starting to get expensive by this stage. >

 

[cowfy]

my excuse for my poor knowledge on the tech. gremlins here.some one indicated no chassis stiffness is gained by the torque tube being it is mated only at the two ends by the front flywheel and at the rear with the clutch/tranny unit, and it is hung by rubbers to the main chassis points.would it be possible to fix the tube with crossmembers to the entire floorplate at certain points to really stiff the whole shebang up, and would this compromise the 'wheel always straight to the ground' of the didion handling?

 

[Gabor K.]

I was looking at some of the numbers for the aluminium that the OP used (6068), for his new plate. To get any meaningfull improvement in stiffness over the aluminium, you'd be wanting to go for something like 4140 alloy steel.
As the OP pointed out, regardless of the grade aluminium just isn't that stiff (resistant to flexing) the way the component needs to be.

With an alloy steel bearing plate, a pumped and cooled oil supply for the gears (mainly the ring and pinion) and a reinforced clutch housing, the capacity of the little Alfa transaxle does seam to have been raised considerably.
If a dog ring engagement gear set that uses wider straight cut gears could be implimented along with a thicker input shaft, the level would be raised again. But it's really starting to get expensive by this stage. >

You have sharp eyes Duk I did not notice that steel bearing plate in the IMSA gearbox. Possibly an extra Autodelta item reproduced from Turbo Motors, Italia. However the Project guy said he used the 7075 T6 alu alloy which is the best alu alloy also called Ergal and used in aerospace, racecar and weapons industry. Not much weaker than the steel counterpart mentioned by you. However Alfa chose steel as good enough!

Compare 7075-T6 aluminum to annealed SAE-AISI 4140

Obviously we will not see the Alfa strengthened transaxle to endure more than 400Hp approximately, as above that things can happen as have been reported here from different projects. Some years I saw a broken clutch input axle from a turbo application, so also the clutch input axle has to be changed. And then something else will pop. As we know now big power needs another gearbox.
A little daunting to see other brands pump 1100 turbo power into original gearbox and it still works after the abuse as nothing had happened!

G.

 

[PSk]

A little daunting to see other brands pump 1100 turbo power into original gearbox and it still works after the abuse as nothing had happened!

Supposedly 1100 hp?, and also how long to they ever actually run it at 1100hp? and also how long does the gearbox last as we cannot be watching the car all the time.

BTW the GTV6 gearbox used to handle a few race meetings with Chev v8's at over 600hp turning them when GTV6's were used for NZ Sports Sedan racing.
Pete

 

[Duk]

BTW the GTV6 gearbox used to handle a few race meetings with Chev v8's at over 600hp turning them when GTV6's were used for NZ Sports Sedan racing.
Pete

I've heard that one before too, but I have serious doubts that it's true!
People have been smashing TA's in Alfas with a lot less than 600hp. MD on GTV6.com broke his TA (ring gear and pinion I believe) in his supercharged GTV track car and he't be doing well if he had 300hp.
Even if the gearbox and diff gears survived a genuine 600hp, and I seriously doubt they could, then the input shaft would have been turned into a bit of licorice.

 

[Alfar7]

Transaxles

Duk
A large part of component breakage is your country`s practice of starting races from a standing start.

These transaxles can take a lot of Hp & torque when driven with skill and common sense.

Building unusable high HP engines has never been a useful idea.

 

[PSk]

I've heard that one before too, but I have serious doubts that it's true!

I was there and spoke to the driver and watched as they rung around NZ wreckers to get another as their current one had just failed. I asked him how long they lasted and he said a few races. Now these races were not long, say 10 laps but these Sports Sedans were quick. The engine was where the front seats should have been :surprise:.


Alfa7, Rolling starts are about as exciting as lawn bowls. Hated them as a driver and spectator.
Pete

 

[alfettaparts2]

Sports Sedans

That's the class these cars run in. Sports sedan. You should have a look on you tube there is some fantastic old footage of the alfetta of Tony Edmonson (chev V8). Beninca's nord engine with 600 plus hp. Tony Riccardello's Alfetta. All the front running cars with hewland transaxles and a full space frame.
Huge hp and huge rubber with the driver trying to hang on at 100% not pooftered around so you don't break things...whats the point of that? I could put a mobility scooter transaxle in my alfetta and make it last a club day but gee that would be fun. You want to go hard you spend the money and do it properly that's what racing is however it's no fun for the people that don't have the money like me lol
Best sedan racing in the country because the rules are basically there are no rules.

 

[Gabor K.]

Well, so no Alfa transaxle in those cars wit 600+ HP.

No surprise because as most of us know the limit for aspirated engines is around 300hp standard GTV6 box and 400Hp upgraded box. Consensus about this here at least. Thats very good for a box which was intended 160-210Hp cars, but not much to play around with if you want more!

G.

 

[alfettaparts2]

Sports Sedan

Gabor...Its fair to say there wasn't much alfa anything in those cars. Maybe the American equivalent would be can-am? That's a subjective call because AUS and NZ also had F5000 back in the day. Pretty much any big HP car (and open wheeler) back in the 60's 70's 80's ran a hewland transaxle. I'm off to Phillip Island Historic's at the end of the month and a walk around the pits its hewlands everywhere. I can take some pictures if interested.
Anyway to not get off topic I love my alfa transaxle but the reality is its limited. There are now more alternative transaxles than hewland.

I'm sure some of these you tube links have been posted before however its worth posting a few again. People know how it works. You watch one and you will find many more to follow. Somewhere there is a race with 1980 F1 Championship winner Alan Jones Driving a 880hp Porsche Sports car mixed in with some Australian sports sedans.

To Beninca's credit there car did have many alfa parts. Have a look at this compairison with the V8 Honda.

Tony Edmonson's Chev Alfetta.

 

[alfettaparts2]

Transaxle

The back of the Edmonson car.