This is definitely going to require photographs. First photograph needed is the rear donut as it sits now.

More to the point has this particular combination of parts ever worked in the past? or is this the first attempt and things aren't working out ?

Please confirm what parts you have?
Alfa 75 twinspark transaxle?
Yoke on the end of the transaxle is Alfa 75 or unknown?
Shortened Alfa 75 rear driveshaft?
Standard Alfetta front driveshaft without slip joint?
Center support is Alfetta (116 style) or later GTV6/Milano style

Hope this helps.

 

Before and after...

 

That looks like a great repair! I always wanted a TS in my Alfetta gt! Good luck and happy racing! Will fallow and see how things turn out!!

 

Driveshaft photos

 

All the driveshaft components are 75 Twin spark. Nothing of the original Alfetta is being used. The rear donut was in chunks when the car turned up. I didn't pay much attention to it when i took it out other than I needed to replace it.

Not 100% sure on the rear yoke but is a 75 TS LSD transaxle as I built that for him few years back.

The owner has had some driveline issues for a while and was running some hybrid thing with cv joints and a slip joint. I recommend he go back to "standard" to start with last year so supplied a 75 TS unit which his workshop modified to suit.

Would be good if we can confirm the correct length of a modified TS rear shaft if someone else has done a similar upgrade.

 

Back when I used to race me Sud, serious Alfetta classic race cars used to run CV jointed driveshafts.

It is what I'd do. I believe the Group A GTV6s did the same ... but ????
Pete

 

Found some before pictures.. was an old donut, they obviously didn't replace it when upgrading the driveshaft. It doesn't look as distorted as the new one I fitted in the before removal picture below.

 

Phil, Alfetta Sedan and Alfa 75 wheelbase is 2510mm.
Alfetta Gt/Gtv/Gtv6 wheelbase is 2400mm.
Of course they have different driveshafts.
You need to source a late Alfetta Gt/Gtv Driveshaft (from 1979 on). NOT A GTV6 ONE 😉.

 

Why not just make the driveshaft fit? Easy to get one welded, it's just tube
Pete

 

Because you need to be very precise and have it high speed balanced.
By far the best solution is to fit an Alfetta gtv driveshaft, especially if known to be unmolested with the balance weights fitted at Arese.
At that point a set of new donuts (carefully marking the reciprocal position of the 2 halves) and it becomes ready to go perfectly satisfactorily.

 

Mmm I think I may have discovered the issue. When they made the driveshaft he was running an early magnesium cluch housing. This was cracked at a race meeting last year so I supplied a new stronger TS housing and also a new 5.5" clutch for him from Richard Jamieson. There seems to be a good 7mm hight difference that may be the cause.

 

The later TS version housing being 7mm shorter from tranmission mounting face to yoke face.

Unless anyone has any suggestions, I think my only option is to lengthen the drive shaft as I don't think I can space out the yoke as it wouldn't leave enough length on the shaft to allow to center on the donut.

I can't believe I didn't check this measurement last year. The positive spin is I learnt something new on the differences on Alfa's transaxle clutch housings tonight.

 

I have a FrankenFetta as well and ran into a similar problem years ago caused by the trans input shaft not seating in the bushing of the rear giubo. Had to increase the ID of the bush slightly. Swore that I had shrunk the driveshaft or stretched the car.

 

Hi Philip
Sounds like you found your issue. The picture of the donut in your post #4 definitely shows a donut being stretched to cover a too wide gap.

We never got the Twinspark 75 in the USA we only got V6 Milano's, so I have never seen an actual twinspark driveshaft. However I have seen a lot of USA spec Alfetta driveshafts.

The donut you show in post #7 is what I call an Alfetta style rear donut, in that it has locating dowels sticking out of the face of the donut that fit into corresponding holes in the yoke on the clutch cover.

When the Milano came out, they redesigned the donut and got rid of the locating dowels on the donut and the corresponding holes in the yoke.

Can you take off the donut shown in post #4 and see if has locating dowels, and also does the yoke have holes for for those dowels.

Hope this helped.

 

Is it possible to shim the yoke out to allow better alignment

 

I wouldn't. The problem is that the front and rear donuts have two jobs. One is to transmit the engine torque and the other is to center the driveshaft.
The middle driveshaft donut is a more conventional design, all it does is transmit the engine torque, the centering function is done by having the two ends of the driveshaft fit into each. This is the more common donut practice. BMW and Mercedes design their driveshafts this way. AFAIK only Alfa uses a donut for torque transmittal and centering.
If you shim the yoke you may interfere with the centering function.

Bye

 

It's a race car => put all the donuts in the bin and run CV joints.

You want to actually race the car don't you, or spend all your time under it trying to finish the engineering of the car that Alfa Romeo never did. There is a reason I do not own a 116 Alfa ... might be awesome to drive but the driveline maintenance is too much for me, and if you try and go fast with a 116 pretty much every driveline component is not up to the job
Pete

 

This is not true at all. Alfa Romeo finished the engineering constantly improving it. It is the sole manufacturer to have built more than 1,500,000 vehicles with the special characteristics of a clutch at the back.
Porsche tried but gave up, relocating the clutch at the front and using a torque tube.
Ferraris have the clutch at the front too in their 365, 456, 550, and others transaxle cars.
Alfa Romeo raced in the 80s up to the 90s with the Gtv6 and Alfa 75 turbo evoluzione.
Gtv6 was Euro Touring Cars champion in 1982-83-84.
Alfa 75 turbo peaked 400HP and almost beated BMW M3 in 1991 Touring Season loosing the championship at the last race with the BMW M3 driven by the excellent Roberto Ravaglia. And it lost not because of the driveline but because of the engine: turbos were constrained by a compressors suction flange diametre which narrowed the engine usable range.
The Alfa transaxle mechanics was very advanced and demanded knowledge, skills and tools.
It is unfair to blame Alfa Romeo by someone who does not have these 3 characteristics. The old sentence "bad worker always blames its tools" is very wise...
The 116/162 saga represented a MASSIVE improvement over the 105/115.
But since I believe this is often not clear, I let the images speak by themselves:

This is a race 1750: look at the front internal wheel! It detaches from the ground!! And this is an improved car equipped with the famous "Slittone" designed by Filippo Surace (yesterday he passed away aged 96, may he rest in peace) and Carlo Chiti. Imagine the standard cars, with the standard sloppy differential linkage to the body!!
Another picture:

Slittone:

This never happened with 116 cars equipped with Watt linkage on both street and race cars (no modification needed at all apart firmer bushes)...
In 1988 Aston Martin released its Virage model, which costed more than 10 Alfettas and was equipped with a rear De Dion which was an incredibly faithful Aluminium copy of the Alfetta steel De Dion (and used a gtv6 as test bench).
In 1994, Mercedes raced in the DTM with the then new C klasse.
The standard C klasse AMG car had a straight six cylinder with cast alloy block and front gearbox.
The DTM had a full alloy v6 engine with rear transaxle, its mechanical layout being more similar to an Alfetta or Alfa 75 than the C klasse that it was supposed to represent on racetracks...

 

This is how Dell'Orto carburetted 3litres gtv6 kicked the 3.5litres BMW in South Africa:

https://www.alfabb.com/threads/south-african-gtv6-3-litre-history-and-registry.155269/

By the way Phil, if you are chasing the top HP and flexibility, you might really want to replace your Webers with Dell'Ortos😉!

 

The racing Alfettas/75s used CV joints in their driveshafts as far as I am aware, but yes the chassis balance is miles better

Pete

 

Pete - plenty of 116 chassis cars have competed at various levels with standard Tailshafts, including down-under.

Phil - nice repair. I’d love to see more photos of the car.

 

NZ drivers must be rougher
Pete

 

Did you mean... NZ drivers must be tougher?

 

Phillip, I sent you a PM

 

Did you mean... NZ drivers must be tougher?

Faster

Pete

True story: I was at a Porsche event here in California a couple of years ago, Mark Weber was there and he did a Q&A. I asked him why he thought Brendan Hartley didn‘t get the expected results in F1. His answer? Some stupid statement about national aptitude. I was dumbfounded so much I failed to remind him of Bruce McLaren, Denny Hulme, Chris Amon, Jim Richards, and more. Seriously, what an arrogant pr..k.

 

Phillip, did you see my PM?

 

Before doing any major mods try loosening the driveshaft nuts to allow some fore and aft movement, start the car in neutral and idle for a minute, shut down and check to see if the flex couplings have found their happy place.

 

Thanks everyone for your advice and help.

After taking it out and measuring everything and doing another refit which was slightly better, but not good enough in my view. Have decided to get the driveshaft lengthened 6mm. This will see him sorted for the next few race meetings and I'll then get a new race driveshaft ordered from CSR in the UK.

I've 3 other race cars to get ready for this summer so be nice to get this one out the door and off for a dyno shortly.

Thanks again.

 

Hi Phil,

I'm having the same issue on my standard Alfetta GTV.
Standard clutch, standard driveshaft.
I only changed the front and the rear donuts because they broken.
The front and the center donuts fits fine but the face of the rear one is 5-7mm far from the yoke face distorting the donuts when you screw the bolts.
The changed donuts are NOS Pirelli and theyr lenght seem to be the same as the old ones.

Maybe some donuts have more compressibility than other?

I changed many times Alfetta donuts but never had this issue before.

Try to investigate before cutting the driveshaft!

Regards,
Alberto

 

Did you try loosening the driveshaft nuts to allow some fore and aft movement, start the car in neutral and idle for a minute, shut down and snug the nuts gradually in sequence front then back, back and forth, until tight?