ALFAGTV6.COM

[PietereQ]

Yes Mats, engine torque. Just for reference. In theory our shafts carry way less torque than in conventional FR layout, so this is really strange. The splines on the shaft were relatively intact, which also leads me to hope that this was a material issue.

[Mats]

Usually those parts are harder then Clint Eastwood, must have been something wrong...

[75evo]

Did you check where the parts made in? I once bought a set of wheel bearings for the 75. The bearing collapsed after 1 week!!! I later found out it was made in China!!! I couldn't believe such an old car would have parts made in China. You can get the best quality from China, but the problem is most companies who want to make parts will tend to just go with probably the cheapest manufacturer there, not the good ones.

BTW, the 156 is still being assembled in China, or if it isn't anymore it probably has it's assembly line shutdown recently. It's built under license for some Chinese auto company, so if you have a 156 which need parts, you can get Chinese parts......but make sure your AAA roadside assistance is fully paid

[slyalfa]

I think it might have been hammered off. if there is some play and it starts to bang back and forth it will sheer the splines. I think that is why alfa calls for the splines to be filled with locktight on the std setup. so there can be no movement at all.

[MD]

Hey Pete. I was beginning to think you were pickled with the rest of the gherkins and socked away for the winter..

What can I say? We are brothers in the pooh (again). I have used your photo to illustrate where my shaft broke using the same basic set up. Not only did it brake the shaft nose piece but made a 50mm hole in the side of my rear engine mount that I especially imported from Holland. Like I am overjoyed. In my case it is a inadequate accurate balancing. We just don't have the gear here to do a proper job on these shaft together with metal fatigue caused by
the crappy balancing. I tell ya, I am spitting chips..

..harder than Clint Eastwood.. that's gold Mats.

[75evo]

MD,

Why don't you go with 2 rubber guibos and 1 CV?

engine---guibo---guibo---cv---clutch

Something tells me that at least 2 rubbers are needed to absorb the vibration. I was thinking of using 3 540i guibos all around. Adapt the drive shaft to fit it. Cheap, strong and will absorb more vibration.

[MD]

Yes there is nothing wrong with your suggestion. However I have tried every kind of rubber front coupling from genuine Alfa, BMW, Mercedes and our local GM car, the Commodore (Opel equivalent)

It chewed them all up. I than installed the coupling in a metal shroud. It pulverised the coupling inside the can and I am still pulling threads off the chassis from time to time. It also turned the metal shroud into a squashed soft drink can.

By then I have had the total shits and decided to go all CV. This was fine for about 4 meetings and then the front of the shaft snapped off. So at this stage, I am thinking I need some matches, you know, the fire starting kind...

No, all is well but it really comes down to how much luck you get with our balancers here.Mostly they couldn't balance a 20 cents piece on the end of a hard on.

[75evo]

MD,

You need to talk to Beninca. One of his brothers designed the software to balance the corvette's shaft. I have full confidence in his work. If he uses the driveshaft for his Alfetta GTV 16v, and TS which spins to 8K, I dont see why your stockish TS will chew donuts unless your balancer is totally clueless.

You're luck the shaft didn't pole vault your car Then who would come he to keep the Greekster in check?

[MD]

I like the way your thinking. The only hassle is that ideally the set up should be looked at totally in the car and any issues dealt with that would assist the balancing solution. Regrettably,the Beninca hangout is around a couple of thousand kilometres away and so that makes for what would otherwise be a logical step quite ackward.

The rear engine mount caught the spinning shaft and contained it from dropping on the ground. Racing rules here also require mechanisms to be fitted to the tunnel to restrain a broken shaft from hitting the deck in the event of a break.

As for the Greekster, well you know the Greeks. I think they like to do some of their own pole vaulitng so I am told..Lucky for the rest of the planet, his propshaft has been out of action for the last twenty years..

(Now if that doesn't flush him out of the woodwork nothing will , heehee.)

[slyalfa]

If it is out of balance you should feel it. and I would say use the old trick Tom showed me. mark the shaft on 1/4s and put on a hose clamp. rev it up and down and move the screw part of the clamp to each of the 4 spots and leave it where you get the least amount of vibration. do this to each end of each shaft. after you have done each one go back to the first and try to fine tune it. then the 2nd etc. if way out you might need more then one clamp. but this is easy to do and works quite well.

[MD]

First up, we all need to cheer up JK. Sadly his father just passed away and we can all relate to how that feels. I am sure he will get square with my last stupid joke when he feels up to it.

slyalfa.
Thanks for chiming in. Sort of been down that track but not exactly the same. My simple technique has been to chalk mark a spinning shaft at around 14-1500 rpm. An out of balance shaft tends to "whip" and the chalk will scribe the off centre out of centreline point.

CAUTION : hand held chalk against a spinning shaft is dangerous. Please work out other means if you intend to do this .

Placing a clamp held test weight opposite the chalk mark can produce vibration reductions. Experimenting with the amount of weight finetunes the result. Rarely 100% effective.

For the cost and effort involved (like zip ) your suggestion is worth trying for sure.

[kevin]

Yes, I'm sure Jim will be back to lecture us Our thoughts are with him at the moment.
We have two alfetta gtv 2.0 that race here that are frightenly fast and light weight ( 770'kg) . Now the one driver has endless issues with broken props , clutch housings , etc . He even went the cv route then went back to coupling cages and it also ended is mash . He is at wits end while the driver of the red light weight gtv who revs to 9000rpm has not had a days issue and has finished and won nearly every race this year ( he literally flies past me through the sweeps) .
There are no coupling cages on the red gtv and it's a standard prop . Clutch is lightweight .
So in summary there is definitely a solution but Its not easy to get all the details out of the successful red gtv owner who also prepairs two championship winning FIAT Abarth 124s.
So at our year end party I will try get the beers flowing and extract info .
I may be biased but I think this has to be the fastest normally aspirated and best handling gtv racing anywhere in the world at moment .

[Duk]

MD, how about using a steel/aluminium donut with rubber bushes in it (like what Jess used with his carbon fibre shaft), for the front coupling followed by your uni and CV joints?

I'm sure you have your radial location of the 2 tailshaft pieces 100%.

[MD]

Hi Duk. Yes all good suggestions and I see you have been quietly sitting on the porch, beer in hand looking far into the blue yonder and pondering. I appreciate it.

The truth of it is that none of the transaxle cars that I have fully rebuilt over the last 30 years has ever had a properly balanced propshaft. Some have been so bad that it rocked the whole cabin straight off the balancer with all new components.(A few quiet words were exchanged at the balancing shop that day )

I have an original 75 v6. The shaft in that is factory balanced and it has stock components. The balance is great. My GTV6 has a custom shaft in it and the balance in that is not as good as the factory one on the 75 but it is acceptable. As for all the racing propshafts, well, the story just goes down hill from there.

It is a combination of stiffer mountings all round and shitty balancing all contributing to the end result. As Kevin's post shows. Some are right and others are crap.

As for alignments, well if three CV's can't adjust to minor alignment issues these cars have we are all screwed and water runs uphill.

[MR2 Zig]

I have a question on this.

What effect does the rotational mass of the cv joint have vs. the mass of the stock rubber coupling? Does it act like flywheel mass? Does it cause odd bending / whipping movements?


Thanks,

Scott