ALFAGTV6.COM

In order to de-hijack the CF Driveshaft thread, I thought I'd post this in its own unique thread:

Does anyone have info on how to mod M5 donuts to fit the GTV6/Milano/75?

Yep! Good move!

At last... we have 2 possible solutions to replace the dreadfully designed guibos in our cars. It surely deserves its own thread!

Now, is Michael going to move the relative posts here? Or maybe repost the pics etc.

The Bmw M5 donut "seems" quite robust. But it is not designed to spin at engine rpms... right? Then again, I don't think Alfa's where designed for that either

The alu wheel with the individual bushes seems nice too. It might even flex enough to take up the misalignment of the driveline.

Hippo58 wrote:
The Bmw M5 donut "seems" quite robust. But it is not designed to spin at engine rpms... right? Then again, I don't think Alfa's where designed for that either

The M5 driveshaft sees around 8000rpm if it can pull its overdrive top gear. I assume BMW tests at that speed. The M5 part is more robust than the M3 but while the design is intriguing I am curious which of the two might be best for a 4 cyl 116.

I work on old Turinese cars as well as Alfas and it is interesting how much lighter and more reliable the old engine-speed Flaminia driveshafts are.

--Carter

Carter,

Are you sure an M5 spins its driveshaft to 8000 rpm? I thought it was way less since the gearbox is up front.

I asked the guy selling the Previa flex couplings if he could share some approximate dimensions:

so u were asking about the measurements?

thickess of plate: 2cm.

hole to hole about: 32 mm

diameter of plate 12.5 cm

the hole's width: i have 2 different ones...14mm or 12.5mm

[ebay item number: 8002272745 ]

Zamani wrote:Carter,

Are you sure an M5 spins its driveshaft to 8000 rpm? I thought it was way less since the gearbox is up front.

Way less in first gear but in top gear the driveshaft is overdriven, spinning faster than engine speed.

--Carter

Hippo58 wrote: But it is not designed to spin at engine rpms... right?

when gear box ran on 5-6 gear speed, probably gear ratio under 1..... shaft spins faster than motor....
maximum velocity should never occur on a gtv6 or a milano, (faster this can be....) in comparison of other engine with front monted gearbox and rear differencial.

however, yure rigth somewhere....about tiredness in regard of time.
masterskills show that a part can fail due to fatigue as much as to bigger sollicitations.
then on a 116 series theses donuts spin all the time...



DAVE H.:

i dont know if this can help you,
bolt circle of donuts here. its 105 mm for shaft side and 110 mm for flywheels sides.
for the front...no need to centre anything, but for rear its needed.

i dont know the price of these.....but with extra machining or problems, this should cost you an extra price.....

in france them are already avaible, near to 80€....110$(for export).......

IMHO, this part had a service & life time endurance.
if them ride you until today, then they should do fine for another 70000 miles and 15 year on a gtv6 near to oem specs.

Darn.... forgot about the overdrive part.

this is the front cross on my shaft , recently replaced after been torn apart... ,the mid section of the driveshaft is the BMW donut .

I think next time I'll just buy the M5 front & rears. I can figure out the machining requirements myself.

Not so worried about the disk-type middle 1 - on my car it was in far better shape than the donut-shaped front & rears.

Thanks for all the input guys.

Dave,You are being pretty sensible here..
Ive looked at his problem for ages and came up with the BMW540 solution (posted stuff on the old forum..)
Its rather easy,the bmw coupling has 12mm thruogh hole and the Alfa 10mm.A simple adaptor turned up on the lathe sorts this..
I spent the day on my lathe turning up the "Previa"discs..Our shafts have too much angular movment to work successfuly here..
The rubber bushes to use with the discs are also not up to the constant and peak forces that are going to act on them..

I was quality manager for a rubber component manufacturer for the motor industry a few years back..I got my data from our old chemist and my test data from different manufacturers components-including "specials"that the manufacturers ordered for racing in "standard production car "racing..

As far as Im concerned,the BMW coupling is the way to go..Dont look at the lesser BMW couplings any less either..They are a great improvment over the Alfa guibo`s.

Chen,Some blokes here used cv joint bolted to machined flywheels on thiere cars...broken cv`s,broken cranks.....

Barry,

You make it sound v straight forward. Good news.

The front donut has a stepped thru-hole, right? Part of the nose bearing thru the middle? Easy enough to have an insert fabricated. In fact, when I do this, I'll make several inserts. Press-fit or circlip?

So which 540i? E?? series?

Do you stick with the original Alfa middle donut?

Thanks for the input Barry. It's time to not have to worry about rotten NOS donuts.

No-one likes rotten donuts.

Dave,I went with the e39 540i.Middle one is std. gtv6.I dont have problems with these-If I do in the future,ill go with the e34 3 series cuopling..
On the rear,I machined up something simmilar to the original Alfetta(ally)coupling.They used a seperate centering yoke incorporating a uni-ball.
This neccessary as the rear coupling carries the bearing or bush to clutch shaft...

I found a cheap source for donuts which are actually slightly stronger than the originals............

Yeah, but avoid the ones with the squiggle of icing on the edge. 'Could really screw up driveshaft balance.