[alfa] Re: alfa-digest V10 #150

[George Graves <gmgraves@xxxxxxxxxxx>]

Alfetta drivelines will often do this if  the engine isn't absolutely 
level with the input to the clutch housing. I.E. if the engine output 
coupling is angled down because the rear mount of the engine has sagged 
and/or if the input shaft of the clutch is pointing slightly down, the 
drive-shaft might seem to have pulled them straight when all 
tightened-up but they aren't. On getaway, the torque of the engine 
against the stationary rear driving wheels will cause the drive shaft 
to momentarily 'jump-up' at the junction between the fore and aft shaft 
as both the back of the motor and the clutch take up the slack at the 
moment of inertia. The only way to check this is to pull the drive 
shaft and while holding a bubble-level hard against the triangular 
Giubo (doughnut coupling) mounting flange on the flywheel check the 
angle of the vertical spirit bubble; it should be dead-center or pretty 
damn close. Do the same with the giubo mounting flange on the nose of 
the clutch input shaft as well (without the giubos in both cases, 
obviously). An even better method would be if one has one of those new 
laser levels. Choose one with a perfectly square side directly opposite 
the light source. That way, when you hold the level flat against the 
engine output giubo flange, the laser beam ought to hit the input giubo 
flange on the clutch assembly dead center and when held against the 
clutch input shaft giubo flange it should hit the engine output giubo 
flange likewise, dead center.  If either are significantly out of 
level, that's your problem. There can be several reasons for this. The 
most obvious would be a bad motor or transmission mount but you say 
that they are all new, so I would suspect an incorrectly mounted deDion 
traingle assembly. It's either loose somewhere or something is bent. I 
really don't see how an engine with new motor-mounts can sag in the 
back, but perhaps the front mounts were incorrectly installed. Maybe 
one of your new mounts was defective out of the box (don't exclude the 
possibility of the hanger bearing being defective, either). Of course 
unless you measure the level of both the transaxel assembly and the 
engine you'll never know. I realize that this is a lot of work. The 
drive shaft is not easy to remove and refit, but you can't do it with 
the shaft in place.  Good luck and let us know what you find.

George Graves
'86 GTV-6 3.0 'S'


On Jun 12, 2004, at 4:09 PM, alfa-digest wrote:

> From: owner-alfa@domain.elided [mailto:owner-alfa@domain.elided] On Behalf 
> Of Mark
> Denovich
> Sent: Saturday, June 12, 2004 12:30 PM
> To: Alfa Digest
> Subject: [alfa] thumpin' milano (again)
>
> So I'm hoping for some insight from the digest with regards to a Milano
> driveshaft problem.
>
> Symptoms:  On a hard launch (not tire squealing, but quick) the
> driveshaft seems thump against the tunnel, felt as if it was under the
> E-brake console.  Otherwise no driveline issues...  very smooth.
>
> What I've checked done:  During the engine swap to my new Verde (last 8
> months or so) I replaced the following:  all engine mounts, all donuts,
> center support, all transmission mounts, poly dedion bush...
>
> I've been underneath, and it all looks good and tight.   The
> transmission mounts have not separated (yet) and I don't see any
> clearance concerns.
>
> I really don't know why my driveline is getting so out of line...  any
> guesses as to where I should look next?
>
> - --Mark
> The Alfa Wiki: http://alfa.denovich.org
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