Prop shaft vibration

[londrasud]

Hello all,

First post here (took some time to authenticate the account) so I've been more active on alfabb.

Car is a 1986 GTV6 2.5 bought last year from over east. Have had the clutch and slave replaced along with new engine and gearbox mounts.

There's propshaft vibration at 1800rpm and some at 3000rpm which is annoying and disappointing.

Anyone have any cool self made tools like the laser sights that alfabb lists for alignment and anyone in Perth willing to help?

Thanks

[john m]

Hi
just saw your post, was there any vibration before the clutch was replaced?
John

[londrasud]

Couldn't really tell you. Drove her all of 200 metres in 2nd gear off the tow truck with a failed clutch slave after I got her shipped over from east.

Had new doughnuts installed along with centre mount and proper balancing done in Melbourne. Spoke with them and they suggested it was alignment issues. I'm thinking it to be the engine mounts . . .

Probably going to need something like this to do root causing: https://m.roadkillcustoms.com/how-to-fix-prevent-driveline-vibration

[MD]

quoting your own source:-
"If the vibration steadily increases with driveshaft speed (either accelerating or decelerating) the symptom is primarily the result of a driveshaft imbalance or yoke run-out. "
If that is the case. the alignment tool isn't going to help.

Mike (a Perth Forum member) may be able to put you in touch with people he uses on his transaxles. Message him on this Forum and take it from there.

[londrasud]

For posterity I will regurgitate some of the notes that I took from the lovely gent at Balancing Services Pty Ltd who did a pukka job on the prop:

• critical speed vibration (which on Alfettas occurs at 3200 rpm) is where maximum unbalance is displayed
• cyclic vibration is symptomatic as the rpms increase - 800, 1600, 3000 etc.
• oscillation is the other type which is caused by misalignment
• misalignment can be rectified by adjustment spacers on the gearbox and engine plates
• the centre coupling can absorb up to 1.5° before vibration starts to occur

Anyway, since then I've found that she burns a litre of oil every 1000km, and the coolant expansion tank needs topping up just as frequently - no doubt related to the water droplets coming out of the exhaust on cold start up.

Am thinking valve stem seals and head gasket, so engine out which is good since the engine bay needs a refresh. So whilst at the spray shop I might as well do the rust spots on the doors, the scuffed sills, the dusty boot, hole in the spare wheel tray, cracked paint on rear panel. Budgeting and planning to be drawn out by the trouble and strife, but we're looking at next year earliest.

Am long out of the game, so was stabbing in the dark earlier this year, but pleased to say we joined the local Alfa club recently and had the opportunity to compare notes where a few names including MB's have popped up.

It's going to be a journey with this one, which I'll log some of as I go along.

Cheers