rattle rattle

[NZAlfa75]

All

My driveshaft has developed a rattle at certain rev ranges, including idle. A loud harsh metallic sound. Ting ting ting...

Guibos are all good. Engine and gearbox mounts are new, but there is only 5mm between the aft engine mount and the driveshaft. Normal? I have a witness mark in the driveshaft (not fresh).

Lying under the car with the engine running I can pinpoint the noise to the front half of the driveshaft or centre bearing. I can move the centre bearing up and down about 10mm.

I don't want to have to pull thing thing out AGAIN, any guess whether it could be out of balance? Maybe time to start playing with hose clamps and weights?

[SamW]

Here are two guesses, and only guesses. One, try tightening the front pinch bolt, I had the same rattle on my Milano, I tried tightening the front pinch bolt, it would work for a while, then it would rattle again, I finally broke the 10.9 bolt and had to replace it. How I finally fixed the rattle is I replaced the entire drive shaft with a spare I rebuilt. The front guibo was the same, but what I did find is that the rear bearing that goes inside the rear guibo was pushed in and not in the rear guibo, so I took my time and made sure the rear bearing actually made it in the rear guibo, since then this new driveshaft has not rattled. I am not sure this was the cause, but it was not right and it is a very easy mistake to make. I think you really need to mount the rear guibo on the drive shaft before bolting it up to the clutch.

[AR4me]

Quote:

Originally Posted by NZAlfa75 I don't want to have to pull thing thing out AGAIN, any guess whether it could be out of balance? Maybe time to start playing with hose clamps and weights?

[Craig]

G'Day Guys,

Sam, there's no pinch bolt on a TS but the rest is good advise.

Richard, clearance is listed as 7mm so you're probably ok, center bearing is mounted in a rubber diaphragm (how come Webster didn't change the spelling of that word?).

The handbrake cable and shift lever/linkage are both possible sources of your noise.

Give us a little history, have you just put this back together or has it been running fine for weeks?

[NZAlfa75]

When I did the big rebuild (and I've driven 9000kms since) I replaced the front Guibo and (I think) the rear. The centre is old but good condition. Things were lubed well.

I've only noticed the noise recently. You hear it at idle and then a couple of other places in the rev range, it comes and goes depending on rpm.

I've been meaning to check the handbrake cables for weeks. Then when I have the car jacked up I forget! I'll check but the sound appears to be further forward.

Gearshift is good, I rebuilt that too so it is tight (as tight as an Alfa gearchange can be ). Exhaust is also good. I feel no vibration while driving.

I really don't want to have to pull this driveshaft again. My exhaust is welded construction and I'm sick of cutting it!

[NZAlfa75]

Jacked it up again today and replaced the rear fuel hoses. Apart from the two 3" lengths of 12mm hose needed, sigh. Typical Alfa to have everything 8mm bore except two locations.

Anyway, Looking from underneath the handbrake cable is very secure. There is no vibration in the cable evident with the engine running. I'm sure the noise is coming from the centre oupling, but it is a rear rattle, like a nut bouncing round a housing. All nuts are tight and there is not a lot of movement in the shaft. The centre bearing seems well located in the housing. I think it is just there to annoy me

[SamW]

You are not a lone, Alfa gave a lot of us this little rattle, I have been chasing one for a while.... But do look at the bearing in the rear guibo next time you have a reason to take it apart.