prop vibration

[rallygaz]

right, had my centre bearing and guibo done and received the car back from the garage and it now got a vibration starting at around 30 mph onwards the vibration gets better the faster I travel !! the mechanic said he dropped the prop from the front undone a big nut fitted new bearing and mount the tightened proop up from the rear to pull bearing into place then tightened the front!! can anyone give me any ideas what could have gone wrong !!! btw the garage has agreed to have another look at it next week and i would like to give them some ideas as to what it might be as they dont seem to know !

many thanks GAZ

[jmc330i]

Did he mark the prop before he split it? If not, it could be now unbalanced as the front and rear are balanced.
The prop is marked to make sure it goes back together correctly, if you can still see the marks.

[rallygaz]

he said he didnt split the prop so he said ???

[Brianmoooore]

Even without the marks, there's only two ways that anyone worthy of the title of 'mechanic' would reassemble the propshaft, but there should be a white dot on each half that should be lined up.
If it turns out that this is the problem, they're unlikely to be aware that the centre bearing needs preload of its mount, either.

[Brianmoooore]

he said he didnt split the prop so he said ???

You can't change the centre bearing without splitting the prop in two.

[rallygaz]

yea brian your right he said he explained what he did when fitting the guibo!! so theres 2 white dots that line up the car in question is a 320i touring !!if no dots how many different way's can you line up the prop ?? 4???

[Brianmoooore]

You can physically fit the two halves together in as many ways as there are splines. Never counted them, but several.
The prop uses universal joints, not constant velocity joints, so anyone who understands how a universal joint works will know that the input and output flanges must lie in the same plane, and the number of ways in can be fitted together is two. Only one way will result in a balanced prop.
They've fitted a new guibo as well? May be a good idea to make sure they know what the arrows embossed around the outer edge of it are for.

[johnl320]

Not the first time a thread like this had popped up, You really must insist that this is a problem THEY need to sort. Don't be fobbed off with some old bullsh1t.

[mrLEE30]

they're unlikely to be aware that the centre bearing needs preload of its mount, either.

this is my money.

they can check this witout rmeoving much more than the rear exhust hangers. (they can check the prop alignment too), they will see the bearing mounts are slotted, loosen then slightly then slide the houseing about 5mm toward the gearbox and tighten in this position. now try the car. if not then look for the rubber guibo thingy the wrong way round or the prop is wrongly aligned

[capnmchl]

^ So say you bought a second hand prop that had been split but not marked up, you would have a 1 in 4 chance of getting it lined up properly?

I may have this predicament....

[jmc330i]

Only 2 ways, as the joints will only line up in 2 ways, one of which is right.
Look at the pic of the prop above. If the prop was split and the joint in the left yellow circle wasn't moved, you could only rotate the other section of prop 180 degrees to get the 2 joints lined up again (along the yellow line).

[DanThe]

Bloody fitterzz,,,

[capnmchl]

Only 2 ways, as the joints will only line up in 2 ways, one of which is right.
Look at the pic of the prop above. If the prop was split and the joint in the left yellow circle wasn't moved, you could only rotate the other section of prop 180 degrees to get the 2 joints lined up again (along the yellow line).

Ahh, touche. My sunday morning maths

[rallygaz]

Right the garage has told me that the rear uj is worn so i need a replacement prop as they cant replace just the uj .... anyone got a 320 touring prop for sale
???

[Grrrmachine]

Props aren't specific to the body style, just the gearbox/diff combination, so any 320i manual prop should be fine. I don't know if 316i/318i props also fit, but a 325i one won't.