Ahhhh, prop bearing? Diff?

[TouringMatt]

It seems i solve a problem, i gain a problem

Changed the rusty fuel tank last week, and whilst fighting with the prop i dropped it.
Everything fitted back up, bearing (just over 12 months old) refitted back to original location, i've now got a whine that is consistant with road speed

Now also worried i could have damaged the LSD, i had one wheel on a ramp and the other i turned to get to the prop bolts

I've had a rear bearing go before and it sounds different to that, replaced the prop bearing when i did the rubber coupling so dont know what it sounds like compared to a diff whine

Could i have damaged the bearing when i dropped the prop?

Cheers
Matt

[daimlerman]

When you re-fitted the prop,did you pre-load the centre bearing?

[TouringMatt]

When i first fitted the bearing 12months or so back i did, before i unbolted it this time i marked where it was and refitted it in the same place - was that wrong?

[daimlerman]

When i first fitted the bearing 12months or so back i did, before i unbolted it this time i marked where it was and refitted it in the same place - was that wrong?

It's what I would do,I was hoping you would say 'no' to pre-loading the thing....
Is the whine similar to last year,before you replaced it?
Did you replace just the rubber or the actual bearing on the prop?
Part 7...
http://www.realoem.com/bmw/showparts.do ... g=26&fg=10

[TouringMatt]

It didnt whine before - the rubber box/prop coupler had gone, and i figured it was best to change the bearing whilst it was all apart.

It was a complete unit, bearing and bracket etc

[daimlerman]

Do'nt know what to suggest,sorry!
Not something silly like a handbrake cable catching on a halfshaft?
Cannot think that dropping the prop would have buggered the bearing...

All the heatshields back correctly and not fouling somewhere?
Clutching at straws here!

[Gyptian]

You need a new part number 26521126713

[toptints]

I too have a whine consistent with road speed... i have had the diff oil changed and it is still the same, so i might look at getting the prop bearing changed ! never thought of that one. Are they difficult / expensive to change ?

Chris

[TouringMatt]

Nope there is no fouling going on, wish it was something that easy!

You need a new part number 26521126713

What part is this? Doesnt come up on realOEM

Nope not expensive or that difficult, just a bugger to get at, exhaust has to come off (completely in my case as its a two piece), heatshields then prop.

Make sure you mark the prop before you split it so the two halves go back in the same alignment

Its just a nasty job lying on your back on a driveway - having a pit/4 poster ramps it would be great!

Matt

[TouringMatt]

Any more thoughts on this? Can you damage the plates in the LSD by turning one wheel and not the other.

Matt

[bastosm3]

it wont damage the plates, but if it was easy to turn one wheel while the other was locked, then the plates might be worn anyway.

i'm not sure what preload the standard diff should have.

but you can check it by jacking one side up (so that one rear wheel is still on the ground ) and then attaching a torque wrench to the hub nut, keep changing the torque setting on the torque wrench untill it clicks just as the wheel turns.

this will tell you what preload you have.

i expect someone on here will know what preload you should have as standard

[TouringMatt]

Thanks for the reply, it was not easy to turn by hand so i guess the plates are ok

Been reading on here and sounds like the whine is pointing toward diff input bearing?

Get no knocking on hard acceleration so prop coupler and bearing (both fairly new) are not suspects
Noise does not change with cornering or load etc, so wheel bearing or diff internals should be good too.
Noise does not change if i pull the handbrake on a touch so its not the shoes rubbing
Need to check the diff bush as i did jack the car up on the casing, but again, no vibration, it just gets louder the faster you go, cant even tune it out with the radio at 70+!


I did have a bastard of a job dropping the prop past the gearbox mount and now worried i've done some damage to the prop itself (UJ's) or the input bearings

TBH i'm losing heart with the car, the problems just seem to be relentless lately

Cheers
Matt

[Grrrmachine]

Was there any conclusion to this? I'm experiencing the same thing and, having removed some culprits from the list (diff and bush, wheel bearing) I'm starting to think I've got a duff prop bearing too. I get a steady roar from the rear, starting at 50km/h and increasing steadily, which is still present when I dip the clutch.

[TouringMatt]

Errrrrr, no

I re-changed my center prop bearing but it didnt solve my problem, i'm currently re-furbing a set of trailing arms so i can eliminate both wheel bearings and any dodgy brake backplate issues i have.
Im still driving it, but i can feel buzzing vibrations, mainly through the pedals, im guessing the o/s/r bearing (which is on its way out) is transmitting the noise through the entire drivetrain

Matt

[Grrrmachine]

Hmm, that's not good. I took mine to a garage and they couldn't find anything wrong with the wheel bearings, and they recommended a diff swap, which I did, and the noise is still there.

Change of tyres is next (winter tyres going on) to see if it's something silly in that department.

[TouringMatt]

There is no play in my bearings, but if (dont try this at home kids!) i support the rear wheels off the ground and have a friend run the car in gear there is a rumble from the bearing.

I wandered if it was tyre noise as i put rear bush inserts in, making the rear beam more solid/transitting more road noise, good test is to drive over a piece of road with different tarmac finished, some are more noisy than others, if the your noise is there regardless (as mine is) its not the tyres

Whats the milage out of interest?

[Grrrmachine]

Milage can't really be trusted, but the clock's showing 200k km which is only about 125k miles. Rear bushes look good my end, but the car is generally scabby and the amount of salt we use in the winter can't have done the underbelly mechanicals any good.

Good comment on the tyres though. I need to get the arse up in the air again and get the wheels rolling to see if the rumble is still present.

[TouringMatt]

I asked about the milage (mines about 168,000) as my bearings have gone within 12 months or roughly 8000 miles of each other, might be coincidence tho!!

A safer way to check the rear end is to unbolt the driveshaft at the diff, that way you are only rotating that wheel - i however went under the car using a long screwdriver as a stethoscope, i could hear and feel the noise!

[Grrrmachine]

Yeah, that's a good tip. I unbolted the drive shafts today and strung them up out of the way, and then revved the car up so that the diff was reading 100km/h. I can feel a little vibration, but I'll put that down to not having two massive gyroscopes at the rear end. Certainly seemed quieter, anyway.

Turning the diff by hand, I could feel the bearings moving. Difficult to describe, but I'm presuming its feedback of turning the prop and gears as well, and isn't a sign of a failed bearing anywhere. It didn't feel like it was grinding on anything.

So it seems my rumble is at the wheels after all; either brake shoes rubbing (they were new six months back) or indeed a wheel bearing. Only thing I can do now is have those bearings replaced and hope the noise goes away, because when I turn by hand I can't hear or feel much roughness.

[TouringMatt]

It was the wheel bearing, had enough of the grumbling noise and changed it.

Managed it in just under 3 hours, not bad considering i was working outside, and it was about 2degs, lovely and sunny tho!

Matt