1994 E36 Vibration in rear axle?

Hi all,


[xposted alt.autos.bmw,uk.rec.car.misc ]

My 1994, E36 320i Coupe suddenly developed significant vibration in the
rear axle. (hear cries of - "I told you so..." )
It only occurs when the transmission is fully engaged and accelerating .

If coasting - nothing.
Rev engine with clutch dipped - nothing.

The frequency of the vibration is related to the gear and current speed.
Low when pulling away. High when doing 40mph and acceleration or going
up hill.

If I drive down a narrow built-up road with the windows doen there is
not much difference in noise level - suggesting its travelling up
through the chassis.

My local garage looked at it and identified the vibration can be felt
under the back seat. However, after checking the axle was "safe" and had
plenty of oil - they suggested I drive it around for another week or so
and then bring it back in, and hopefully the source of the problem will
be more identifiable.

I'm worried that something may go horribly wrong in that time. I suspect
its their usual response when they dont want to spend TOO long looking
in the wrong place for a problem.

I suspect something is warped or rather loose and shifting under the
strain of load.

Any ideas?

Oh it seems the rear axle had already been replaced and it had yellow
chalk marks underneath covered in grime.

I may try to nip it into another chap who always worked wonders on my
previous car but always wanted cash payments and his shop was really
small and surrounded by no parking zones! PITA parking 200m away and
walking to give him the keys!

--
Lordy

"Lordy" > wrote in message
.. .
>
> Hi all,
>
>
> [xposted alt.autos.bmw,uk.rec.car.misc ]
>
> My 1994, E36 320i Coupe suddenly developed significant vibration in the
> rear axle. (hear cries of - "I told you so..." )
> It only occurs when the transmission is fully engaged and accelerating .
>
> If coasting - nothing.
> Rev engine with clutch dipped - nothing.
>
> The frequency of the vibration is related to the gear and current speed.
> Low when pulling away. High when doing 40mph and acceleration or going
> up hill.
>
> If I drive down a narrow built-up road with the windows doen there is
> not much difference in noise level - suggesting its travelling up
> through the chassis.
>
> My local garage looked at it and identified the vibration can be felt
> under the back seat. However, after checking the axle was "safe" and had
> plenty of oil - they suggested I drive it around for another week or so
> and then bring it back in, and hopefully the source of the problem will
> be more identifiable.
>
> I'm worried that something may go horribly wrong in that time. I suspect
> its their usual response when they dont want to spend TOO long looking
> in the wrong place for a problem.
>
> I suspect something is warped or rather loose and shifting under the
> strain of load.
>
> Any ideas?
>
> Oh it seems the rear axle had already been replaced and it had yellow
> chalk marks underneath covered in grime.
>
> I may try to nip it into another chap who always worked wonders on my
> previous car but always wanted cash payments and his shop was really
> small and surrounded by no parking zones! PITA parking 200m away and
> walking to give him the keys!

I would be suspicious of one of the swivel joints in the drive line. If
worn, they may be displaced under load and thus become unbalanced. The
driveshaft vibration then gets transmitted to the rear floor area via the
center support bearing. Unfortunately, once fully diagnosed, the driveshaft
would have to be replaced to repair it as it must be properlly aligned and
balanced or you will have this same problem continuously.

-Fred W

> I would be suspicious of one of the swivel joints in the drive line. If
> worn, they may be displaced under load and thus become unbalanced. The
> driveshaft vibration then gets transmitted to the rear floor area via the
> center support bearing. Unfortunately, once fully diagnosed, the
driveshaft
> would have to be replaced to repair it as it must be properlly aligned and
> balanced or you will have this same problem continuously.
>
> -Fred W

Could be a CV joint on one of the rear driveshafts? Sound familiar to the
noises in my friends FWD gti when his CVs went. When my CVs go they never
behave that way, only clunk on turning, strange.

J

"Coyoteboy" > wrote in message
...
>
>> I would be suspicious of one of the swivel joints in the drive line. If
>> worn, they may be displaced under load and thus become unbalanced. The
>> driveshaft vibration then gets transmitted to the rear floor area via the
>> center support bearing. Unfortunately, once fully diagnosed, the
> driveshaft
>> would have to be replaced to repair it as it must be properlly aligned
>> and
>> balanced or you will have this same problem continuously.
>>
>> -Fred W
>
> Could be a CV joint on one of the rear driveshafts? Sound familiar to the
> noises in my friends FWD gti when his CVs went. When my CVs go they never
> behave that way, only clunk on turning, strange.

Yes, it could be, but because the OP specifically mentioned sensing the
vibration in the rear floor rather than a rear wheel, I would suspect
something in/on the drive shaft vs. the rear axle.

-Fred W

"The Malt Hound" <Malt_Hound@*no spam please*yahoo.com> wrote in
:

>
> "Coyoteboy" > wrote in message
> ...
>>
>>> I would be suspicious of one of the swivel joints in the drive line.
>>> If worn, they may be displaced under load and thus become
>>> unbalanced. The driveshaft vibration then gets transmitted to the
>>> rear floor area via the center support bearing. Unfortunately, once
>>> fully diagnosed, the
>> driveshaft
>>> would have to be replaced to repair it as it must be properlly
>>> aligned and
>>> balanced or you will have this same problem continuously.
>>>
>>> -Fred W
>>
>> Could be a CV joint on one of the rear driveshafts? Sound familiar to
>> the noises in my friends FWD gti when his CVs went. When my CVs go
>> they never behave that way, only clunk on turning, strange.
>
> Yes, it could be, but because the OP specifically mentioned sensing
> the vibration in the rear floor rather than a rear wheel, I would
> suspect something in/on the drive shaft vs. the rear axle.
>
> -Fred W
>
>
Thanks for all your advice, FWIW its now a bit worse (surprise!),
and I can now feel mild virbration when coasting with clutch engaged.
When clutch is dipped I *think* there is vibration - but will probably
know for sure tomorrow!



--
Lordy

Lordy > wrote in news:Xns95E1ECF8ED69Clordybigfootcom@
130.133.1.4:

> Thanks for all your advice, FWIW its now a bit worse (surprise!),
> and I can now feel mild virbration when coasting with clutch engaged.
> When clutch is dipped I *think* there is vibration - but will probably
> know for sure tomorrow!
>

I took it back to the garage and they confirmed it was the rear axle and
were sourcing a new one.

"Is it OK to drive" I asked. They "checked". "Yes" they said.
"are you sure ?"
"Yes"

Here comes my lesson on personable responsibility!

Being a complete layman, but having a rough understanding of the kind of
stresses involved, my instinct was NOT to drive the car. But I "needed" it.

I asked many times, was it OK to drive. They said "Yes" and let me take it
away.


Just dropped my daughter off to StageCoach, on the return journey, I'm
pulling away at the lights and "CRACK!", something bad happened (I suspect
the axle cracked but I havent looked underneath properly!) I limped about
200 yards to a unrestricted parking zone, praying that the damage costs
were not escalating with every metre travelled. There was a distinct
"clonk" with every revolution of the wheels.

I suspect I'll have a bitch of a time getting the garage to cover some of
the additional repair costs (if any). I'm tempted to take it to another
garage completely.

It reminds me of the people in the twin towers (9/11) who were on their way
down the stairs and out of the building but some security guy said it was
safer to go back up! Sometimes you have to go with your gut feeling in
deference to "expert" advice! If your car is making weird noises dont drive
it regardless of what anyone says!

The irony is, I tried to do the right thing, as soon as I noticed the
slightest sound, I took it in to the garage.

--
Lordy

I have a 92 325is and it makes an awful rotation clunking when going under
load/acceleration only on right curves and turns. I tihnk we have the same
problem. But the wheel bearing are still good/replaced center support
bearing/motor mounts and tranny mounts good! what could it be?

I just took about my diff today and its looks absolutley perfect...maybe
bent/unaligned drive shaft or axles.

Have you beat on the car alot...rip hull shots, burn outs ect? I CANNOT
FIGURE IT OUT....
Brendan-

I have a 92 325is and it makes an awful rotation clunking when going under
load/acceleration only on right curves and turns. I tihnk we have the same
problem. But the wheel bearing are still good/replaced center support
bearing/motor mounts and tranny mounts good! what could it be?

I just took about my diff today and its looks absolutley perfect...maybe
bent/unaligned drive shaft or axles.

Have you beat on the car alot...rip hull shots, burn outs ect? I CANNOT
FIGURE IT OUT....
Brendan-