Driveline Vibration

[waltb]

In the past year or so my E12 has had a drive line vibration that is slowly getting worse. It mainly vibrates around 40mph road speed. At 50mph and above it goes away. I have since changed the guibo since it was cracked lightly (no change in vibration) and checked things like the center bearing (looks good, rubber surround still ok).

I finally had time to really check the car out this weekend. I jacked up the rear end and removed the tires and ran the car in gear. I get the same exact vibration feeling at ~40mph. So it can't be the tires or rims. Engine speed does not matter to the vibration either.

I had a helper keep the speed in the ~40mph range. I touched the rear subframe and can definitely feel the vibration on the rear subframe. However if I touch the engine I don't feel it. I held the exhaust with a gloved hand and it is not causing the vibration either.

So I presume it is likely to be bad universals in the drive shaft. I changed the driveshaft many years ago, like 20yrs ago, and dont really drive the car that much (maybe 3K a year) but I presume the u-joints could have hardened up in 20 years.

So does this sound like the typical driveshaft issue? I presume in a few weeks when I put the car away for the winter I can pull the exhaust and driveshaft and check it out.

So any suggestions for a place to rebuild driveshafts? I am in the PA and OH area if that matters.


Walt B.

[pappentl]

Walt, check your center support bearing, from my similar experience it's more likely to be the bearing than the u-joints.

...tom



-----Original Message-----
From: waltb <wbarie@connecttime.net>
To: tech_forum <tech_forum@firstfives.org>
Sent: Sun, Oct 13, 2013 1:58 pm
Subject: Driveline Vibration

#AOLMsgPart_1_7234207e-f5bd-4d38-8437-3c2aaead62b9 td{color: black;} In the past year or so my E12 has had a drive line vibration that is slowly getting worse. It mainly vibrates around 40mph road speed. At 50mph and above it goes away. I have since changed the guibo since it was cracked lightly (no change in vibration) and checked things like the center bearing (looks good, rubber surround still ok).

I finally had time to really check the car out this weekend. I jacked up the rear end and removed the tires and ran the car in gear. I get the same exact vibration feeling at ~40mph. So it can't be the tires or rims. Engine speed does not matter to the vibration either.

I had a helper keep the speed in the ~40mph range. I touched the rear subframe and can definitely feel the vibration on the rear subframe. However if I touch the engine I don't feel it. I held the exhaust with a gloved hand and it is not causing the vibration either.

So I presume it is likely to be bad universals in the drive shaft. I changed the driveshaft many years ago, like 20yrs ago, and dont really drive the car that much (maybe 3K a year) but I presume the u-joints could have hardened up in 20 years.

So does this sound like the typical driveshaft issue? I presume in a few weeks when I put the car away for the winter I can pull the exhaust and driveshaft and check it out.

So any suggestions for a place to rebuild driveshafts? I am in the PA and OH area if that matters.


Walt B.









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[Trevor M]

I think you're on the right track with the driveshaft. Did you inspect it carefully to see maybe one of the balancing weights came off?
They were usually spot welded to the driveshaft towards the end of the tube.

[waltb]

Thanks for the hints.

Actually the driveshaft looks almost like new although it has been in the car for 20 years. It is still nice and black with very little rust. I do remember a few weights welded onto the shaft so I will have to check to see if it looks like any of the weights are missing from the shaft.

In the next few weeks I will remove the driveshaft from the car and hopefully something will be obviously wrong with it like a U-joint bound up or the center bearing is bad. It would be nice to get my car back to its smooth running self.

So any hints on where to get a rebuilt one?

Walt

[alotawatts]

The center support bearings often need shims on the mounts to keep things level/plumb ...... you probably know that.......

[peter claassen]

Its the universals that stew from the cat after hot driving.

there is a place in Portland that specializes in BMW driveshafts



On Sun, Oct 13, 2013 at 3:37 PM, pappentl <pappentl@aol.com (pappentl@aol.com)> wrote:

Walt, check your center support bearing, from my similar experience it's more likely to be the bearing than the u-joints.

...tom



-----Original Message-----
From: waltb
To: tech_forum
Sent: Sun, Oct 13, 2013 1:58 pm
Subject: Driveline Vibration

#AOLMsgPart_1_7234207e-f5bd-4d38-8437-3c2aaead62b9 td{color: black;} In the past year or so my E12 has had a drive line vibration that is slowly getting worse. It mainly vibrates around 40mph road speed. At 50mph and above it goes away. I have since changed the guibo since it was cracked lightly (no change in vibration) and checked things like the center bearing (looks good, rubber surround still ok).

I finally had time to really check the car out this weekend. I jacked up the rear end and removed the tires and ran the car in gear. I get the same exact vibration feeling at ~40mph. So it can't be the tires or rims. Engine speed does not matter to the vibration either.

I had a helper keep the speed in the ~40mph range. I touched the rear subframe and can definitely feel the vibration on the rear subframe. However if I touch the engine I don't feel it. I held the exhaust with a gloved hand and it is not causing the vibration either.

So I presume it is likely to be bad universals in the drive shaft. I changed the driveshaft many years ago, like 20yrs ago, and dont really drive the car that much (maybe 3K a year) but I presume the u-joints could have hardened up in 20 years.

So does this sound like the typical driveshaft issue? I presume in a few weeks when I put the car away for the winter I can pull the exhaust and driveshaft and check it out.

So any suggestions for a place to rebuild driveshafts? I am in the PA and OH area if that matters.


Walt B.




...tom
and now an '80 528i, the 7th and last in the series
1981 528i, no. 6 in a series... only 270 k miles

--
p     c     l     a     a     s     s     e     n


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[waltb]

Updating from a post many months ago. I finally purchased a rebuilt driveshaft and installed it. It completely fixed the vibration issue. Looking at the old driveshaft that I removed everything looked pretty good. No obvious bad CV joints and the center bearing felt ok. Strange but a new shaft fixed the problem.

WB

[Mike W.]

Not so strange. BMW driveshafts get notchy and stiff, not sloppy. E12s don't seem as affected by it as the next generation but they're not immune either. It's slight enough you can't tell unless you disassemble it, and the front U joint is usually the culprit, but once apart you can feel the notch as you move it.

[oceancab]

I'm kind of in the same boat, with a very minor vibration from 20-30 mph, but don't really want to shell out for a new driveshaft, would it be okay to continue driving it as it is and just accept it?

[Mike W.]

Not a problem, it'll let you know when it's getting to be time, it'll get worse, gradually.

[wkohler]

Generally once it gets bad enough, you will start eating center-support bearings and that's usually a pretty good sign that you're going to need a shaft.

[Mike W.]

Generally once it gets bad enough, you will start eating center-support bearings and that's usually a pretty good sign that you're going to need a shaft.

That's gotta be really bad, when the D/S went on my E28 I got uncomfortable with the vibration, first on take off then at speed on full throttle and I never lost a center support. And it seemed bad to me.

[wkohler]

Well, I'm sure you're trying to block it from your memory as much as I am mine but I have gone through a few CSBs and driveshafts in my day.