When do 540 driveshafts go?

[zhandax]

I got to pay some stupid tax this week. I know motor mounts on German cars are a maintenance item, and need to be replaced at most by 150k miles. I replaced them on the departed E28, the W124, and even wondered how soon the new R129 would need them.

OK, maybe I am getting old. On the best car I have ever owned, that I drive to work every day (and usually push to 90mph at least once on the trip) it never even occurred to me. On the way in last week, at 80mph on two week old pavement it sounded like a pebble hit the undercarriage of the car. After that, it sounded and felt like I was driving in the rumble strip. I thought I had thrown a wheel weight. When I exited and got to the stop light, the car was vibrating up and down. So much for the wheel weight. It occurred to me to check for codes around lunch time and I tried to do that by memory (been a couple of years since the last stomp test). I stomped the pedal 5 times and turned on the key. This didn't work so I tried it again (a couple of times). When I started the car to clear the excess gas, the engine raced to redline. I shut it off and tried again with the same results. I popped the hood to be reminded the cowling prevents any viewing of the throttle cabling and when i restarted it, it did so and idled normally. During lunch I look here and get reminded that I need to turn they key first and afterward get a 1444. Logistics (could not get parts by the weekend, had to be at work the next day, and the R129 is jacked up in the garage for another project) dictated I take it to the indie. I find out the next day that a motor mount broke, and the engine racing had allowed the fan to hit the shroud, breaking both. It also stretched the upper rad hose and cracked the neck on my 3 year old radiator. On Monday, I find out that there was still a vibration and they were putting it back up to check. The trans mounts were shot as well. After all this is replaced and I pick it up, I am told that there is still a vibration between 20 and 50mph and they think it is the driveshaft. Since they are downtown, 50 may be as fast as they could get it. It is there until 80.

Sorry this is so lengthy, but if it helps someone else realize that they MUST change their motor mounts while it is relatively painless, maybe it is worth it.

Finally the question... I don't see the constant "gotta replace the driveshaft by xxx" like I did on the E28. Is this the most likely culprit or is there something else worth checking? For a little background: entire front suspension and all 4 struts replaced in last 2-3 years, front end alignment and all 4 tires balanced and rotated the week before this happened. The car does have a PS drip but other than that, drove flawlessly before this. If it does need a driveshaft, will I be OK driving for a few weeks before I can get some vacation to have it replaced?

[h2oyo]

I got to pay some stupid tax this week. I know motor mounts on German cars are a maintenance item, and need to be replaced at most by 150k miles. I replaced them on the departed E28, the W124, and even wondered how soon the new R129 would need them.

OK, maybe I am getting old. On the best car I have ever owned, that I drive to work every day (and usually push to 90mph at least once on the trip) it never even occurred to me. On the way in last week, at 80mph on two week old pavement it sounded like a pebble hit the undercarriage of the car. After that, it sounded and felt like I was driving in the rumble strip. I thought I had thrown a wheel weight. When I exited and got to the stop light, the car was vibrating up and down. So much for the wheel weight. It occurred to me to check for codes around lunch time and I tried to do that by memory (been a couple of years since the last stomp test). I stomped the pedal 5 times and turned on the key. This didn't work so I tried it again (a couple of times). When I started the car to clear the excess gas, the engine raced to redline. I shut it off and tried again with the same results. I popped the hood to be reminded the cowling prevents any viewing of the throttle cabling and when i restarted it, it did so and idled normally. During lunch I look here and get reminded that I need to turn they key first and afterward get a 1444. Logistics (could not get parts by the weekend, had to be at work the next day, and the R129 is jacked up in the garage for another project) dictated I take it to the indie. I find out the next day that a motor mount broke, and the engine racing had allowed the fan to hit the shroud, breaking both. It also stretched the upper rad hose and cracked the neck on my 3 year old radiator. On Monday, I find out that there was still a vibration and they were putting it back up to check. The trans mounts were shot as well. After all this is replaced and I pick it up, I am told that there is still a vibration between 20 and 50mph and they think it is the driveshaft. Since they are downtown, 50 may be as fast as they could get it. It is there until 80.

Sorry this is so lengthy, but if it helps someone else realize that they MUST change their motor mounts while it is relatively painless, maybe it is worth it.

Finally the question... I don't see the constant "gotta replace the driveshaft by xxx" like I did on the E28. Is this the most likely culprit or is there something else worth checking? For a little background: entire front suspension and all 4 struts replaced in last 2-3 years, front end alignment and all 4 tires balanced and rotated the week before this happened. The car does have a PS drip but other than that, drove flawlessly before this. If it does need a driveshaft, will I be OK driving for a few weeks before I can get some vacation to have it replaced?

Did they say what they thought was wrong with the driveshaft? I would check the guibo and center bearing. You will have to drop the exhaust to see it properly but that isnt a big deal. If you havent replaced either of them as of yet, yes they are both wear and maintenance parts.

Johan

[zhandax]

I specifically asked them to check the guibo and center bearing when I took it in and afterward, they specifically mentioned the u-joints getting stiff. I know these are staked and this means a new driveshaft. I guess the big question is whether I am OK driving it for a couple of weeks until I can get it replaced. I discovered my home HVAC is 20 years old when it quit twice in a week and it may leave me some vacation for football games if I could get both replaced on the same time off. I already planned the HVAC replacement for the week before Labor day.

[genphreak]

It should only be the centre bearing unless the guibo was toast anyhow. After all that wobbling it'd give out as it isn't (can't) be designed to cope with an untethered engine+gearbox. Two piece tailshafts all have this limitation. Every bimmer I've bought has had a blown shroud- I take it to mean the mounts need replacement. Better than buying insurance that won't pay up I say... Sounds like you need to the tailshaft uni joint too- it can be done at home quite easily- just need the know how- Rustam did a nice write up on that, also see here

[shogun]

I tell you a story my wife experienced about 5 years back when I was on an overseas trip.
suddenly there was this big noise under the chassis between seats and the noise got stronger when accelerating or decelerating. So she went to the next shop and asked for help.
Inspected, they reported to her: driveshaft shot, do not drive anymore, it can damage more, you need a complete new driveshaft.
As the cost is pretty high for that, she called me overseas and told me the story. I told her to wait till I get home.
So when I got home I inspected the driveshaft with my friends in our wrenching place. Lifted the car on the rear, removed the heat shield and then turned the rear wheels so see the driveshaft turning. We could see clear marks where the driveshaft had touched the body.

Then we noticed that the 2 bolts which hold the center bearings got lose.
So we preloaded the thing again, fixed the center bearing and since 5 years no problem at all, while the shop said it has to be replaced immy and is beyond repair.

In any case, whatever is your problem, check it out, a driveshaft can be repaired by professional shops anyway.

[zhandax]

The closest rebuilder to me is in Atlanta. On the e28 however, my tech did install the driveshaft I got from Driiveline. I assume they would again. Should I just get one from Driveline and be done with it?

[genphreak]

ROFL! Indeed!

Few shops would remove the exhaust and heatshields to inspect and report... much easier to say 'new shaft' and charge accordingly before finding out that they can pre-load the bearing (and still charge accordingly)... Nick

[zhandax]

Nick, I will assume your latest post refers to Shogun's wife's experience. They way my tech put it was "you may not find it objectionable, but the u-joints seem to be getting a bit stiff". In fact, he mentioned something off record which may keep it going a bit longer, but the undercurrent I got was if I intend to keep this car, I need a driveshaft.