2007 Z4MC Drive Shaft U-Joint

[Z4MC Junkie]

Hi. The back end of me 2007 Z4M Coupe w/125K miles is making a horrible rubbing/grinding noise whenever I take sharp turns (e.g., every time I maneuver thru my office parking garage). My mechanic told me that the U-joint connecting the driveshaft to the universal has failed and that he needs to order a new drive shaft from Germany ($1800 part + $1000 labor) since you can't buy the U-joint separately. I called my local BMW parts department to cross check my mechanic's diagnosis and they told me that the drive shaft doesn't connect to the universal with a U-joint, it connects with a "joint w/o cured bushings" whatever that is.

Is my mechanic taking me for a $2800 ride or is my cheapskateness clouding my judgement?

[grannyknot]

Ask you mechanic to remove the driveshaft and take it to shop that works on tractor trailers, they will have no problem replacing the U joint and re-balancing, they will probably do it for a couple hundred bucks. Ask for a Spicer U joint replacement.

[Z4MC Junkie]

Thanks. So does a U-joint connect the drive shaft to the universal in a 2007 Z4MC?

[DukeofAlexandria]

Originally Posted by Z4MC Junkie

Thanks. So does a U-joint connect the drive shaft to the universal in a 2007 Z4MC?

Not sure if serious, or actually stupid…

https://en.m.wikipedia.org/wiki/Universal_joint

Google is your friend.

-Duke

[Steeler]

Originally Posted by DukeofAlexandria

Not sure if serious, or actually stupid…

https://en.m.wikipedia.org/wiki/Universal_joint

Google is your friend.

-Duke

That's a bit harsh, we aren't all DIY'er's.

@Z4MC Junkie, grannyknot is correct, the UJ can be replaced, if indeed it is the U-joint.
The driveshaft is a 2 piece unit with a splined connection and a centre support bearing.
Lots of parts that can wear.

The labor cost quoted is likely not too far off due to the number of parts that need to be removed to get at the driveshaft and therefore reinstalled.
However you should not need a complete new driveshaft.

Get a 2nd and even 3rd quote, preferably from a BMW independent shop, not a dealership.

[DukeofAlexandria]

Originally Posted by dbarton62

That's a bit harsh, we aren't all DIY'er's.

@Z4MC Junkie, grannyknot is correct, the UJ can be replaced.
The labor cost quoted is likely not too far off due to the number of parts that need to be removed to get at the driveshaft and therefore reinstalled.
However you should not need a complete new driveshaft.

Get a 2nd and even 3rd quote, preferably from a BMW independent shop, not a dealership.

I mean...he effectively said "does a u-joint connect the drive shaft to the u-joint...?". Additionally, had a tech from BMW on the line and didn't think to ask even a modicum of information regarding what they meant when they were discussing the u-joint parts with him. Either take it to a reputable BMW service center, or use google.

Additionally, I've never heard of 'rubbing/grinding' noise when taking sharp turns via a driveshaft. Could the u-joint be faulty...maybe, but even then it's more of a vibrational feel/sound you'll hear on accel/decel. Rubbing/grinding when turning points more to wheel hub/CV joints or maybe even control arm bushings if it's only happening when he turns. (I've seen really rounded out bushings make some really awful and weird sounds.)

EDIT - This also could be due to camber thrust on the rear tires because it's slammed to the ground or has some crazy 10deg camber on the car resulting in premature wear of CV joints when turning sharply. Just another possibility.

You don't have to be a DIY'er to google stuff....come on now.

-Duke

[Z4MC Junkie]

Thanks DB.

Duke - I know what a U-joint is. The reason for my post, if you read it, was due to BMW telling me I couldn't buy a replacement U-joint because that's not what's used for the Z4MC drive shaft/universal connection. Why don't you go troll BMW of Fairfax? Better yet, why doesn't a bright guy like you head to Munich and help design the next Z series instead of wasting your brilliance trolling BMW message boards? LMAO

[DukeofAlexandria]

Originally Posted by Z4MC Junkie

Thanks DB.

Duke - I know what a U-joint is. The reason for my post, if you read it, was due to BMW telling me I couldn't buy a replacement U-joint because that's not what's used for the Z4MC drive shaft/universal connection. Why don't you go troll BMW of Fairfax? Better yet, why doesn't a bright guy like you head to Munich and help design the next Z series instead of wasting your brilliance trolling BMW message boards? LMAO

"Trolling" a forum because I told OP to use google and do the least amount of research feasible and you've literally discussed the U-Joint connecting into the Universal twice now.....THEY ARE THE SAME THING.

But no no, I'm the one trolling....lol, what a joke of post.

But on a serious note, I still have doubts it's your drive shaft. I've never heard of a 'rubbing/grinding' noise from a driveshaft with a faulty guibo, center bearing, or u-joint issue, especially when turning the car. Shuddering, shaking, heavy vibration that increases with speed on accel and decel 100% your drive shaft but again that's not what you've described. Do you hear it underneath you or in the front, or under your feet, or in the rear? I mean, you've already questioned your Mech, and what you've describing just doesn't make sense for a faulty u-joint in that driveshaft.

-Duke

[maupineda]

It can also be a worn out differential. Seems mileage is high. More than mileage is service history

[Z4MC Junkie]

Thanks - As DB suggested, I'll get a second opinion (if that's okay with the self proclaimed Duke of ZPOST). Other than hearing a grinding/rubbing noise when making sharp turns at slow speeds, the car drives without any issues which is another reason I was hesitant about spending $2800.

[Michael9218]

Definitely get a second opinion.

Does not sound like a worn driveshaft U-joint to me. The driveshaft has three flex points. At the front is a rubber flex disk where it attaches to the transmission, in the middle is a carrier bearing and the U-joint, and at the back is a constant velocity (CV) joint. The U-joint has a very slight angle to it so these I've never heard of wearing out. Anything is possible, but I would say unlikely.

More likely the diff if it's only making the noise while making sharp turns.

If it is the driveshaft (or diff), source a used one from a salvage yard (including online salvage via eBay).

[DukeofAlexandria]

Originally Posted by Z4MC Junkie

Thanks - As DB suggested, I'll get a second opinion (if that's okay with the self proclaimed Duke of ZPOST). Other than hearing a grinding/rubbing noise when making sharp turns at slow speeds, the car drives without any issues which is another reason I was hesitant about spending $2800.

I'm telling ya man, the more I think about it and you describe the situation, the more I doubt it's the driveshaft.

It could be the diff, but I'm willing to bet it's a CV joint that has a broken boot and is grinding when you turn since all the grease has run out of it. If you want, you can also ask a mech to put it on a lift and you take pictures of the u-joint, guibo, driveshaft bearing, rear driveshaft to diff cv, and then the cv axles (ask for clear pictures of the cv boots!).

Listen, I'm honestly trying to help you out here hah. WHERE is the noise coming from? Go to a garage and make turns and open the door and stick your head out and listen for where it's coming from. A CV axle costs a fraction of a driveshaft and a diff can be rebuilt.

Let us know, thx!

-Duke

[wdb]

Realoem doesn't show the U-joint as being a replaceable part. That may be where the mechanic is coming from. Doesn't mean it can't be done but someone would have to find the correct size U-joint.

https://www.realoem.com/bmw/enUS/sho...diagId=26_0202

[Vanne]

Sounds like the carrier bearing to me. Check item 8.

[Z4MC Junkie]

I took the car to another garage to get a second opinion. They identified root cause as worn out/broken down differential fluid so they replaced the fluid for $400 ($125 for the fluid, $275 for labor). They also mentioned that when they drained the old fluid, it had some metal shavings in it. They told me that if the grinding noise returns then I should replace the differential ($4500 for a rebuilt one).

[Barryb97]

Sounds like Limited Slip Differential to me. Change the fluid to the high friction modified fluid. There are other posts about it on the forum.

[XMetal]

Originally Posted by Z4MC Junkie

I took the car to another garage to get a second opinion. They identified root cause as worn out/broken down universal fluid so they replaced the fluid for $400 ($125 for the fluid, $275 for labor). They also mentioned that when they drained the old fluid, it had some metal shavings in it. They told me that if the grinding noise returns then I should replace the universal ($4500 for a rebuilt one).

What is universal fluid that you're referring to? Did you mean differential fluid? The universal (U-Joint) don't have fluid.

[vt100]

Originally Posted by XMetal

What is universal fluid that you're referring to? Did you mean differential fluid? The universal (U-Joint) don't have fluid.

Also (if it is differential fluid) there will always be shavings in diff fluid after it's been driven for several thousand miles..

[belcom]

Originally Posted by Vanne

Sounds like the carrier bearing to me. Check item 8.

I've replaced center support bearing at about 105K and the bearing was shot and rattled badly when shaken in hand. A broken center support bearing could possibly cause drive shaft vibrations during hard acceleration but not sure how it would relate to grinding/rubbing when turning. Perhaps it could be a combination of worn out differential bushings and bad center support bearing as well... who knows.

But the mechanic that just told you to go spend $2800 without taking it apart and confirming the actual cause is definitely a crook. And so are the people that charged you $275 for labor to replace differential fluid. It takes like 15 minutes to drain and fill the fluid Unless maybe they needed to flush it multiple times.

I've personally helped a friend replace the handbrake assembly in his Z4MC which requires driveshaft removal and we had never done it before. It took us about 3 hours start to finish. Maybe 4 if you are having beers and take smoke breaks

[Z4MC Junkie]

I meant differential fluid.

Belcom - Over the past 3 months, three different highly-rated German car garages have come back with three different diagnoses (i.e., bad u-joint, bad CV joint and bad differential). If I had a hydraulic lift in my back yard and the time I could probably diagnosis the problem myself but I don't so I'm stuck dealing with incompetent and/or crooked garages. What else can you do?

[wdb]

The problem is that there is an exhaust system and heat shielding between the mechanic and the driveshaft. They’d spend an hour labor plus exhaust gaskets just to do a proper diagnosis. The diff fluid can be done without removing anything besides the drain and fill plugs.

[Michael9218]

If it is the diff, look to buy a used one. You may be able to fit one from an E46 M3. Many more of those available.

I would say it’s highly unlikely to be the U-joint. If it only makes noise when turning, I would rule out the driveshaft and the axle shafts. Likely the diff.