Still have a vibration after new flex disk and hanger bearing

[JimJames1988]

Hey everyone,

New to the forum... I have a 540i manual and had a vibration issue above 30mph and under hard acceleration. Started out under acceleration and then eventually I couldn't get the car up to speed due to the vibration. I didn't keep driving the car by the way, so it got parked until parts arrive and I could replace it. So I installed a new guibo (flex disk) and hanger bearing. Guibo was cracked and the hanger bearing was just in case, but it seemed to be on it's way out too. So I got everything back together, too the car up the road and all seems to be fine until I really got on it in high rpm I still have that vibration. I used BMW parts, everything was torqued to spec. From what I've read online the csb has to be preload? I left the csb loose, spun the wheels to ensure it would fall in place, then tightened it up. I had to remove the transmission mount, didn't install new mounts either. Everything looked to be inline. Any ideas??? I also have the crack, looks like it's been there for a while. I'm assuming it's just the outer casing, from what I've read in the Bentley manual, it has an aluminum driveshaft. Tried to search if this was an issue, but no results either. I need my car back on the road and I'm short on money, so I really don't want to install a new driveshaft either.

[tptrsn]

You're supposed to push the center support bearing toward the front of the car a centimeter or so before you tighten it down.

But wow, that driveshaft looks like it's about to come completely apart to me! Hopefully I'm wrong and someone will correct me about that..

[JimJames1988]

You're supposed to push the center support bearing toward the front of the car a centimeter or so before you tighten it down.

But wow, that driveshaft looks like it's about to come completely apart to me! Hopefully I'm wrong and someone will correct me about that..

Thank you!

I really hope this isn't anything serious. I found a driveshaft locally for $350... Even if it needed it, how would I even align it with the transmission or differential flanges? Isn't everything supposed to have it's specific spot, Bentley calls for everything being marked.

[tptrsn]

I think there's a good chance that if you just swapped in the replacement driveshaft it would be fine. Ideally you would want to keep the front and rear halves aligned to each other, but I've done a fair amount of swapping one or the other half of BMW driveshaft, and so far no trouble.

[rdl]

Hey everyone,
...
all seems to be fine until I really got on it in high rpm I still have that vibration.
...

Does the vibration now depend on engine RPM regardless of road speed, or road speed independent of engine RPM? The first would be engine related, the second driveline.

I'm wondering if you had a driveline vibration (i.e. any speed over 30 mph) that you've repaired and now an engine related vibration is detectable. If engine load (foot to floor vs coasting) affects the vibration it would be worth looking at engine and transmission mounts.

[JimJames1988]

Does the vibration now depend on engine RPM regardless of road speed, or road speed independent of engine RPM? The first would be engine related, the second driveline.

I'm wondering if you had a driveline vibration (i.e. any speed over 30 mph) that you've repaired and now an engine related vibration is detectable. If engine load (foot to floor vs coasting) affects the vibration it would be worth looking at engine and transmission mounts.

I didn't take it into third, but first at high rpm was fine, then second at high rpm seems to kick in. Similar to what was happening before, but not as intense. Do I need to do all mounts at the same time or can I just replace only the transmission mounts? I was planning on disconnecting the rear driveshaft to see if the vibration shows up while sitting in place.

[rdl]

I didn't take it into third, but first at high rpm was fine, then second at high rpm seems to kick in. Similar to what was happening before, but not as intense. Do I need to do all mounts at the same time or can I just replace only the transmission mounts? I was planning on disconnecting the rear driveshaft to see if the vibration shows up while sitting in place.

I wouldn't disconnect the driveshaft as a test - you can accomplish the same result by simply revving the engine in neutral.

Based on this description, it seems more likely road speed than engine. I'd try getting over initial vibration speed then dipping the clutch & letting the engine idle. If the vibration persists until the car slows down, it's not engine related. Which leaves tires or driveline.

If it's road speed dependent, are you sure it isn't tire balance or runout? It takes some experience, but driveline or engine vibration will be 3 times or more higher frequency than tires.

But, there is a further consideration - load or torque. Were you accelerating slowly or hard? Engine, transmission and driveshaft supports or joints may be smooth at light throttle, but vibrate when torqued up.

A quick and dirty, superficial check of engine and transmission mount is to check clearance of the fan blades to shroud top & bottom. They should be approximately equal. If there is a noticeable difference, say over 1/2" difference, the mounts become suspect and should be inspected.

I wouldn't buy/replace any mounts yet. For one thing, the picture of the driveshaft in your first post isn't pretty.

[JimJames1988]

I wouldn't disconnect the driveshaft as a test - you can accomplish the same result by simply revving the engine in neutral.

Based on this description, it seems more likely road speed than engine. I'd try getting over initial vibration speed then dipping the clutch & letting the engine idle. If the vibration persists until the car slows down, it's not engine related. Which leaves tires or driveline.

If it's road speed dependent, are you sure it isn't tire balance or runout? It takes some experience, but driveline or engine vibration will be 3 times or more higher frequency than tires.

But, there is a further consideration - load or torque. Were you accelerating slowly or hard? Engine, transmission and driveshaft supports or joints may be smooth at light throttle, but vibrate when torqued up.

A quick and dirty, superficial check of engine and transmission mount is to check clearance of the fan blades to shroud top & bottom. They should be approximately equal. If there is a noticeable difference, say over 1/2" difference, the mounts become suspect and should be inspected.

I wouldn't buy/replace any mounts yet. For one thing, the picture of the driveshaft in your first post isn't pretty.

Took it out for another road test to 45mph, got it in forth this time. I didn't get on it, but as I get over 30 there is a light vibration I can feel. I pushed the clutch in and it still persists. If I get on the throttle a light heavier, the vibration will pick up a bit.

I have all brand new tires, probably 1000 miles on them. Bent a couple wheels a couple years ago so they were professionally straightened. When revving up the engine sitting still, minimal movement too. I'll have a peak at the engine mounts though.

I'm thinking the hanger bearing is the issue as I never preloaded it. Really not looking forward to drop everything again lol.