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Off balance driveshaft

29K views 19 replies 10 participants last post by  lszlszx 
#1 ·
Folks,

I'm like 97% sure my driveshaft is off balance. I had the guibo and center support/bearing replaced a year ago and it had a vibration afterwards and now, at highway speeds, feels worse. A strong yet minimal vibration.

So I'm thinking maybe it's off a spline tooth or two.

If my theory is correct, would that condition present itself as getting worse over time...and what would the consequences be? Center bearing stressed and going bad...maybe other things too?

I don't think that the centering sleeve was replaced...could that have caused the vibrations I'm feeling you think? Could the vibration have caused center support bracket to loosen over time and cause vibrations to get worse?

Finally, are all driveshafts marked with factory balance 'dots' to match the two halves together and would they yet be visible after 193K?

Thanks!

Doug
 
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#2 ·
I've just done some more studying up on driveline vibration and one person here opined that the driveshaft won't give off vibration even if the splines from front and back driveshaft is misaligned...he said diff bushings. I did the read dif bushing but not the others. Maybe this could be it too?

Anyway, please help me folks, can't drive comfortably above 55 mph and in NJ, that's just not safe on the highways!

Doug
 
#4 ·
I know the center support and bearing was replaced and since I'm OCD, get concerned about everything! LOL

I read a diy on rebuilding driveshaft and got worried that maybe the two halves weren't together right. I know the driveshaft is factory balanced, but I'm thinking that if the two halves were off by even a single spline, that I'd feel it.

Good to read your post, though, as that seems to point a little more to rear diff bushings...I think anyway.

Given my mileage, I know it could be other things, but I also want to eliminate the less expensive things first...before thinking half shafts from diff. Rear bearings are new, guibo/support/bearing are one year old and had vibration before and a little less after these replacements.

I know vibrations are hard to track and involve a lot of guessing...but really appreciate your taking the time to read and offering your opinion, Miles!

Doug
 
#5 · (Edited)
If you want to find out if its your driveshaft: Get out your iphone! There is an iphone application ( I think its called Vibration) that will turn your iphone into a frequency analyzer!
Here's what you have to do:

1.) Install the app
2.) Drive the car at the speed that produces the vibration
3.) Place the iphone on a hard surface where you can feel the vibration.
4.) Write down the rpm and what gear you are in at this vibration
5.) Run the application
6.) Pull over to view the data.

What you will see is a graph that has a big peak (more than one if there are more sources of the vibration). The peak will tell you what frequency is the vibration being produced at. For example: If the peak is at 40 hz, that corresponds to 2400 RPM (just multiply the hz by 60). All you have to do is then figure out what is spinning at 2400 rpm. If you look at your recorded values from 3.) above and see that the engine was at 2400 rpm, you know it was the engine.

However, its more likely to be the tires, wheels or driveshaft. The good news is that the drive shaft spins at a different speed than the tires, so it is easy to distinguish between the two. The driveshaft is spinning slower than the engine. Just divide by the gear ratio of the gear that you are in (i.e. my fifth gear is .8 times the engine rpm.) to get the driveshaft rpm. Divide this number by the differential ratio to get the speed of the wheels/tires.

Good luck, I hope this helps you find your vibration.
 
#6 ·
Twright,

That is so awesome! Getting my sons on finding the app now.

So, let's say I find that is is associated with speed of driveshaft...

Could the issue still be, say, the diff bushings I didn't replace?

Also, any hints for 'breaking down' sources of vibration; i.e., how to distinguish center bearing from guibo from diff bushings? I know lots of this is seat of the pants and guessing...but it'd give me more to notice and think about...and that translates to, I hope, fewer parts being swapped in for naught.

Anyway, very cool tip...can't wait to see what it says!

Doug
 
#7 ·
Okay, did that, but think I have to do it again to view just frequency...we had it on time series I think.

Anyway, once I know rpm of max vibration, then how might I distinguish from different rotating things of same speed...or maybe I'm just stupid.

I'm thinking that driveshaft spins one speed, but isn't that the same speed as the half shaft or 'incredibly close' to speed of wheel bearings? The outer tire speed of rotation is different than its associated wheel bearing...right?

I'll figure it out eventually, but if you can blab a little more, that might help.

Also, anyone think there's any point to me crawling underneath car now and maybe seeing if I can't adjust center support if it doesn't seem perfectly symmetrically oriented?

Doug
 
#8 ·
The vibration is solely in the driveshaft? Are you sure it's not something like a bent wheel or control arms?

Usually a diff bushing won't cause any kind of vibration, rather it will make clunking noises and stuff when you put load on the diff by shifting.

If the CSB/Guibo/Driveshaft are all good and you're positive it's something in the driveline, my next guess would be engine/trans mounts.
 
#9 ·
Alec,

I'm almost sure it's in the driveline, but not positive. I did have rear diff bushing replaced and that did take care of clunk. At the time I did that bushing, also had rear wheel bearings, guibo, and csb replaced all because of a vibration.

Still had some vibration afterwards...and just recently, it's gotten significantly worse. So I'm 'thinking' that if the driveshaft wasn't put together exactly right when reassembled (I didn't do it), that that extra play would then, perhaps, loosen up center support bracket...maybe degrade center support bearing sufficiently for me to feel what I'm feeling now.

Am crawling underneath now to see what I can see!

Doug
 
#10 ·
was the center bearing pre-loaded before installing? Have you inspected your guibo joint? typically, a failing center bearing will make a loud "BANG" or clunk when accelerating if they are going bad. The driveshafts do have to be installed in a certain position. Most importantly, our driveshafts have a constant velocity joint that can freeze over time (salt/corrosion/old age) and cause a lot of vibration.

here is a good tutorial on installing one. It's from a 1970's BMW 2002, but surprisingly the procedure hasn't changed much since then

 
#11 ·
Jons,

Thanks a bunch for that...this is the first time I understood the reference I'd seen to preloading...and the packing with grease (as opposed to just 'using' grease). You know, I can't imagine that a shop that works on all cars would know all these peculiarities of BMWs, so I can't say that it was done right.

I just got down there and looked...and btw, took out M1 5w30 for BMW 5w30 (knew you'd want to know and will provide report (not UOA, just 'my' A)--anyway, obviously I can't see anything without dropping exhaust and heat shield and ain't doing that without getting new gaskets for exhaust. I'll also need new bolts, right? ...and I do know guibo bolts are one-time use only. Same for bolts on back end of driveshaft anyone happen to know?

Thanks guys. Even though it's still got the vibration, it's real nice to get that helpful vibration from you all!

Doug
 
#12 ·
The vibration is unlikely to be a wheel bearing. Wheel bearings make noise first and for a long time , before vibration sets in.

There is not much way to distinguish which item on the driveshaft is causing it, if you are relying on only the iphone. Once you take it apart, you can usually see the worn part.

The axles spin approximately 3 times slower than the driveshaft. Their speed (compared to the driveshaft ) is determined by the diff ratio.
 
#13 ·
Thanks for that! The Iphone thing was very cool, but neither me nor my genius kids can figure it out...but it's a cool thing to know about.

I 'sort of' gave up...and gave my car to my mechanic and am awaiting feedback.

I'm sorry to have wasted anyone's time pretending I was going to do something myself...I got as far as getting my jack stands out and then started realizing about all the little things that could go wrong...and about all the things I don't know that I don't know.

Please send positive vibrations to North central NJ for my car and all the other E46s in the neighborhood...couldn't hurt!

Doug
 
#14 ·
as an idiot-sort of---here is my view----about 6 months ago-when i put the car in reverse i would hear a click-click-click- --after that--everything fine---starting about 2 months ago--once or twice when i hit the gas as normal the car would shimmy in the rear---it would feel like the rear wheels just spin and hop in place at the same time and the car doesn't move--the traction control light also comes on sometimes---now when i do it it is all the time----now i am at a point where i cannot accelarate very fast at all --i must be very easy on the gas--if i do it to much i get that hop--even when moving--at first it was only stopped at a light-----i believe this issue also causes the computer to misfire and give me a p1347 code(ingnition module system or misfire) and makes the vibration worse------so here is what i am saying--at first i thought this may have been a diff bushing--the diff bushing did have a big crack in it anyway but was not horrendous--the part was only 30$ so f it?!----this did not fix the problem--i bought a used driveshaft on ebay--i installed this driveshaft wrong(not lined up with marks) and at exactly 25 mph i got a huge vibration in the wheel and everywhere--i now know what a driveshaft that is unbalanced feels like--it destroyed the center bearing(i may have also put to much preload) and when slowing down i get a rattle next to me---but during this--the main issue was still present!---put back old driveshaft lined up and back to where it was----so i open the back seats to listen the trunk--cause there is noises in the rear--clunks,shackles,clicks--i chased the noise instead of the problem--i hear from left rear--so i move the axle toward the diff and back to the wheel--when it goes to the wheel it travels further and clicks and bangs--like the circlip holding the cv joint is broken--the other axle moves slightly back and forth--this is normal though--i checked other cars for the same feel and nothing like me lr axle---i found something physically wrong!!--bought a used axle on ebay for 100$--i feel confident this will fix it---if it does just think---a bad axle can cause the engine to misfire!!!
 
#16 ·
Oops, should have updated this post...one of the issues with writing too much here!

My issue was a flatspotted front wheel. It balanced fine, but still translated a vibration. The only reason we (Marco) caught it, was that they use an old school, slowly spinning wheel balancer. He noticed the hop on the inside rim.

Thus, now, when someone says that they have a vibration that doesn't appear below a certain speed, I always think flat spot. I also think that the guys balancing our wheels are often at the lower end of the 'pay scale' and also, that so many machines spin so fast, they'd never notice the flat spot.

Jack car up, spin wheel, look for hop in wheel rim. If you see it, move that wheel to the rear...and if the tires haven't been rotated and have been on a while, you should technically keep the tire in the same corner...though to just 'test,' I think moving it temporarily to the rear would be fine. If that's it, you can move the tire back where it belongs, but keep that wheel in the back. Confusing, huh? LOL
 
#17 ·
Sorry to revive this from the dead, but this is a damn good example of what it means to "preload" the csb.

I wish my vibrations could be attributed to a flat spot like your car dmax, although my tires are brand new. I'm supposing it must be the used driveshaft that's causing vibration around 50 - 55 mph.
 
#18 ·
It was a flatspotted wheel, not tire...banged up on the inside rim. Again, with these high speed balancing machines, the tech would 'see' the wheel can be balanced and would balance it...but you'd still feel it. And, so many shops, by default, balance with weights only on the inside rim or stuck onto the barrel. The best balancing is done with weights on both the inside and outside rim...but so many don't want to destroy the beautiful look of their wheels...shops won't do that on alloys unless you specifically tell them to.
 
#19 ·
Bent wheels and wheels that have inside bores that are too large are the primary vibration problems that seemed to get overlooked all the time. There is an occasional problem with brake caliper that hangs, loose or worn suspension components, a bad tire or Xi front axles that cause issues, but wheels are the most overlooked problem I seem to see.

Even Hunter Road Force balancing machines will zero out a balance on a bent wheel that will still cause vibrations. You cannot put weight on something that is out of round and make is spin without causing some sort of problem. The part needs to be true and turn properly without a lot of run out or dimensional variation, then it can and should be balanced.

Has a lot less to do about wheel weight placement, they can be placed on the inside barrel, some can be placed up higher hear the wheel spokes and not be on the outside portion of the wheel and still be hard to see.

Only about 10-20% of the wheel techs look for and find bent wheels from my experience. Most blindly and cluelessly mount the wheel on the balancer, once the balancer indicates no weight required, they consider their job done. Part if the problem is no training and awareness to bent wheels.

I have personally seen Hunter Road Force machines balance a wheel and indicate zero weight required while there is an imbalance felt in the machine while the wire is under load on the roller.
 
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