Hi Guys,
I'm fairly new to the BMW world (I've owned my 99 328i for 6 months or so). I'm fairly competent with a wrench though. I've completed a VANOS rebuild and subframe reinforcement. Anyway, I've been having driveshaft vibrations. Even after replacing the CSB, Guibo, center clamp coupler thing, and the bushing that the transmission output shaft goes into, as well as verifying that the driveshaft is aligned, it has a vibration.
Symptoms: Drives lovely smooth including at speed. But, vibrated under high torque loads. Especially bad if I brake and step on the gas at the same time. The lower the gear the worse it is. It's a pretty aggressive vibration and I don't want to replace my CSB, ect again in 5K.....
The U joints don't seem to have an abnormal amount of play. Is there a measurement for this? This is a slight thud when getting on / off the gas but it's pretty small. there's also a fair amount of play in the diff (270K on the chassis) that is likely the cause of this. One U joint (the rear one if I remember correctly) feels slightly stiff while the middle U joint is looser.
I'd really appreciate any help. I really don't want to spend a bunch of money on these parts again....
Thanks in advance,
-Brendan
The common point of U-Joint failure is the one closest to the differential. Any X/Y or rotational play is bad.
Also if you didn't use OEM parts, a vibration can and more than likely will be felt.
Cool. I'll check for X-Y play
You inspected the differential drive line from transmission to rear dif an found no abnormal play. You describe a shuttering (vibration) in the drive line upon acceleration and even more so when you applied more drive torque by applying the brakes while your foot was still on the accelerator...ie right foot on the gas, left on the brakes.....and lots of vibration....To me, this does not resemble an out-of-round, out-of-balance scenario (although it may be possible) but I think more so as a power delivery issue from your engine. If one or more of your 6 cylinders has compromises upon power demand it can become transmitted as vibration. Drive shaft issues involving u-joints, or in some other German cars, flex-joints, typically are quite profound when they fail but all have a distinct frequency. Find a BMW indy, not an Audi, VW or Mercedes guy, ...and pay him to inspect your car. BMW cars are different from the other German cars... The money will be well spent.
There is a very small (1/16 inch or so) amount of play in the Unjoint at the diff.
Eaglesail: I tend to agree with you. It's only noticeable in first gear. Although the magnitude of a vibration will be largest at its resonant frequency (which in our cars tends to be 25-35 mph), it should be noticeable under light or heavy throttle. The vibration happens most at 15mph and only under heavy throttle. :Sigh: I don't like paying other people to work on my car, but I may do that. The motor runs very smooth, has good power and only about 85K on it. I doubt that is the cause, but it is very possible.
Other thought: Could this be caused by bad trans / motor mounts?
Thanks for your help
-Brendan
Last edited by capnslow; 04-25-2018 at 02:41 PM.
What brand flex disk and CSB did you use?
Hey guys, here's an update:
I checked motors mounts... drivers side was SHOT!!! Replaced those and the problem persisted, but I'm sure they were not helping anything.
dhurley34: Flex disk: Meyle, CSB: REIN. Yes, I know the REIN csb is very cheap, but I've heard a number of people having luck with them, and it isn't the cause of this problem: read bellow
Looking today, there is significant rotational play in the Ujoint at the diff. Ex: with the trans in neutral, I can hold the input flange on the diff and rotate the driveshaft a bit back and forth. Aka, the U joint has lots of slop (the needle bearings are bad). Effectively, under load (especially in 1st gear) the torque applied to the joint is binding up the bearings and causing the driveshaft to be pushed around in a circle due to the binding (aka, vibrating / thunking). At higher speeds / lower torque loads the symptoms are very slight.
Plans moving forward:
I ordered 2 Neapco P/N 1-0431 U joints and will be rebuilding them myself. I am away that they don't "fit" and our driveshafts are "unserviceable." I may or may not follow the methods described in the below DIY but plan to upload some photos of what I do. I am an mechanical engineering student with a background in precision machining so I understand the critical aspects of this rebuild.
https://www.bimmerforums.com/forum/s...-Joint-change)
I hope this is helpful to someone out there! Thank you all for the help
-Brendan
Last edited by capnslow; 06-24-2018 at 11:12 PM.
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