Do the U-joints on the driveshaft really have to be lined up with each other?

[Schwarz325]

Alright so, i drove my m50 e30 for a few days and there is some vibrations. My buddy confirmed it was driveline vibrations last night, so i think the d/s is out of whack. I checked and made sure everything was tight, nothing was hitting the shield or anything.

When i had the driveshaft apart to change the CSB, i marked it but the marks kinda faded, so i somewhat guessed how it went back together. I checked the u joints and they're not lined up with each other.

How important is that they're in line with each other? Or should i pull the d/s and have it balanced the way it it?

[nando]

the white markings (if they're still there) on the crankshaft have to be lined up or it WILL vibrate.

so yeah, it sorta matters.

[MattM]

the white markings (if they're still there) on the crankshaft

which markings are you referring to? picture?

[Jand3rson]

How important is that they're in line with each other? Or should i pull the d/s and have it balanced the way it it?

Very important. Driving with it improperly aligned has probably already started to throw it out of whack. Pull it, and take it in to be balanced with both parts together, and they will mark it when they do it where it needs to be reassembled.

[Schwarz325]

I couldn't find any marks on it, but honestly i never really looked for any. I just sprayed it with some paint but it faded, cuz the d/s was off for like 3 weeks before i re assembled it.

So, if i line the u joints up in line with each other, i am assuming i still need to balance it?

[e46s54dr]

If there wasn't a mark or no longer a mark to line up the driveshaft, you will have to pull it out and get it rebalanced for sure. Also make sure you preload the center support bearing when you reinstall it.

[Jand3rson]

If there wasn't a mark or no longer a mark to line up the driveshaft, you will have to pull it out and get it rebalanced for sure. Also make sure you preload the center support bearing when you reinstall it.

People have been debating this ever since I got into E30's almost 10 years ago, and probably before. I know several people who say they've never preloaded it, and several people who say you HAVE to do it. I've installed 3 driveshafts on my car, and only preloaded 1 CSB, and never felt a difference.

[DREWHALL]

which markings are you referring to? picture?

I believe he meant driveshaft. I don't think there are any marks on the crankshaft that need to be lined up with the u-joints lol.

[e46s54dr]

People have been debating this ever since I got into E30's almost 10 years ago, and probably before. I know several people who say they've never preloaded it, and several people who say you HAVE to do it. I've installed 3 driveshafts on my car, and only preloaded 1 CSB, and never felt a difference.

That may be the case but I was alway taught that the proper way to do the job is to preload the csb. It really isn't all that hard to do and I would consider it as cheap insurance. To me It's like slapping on a timing belt and not rotating the crank assembly and cam to double check your timing marks.

P.s. You've already replaced your driveshaft on 3 seperate occassions? I rest my case. LOL. Jk

[Jand3rson]

That was supposed to say "cars". 3 driveshafts on 2 E30s.

[JGood]

That may be the case but I was alway taught that the proper way to do the job is to preload the csb. It really isn't all that hard to do and I would consider it as cheap insurance. To me It's like slapping on a timing belt and not rotating the crank assembly and cam to double check your timing marks.

Exactly. If the Bentley manual says to do it, I can't imagine it's not at least somewhat useful. Maybe your driveshaft won't blow up and cause the end of the world if you don't, but it might extend the life of that and the CSB & guibo if it's preloaded.

I believe there is a way to get the driveshaft reinstalled correctly as it was from the factory. If you lay the rear half with the u-joint laying flat on the ground, and the front half with 2 of the 3 corners of the triangular flange touching the ground, the halves will go together. If not, you have to rotate the front half 120 degrees until it does slide in. When together, the drive shaft will sit perfectly on the ground, the rear section laying flat and the front section laying flat. Since the rear is a square, there are 2 possibilities, so you may have it flipped 180 degrees. But you may be able to get it in those positions and look for factory markings, that may help. And you can also use this to ensure that you aren't one tooth off when reassembling even with the markings.

Maybe someone can clarify/simplify that^.

[jrdeamicis]

With the angle of the transmission entering in the CSB, if you do not preload the CSB you will have a 1st gear shudder. Then it will smooth out after that. I was able to see this for my self while hanging out at my driveshaft shop, my guy was able to show me on the balancing machine what happens when not preloaded. Its so easy to preload, there is no reason to not do it.

[Eric]

I got my E30 M3 drive-shaft in 2 pieces when I bought it. I lined it up like the poster above me mentioned, and I had a real bad vibe starting at 95mph and getting worse until it was undrivable over 140mph. I took the drive-shaft out and had it balanced locally who also installed a new CSB for cheap insurance. When I got it back, I noticed that it had two nice white dots near where the drive-shaft can separate.

I no longer have bad vibes

[ZekeTheSneak]

WTF is this preloading, explain

[justin_l_]

Loosely mount center bearing to body, pull one way then tighten so the rubber holding the bearing has tension. Once again, I have done it on some and not on others, both have held up fine. My factory service manual says nothing about preloading so it's up to you.