Help diagnosing driveshaft vibration

[grantmiller1]

I'm trying to nail down a vibration while driving on the freeway, hoping for some tips.

First, some backstory:

I have a 89 325i manual trans. I have one of the oddball cars with the driveshaft balancer (pn 26111434254) on it. I pulled the balancer off 4 years ago when I installed a DSSR kit. I had some vibration from the driveshaft, but it was bearable.

Two weeks ago, I installed a new driveshaft from Driveshaft Specalist (in San Antonio) along with a new Meyle HD Guibo.

Before I ordered the driveshaft, I checked with Driveshaft Specalist and they said I would not need the driveshaft balancer with their driveshaft.

To my dissapointment, there's still some vibration. And it's worse than before.

I'm 99% sure I've installed the guibo correctly. I torqued all the guibo bolts to spec, got the driveshaft to diff bolts "guten-tight". I put a pre-load on the CSB.

Here's what I'm hearing/feeling:

- At lower speeds (25-40 mph) , I can hear some prop shaft noise, but no vibration

- Vibration starts at around 40

- Vibration noticable at 60 mph in 4th gear (~3k RPM)

- Vibration is very noticable at 60 mph in 5th gear (~2.5k RPM) like a thump-thump-thump-thump

Put the clutch in, vibration goes away. That rules out wheels/tires as a culprit.



I've refreshed a lot of parts on this car in the last 2-3 years, so I'm scratching my head as to what's going on. Also pulling my hair out!! :)

- Rear and front subframes reinforced, powder coated, poly 80A bushings
- New wheel bearings all around
- New shocks and springs (Bilstein B8, H&R OE Sport)
- New rear and front shock mounts
- New rear half-shafts
- Metric Mechanic 3.73 LSD 3-disk
- 80A poly diff bushing
- New front control arms, 80A poly control arm bushings
- 80A poly motor mounts
- Beefier front and rear sway bar mounting with 80A poly bushings
- New wheels and tires (Maxilite alpina reps, Contential ExtremeContact DWS 06)


I don't really want to drive this long distance (it's not a pleasant drive with that vibration), not looking forward to the drive to the E30 picnic, but I'm going to do it.

One thought I had was that I probably over-torqued the bolts for the transmission bushings (80A poly) when I was putting things back together two weeks ago. That's not too hard to fix.

I have a 1 year warranty on the new driveshaft, so I'll be contacting them.

If that goes nowhere, I may see if a local driveshaft shop will check the balance just to make sure I'm not crazy.

Should I have put the driveshaft balancer back on? Is it necessary with a balanced driveshaft?


If you've read this far, you get a gold star for the day and I appreciate your dedication.


Open to any ideas, questions, and things to check.


Attaching pictures of the new guibo to see if I've done this correctly:









Thanks!

-Grant

[It's Soda Not Pop]

If it goes away when you push the clutch in. It's probably Getrag rattle.

[bmwman91]

Driveshaft speed is only dependent on vehicle speed, not engine speed. If changing gears changes the vibration, and particularly if disengaging the clutch stops it, then there's a good chance that it is not your driveshaft that is causing the issue. The only way that I can see it being the driveshaft after what you said is if the guibo, U-joints, or CSB are failing since those might respond differently as output torque changes. Since you replaced those and it sounds like you took care to install them properly, I do not think that's the issue.

Just to confirm, you don't get any vibration at any point in first gear if you wind it out to redline? Just want to rule out anything directly proportional to RPM.

Since you have a nice new MM diff, I don't think that input shaft bearing failure is on the table.

Get under there and give the driveshaft a good shake up & down and left & right to see if there's radial play in the transmission output shaft bearing.

If there is a steep hill somewhere near by, like steep enough to make the car work hard in 2nd or 3rd hear, try going up that at ~2500RPM in one of those gears to see if the vib appears at low speed and high load/torque output. If no hills, you can also just use the brakes.

[uturn]

Did you replace the centering bushing in front of the driveshaft?

[grantmiller1]

If it goes away when you push the clutch in. It's probably Getrag rattle.

I guess that's good to hear? hahah I do have a rattle when in neutral, getting the trans input bearing has been on my list. Guess that just jumped up to the top of the list!

[grantmiller1]

Driveshaft speed is only dependent on vehicle speed, not engine speed. If changing gears changes the vibration, and particularly if disengaging the clutch stops it, then there's a good chance that it is not your driveshaft that is causing the issue. The only way that I can see it being the driveshaft after what you said is if the guibo, U-joints, or CSB are failing since those might respond differently as output torque changes. Since you replaced those and it sounds like you took care to install them properly, I do not think that's the issue.

Just to confirm, you don't get any vibration at any point in first gear if you wind it out to redline? Just want to rule out anything directly proportional to RPM.

Since you have a nice new MM diff, I don't think that input shaft bearing failure is on the table.

Get under there and give the driveshaft a good shake up & down and left & right to see if there's radial play in the transmission output shaft bearing.

If there is a steep hill somewhere near by, like steep enough to make the car work hard in 2nd or 3rd hear, try going up that at ~2500RPM in one of those gears to see if the vib appears at low speed and high load/torque output. If no hills, you can also just use the brakes.

1st gear and redline, I think there's no vibration, but I'm going to check this and the steep hill test tomorrow and report back. Thanks!

[grantmiller1]

Did you replace the centering bushing in front of the driveshaft?

That one did occur to me. I had assumed that it was replaced on the new driveshaft, but all options are on the table at this point. I happen to have one that I'll put in.

[hasa]

There were no gearbox mounts in the pictures, are they original or have original dimensions? Guibo in the second picture was "angled" and that 100% sure makes vibration if that is the case when driving. But it should be straight when everything is original and mounted correctly.

[Kelso840]

There were no gearbox mounts in the pictures, are they original or have original dimensions? Guibo in the second picture was "angled" and that 100% sure makes vibration if that is the case when driving. But it should be straight when everything is original and mounted correctly.

I noticed the driveshaft angle as well but it could be because there's no trans mount. Is the nut in photo Forum contacting the transmission? Do you get more space when the trans is fully mounted?

[moatilliatta]

What about 3rd gear at 70?

Id toss those 80a thru bolt mounts in the trash and put rouge units in there.

The balancer that goes around the guibo doesn't really do anything.

[grantmiller1]

1st gear and redline, I think there's no vibration, but I'm going to check this and the steep hill test tomorrow and report back. Thanks!

Sorry for the delay. Drove around today to gather some info.


1st gear @ 5000 RPM has no vibration

2nd gear up a steep hill has a little vibration (maybe 2 on a scale of 1-10). Only noticeable from the gearshift.

3rd gear up a steep hill has slightly more vibration than 2nd gear, but only noticeable from the gearshift.

Also:

2nd gear @ 5000 RPM, no noticeable vibration (maybe the same amount as at 2500 RPM)

Ditto for 3rd gear @ 5000 RPM.

3rd gear at 70 mph? I think I got close one time and not a lot of vibration.

[grantmiller1]

I re-torqued the trans bushing bolts to the correct spec 9-12 ft-lb and took some pictures of the trans mount for y'all.


Confirmed that 3rd gear @ 70 MPH has no vibration.


Took a short drive and no change in vibration.


I don't feel any part of the guibo or bolts/nuts hitting anything when it's up on the lift. There's clearance between it and the trans.

[Kelso840]

When you say "vibration through the gearshift" are you talking about the shifter itself wobbling/vibrating? I see you have poly bushings on the trans mount and a DSSR shift linkage. That's at least two points of vibratory isolation you've increased rigidity.

Without seeing/feeling your specific sensation, you might be feeling drivetrain vibration that was normally dampened by the 2 piece driveshaft, stock trans bushings, and a more forgiving shift selector geometry.

Does your shifter have a rubber isolator?


Do you have the old driveshaft and have you swapped it back in to see if the vibration goes away?

[grantmiller1]

When you say "vibration through the gearshift" are you talking about the shifter itself wobbling/vibrating? I see you have poly bushings on the trans mount and a DSSR shift linkage. That's at least two points of vibratory isolation you've increased rigidity.

Without seeing/feeling your specific sensation, you might be feeling drivetrain vibration that was normally dampened by the 2 piece driveshaft, stock trans bushings, and a more forgiving shift selector geometry.

Does your shifter have a rubber isolator?


Do you have the old driveshaft and have you swapped it back in to see if the vibration goes away?

Yes, the vibration through the gearshift is just what I'm feeling when my hand is on it. The gearshift is not wobbling. This is very likely normal, but I mentioned it anyways.

I installed the DSSR shift kit 4 years ago, so I can't remember if it has the rubber isolator or something else.

I do still have the old driveshaft. I can see about getting that swapped back in this week or the weekend after E30 picnic.

[Kelso840]

Gotcha. Yeah, I bet you're just feeling more vibration with the new driveshaft.

The rubber isolator would be on the shift lever itself, not the DSSR linkage. The photo I posted is looking up the skirt of a shift lever to show how the lower section that goes into the shifter cup is isolated from the top part your hand holds via rubber. I can't remember if the stock e30 shifter lever is designed like that or not.