UPDATE: Fixed - Driveline vibration.. what'd I do wrong?

[etxxz]

tranny mounts are green poly

Sure is not RPM based? i had problems with poly tranny mounts. try the OE rubber mounts. stock e30, or e36 ones will work in your case. switched back, no more problems.

[Nairb]

Sure is not RPM based? i had problems with poly tranny mounts. try the OE rubber mounts. stock e30, or e36 ones will work in your case. switched back, no more problems.

Not RPM based.. tested multiple times.. purely speed based.

I am 98.2% sure that it is the OEM tranny crossmember. The poly bushings have less than 500 miles on them, pretty sure they are not shot yet, but I will thoroughly inspect them when I swap tranny mount.

Waiting on a White325is tranny brace.. :D

[etxxz]

my problem was the poly bushings somehow too stiff caused vibrations. (brand new). not preloaded.. but that was rpm based.. hmmm. what's wrong with you cross member then? can't be people using them all the time.

[Nairb]

Ok, this has been bugging me but I haven't had any definitive search results..

When I put the driveshaft in, I had to loosen the collar nut and "extend" the driveshaft so it would meet the tranny.. probably about an 3/4in to about an inch.. would that be enough to throw off the whole balance of the driveshaft?

Just ordered a White325is tranny brace.. will install and report back, but I would like clarification.

[4_stroke]

I suspect that one of the issues may be related to the mods you have already done. changing things further away from stock will make the problem harder to resolve.

Just to clarify a few things..

1) You say the problem relates to road speed. If you de-clutch and coast (taking the driveline off load) does the vibration change at all

2) Does the vibration change when turning corners

3) Can you run the engine with the wheels on stands so you can see the driveshaft spinning (looking for it spinning out of true)

4) Is there any radial play in any of the driveshaft joints.

5) How soon after fitting the giubo did the problem start.

I do not think its related to the motor mounts. it seems more like a drive shaft/coupling issue.

There was also an earlier comment regarding the pilot bearing. Have you checked that this is holding the shaft true without the coupling bolted up.

[Nairb]

I suspect that one of the issues may be related to the mods you have already done. changing things further away from stock will make the problem harder to resolve.

Just to clarify a few things..

1) You say the problem relates to road speed. If you de-clutch and coast (taking the driveline off load) does the vibration change at all

2) Does the vibration change when turning corners

3) Can you run the engine with the wheels on stands so you can see the driveshaft spinning (looking for it spinning out of true)

4) Is there any radial play in any of the driveshaft joints.

5) How soon after fitting the giubo did the problem start.

I do not think its related to the motor mounts. it seems more like a drive shaft/coupling issue.

There was also an earlier comment regarding the pilot bearing. Have you checked that this is holding the shaft true without the coupling bolted up.

1. De-clutching at around 25 mph does nothing to change the vibration.

2. The vibration does not change around corners (also tried de-clutching around corners at 25mph.. no change.)

3. I may have to take it to a shop for this.

4. Driveshaft was purchased rebuilt from a very very reputable driveshaft service.. (Portland Driveline) using the OEM joints. I inspected the joints prior to installation and honestly, the whole thing looked and felt like a brand new driveshaft.

5. The problem did not start after installing the giubo. I bought the car with a badly damaged giubo and CSB.. I replaced it shortly after buying the car, and this is where I'm at now.. however, the tranny does not have the proper "modified" crossmember.. so I am thinking that is the problem.

Other than that.. the transmission is smooth as silk. Other than the offset angle, it does not grind, moan, whirr, or make any other out of the ordinary noises..

The engine does not seem to shake at all, but when 25mph rolls around, the whole car starts to jar and you can definitely feel it right through the floorboard in the middle of the car..

[bmwguy325is]

When you pulled the shaft aprart did you get the splines aligned back where they should?

[Nairb]

I didn't actually separate the halves.. just loosened the nut, mated it with the tranny, tightened the nut.

[Gruelius]

then its fine, make a reference mark though as the tailshaft would have been balanced in one orientation.

[Wh33lhop]

How did you replace the CSB without separating the driveshaft?

Also, did you preload the CSB?

[Nairb]

How did you replace the CSB without separating the driveshaft?

Also, did you preload the CSB?

Well I just cut the center bearing out of the CSB, slid it over the tailshaft and then epoxied it back to the driveshaft once I had it all back together.

Or.....it came together as 1 piece from Portland Driveline with CSB already installed.

I pushed the CSB as far toward the front of the car as I could..

[4_stroke]

When you refer to the angle offset what do you mean exactly. The driveshaft must be aligned with the transmission output flange. The aftermarket stock giubo cannot take much angular misalignment. The aftermarket one probably less.

[Nairb]

Ok.. so I put the White325is modified trans brace in the car.. and it's still vibrating. It is a much different vibration, but a vibration none the less. Now instead of 25mph, it starts at 35-40 and up. It is a much tighter vibration.. more like a buzzing..

I will get pics of my mount/guibo and all that up later.

I think I may go to oem tranny mounts..

[matthugie]

With poly trans mounts you get some vibration and increased nvh. I agree with trying OEM mounts, if it goes away you can be pretty sure that's what it is.

[Nairb]

Here is a pic of the setup so far.. do the green mounts look too tall?