Diagnosing Driveline Noise

[FunElan]

Hey all, 

 

I've had this interesting "click" sound in the driveline since getting everything past the trans refreshed (G245 5 speed). The driveshaft was aligned twice by a reputable shop in SoCal, the first time was right after the newly balanced unit, new e21 mount, center bearing, and flex disc were installed. A few months later, the flex disc was cracked, so they realigned the driveshaft and chalked it up to the new e21 mount "settling."

 

My searches here led me to checking the tightness of the 36 mm castle nut on the hub (thanks for posting this more than once @TobyB) - with a 3 foot pipe extension, those bastards were pretty damn tight, and I did just have a shop redo the bearings last year anyway. 

 

So my hypothesis is that perhaps the nuts on the flex disc are hitting the shift linkage, but it only happens on certain "takeoffs." It's difficult to hear this when moving, but in the videos you can kind of tell it only happens when the unit goes from no load -> load. I did get up under there recently and found that there's not a ton of room above that flex disc. If the driveshaft is considered "aligned," does this mean I should maybe try a new shifter setup?

 

Today I went to my favorite "noise finding" alley, which has a wall on one side, to get some video. Also attaching a (bad) photo of the shift tower situation, with the old cracked flex disc. Thanks in advance

 

 

Edited October 16, 2020 by FunElan
file reupload

[dlacey]

I would check play in rear wheel bearings, worn CV joint, worn Prop UJ

[adawil2002]

Video links aren't working.

 

Does this only happen under power?

Does this happen in neutral while coasting?

As long as the driveshaft is in plane, you should be OK. Never heard of an E21 transmission bushing needing to "settle"

Did you go from the 1600 3-flex disc driveshaft to the later single flex disc?

How many miles/kilometers from flex disc install to replacement?

Take a photo of the fan clearance from the top & bottom of the radiator.

 

 

 

 

 

 

[FunElan]

6 hours ago, dlacey said:

I would check play in rear wheel bearings, worn CV joint, worn Prop UJ

 

These were all replaced/refreshed last summer. Is there a manageable way to test play in the Ujoint? I assume I have to lock the driveshaft somehow?

 

4 hours ago, adawil2002 said:

Video links aren't working.

 

Does this only happen under power?

Does this happen in neutral while coasting?

As long as the driveshaft is in plane, you should be OK. Never heard of an E21 transmission bushing needing to "settle"

Did you go from the 1600 3-flex disc driveshaft to the later single flex disc?

How many miles/kilometers from flex disc install to replacement?

Take a photo of the fan clearance from the top & bottom of the radiator.

 

 

 

 

 

 

 

 

Weird...here are the links to youtube: 

 

https://youtu.be/sRX8lYokbl8

https://youtu.be/ggxeXJ-PAxs

 

I only hear it when taking off from a stop. In one of the videos, I keep driving for a few seconds more and it doesn't happen. The car has had the 5 speed in for over a decade, I just installed new parts. I'll get a photo of the radiator clearance today!

 

 

[adawil2002]

Had a similar sound with Vern & had to rebuild the differential.

 

 

 

[FunElan]

8 minutes ago, adawil2002 said:

Had a similar sound with Vern & had to rebuild the differential.

 

 

 

 

 

Interesting....I just had the diff rebuilt. This sounds to me like the noise is ahead of the diff. Maybe I need to get the car on a lift and have someone "drive it"

Edited October 16, 2020 by FunElan

[Dug Nichols]

Can you feel the click-click in the trans tunnel? If yes, it's the center support bearing

[TobyB]

How about the splines in the center of the driveshaft?

Center bolt/ nut nice and tight?

 

Or the output shaft flange nut on the trans?

 

t

 

Edited October 17, 2020 by TobyB

[rcf925]

CV Joints will click when going bad