Thwap, thwap, thwap sound - what's your guess?

[man_mark_7]

Drove ~30 miles mostly highway driving to a 4th of July bash today. Car ran and sounded great. Drove ~28 miles home and car was perfect UNTIL: pulled off the highway and slowed down to about 30 mph. Started to hear and feel a thwap, thwap, thwap almost hard rubber on metal sound. As long as I was accelerating there was no noise. As soon as as I let off the throttle I would hear the sound again. I made it home the last couple miles by slowwwwly accelerating until I hit a bit over the speed limit, rapidly braking (while hearing the noise), then sloooowly accelerating up to speed again.

 

It's past 11 pm here so I will put the car up on stands in the morning and report what I find. I thought it would be interesting to see what everyone's guess is? I'm thinking guibo or u-joint?

 

M

['76mintgrün'02]

 I'm thinking guibo or guibo.

[Mike Self]

When did you last check your rear tranny mount, and is it the original 02 part, or the larger (and sturdier) E21 or Bavaria mount?  When the rubber mount turns to black goo, it'll allow the rear of the tranny, and thus the front of the driveshaft to waggle a bit, so something there that's rotating can hit part of the car that isn't.  

 

mike

[Adamha]

Guibo or center bearing.

[2002iii]

Definitely center bearing seized up, same thing happened to me. It only gets better when you accelerate because the bearing floats with the centrifugal force applied to it. I would buy both the center bearing and guibo, if ones bad the others probably on its way and you might as well while your down there.

[man_mark_7]

I am appalled, ashamed and embarrassed to state my findings: loose lug nuts on the left rear. Should have been the first thing I checked, but the car wasn't shimmying or anything of the sort. It also had a distinctly hard rubber feel to it. It must have been as the rim shifted from lug to lug that some of the shock was being taken up by the tire.

 

At least Gertrude won't be off the road waiting for parts.

 

Live & learn, with the focus on live.

 

M

[PaulTWinterton]

The title of the post suggested a flat to me IMMEDIATELY.  Recently had a guy drive by my house and that was the exact sound of his tire being shredded.  He was oblivious as he listened to music through earbuds.

 

 

[tech71]

Glad you caught it before you lost the wheel. Not the first and won't be the last this has happened too.

[jgerock]

2 hours ago, man_mark_7 said:

I am appalled, ashamed and embarrassed to state my findings: loose lug nuts on the left rear. Should have been the first thing I checked, but the car wasn't shimmying or anything of the sort. It also had a distinctly hard rubber feel to it. It must have been as the rim shifted from lug to lug that some of the shock was being taken up by the tire.

 

At least Gertrude won't be off the road waiting for parts.

 

Live & learn, with the focus on live.

 

M

I recommend removing that wheel and closely inspecting the (4) studs and the wheel for damage.

[adawil2002]

21 minutes ago, jgerock said:

I recommend removing that wheel and closely inspecting the (4) studs and the wheel for damage.

 

+1 plus re-torque all your lug nuts. Spec's depend which wheels you are running. Alloys 74-80 ft. lbs. & Steel 90 ft.lbs are what I have been running.

[onestogie]

Well, I’m happy I found this post. My car was making the same, awful noise from the rear end. Took a torque wrench (62 ft/lbs) to each wheel, found that the right rear needed a bit of tightening. I guess we didn’t do proper diligence when inspecting the brakes earlier in the week.

['76mintgrün'02]

On 7/5/2019 at 10:29 AM, adawil2002 said:

Steel 90 ft.lbs

that's too much 

 

(the following came from the Torque Specs in the reference section)

 

Wheels: 

Wheel nuts or studs  59 - 64 ft-lbs

 

COPYRIGHT 2002, BMW 2002 FAQ, Rob Shisler and Steve Kupper.

All Rights Reserved.

 

 

 

Edited July 14, 2019 by '76mintgrün'02

[man_mark_7]

6 hours ago, onestogie said:

Well, I’m happy I found this post. My car was making the same, awful noise from the rear end. Took a torque wrench (62 ft/lbs) to each wheel, found that the right rear needed a bit of tightening. I guess we didn’t do proper diligence when inspecting the brakes earlier in the week.

 

Definitely an easy to do thing that I should check more often.

[rstclark]

Reminds me of the old commercial where the customer asks the mechanic What does the Thwap Thwap Thwap sound like to you ?

To which he responds " Sounds like two weeks in Waikiki to me"

Glad you found the problem before it got much worse

[thinksound_mike]

had the same issue last year. i'd retighten and they would loosen over time. ended up using blue thread locker on the lugs and haven't had an issue since.