Excessive Noise Transmitted Through The Floor

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Amskeptic
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Excessive Noise Transmitted Through The Floor

Post by Amskeptic » Wed Sep 19, 2018 11:45 pm

The bad news is, these cars can be pretty quiet. I have driven many air-cooled VWs, and some are civilized and some are coarse. The coarse ones have an obvious increase in noise up the hill. Buses are especially prone to this. You can hear a dudududududu under the floor, and it magically disappears when you are going down the hill. You soon start wishing that you could just drive downhill all the time.

Unfortunately, my 1977 Westfalia raised the bar as far as civility in my experience, what a lovely quiet car that hardly changed note between the downhill and the uphill. It was a joy! a joy I tell ya . . . until it wasn't.


A) Refresher On What I have Been Whining About

viewtopic.php?f=77&t=13636#p229714

Salient quotes below, feeeeel the thick disappointment ... this, because the transaxle slipped off the bottle jack and dropped to such a degree that the shift coupler cage got bent, and the shift rod end got bent upwards.

Image

June 11, 2018
. . . and we wrecked the beautiful turbine smoothness of that engine. God knows how, maybe the angle of the transaxle yanked the nose cone mount. It did distort the shift coupler cage. Suddenly it sounds like every other VW bus, thumpy through the floor, shifter bringing noise up to the front cabin. Could not bear it. No, please! My favorite thing about this car is the sound of that cooling fan and transaxle whine, just smooth, quiet, no dudududu coming through the floor under load . . .
Yeah, so it is a little better, but not enough!
What happened to my mannerly VW? Was it the act of separating the engine and transaxle? Did I inadvertently bend the shift rod? My princess is so . . . coarse, now.
July 6, 2018 (after adjusting the position of the transaxle and engine at a truck stop)
. . . Back on the road, the thumping in the floor was much less, and the gear shifter rattle was more a little buzz and I knew exactly why that was.

B) The Solution (September 17, 2018)
As I was painting the heater wye, I noticed that the rear shift rod was actually bent. It was going through the cross members way close to the bottoms of the provided holes, and it was almost pressing on the bottom of the shift tube in neutral:

Image


After dropping the nose cone mount, I stuck a 15mm socket over the shifter cage against the ceiling above, then bolted the nose cone mount back up to trap the socket. Then I crammed another socket (3/4?) over the shift rod right where it enters the shift rod tube. Then I grabbed my old BMW spark plug "T" bar and bench pressed that thing up hard against the shift rod at the bend point (totally lousy access with the heater wye in the way). It actually gave! Then I dropped the nose cone mount, fished out the socket, popped out the other socket, and saw that the shift rod was now "more centered":

Image


Image

So, it actually turns out that the "float" provided by the rear shift rod bushings is within very specific parameters. Who knew? I always thought it was just lots of wiggle room for the movement of the transaxle under acceleration and deceleration. Nope. The range of movement of the shift rod is just enough so long as it is not bent. It is a fairly involved process to get it within range, and I will do a write-up when I have the time.

Now that I have the shift rod straight, it is within the float range at all times, and my lovely civilized quiet NaranjaWesty is back. You can barely tell a difference between off-throttle and full-throttle on the highway. You can't hear the engine with the windows down.

This shift rod thing is unbelievable, the noise it transmits. And we all take it for normal, unless you have experienced the civility of a truly together VW. I look forward to straightening the BobD's shift rod. The BobD has that floor thump under load too, It must have a bent shift rod from when the jack failed in Yuma back in 2010.

viewtopic.php?f=58&t=9053#p162950


Lawdy lawdy if the BobD shows the same improvement I have heard here, I will not only be very happy but on the war path to visit every single VW bus owner in the country who has all that dudududu under load. Stay tuned . . . this post will be updated when I get back to Atlanta.
BobD - 78 Bus . . . 112,660 miles
Chloe - 70 bus . . . 206,845 miles
Naranja - 77 Westy . . . 116,898 miles
Pluck - 1973 Squareback . . . . . . 55,570 miles
Alexus - 91 Lexus LS400 . . . 84,465 miles

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Re: Excessive Noise Transmitted Through The Floor

Post by Jivermo » Thu Sep 20, 2018 3:47 am

Wow! Great repair, the pics really help explain it.

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tommu
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Re: Excessive Noise Transmitted Through The Floor

Post by tommu » Thu Sep 20, 2018 8:05 am

It is amazing how long the shift rod is - wobbling around in it's tunnel. Has this changed your view on the importance of a good rear shift rod bushing?

NOS ones are available from the UK: https://www.customandcommercial.com/vw- ... -79_36914/

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Amskeptic
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Re: Excessive Noise Transmitted Through The Floor

Post by Amskeptic » Thu Sep 20, 2018 10:57 am

tommu wrote:
Thu Sep 20, 2018 8:05 am
It is amazing how long the shift rod is - wobbling around in it's tunnel. Has this changed your view on the importance of a good rear shift rod bushing?

NOS ones are available from the UK: https://www.customandcommercial.com/vw- ... -79_36914/

Those bushings are good for the life of the car if they have remained lubricated. People have replaced those bushings (cuz there were new ones to sell) hoping to get of rattles, but the rear shift rod is not the rattler, the front one is when its bushing fails.

This issue is not a rattle so much as a drumming.
Colin
BobD - 78 Bus . . . 112,660 miles
Chloe - 70 bus . . . 206,845 miles
Naranja - 77 Westy . . . 116,898 miles
Pluck - 1973 Squareback . . . . . . 55,570 miles
Alexus - 91 Lexus LS400 . . . 84,465 miles

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bradleygt
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Re: Excessive Noise Transmitted Through The Floor

Post by bradleygt » Fri Jan 31, 2020 7:05 pm

any chance of a video?
an ounce of prevention is waaay more than a pound of cure

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Amskeptic
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Re: Excessive Noise Transmitted Through The Floor

Post by Amskeptic » Sun Feb 02, 2020 7:54 am

bradleygt wrote:
Fri Jan 31, 2020 7:05 pm
any chance of a video?
Ah no. Not there yet.
Colin :blackeye:
BobD - 78 Bus . . . 112,660 miles
Chloe - 70 bus . . . 206,845 miles
Naranja - 77 Westy . . . 116,898 miles
Pluck - 1973 Squareback . . . . . . 55,570 miles
Alexus - 91 Lexus LS400 . . . 84,465 miles

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