Thumping @ 25 mph

[hArte]

On my 1985 Vanagon I notice a substantial and regular thumping beginning @ about 25 mph then dissipating as the speed increases to being almost gone.As I decrease speed the thumping again becomes apparent. I checked air pressure and did an inspection at each wheel . Nothing seems to be amiss .Could this be related to a wheel balance issue ? Ideas please ?

[E1]

Could be CVs, a bent wheel, or something dragging, but first torque the wheels.
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If ever twice as rich, we’re gettin’ a double-wide
’84 “Westfailure”/2.1 Digijet/5.43 Ring & Pinion/Peloquin/D-rated BFG KO2s

AI has spoken to further illiteracy, to steal, to cheat, and to replace humans

[DuncanS]

Torque the wheels? If this means make sure the lug nuts/studs are tight, then do it. With weight on the wheels, when standing still, you can't tell if a wheel is loose.

Year and model of car is always needed on a post.

Duncan

[dougnlina]

A damaged tire can do this, accidentally hit a curb, rock or drop something heavy (the van) on a sidewall? Tire can look undamaged but have internal ply damage.
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"Grover" a '87 Syncro Poptop 1.8T

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[Wildthings]

Gentle run the palms of your hands over the tread of your tires and see if you can feel even the slightest raised area.

[do.dah]

Probably more indicative to run your hands over the sidewall. And look at it from the side.

[dobryan]

I would carefully jack up each side and spin each wheel and look for anything abnormal. Certainly sounds like a damaged tire or rim. Look at the inside sidewall as well when you do this.

Also while the wheel is off the ground you can grab it at 12 and 6 o'clock and rock it to see if there is too much play. There should be a tiny bit but not a clunk.
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Dave O
'87 Westy w/ 2010 Subaru EJ25 (Vanaru) and Peloquin TBD

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[Timwhy]

Steele belt broken inside the tire until it finally blew out. Looking at the tire showed nothing visible, better to take to a tire shop if you can't narrow it down.

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'09 VW Tiguan (dead)
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'90 Cabby
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[Abscate]

Fill that in with Bondo, colour match with Rustoleum, and sharpie in the tread, and you are good to go to skills for a wheel alignment
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[E1]

I already bought that from Tim.
_________________
If ever twice as rich, we’re gettin’ a double-wide
’84 “Westfailure”/2.1 Digijet/5.43 Ring & Pinion/Peloquin/D-rated BFG KO2s

AI has spoken to further illiteracy, to steal, to cheat, and to replace humans

[Syncronoid]

Does it happen accelerating, decelerating or coasting? Check your axle nuts are tight and if there is any side to side play of your wheels (need to jack up each wheel).
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'90 Syncro Westy w/GW2.5L

[Wildthings]

[hdenter]

Pull the wheels all the way off and inspect them. We had a problem with my wife's Passat years ago. She had driven over some debris in the road and we were concerned about damage. I looked things over well and could not find anything, but there was a new hum/vibration. Eventually found that the inner lip of the wheel had been bent where I couldn't see or feel it by reaching around.

Hans
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'79 triple white convertible bug
'84 sunroof vanagon
'85 weekender

[E1]

Wildthing’s comment about “buying another set of his Avons” brings up a point.

I do not think Tim’s tire should be interpreted as a manufacturer’s failure.

It’s pretty clear it impacted something, like a piece of angle iron, or whatever.
_________________
If ever twice as rich, we’re gettin’ a double-wide
’84 “Westfailure”/2.1 Digijet/5.43 Ring & Pinion/Peloquin/D-rated BFG KO2s

AI has spoken to further illiteracy, to steal, to cheat, and to replace humans

[Shonandb]

As soon as I turn on the sound system, my Bus thumps all the time!

Sorry, I couldn't resist. As others have said, it is probably a shifted belt or bent rim in one of your tires. If a balance issue, you'd notice it at higher speeds too, especially over 60mph.
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76 Westy with a 2.5L Subaru SOHC + Vanagon (010) Automatic Transaxle
Build & Trip Thread: https://www.thesamba.com/vw/forum/viewtopic.php?t=758760
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[Timwhy]