Thumping noise and feel at slow speeds

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Hubster43
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Thumping noise and feel at slow speeds

Post by Hubster43 » Mon Jun 12, 2017 8:15 am

We have a 76 Westy that we have owned since 1990. It has been through many adventures and a couple of engines. We had a new "used" transmission installed during our honeymoon in 1990 after breaking down in Salt Lake City. It has never been quiet, but it has never failed us. Recently we have been experiencing some terrible thumping at slow speeds while braking. I originally was sure that it was the front discs, so I replaced pads and had someone replace the rotors. That didn't help out. I have checked the rear brakes and there is plenty of pad material left. I did have "new" cv joints installed last year, and one of them was defective and had to be re-replaced. I have a feeling that it is related to the transmission since when I lift the rear end and spin the wheels, there is a definite thumping sound coming from both of them. You can feel the thump and it feels like it is coming from the transmission junction. If you hit the brakes at higher speeds, everything is fine, but when you are coming to an almost complete stop, things get rather noisy and rocky. It seems like it is mainly when in neutral or with the clutch in. I tried an experiment last week where I put one foot on the accelerator and the other on the brake and when going slowly in first gear everything was smooth, no thumping feeling even under harder braking. Wheel bearings are good in both rear wheels. Transmission fluid was changed last year to some of that expensive Redline stuff.

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sgkent
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Re: Thumping noise and feel at slow speeds

Post by sgkent » Mon Jun 12, 2017 1:07 pm

Could be in the trans - maybe a loose pinion nut. Or maybe a CV or even a screw head that is embedded in the tire. Did you check the torque on the Axle flanges in the back? Did you check the wheel lugs for tightness? Spin the tires and look for debris? I have been in cars that picked up a bolt in a tire. It feels like the car is going over potholes. You can also drain the trans and refill it with Stalube GL4. See whether the debris that comes out is chunks of steel or just fine particles.

You say it has never been quiet - as in clunky or as in a whine?
TBone208 wrote: "You ppl are such windbags. Go use your crystal ball to get rich & predict something meaningful. Nobody knows what's going to happen. How are we supposed to take ppl who don't know the definition of a recession & "woman" seriously?"

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Hubster43
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Re: Thumping noise and feel at slow speeds

Post by Hubster43 » Mon Jun 12, 2017 5:00 pm

Never clunking until last year. Just a nice growl that we have gotten used to. When I changed the transmission fluid last time it was surprising clean. I regretted using the Redline stuff right afterwards. I think I thought it was going to be the magic bullet to quiet things down back there. It is very possible that the noise started right after that. I don't think it is anything in the tires since I can't get the clunking under acceleration. It hate to dump the redline stuff since I paid too much for it. I checked the level last week and it was very clean and full.

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sgkent
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Re: Thumping noise and feel at slow speeds

Post by sgkent » Tue Jun 13, 2017 9:49 am

With the inner CV's disconnected does the thunk go away when you rev and decal the engine or turn the differential by hand while in neutral? You have to turn both sides the same direction. You can also try moving the axles in and out to temp regrease the CV joints and see if it quiets down.
TBone208 wrote: "You ppl are such windbags. Go use your crystal ball to get rich & predict something meaningful. Nobody knows what's going to happen. How are we supposed to take ppl who don't know the definition of a recession & "woman" seriously?"

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Amskeptic
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Re: Thumping noise and feel at slow speeds

Post by Amskeptic » Wed Jun 14, 2017 6:11 am

Hubster43 wrote:
Mon Jun 12, 2017 8:15 am
terrible thumping at slow speeds while braking.
Forget the transmission and axles if this occurs only while braking.
Drive at 10-15 mph on a parking lot or abandoned road and apply just the hand brake. Does the car make the noise? Do you feel a pulsing?
Colin
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles

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