Drivetrain thumping during acceleration and hill climbs
10-22-2013, 07:23 PM
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Drivetrain thumping during acceleration and hill climbs
I have a 1999.5 B5 1.8TQ with 281k miles.
About 10k miles ago I noticed a metallic squeaking sound coming from under the vehicle that sounded like a bad bearing. The sound roughly corresponded with the wheel rotation speed and only was heard when I put the car in a "load" state (accelerating or climbing up hills) while in the 5-20 mph range. At constant speed on a level slope or during deceleration, the car did not make a peep. It may have been my imagination, but engine braking seemed to decelerate the car quicker after the sound appeared than before.
Driveability was not affected and no fluids were dripping from the underside of the car, but as a precaution I took the car to a shop to get their assessment. They put it on their rollers and tried to reproduce the conditions causing the issue but they couldn't replicate the "load" condition very well. They put the car on the lift and checked the drivetrain area for any obvious defects or excessive play in the bearings and found nothing out of the ordinary. They told me to bring it back when the issue got worse, and shortly after the visit to the shop, the sound completely disappeared for a while.
Fast forward to this past weekend when I was doing some mountain driving in southern Utah. On an uphill climb on a 7% grade I was accelerating normally (not aggressively) and all of a sudden I started hearing a thumping sound coming from under the floorboards. I immediately backed off the power and limped my way up the hill and upon reaching level ground the symptoms disappeared. This occurred during subsequent hill climbs.
On my drive back home to southern California I noticed that the symptoms occurred more often; they would return when climbing even a barely perceptible uphill grade. The sound would start as a pitter-patter but increase in intensity as the road steepened. I would always let off the gas when this happened, so I am not sure what would happen if I tried to accelerate through the thumping sound and vibration--not sure I would want to find out. Still, during normal cruising, deceleration, and hill descents the car continues to exhibit no obvious problems.
Any idea what would be the likely culprit? Also, does anyone have a good diagram of the drivetrain system in the B5 A4? I don't have access to ETKA at home.
About 10k miles ago I noticed a metallic squeaking sound coming from under the vehicle that sounded like a bad bearing. The sound roughly corresponded with the wheel rotation speed and only was heard when I put the car in a "load" state (accelerating or climbing up hills) while in the 5-20 mph range. At constant speed on a level slope or during deceleration, the car did not make a peep. It may have been my imagination, but engine braking seemed to decelerate the car quicker after the sound appeared than before.
Driveability was not affected and no fluids were dripping from the underside of the car, but as a precaution I took the car to a shop to get their assessment. They put it on their rollers and tried to reproduce the conditions causing the issue but they couldn't replicate the "load" condition very well. They put the car on the lift and checked the drivetrain area for any obvious defects or excessive play in the bearings and found nothing out of the ordinary. They told me to bring it back when the issue got worse, and shortly after the visit to the shop, the sound completely disappeared for a while.
Fast forward to this past weekend when I was doing some mountain driving in southern Utah. On an uphill climb on a 7% grade I was accelerating normally (not aggressively) and all of a sudden I started hearing a thumping sound coming from under the floorboards. I immediately backed off the power and limped my way up the hill and upon reaching level ground the symptoms disappeared. This occurred during subsequent hill climbs.
On my drive back home to southern California I noticed that the symptoms occurred more often; they would return when climbing even a barely perceptible uphill grade. The sound would start as a pitter-patter but increase in intensity as the road steepened. I would always let off the gas when this happened, so I am not sure what would happen if I tried to accelerate through the thumping sound and vibration--not sure I would want to find out. Still, during normal cruising, deceleration, and hill descents the car continues to exhibit no obvious problems.
Any idea what would be the likely culprit? Also, does anyone have a good diagram of the drivetrain system in the B5 A4? I don't have access to ETKA at home.
10-23-2013, 04:28 AM
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Drive shaft center support bearing
I have a 1999.5 B5 1.8TQ with 281k miles.
About 10k miles ago I noticed a metallic squeaking sound coming from under the vehicle that sounded like a bad bearing. The sound roughly corresponded with the wheel rotation speed and only was heard when I put the car in a "load" state (accelerating or climbing up hills) while in the 5-20 mph range. At constant speed on a level slope or during deceleration, the car did not make a peep. It may have been my imagination, but engine braking seemed to decelerate the car quicker after the sound appeared than before.
Driveability was not affected and no fluids were dripping from the underside of the car, but as a precaution I took the car to a shop to get their assessment. They put it on their rollers and tried to reproduce the conditions causing the issue but they couldn't replicate the "load" condition very well. They put the car on the lift and checked the drivetrain area for any obvious defects or excessive play in the bearings and found nothing out of the ordinary. They told me to bring it back when the issue got worse, and shortly after the visit to the shop, the sound completely disappeared for a while.
Fast forward to this past weekend when I was doing some mountain driving in southern Utah. On an uphill climb on a 7% grade I was accelerating normally (not aggressively) and all of a sudden I started hearing a thumping sound coming from under the floorboards. I immediately backed off the power and limped my way up the hill and upon reaching level ground the symptoms disappeared. This occurred during subsequent hill climbs.
On my drive back home to southern California I noticed that the symptoms occurred more often; they would return when climbing even a barely perceptible uphill grade. The sound would start as a pitter-patter but increase in intensity as the road steepened. I would always let off the gas when this happened, so I am not sure what would happen if I tried to accelerate through the thumping sound and vibration--not sure I would want to find out. Still, during normal cruising, deceleration, and hill descents the car continues to exhibit no obvious problems.
Any idea what would be the likely culprit? Also, does anyone have a good diagram of the drivetrain system in the B5 A4? I don't have access to ETKA at home.
About 10k miles ago I noticed a metallic squeaking sound coming from under the vehicle that sounded like a bad bearing. The sound roughly corresponded with the wheel rotation speed and only was heard when I put the car in a "load" state (accelerating or climbing up hills) while in the 5-20 mph range. At constant speed on a level slope or during deceleration, the car did not make a peep. It may have been my imagination, but engine braking seemed to decelerate the car quicker after the sound appeared than before.
Driveability was not affected and no fluids were dripping from the underside of the car, but as a precaution I took the car to a shop to get their assessment. They put it on their rollers and tried to reproduce the conditions causing the issue but they couldn't replicate the "load" condition very well. They put the car on the lift and checked the drivetrain area for any obvious defects or excessive play in the bearings and found nothing out of the ordinary. They told me to bring it back when the issue got worse, and shortly after the visit to the shop, the sound completely disappeared for a while.
Fast forward to this past weekend when I was doing some mountain driving in southern Utah. On an uphill climb on a 7% grade I was accelerating normally (not aggressively) and all of a sudden I started hearing a thumping sound coming from under the floorboards. I immediately backed off the power and limped my way up the hill and upon reaching level ground the symptoms disappeared. This occurred during subsequent hill climbs.
On my drive back home to southern California I noticed that the symptoms occurred more often; they would return when climbing even a barely perceptible uphill grade. The sound would start as a pitter-patter but increase in intensity as the road steepened. I would always let off the gas when this happened, so I am not sure what would happen if I tried to accelerate through the thumping sound and vibration--not sure I would want to find out. Still, during normal cruising, deceleration, and hill descents the car continues to exhibit no obvious problems.
Any idea what would be the likely culprit? Also, does anyone have a good diagram of the drivetrain system in the B5 A4? I don't have access to ETKA at home.
It sounds exactly like mine did when the center support bearing on the driveshaft decided to fail. Get under there and pull the heat shield. Grab the drive shaft and wiggle it. You will feel and maybe hear the center support bearing looseness. Find a rebuilt drive shaft and swap. $500 DIY or $750 +- at an indy shop.
10-23-2013, 07:24 PM
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Thanks. After doing a search on center support bearing problems it looks like it's a pretty common issue. When I take it in again I will also have them check the universal joint and driveshaft to see if they are also contributing to the shuddering and thumping.
10-24-2013, 04:48 AM
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Going to the dealer? That's going to be expensive.
10-26-2013, 02:17 PM
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No, an independent shop. I'll probably have them replace it with a rebuilt shaft if they can source one. Otherwise, I will supply one from Raxles, Fleet Pride, etc. and they can install it.
11-02-2013, 11:40 AM
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Following up on my earlier post, the shop confirmed that the center support bearing was the culprit. They are quoting me ~$450 for a rebuilt driveshaft plus < 3 hours of labor for a total of around $800. Sounds like a fair price given the work involved. Thanks Huskerbob for pointing me in the right direction.
11-03-2013, 02:53 AM
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Following up on my earlier post, the shop confirmed that the center support bearing was the culprit. They are quoting me ~$450 for a rebuilt driveshaft plus < 3 hours of labor for a total of around $800. Sounds like a fair price given the work involved. Thanks Huskerbob for pointing me in the right direction.
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2001, accelerating, acceleration, climbing, consistent, drive, feel, floorboard, hill, jennifer, patter, pitter, shaft, sounds, taurus, thump, thumping, walcott
