shoebear
Veteran Member
- Joined
- Aug 1, 2002
- Location
- Colorado Springs, CO
- TDI
- 1998 Jetta, 2003 Jetta Wagon, 2005 New Beetle, 2013 Sportwagen
I've had an issue on my 2003 that has gotten worse over the last 2-3 years and about 75K mikes, and I'd like suggestions on how to diagnose it.
From about 40-55 mph and under acceleration, there is a pulsing vibration that seems timed about to the rotation of the wheels. The pulsing is uneven; some pulses seem stronger than others. I feel this primarily in 4th gear, because it's the most appropriate for acceleration in this speed range. However, I've felt it also in 3rd gear. The stronger the acceleration, the stronger the pulsing, and if I engage the clutch and take my foot off the accelerator, the pulsing stops completely. This has been consistent across 4-5 sets of tires (both summer and winter) and numerous balances.
Clues -- maybe relevant and maybe not:
My current hypothesis is that one of my inner axle CV joints is going lopsided at certain speed/load combinations, causing the axle to flop around. How can I test this? My only idea is to strap a camera down there and watch the axle when it's pulsing. I'm thinking a GoPro, but I would have to buy one.
Perhaps the engine is too far to the right and causing the inner CV joints to run off-center, causing a floppy axle. I plan to center the engine in the next couple of weeks when I have time to do it; if this is the issue, re-centering should improve or eliminate the pulsing.
I would appreciate any ideas about causes, diagnosis, and cures. Thanks!
From about 40-55 mph and under acceleration, there is a pulsing vibration that seems timed about to the rotation of the wheels. The pulsing is uneven; some pulses seem stronger than others. I feel this primarily in 4th gear, because it's the most appropriate for acceleration in this speed range. However, I've felt it also in 3rd gear. The stronger the acceleration, the stronger the pulsing, and if I engage the clutch and take my foot off the accelerator, the pulsing stops completely. This has been consistent across 4-5 sets of tires (both summer and winter) and numerous balances.
Clues -- maybe relevant and maybe not:
- I lost my right axle at freeway speed about 6 months ago. The inner CV joint was apart and the 8mm bolts from axle to transmission were snapped. A shop replaced the axle for me (had no time at that point to do it myself).
- About a month ago, I was under the car and noticed that the 8mm bolts were loose. One or two had backed all the way out and were only being held in because the head was against the rubber CV joint boot. I took it back to the shop that installed the new axle and had them retorque the bolts. I checked them again this past weekend after a few thousand miles, and they were all still tight. This will be a regular check for me at <= 5K mile intervals until I'm satisfied that they are not loosening after being torqued properly.
- I had my transmission mount replaced about a year ago, and I replaced my engine and dogbone mounts about a month ago. This didn't help; if anything, it made the pulsing more noticeable.
- Both the transmission and engine mounts have oval holes for the bolts that go down and engage the aluminum adapter block. These allow for about 1-2 cm adjustment for the engine left or right. When I replaced the engine mount, I noticed that on both the engine and transmission mounts, the engine is adjusted all the way to the right.
My current hypothesis is that one of my inner axle CV joints is going lopsided at certain speed/load combinations, causing the axle to flop around. How can I test this? My only idea is to strap a camera down there and watch the axle when it's pulsing. I'm thinking a GoPro, but I would have to buy one.
Perhaps the engine is too far to the right and causing the inner CV joints to run off-center, causing a floppy axle. I plan to center the engine in the next couple of weeks when I have time to do it; if this is the issue, re-centering should improve or eliminate the pulsing.
I would appreciate any ideas about causes, diagnosis, and cures. Thanks!
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