# HELP! Vibration at highway speeds and "klunk"... sporatically under acceleration (typically in 6th).



## ScottieDucati (Feb 17, 2005)

So..... I'm sadly starting to get very frustrated with my recently acquired S4 Avant 6-speed. I want to be excited about this car, but thus far it's been nothing but an uphill battle. I purchased the car in January, with 104,000 miles on the clock. My main qualifications in deciding to purchase this car were that it was a) all stock and not "enthusiast" owned, b) it was black on black leather, c) it was a 6-speed Avant, d) the car had been maintained for the last ~60k of its life at a reputable Audi service center / independent dealer. 
I knew and expected the car would need several regular maintenance items in the near future... I have extremely high standards for my cars and how I expect them to drive, I don't think I've ever bought a pre-owned car and left it alone for long. 
However, shortly after I brought the car several drive-ability issues began to rear their ugly head, including the infamous rear-diff "clunk" and shuddering under power higher in the RPM range, as well as a metallic rattling noise coming from below the center console / cabin. 
I pretty much expected with this kind of mileage that most of the "soft" mounts in the car would be pretty much done. To my surprise the one area that seems to be in decent condition is the OEM suspension, which is free of rattles or leaks and still feels pretty tight. In any event, my main concerns were initially to have the mounts checked, and to solve the rattling sound.... so it all started out innocent enough, but has resulted in pretty much a complete overhaul of drive line mounts and components. 
To date I have done the following:
- RS4 Motor Mounts, Tranny Mounts + Snub Mount
- SouthBend RS4 Clutch
- 034 Motorsports Rear Differential Mount (Street Density)
- 034 Rear Differential Carrier Bushings (Street Density)
- Rebuilt Center Driveshaft
- EPL Stage 1 Chip (which is the balls, and ignores the EGTs and rear 02 Sensors, all of which needed to be replaced on my car)
- Piggy-pipe Mod
- New wheels + Tires from Tire Rack as the car came with some pretty banged up OEM S4 wheels and 30k+ mile old winter tires.
- New rear brake rotors and pads.
So... the good news: 
- No more rattling sound (drive shaft fixed that)
- Car drives very smoothly in all areas of the RPM range (thanks to the Chip), with incredibly silky sooth power that comes on like a freight train.
- Shifting performance is greatly improved, much more precise, and a LOT smoother (thanks to the new mounts throughout the drive line)
However, here's the bad news... 
1) I still have a vibration above 60 mph. It's mostly felt through the seats, and is not felt more dramatically through the steering wheel. 
The wheel bearings have all been checked (and were initially thought to be an issue that turned out to be the OEM wheels were almost all bent one way or another). The axles (at least fronts) were also checked, I replaced my front CV boots and they were freshly packed. The wheels were brand new and tires balanced by tire-rack, my independent mechanic also re-checked the tire balancing and added 5g to two of the wheels, and they were balanced at 60 and 80 mph. 
2) Every so often, typically in 5th or 6th gear, I will still get a clunk from the rear of the car. This is MUCH more reduced than it was before, however it's more abrupt / harsh in nature, whereas the clunk from the rear diff mount being blown was a soft clunk, this one is a hard clunk and feels like it is related to the drive-train... even though the drive shaft and rear CV are freshly rebuilt with all associated seals and bearings, done by a mechanic I trust that works heavily on AWD and RWD cars. 
I'm at a loss, my mechanic can't seem to locate the vibration, and did not experience the clunk on his test drive, likely because it only happens rarely and usually it's in 6th gear while accelerating / loading in the lower (2500-4000) rpm range. 
If anyone has any educated guesses, or a recommendation for a shop that knows the S4 / Audi drive trains and chassis *really well.* I would be much appreciative. 
I really really want to love this car, however I have been unable to even think about driving it without a glass foot....


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## jettasmooth (Aug 7, 2002)

*Re: HELP! Vibration at highway speeds and "klunk"... sporatically under accelera ... (ScottieDucati)*

hey duder. You need to post this up in the S4 forums. http://****************.com/smile/emthup.gif


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## ScottieDucati (Feb 17, 2005)

*Re: HELP! Vibration at highway speeds and "klunk"... sporatically under accelera ... (jettasmooth)*

Dizone.


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