Slight vibration under acceleration

[ChrisA]

I’ve had a slight vibration under acceleration since I put the car back on the road. It comes in at about 40mph and there’s a slight buffering noise, that disappears as you get faster.

I’m convinced it’s the drive shaft support bracket. So I’ve gone and brought one of these and, by applying a bit of man maths, I’ve gone a treated her to a black tip Miltek.

Getting fitted on the 23rd, fingers crossed this fixes it.

https://www.jxbperformance.com/products ... er-upgrade

[TOPMAN]

That’s was a bargain


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[srichards]

Isn't 40 mph where the torque converter lock up happens?

[ChrisA]

Isn't 40 mph where the torque converter lock up happens?

That’s far too technical for me to know what you’re talking about let alone suggesting. Can you tell me more?

[srichards]

The torque converter does something at around 40 mph. It's called lock up. I don't have much more technical knowledge beyond that, sorry! I could feel 'something' on mine when it was around 38-42 mph or so. You could just feel there was something occurring.

All I know is it's for efficiency as you remove the drag from the liquidy stuff and make a direct drive I think. Hopefully someone will explain it properly...

[Shoppinit]

No, the torque converter locks and unlocks all the time at all different speeds.

Vibration under acceleration is usually either inner CV joint or coil packs. Probably the former.

[srichards]

No, the torque converter locks and unlocks all the time at all different speeds.

Vibration under acceleration is usually either inner CV joint or coil packs. Probably the former.

Oh. I thought it only locks at 40mph. Someone told me it did. Every day you learn something new

[Shoppinit]

Yeah, the TC transmits power via fluid resistance between the impeller and the turbine. Because it's fluid, the turbine never quite reaches the speed of the impeller, so when they get to within about 10% of each other, the electronic clutch comes into play to clamp them together. It's essentially a fuel saving device and locks up when the car detects you're at cruising speed. It won't lock under acceleration, for example. Well, maybe very light acceleration.

[Shoppinit]

Still, it's easy enough to test for with the Vagcom. You can see when the clutch is open, in the process of locking and locked in real time. If it coincides with your noises then that would be it.

Most whining is belt noise or cavitation. I'd want to double check the ATF level. And make sure the right ATF is in there.

Or it could be the propshaft centre bearing.

[ChrisA]

Still, it's easy enough to test for with the Vagcom. You can see when the clutch is open, in the process of locking and locked in real time. If it coincides with your noises then that would be it.

Most whining is belt noise or cavitation. I'd want to double check the ATF level. And make sure the right ATF is in there.

Or it could be the propshaft centre bearing.

Thanks Shop. I’ll try and look into the Vagcom diagnostic when I’m feeling brave enough.

The whining isn’t belt noise, although I do have some whining coming from the belt area. No, it’s certainly a drive whine. Unit20 did a gearbox services shortly before I took the car off the road, so I’m certain it was done properly, however this was coming up 4 years ago now (but less than 1k miles ago). I’m going to get the fluids replaced this month though just to be on the safe side.