Haldex or tires ?

[Vagfan]

Hi everyone, the following happens on my car:

In the morning i hear and feel, about 3 or 4 times, a sort of hesitation/blocking on the rears. It's only a very short moment, maybe 0,5s. It sounds like there is a very small firecracker ín my tyres which gives a sort of metallic/grinding noise which is muted by the rubber of the tyre. It does it when turning at low speeds, but also straight accelerating and when off throttle, all at random. After a mile or so, it's gone. No more noise. Full throttle when warm gives normal quattro drive. I already could heard it last summer, but far less. It's becoming more pronounced now, maybe because of the cold ? There are no faults reading out OBD and the haldex got it's new oil 4 months ago.

I have read a lot about Haldex quircks icm with the Michelin Pilots 4s (i have those new all around since last summer, staggered so 255 front (at 2,8 bars) and 235 rear (at 2,4bars) and had about 2500 miles since then. Weird thing is that i don't have the 'standaard Michelin problems' such as the TC light coming on. Also it does it when driving straight, not only when turning at low speeds which also acquit the haldex. I don't have to kill the ESP for normal drive. And as said before, the sound is only audible/feelable untill 2-3 minutes after the cold start and about a mile of driving. After that first mile i can put full lock on and the car turns in circles around without any strange noises or dragging.

I discussed this with my Audi dealer. They are known with the Haldex quircks but think this is something else. They said to me that they have more 'S and RS-cars' at their dealership on which the owners have the same complaints. They disappear or grow less when it's getting warmer again ? They think it's the rear tyres settling in. You would think that is bullcrap, but when i drive the car more through the day it's almost not existing. Only after the night and a longer time stationary on my driveway it will pop up.

Does this sound similar to any of your cars ?

 

[flybynite]

I have read a lot about Haldex quircks icm with the Michelin Pilots 4s

Nothing wrong with the PS4S but it has the same problem as any other Non-RO2 Tyre, it's rolling radius is outside the difference specified by Audi for haldex cars if used in the OEM staggered config. The RO2 tyres like the Pirelli are a non-standard size for a 255/30/19 to keep the rolling radius difference within limits. I use PS4S with no issues at all but in a square setup not staggered.

There will be people argue either way if this makes a difference until the cows come home but I see the logic of the limit Audi set and stick to it. I have had the RO2 Pirelli next to a PS4S and standard Audi AO Pirelli and there is a marked RR difference

Have you done a Haldex oil change and more importantly checked the gauze on the pump strainer? That can cause issues, pump may be on its way out.

Have you watched the Volkswizard Haldex service video? Is your problem like he shows in the beginning on the Golf 7R?

 

[Vagfan]

I didn´t check the gauze on the pump strainer because i let it service at a (RS)-dealer because it's on warranty. I think they won't clean the gauze, just refresh the oil ? I watched the Volkswizard video on Youtube as you mentioned. That car lost reardrive seeing that wheelhop at the fronts. I don't have that (untill now at least). I know about de non RO2 tyres with PS4S as the worst, but i have no TC lights whatsoever. And the most particular is that the sound the rear makes is only noticable en audible for the first couple of minutes of driving which sound like wheelspeedcorrections at the back, but only when bare cold in the morning. As example. Yesterdag i did 4 drives with the RS3. At 8am i left for work, could hear and feel 3 corrections on the rears. At 2pm i went to a customer. No corrections at the back. I left there at around 5pm, no corrections. In the evening i collected my son at 10pm. No corrections. This morning at 11am i drove again.....and heard 3 or 4 smaller corrections...and so on... The rears will correct in corners but also on straights ! Tried again 2 full left and right circles on a parkinglot. No dragging or noises whatsoever. When it's the diff or pump, that would not be possible without grinding noises is it ?