ghostrider990

A few times lately, I've experienced a rather abrupt and noticeable "thud" from the transmission or rear differential (not sure) when in reverse at slow speeds, and also in D mode, at varying speeds,mostly under deceleration / downshifting. I have no idea exactly what circumstances preclude this anomaly, but it has become more apparent and frequent in the past two months.

Has anybody else had any issues like this, or noticed odd shifting or clunking under deceleration?? I don't think this is anything but an odd happenstance at this point, but it isn't normal, and never did it before this point.

just a tick under 16k miles on the clock.. Bone stock '17 s4.

gr

mplsbrian

I'm only about a thousand miles over you (also bone stock) but I experience no jerkiness or noises while decelerating.

Do you have the sport diff or the standard diff? I have the sport diff fwiw.

I do occasionally feel a small amount of clunkiness/jerkiness, particularly before the car is fully warmed up while at lower RPM & engine speed, but usually only on acceleration and I have always believe what I am feeling is nuances with the torsen-based quattro. This is my first full time AWD car.

jondin2000

m332is

If you're in Sport mode (transmission) the downshifts and rev matching are way more pronounced.

ghostrider990

Yes, Sport Diff on mine -- which was actually my first thought, the first time i felt it, in reverse, and backing down my moderately steep driveway.
And let me be clear: this is NOT jerkiness while on and off the throttle -- I find THAT to be "normal" for this car, and have experienced those sensations since the car was new.
I have also experienced the "unintended acceleration" or whatever we've decided to call that situation, where the throttle stays on after we let up off the pedal. Yep, it's happened - but only twice. And NOT repeatable on demand.

This is a distinct CLUNK or THUD, like when an automatic trans. lockup converter suddenly catches-up to itself late, after having missed an up or downshift.

Like i said, just started happening, and it is happening a bit more now. Not consistent or enough to take to the dealership -- but just looking to see if there is any consensus out there of similar behaviors.

gr

Mr.Meme Yo Girl

I've noticed slow/clunky shifts usually during 1st and 2nd gear at slower speeds. the worst is when slowing down to a near stop and shifting down from 2nd to 1st, it feels like its slams the gear and car jerks. also sometimes when shifting from 1st to 2nd, the car does also shift hard and just feels like it nearly missed the gear change or something. i always feel like the transmission is getting damaged somehow from that happening and i get a sick feeling in my stomach lol. I cant say for certain that I've head an audible thud but ill pay more attention for it. As mplsbrian mentioned, when the car is cold the transmission is noticeably jerky and slow which is why i always let it warm up a bit before driving. I'm right under 12k miles with no sport diff. I'm just hoping our cars don't have transmission issues, its enough to deal with knowing theres been reports of the engine going lol

m332is

The ZF 8 speed is used in a number of platforms and across many manufacturers. I have not heard of issues with other high performance cars.

mplsbrian

Ghost - had a thought while driving today. What if the clunk is excess movement in your transmission mount (or other mounts e.g. differential)? See below for a video of what I mean. Might be worth checking underneath to make sure your bushings for subframe, transmission, rear diff, etc mounts are all intact. Never heard of a failure this early but you did say the problem developed recently.

As you can see in the video below (which is not a B9 but these exist on the B9, as do aftermarket upgrades for them from companies like 034 and ECS) there is a lot of movement and if that bushing was gone or damaged I could imagine clunking sounds in an otherwise normal-seeming car.

ghostrider990

Thanks Brian.

I won't say this isn't possible, but to me alot of these aftermarket companies that sell stiffer urethane bushings actually make you feel MORE movement and transfer movement and vibration back into the chassis itself - maknig for a harsher experience.

Nope. This is definitely an abrupt thud, and suspect of the torque converter on upshift and downshift. Also happened that one time in reverse on a decline, which made me suspect the rear or even center diff.....but I doubt it's bushing related. But I get where you're coming from.
Sometimes things fail, and it can mask itself as another issue altogether!

There IS still that little issue of my leaky front CV Axle Boot that I need to get looked at next time I'm at the dealership -- but that really shouldn't be related to this.

Thanks for the input.

ghostrider990

Who pissed in your sauerbraten???

With 3500+ posts to your credit, it seems kind of obtuse that you'd show-up randomly to troll the S4 forum, flame a guy who regularly contributes to the other owners here, and then offer no thoughts or ideas of your own towards the betterment of the community.

So, show with your wealth of experience and knowledge, please do tell us how the Quattro system works, and what YOU think is happening.

gr