Screech sound @ WOT shift

[xmetallicaxguitaristx]

Ok.. so I know this can be nothing good... lol

Whenever I am doing hard shifts (A4) @ WOT into 2nd, or even third, I sometimes get a screeching sound that sounds ****ing terrible and only happens for like .2 seconds during the shift.

The best way I can describe the sound.. is when you hear a POS car with its belt slipping or something.. Picture that, but only for a split second and during a hard shift.

What is the actual cause of this? Is this my band going? I know nothing about transmissions.. So I don't even know where to start.

[grayman]

Re: Screech sound @ WOT shift

do you have your AC on while this is happening?

[xmetallicaxguitaristx]

Re: Screech sound @ WOT shift

Yes I always have A/C on. FL + 95* + 100% humidity = not fun.

What would that have to do with it? The sound sounds like it is coming from the bottom of the car, like the transmission.. Are you saying my acc. belt is slipping when I shift?

[Skinny]

Re: Screech sound @ WOT shift

I was going to say something about the belt slipping on the shifts. I've seen it before but more often with the V8 dual-belt design. It also could be the A/C compressor itself if it's not switching off like it should at WOT.

[Meatyshells]

Re: Screech sound @ WOT shift

um, are you sure its not the tires chirping?

[xmetallicaxguitaristx]

Re: Screech sound @ WOT shift

um, are you sure its not the tires chirping?

Yes, because to get the tires to chirp, I have to let off the gas @ 5850 (stock shift point) and then hit it again after the shift.. it's a weird timing thing... But this most definitely isn't the tires chirping.. because you can feel when the tires chirp. I have a transgo HD2 and corvette servo btw... This occured a little bit before I had the shift kit/servo, and now it happens alot after the kit/servo... Which is why I am thinking my transmission is ****ed.. which I hope is not the case..

I have to go somewhere in a few minutes.. I'll try turning off my A/C. So if it doesn't make the noise with A/C off (which I doubt) my compressor clutch or some bearing is ****ed?

What if I turn it off, and it still makes the noise? What the hell is creating that noise? Could something be slipping? It doesn't grab as hard when it happens, but it still shifts fast/hard.




Also, I did some scans before/after the shift kit. My shift times were pretty close to the same, even though I can physically hear it shifting WAY faster.. Is this just the scanner? Stock transmission with just a little bit higher line pressure and commanded shift times of 0.15, shifted in about 0.5-0.6 seconds, ONLY at part throttle.. @ WOT it was more like 0.6-0.8...

Now with the shift kit/servo it is 0.5 @ WOT every time, but it sounds faster than that.. It also has way more pressure @ WOT even though I changed the line pressure back to stock because it does that mechanically.





I really hope my transmission isn't ****ed.. lol


EDIT: Another weird thing... If I am in 2nd, and I am going 30-32 mph, and floor it (it will drop down into first) it will chirp shifting into 2nd automatically every time, even floored.

If I am in 1st, and manually shift into 2nd, it will sometimes make that screech sound, sometimes chirp.

If I am in D (not OD but D) It will chirp half the time but not make that screech sound too often), If I am in OD It makes the screech sound only dropping into 2nd @ 65 mph once it shifts into 3rd it makes the sound.


Everyone I talk to says it's fine to upshift manually, but with the kit, or ever, it's bad to downshift manually because there is not enough pressure in the trans for it to shift safely, unless you are hitting the gas a little bit or something.

[Meatyshells]

Re: Screech sound @ WOT shift

why do you have to let off the gas when it shifts and then give it gas after the shift?

[xmetallicaxguitaristx]

Re: Screech sound @ WOT shift

why do you have to let off the gas when it shifts and then give it gas after the shift?

No idea.. but if I hold the gas down full throttle through the shift it makes that screech.. If I let off then hit it again, it will chirp the tires and not make a screech.. and shift faster.

[Meatyshells]

Re: Screech sound @ WOT shift

is this problem when the trans gets hot? or all the time?

When i had my auto, the trans would slip at wot and would ping off the revlimiter unless i let off the gas. But only when the trans was hot

[xmetallicaxguitaristx]

Re: Screech sound @ WOT shift

Mine doesn't slip like that.. so I don't even know if it's slipping. It has never "missed" a shift and bounced off the rev limiter. I haven't been including the trans temps with the scans, but maybe I should start. I think I should also get a transmission cooler.. Part of the reason I got a shift kit was to help the transmission last longer, but I also realize if something is already failing it will just speed up the death of the transmission, which I hope is not the case.

I don't really let off the gas so to speak, when I look at the frame by frame view in the scan log, one frame I am @ 99.6% TPS then the next I would be at say... 66% and the next 99.6%.. If you know what I mean. I just slightly let off the gas and hit it instantly.. and for some reason that gives me a faster shift. A lot of people that I talk to with A4's say they do the same thing.

[xmetallicaxguitaristx]

Re: Screech sound @ WOT shift

Ok I just drove it around for a while.. now it isn't doing it anymore for some reason... I don't know why. But I first tried without the AC, and it didn't make the noise, and it chirped. Then I tried with AC on, and it chirped again.

So now it isn't screeching.. Could it be that when I drove it the other day it was just too hot or something?

[frydbrain]

Re: Screech sound @ WOT shift

I know this tread is old but I'm experiencing the same problem too. Are you still having this problem? Anyone else? Mine does it with the AC off.

[flamingchicken]

Re: Screech sound @ WOT shift

mine does it when i am romping on it. i have always believed it to be the belt spinning at a high rate of giddie-up then being slowed fast by engine rpm change...but thats just my .02

[a-master]

Re: Screech sound @ WOT shift

check your belt for wear and tear, and see if is on all the pullys correctly. if it needs to be replaces, they are not too expensive...