hey everyone, im just curious...I have a 2004 Touring 5AT and whenever i shift to 3rd gear in the "manual mode" at higher RPMs, i hear like a loud "THUD" comming from the back of the car. Does anyone know what that is? is this normal? Thanks

 

Sometimes I hear that noise too, and I’ve always been curious as to what it is and if anyone else on the forums is having the same problem. If you shift it at a higher RPM it will either lessen or you won’t feel it. I'd really like to know the answer to this as well. Just out of curiosity, do you hear like a ticking noise about 20 seconds apart after you shut your car off? I always get this little ticking sound when I shut my car off, and it is very noticeable and annoying.

 

when shifting, apply constant throttle presure. I think the thud is normal if you dont accelerate. It take time to learn to drive the manumatic mode, like a manual.

 

I think this may shead some more light on it too ... https://my350z.com/forum/showthread....at+manual+mode

 

Here are some possibilities

1) It might be the torque converter locking or un-locking. At higher RPMs 3rd gear employs a lock-up clutch which mechanically connects the engine-side shaft to the drivewheel-side shaft much like a clutch connection in the 6MT. When the lock-up clutch engages you might get a thud.

2) You might have lifted-off the throttle when you shifted. When shifting in manual mode, the 5AT likes a constant or accelerating throttle unless you are downshifting and your shift puts you way over the rev-limiter. If the computer determines you're going significantly over the rev-limiter it will delay or cancel the shift command. Speed difference might cause a jolt or thud when it locks or couples.

3) You are in an aggressive shift profile which would cause the shifts to prefer faster shifting over smoother shifting. You'll get a thud or jolt similar to the F1 shifters in the most aggressive algorithms because of fast shifting.

4) It might be your LSD locking up.

5) You broke it.

 

I'm thinking im case number 3. I think most of us that have had that noise/jolt, probably are. Thanks for the broken down list of possible issues . Any idea why my Z makes a ticking sound when i shut it off?

 

You sure the thud isn't your gym bag sliding around in the back due to the excessive acceleration?

 

I believe you are referring to the metal contracting. When the engine's hot, the metal in the engine and whatnot expands. Once you turn off the car, it starts cooling down, and thus parts in contact with each other start "sliding" relative to each other ever so slightly and this is what you hear.

 

Thanks, for the clarification. I haven’t heard anyone else speak about this … am I the only one who has had this noise after the car is shut down?

 

Both my SS and G do this when they are shut off - as well as moms Tahoe...I would'nt let it bother you.

As for the thud, I usually get it when im accellerating fast and shift too early! I dont think I ever got a thud when I'm off the gas and shift - at higher RPMs. Normally I'll be playing with someone and take the gear to around 5K and let off the gas, then shift to the next higher gear.

lowtempo is right though. I've come to where I can make the shifts in MM mode just as smooth as in D depending on how hard I'm on the gas and how long I want to keep a certain gear.

 

You're not the only one...pretty much every car I've ever driven has done it at some point. Can't fight the laws of physics.

 

thanks a lot, i think i have a better understanding of it

 

Well, with both my other cars I’ve heard the cricks and cracks after shutting it down, and I knew it was normal. The thing that got me about this was that it was the same cracking noise repeated in synchronized time at the same volume, not random like my other cars. Glad to see I’m not the only one. It doesn’t even bother me; I just wanted to make sure it isn’t something I needed to worry about.

 

Maybe your car is talking to you. I have had inanimate things talk to me before, well before I got help anyways.