Knocking sound when shifting 2008 5-speed GT

[DPHC13]

Hey guys I'm having a problem with my 2008 GT 5-speed. When I shift I get a "knock". It's like this... Start off in 1st, pushing clutch *knock put into 2nd let off clutch *knock... repeat. It's hard to tell if it's coming from the front or the back. Its easy to replicate all I have to do is drive at a steady pace and let off the gas, when i get back on the throttle it knocks. I am not gunning it back on the gas either i'm just rolling on it. Listen to the video and see if one of you have dealt with this before. I checked the Motor Mounts and they seem good. I've replace the rear lower control arms. It's like when the car is under a load something shifts and knocks. The sound is actually like if you lightly knocked on a door with your fist. Would low oil in the pumpkin maybe cause this? I also checked the driveshaft and nothing is obvious. Their is about a half inch of play when you turn it. Also if i pull on it front to back it moves a little bit. ALSO in the videos I'm giving it gas then letting off then getting back on it thats why its knocking every couple seconds normally it only does it when i shift.
THANKs
http://vid80.photobucket.com/albums...8-D6D1-4F9A-800D-A83E85E40D61_zpskso5txja.mp4
http://vid80.photobucket.com/albums...6-7F1C-4103-A25D-29F01D8677FC_zpszb8yfuk2.mp4

 

[BEAST]

Loose cross member.

 

[DPHC13]

Is the cross member the aluminum brace that holds up the trans? It also has a rubber bushing (block) attached to it? If thats what your talking about than I checked it and it's tight and I also removed it and checked the bushing and that good to.

 

[BEAST]

Damn. Have you checked the upper control arm mount?

 

[Boss281]

Stock upper control arm or aftermarket? I remember in the earlier cars where aftermarket uppers had different size bolt holes from the stock mount, or something like that, and shifting caused that loud knock in the back. I bought a 2007 used and it's doing this, and I think it's because an aftermarket upper control arm was put in the stock mount, and the bolt is moving around the bolt hole on the mount. It's only a mm or two, but the difference is enough to generate the sound. Just a thought if you have an aftermarket upper...

 

[DPHC13]

The rear upper is stock and I bought a new poly bushing for on top of the pumpkin. I checked the arm and the bushings seem tired like if I take a bar and pry them they move real easy.... I mean REAL easy. They don't show any signs of ripping or anything. I guess I'll try and replace that bushing and see what happens. It looks like a real PITA to get out. I'll take some pics of the job. If anyone has any more suggestions that would be great. Thanks!

 

[Dino Dino Bambino]

If anyone has any more suggestions that would be great.

Transmission mounts
Driveshaft U-joints
LCA or UCA bushings

 

[JeremyH]

I had this same issue a long time back, was more a clunk then a knock but under the same exact conditions you are describing. I believe it was the aftermarket shifter or one piece driveshaft that fixed it as I never had it after that. So check the shifter mounts and the driveshaft boots and middle bearing etc.

 

[DPHC13]

I will check the shifter later today. I have a steeda short shift block. Lastly when I shift it really sounds like crap. Maybe something worked loose.

 

[JeremyH]

I have seen the bolt for the shifter linkage back out causing shift alignments to be off.

 

[DPHC13]

Well I checked everything and the only thing my small brain can think of right now it the rear upper control arm and the bushings. I have the differential bushing so I'm gonna change it and see what happens. This is my progress so far.
Needless to say it is NOT NOT NOT fun getting this thing out! Let's see how it Gos getting the new one in.

 

[Boss281]

On Monday I'm putting in a new upper control arm mount, adjustable upper control arm, and the the two lowers (all BMR). I'll be really surprised if the clunk is still there...

 

[DPHC13]

I think mine is a one inch drop. So I replaced the differential bushing on top of the pumpkin and it didn't do a thing. Sucks. So here is a new video. Let me explain what's going on here. This is my car jacked up so the wheels can spin freely and I can see and hear what's going on when the clutch is let out and the drivetrain is engaged. This is and extreme example because I'm haveing my helper almost pop the clutch so I can really hear and I was hoping to see what was happening. But as you can tell nothing is getting jarred and nothing is moving like crazy. I was hoping for some kind of bad bushing or a bad motor mount. So I hope after watching someone has had a similer problem and can tell me what the hell is going on.

 

[Boss281]

Well, a BMR upper control arm, paired mount, and lower control arms were installed and the clunk is still there, although the ride was much smoother that with the previous owners UMI kit. Stumped, the 2007 went back up on the lift with a driver, and we shifted gears with the suspension hanging. The clunk is clearly coming from the slip joint area of the aluminum drive shaft (Powerhouse model) when the clutch is engaged or disengaged. Are there dampeners or something else inside that could come loose and cause this clunking sound.

 

[skwerl]

With the car on jack stands and in neutral crawl under the car and turn the driveshaft back and forth by hand. On my MT-82 I was able to replicate my clunk and mine is coming from inside the transmission, although usually it's a u-joint.

 

[Boss281]

If that's directed my way and not the OP, I've done that. Definitely coming from the slip joint...

 

[DPHC13]

I'm gonna get a adjustable rear upper control arm so I can corect the pinion angle. I'm thinking that the pinion angle is off and it's causeing the shaft to pull out of the differential. It's a long shot but I need to fix the pinion angle anyway. I'm hoping it's anything but the transmission. I wish it was a U joint but they look so damn good (no slop) when I shit it into gear. I'll keep you posted and thanks for the replies. boss281 is the "slip joint" the part of the shaft that is covered but a rubber boot? On the stock driveshaft

 

[Boss281]

Yep, it allows for suspension travel. On my powerhouse driveshaft it's protected by a rubber boot as you describe...

 

[Boss281]

I am going to replace the Powerhouse driveshaft with a Steeda model after the holidays...