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Discussion Starter #1
Cross post from N-Bunch of F'in letters.

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After installing a Group N trans mount and Whiteline x-member bushings a month or so ago, I get the occasional light knock when accelerating from a stop, straight or turning. This occurs in day to day driving, not necessarily when stomping on it. Feels like it's coming from in front of my feet, as the clutch begins to engage. Aside from this, the NVH is enjoyable.

-I've checked/double checked torque on the bolts I touched during install,
-My sway bar brackets, and endlinks (all Whiteline) are torqued, and have plenty of grease on the bushings, bushings are not worn,
-CV's are good, no play, no tears,
-It's unseasonably cool right now (garage floor a little cold and wet), so I did a quick visual/feel inspection on the motor mounts, appear to be good, bolts (at least the ones I can see are snug)
-OEM pitch stop checks out

I'll be doing Group N motor mounts as time allows, just wondering if the trans mount was able to accentuate a "tired" motor mount? I realize the engine is stabilized from the trans mount as well.

Didn't add in the original post that strut bolts are torqued, and BJ boots are in tact. Didn't jack up the front end to check for BJ play however, was on ramps.
 

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Discussion Starter #2
Should clarify; it happens from a stop, whether I'm going straight or turning.
 

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Disregard; I thought you were talking about pulling timing
 

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If it wasn't there before the bushings, but is now, then I'd suspect the bushings introduced it. Maybe the tranny or crossmember is knocking into something now due to a change in play. You could always unbolt and retorque and see if that changes things.
 

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Discussion Starter #5
EJ257...none of that knock :)

Teflon, have already done that, no change. I've looked for points of contact as well, none found. It sounds a helluva lot like your typical sway bar pop, but they've been greased, torqued, etc... and the noise showed up post trans mount install.
 

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I'd guess the torque of the motor is now pushing the tranny into something like the tunnel or another part.
 

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Discussion Starter #7
Plenty of clearance around the trans from engine bay through tunnel, the trans is pretty locked down now. The nearest, OEM soft, bushings are the carrier bearing, and the engine mounts. The carrier bearing is good, but I'd love to find the time to more closely check/upgrade the engine mounts.

In an effort to describe the sound more ambiguously it's more of a "thunk" than a "knock".
 

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Discussion Starter #8
Additionally, this thunk like sound is just that, a sound, and not violent in any way. It can't be felt, a bit misleading in my first post. It sounds like it's coming from right in front of my feet, rather than feeling that way. There's a motor mount in that area, I think that's the side of the engine that lifts during acceleration (?). Just thinking out loud. I can't say I've had my hood open and revved the engine lately.
 

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Ancient thread revival...

I have this same issue on my 02, with 20300 miles (yes, under 21K miles) It happens under braking, and again when I get off the brakes and back on the power. Its a distinct sound the sounds like someone knocking 1-3 times on the firewall just above the accelerator pedal. All the mounts are like new. Under braking, I get from one to 3 knocks depending on how hard I am on the brakes, then as soon as I'm back on the power, there is 1 knock as the nose lifts under acceleration. No noise through the corner. I can't see anything that is even close to having contact with the firewall either. The car is my commuter car, its in like new condition (I put the second set of tires on it since new back in January.) You can just about eat off the underside of the car.

Does anyone have any ideas?

Thanks,
Will
 
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