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Discussion Starter · #1 ·
Still trying to get to bottom of this.
2007 XC90 AWD 3.2
Shudders at stoplight after warms up, goes away in neutral.
It had the 2/3 bang which thankfully went away after 2 drain and fills, but did not cure the shudder.
I've changed the upper and lower trans mounts and plugs.

Here's what my wife noticed: it goes away temporarily after the car is parked on sloped driveway. It returns after about 20 miles and a few stop lights.
So why when warm?
fluid level and or condition?
Worn motor mounts?
Would fluid temp affect communication between why and tcm?
 

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if there is no high speed engine miss, then it must be something happening in the transmission. Since it occurs after the transmission has been operated enough to warm the transmission oil, ATF, then it might be related to the viscosity of the oil being reduced when warm. Shudder sounds like a catch & release, and that could happen in a wet clutch mechanism, which this transmission has. If there is an easy fix I am not aware of it.
 

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I have 2 thoughts.It may be the torque converter lockup clutch not dis-engaging.And the source of that would be a contaminated solenoid. Or,,and this sounds impossible,the rear brake drum shoes are damaged.I had this happen to me,and I thought for sure it was the T converter.I took the car to a tranny shop owned by a guy that worked for me at my tranny shop for 10 yrs.He nailed it! said he saw this before.We pulled of a rear wheel and rotor and sure enough the linings on the E brake shoes came apart.I know it sounds weird but IMO it's worth a look.If the brakes are good,I would send out a fluid sample for analysis before condemning the transmission.
 

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Discussion Starter · #6 ·
Wow. I was thinking along same lines. My rears need changing...E brake hasn't worked and with multiple systems interacting it makes sense to me ( Google BMW Trifecta )
 

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Could it be something simple, like unmetered air intake (a leak in a vacuum hose)? This typically is worst when iding in "D". Smooths out somewhat when in "N", but that's because the engine load is removed.
 
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