15 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHLoud clunk sound on fast shifts.
Reported or suspected cause
transmission mount in spite of what you might think
Suggestion or failed attempt
No successful repair reported for this finding.
0
Identified cause
1
Suspected cause
0
Reported fixes
Read evidence and context
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that suspect a cause
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Suspected cause · Original poster
So if you have a loud clunk on aggressive 1-2 or 2-3 upshifts it's probably the transmission mount in spite of what you might think!
Leading evidence: 'transmission mount in spite of what you might think' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, the most frequently mentioned possible cause is 'transmission mount in spite of what you might think' (1 discussions; 0 report identifying it and 1 suggest it). The most frequently discussed action is 'Check cv boots/joints while you were' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
Source reports, not a diagnosis or a success probability. Counts refer to discussions and can overlap.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that contain suggestions
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Suggestion
Did you check your cv boots/joints while you were under there?
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that contain suggestions
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that report an unsuccessful attempt
1
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Unsuccessful attempt · Original poster
Since it was easy, I replaced the motor mounts with no change.
Counts describe captured discussions, not unique people or a diagnosis. Author identities are not reliably stored. Exact duplicate evidence is counted once across matching discussions; one discussion counts at most once per action/state. Multiple repairs reported together remain a combination. Suggestions and failed attempts do not establish a fix. Matches cover whole discussions and can include related faults, model variants and incomplete threads.
15 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
0 evidence records excluded for query context · 0 excluded by outcome qualification · 0 adjusted by outcome qualification.
1 acknowledgements have no verified action link; they do not establish a repair result.
Need help diagnosing a sound. The car is a 2003 C2 cab with 80K miles. I have a pretty loud clunk/thud sound from the rear when I shift quickly between 1->2 and 2->3. I don't hear it when taking off in first nor do I hear it during normal driving. I don't believe it's suspension-related since I don't hear it when going over bumps in the road. The car has nearly new Bilstein B8 struts and Eibach springs and sways. The clutch was done and the flywheel refinished about 6K miles ago.
Since it was easy, I replaced the motor mounts with no change. I also pulled down the underpanels and looked at the trans mount. It shows its age but it isn't broken or anything. I doubt that it's the cause.
Anyone else had this noise?
Did you check your cv boots/joints while you were under there?
Lug nuts torqued?
Since it happens when shifting its got to be torque shift related,, something
is rotating with too much play.. OR don't underestimate something flopping
like the air cleaner or similar components. rear deck lid parts etc..
I did. CV boots look good. I tried twisting the axles in the direction they rotate and there was no play. I was able to slide the axles side to side (ie from the trans toward the hub and back) and it moves and creates a clunk sound on both sides but I'm not sure if that's normal.
I took a pretty deep dive all around the engine/trans and couldn't see anything obvious.
It could be the DMF hitting the spring stops on high torque. The DMF is sprung to reduce the drive train shock of sudden torque, and to reduce vibration.
If the DMF locks, you get a ringing sound from the trans when lugging.
If the springs break you get a knocking noise at low speed or when shutting the engine off.
If the springs are just weakened, the DMF could hit the hard stops when sudden high torque is applied. Just a hypothesis.
Yea, lay off the power shifts and do timed speed shifts allowing more time for the 1-2 shift, and then less and less for the higher gears because there is less torque/RPM difference as the gears go higher. You can get a lot more miles from your DMF..
Hi all, just wanted to revisit this thread with an update/solution. In my first post I said that I didn't think the the trans mount was the cause of the noise. Well, I couldn't have been more incorrect. For the hell of it, I bought the transmission mount insert from
@Function-First
since it was cheap/easy. I went with the softest version and I am happy to report that the clunk is 100% gone! As a bonus the shifter action is massively improved. Yes, there is a slight increase in NVH but it's pretty minor and tradeoffs are worth it. So if you have a loud clunk on aggressive 1-2 or 2-3 upshifts it's probably the transmission mount in spite of what you might think!
Not really, it's pretty straightforward. Some silicone spray is helpful for inserting the bushing. Also, the directions call for removing the studs for the upper bracket. On mine, one of the studs came out with the nut and I found it wasn't necessary to remove the other one to complete the job. Also, reinstalling the upper bracket back over the lower one is kind of a pain.
