Tomster
Beware of idiots
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- #1
Some have reported that they have a loud raspy metallic sound when the engine is in the 4K RPM range at operating temperature. I have noticed this on one of my R models and have read reports of dynamat being used to eliminate the problem.
First a quick description of the problem and the reason for the nuisance problem. There is a sandwich plate that interfaces between th engine block and the bell housing of the transmission. Its fastening and construction is such that the vibration of the engine can cause it to buzz with sympathetic harmonics that cause the plate to vibrate. I noticed that when I was under the car today, that this plate can be moved around with my fingernail. Many have decided to take their car into their dealerships to get the problem fixed. My experience with the problem is that the engine must be at operating temperature to obtain or observe the defect. This can lead to frustration because (unless fully understood) is not easily reproduced. You would almost have to pull into the dealership at operating temp and tell the tech to jump in and go for a ride.
I have read other people's reports of how changing the harmonics of the sandwich plate by using dynamat has been helpful. I recently bought some dynamat and decided to give it a try. In conjunction with getting one of my other Rs prepped for track, I decided to spend a little time under HR871 to give it a shot. As a side note, I think it would be stupid to drop a transmission to replace a plate (which has been updated due to this issue) when a simple change in harmonics could solve the problem. So up on Jacks she went.
Examination of the sandwich plate found exactly as described..... a flimsy aluminum plate held by few fasteners. I took a few quick measurements and cut out a piece of dynamat to fit the majority of the exposed portion of the plate.
I then cleaned the plate with 90% isopropyl alcohol to prep the substrate for adhesion.
I applied the dynamat and pressed it down ensuring that it had firmly adhered to the sandwich plate. Once all that was confirmed, then came my favorite part..... test drive!
I warmed her up gradually until 190F. Once there it was my mission to get it up to operation temp (212ish)... the temp that usually produced the metallic buzz at or near 4k RPM.
The result?? No buzz, not rattle, no nothing.
If you are having this issue, dont take it to the dealer and have them tear your drivetrain apart..... buy some dynamat and spend about a half hour fixing the underlying problem.....
First a quick description of the problem and the reason for the nuisance problem. There is a sandwich plate that interfaces between th engine block and the bell housing of the transmission. Its fastening and construction is such that the vibration of the engine can cause it to buzz with sympathetic harmonics that cause the plate to vibrate. I noticed that when I was under the car today, that this plate can be moved around with my fingernail. Many have decided to take their car into their dealerships to get the problem fixed. My experience with the problem is that the engine must be at operating temperature to obtain or observe the defect. This can lead to frustration because (unless fully understood) is not easily reproduced. You would almost have to pull into the dealership at operating temp and tell the tech to jump in and go for a ride.
I have read other people's reports of how changing the harmonics of the sandwich plate by using dynamat has been helpful. I recently bought some dynamat and decided to give it a try. In conjunction with getting one of my other Rs prepped for track, I decided to spend a little time under HR871 to give it a shot. As a side note, I think it would be stupid to drop a transmission to replace a plate (which has been updated due to this issue) when a simple change in harmonics could solve the problem. So up on Jacks she went.
Examination of the sandwich plate found exactly as described..... a flimsy aluminum plate held by few fasteners. I took a few quick measurements and cut out a piece of dynamat to fit the majority of the exposed portion of the plate.
I then cleaned the plate with 90% isopropyl alcohol to prep the substrate for adhesion.
I applied the dynamat and pressed it down ensuring that it had firmly adhered to the sandwich plate. Once all that was confirmed, then came my favorite part..... test drive!
I warmed her up gradually until 190F. Once there it was my mission to get it up to operation temp (212ish)... the temp that usually produced the metallic buzz at or near 4k RPM.
The result?? No buzz, not rattle, no nothing.
If you are having this issue, dont take it to the dealer and have them tear your drivetrain apart..... buy some dynamat and spend about a half hour fixing the underlying problem.....
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