Vibration at 2900-3100 rpm
10-15-2003, 04:33 AM
#46
Burning Brakes
Join Date: Apr 2002
Location: Denmark
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Rufus,
I am wondering too - And there are a lot of myths about these matter
Last week I visit Porsche Centrum in Køge and talked to Kim (the owner, who have been to great help for me), he said: 'If you have such vibration (typically at 180 Km/h) then go home and tighten the clamps in front and rear of the transaxle' (To be tighten with 80 Nm) - I did, but no change
For sure that's is harmonic vibration starting form the engine/trans unit
Many people said like Kim, it is starting from the trans axel, Earl and Wally have good experience with Loctite (I do not like to try this, for how to get it apart later?)
Other (DoubleNutz and Scott C) claim that's due to the trans shaft bearings are moving backwards and DoubleNutz claim he just put an extra bearing in without removing the transaxle or engine - I don't know how DobleNutz did it. I mean, with all the units installed there is not space to get the bearing in - Maybe if removing the flywheel?
It seams (for me) that the engine/drive unit has a harmonic vibration area around 3000 RPM - I can also feel it (slightly) around 1500 RPM - When every thing are new and 100% Ok these vibrations are absorbed of the engine and transmission mounts, then over time something changed (mounts, bearings etc) and then the vibrations get stronger and the engine mounts cannot absorbe them all
From the 'Project 928' book, it is also well known that Porsche did many test regarding eliminating vibrations from the trans unit during the development of the car
As I said above, as a test, I installed the two small engine shocks from my 1980 model, and the result is great but still not 100% - Just now I am wondering how to install one more set of engine shocks on the gearbox - But maybe, that like placing a bucket under the leaking roof!
As Rufus, I would like to get the 'real answer'
Regards from Erik in Denmark
I am wondering too - And there are a lot of myths about these matter
Last week I visit Porsche Centrum in Køge and talked to Kim (the owner, who have been to great help for me), he said: 'If you have such vibration (typically at 180 Km/h) then go home and tighten the clamps in front and rear of the transaxle' (To be tighten with 80 Nm) - I did, but no change
For sure that's is harmonic vibration starting form the engine/trans unit
Many people said like Kim, it is starting from the trans axel, Earl and Wally have good experience with Loctite (I do not like to try this, for how to get it apart later?)
Other (DoubleNutz and Scott C) claim that's due to the trans shaft bearings are moving backwards and DoubleNutz claim he just put an extra bearing in without removing the transaxle or engine - I don't know how DobleNutz did it. I mean, with all the units installed there is not space to get the bearing in - Maybe if removing the flywheel?
It seams (for me) that the engine/drive unit has a harmonic vibration area around 3000 RPM - I can also feel it (slightly) around 1500 RPM - When every thing are new and 100% Ok these vibrations are absorbed of the engine and transmission mounts, then over time something changed (mounts, bearings etc) and then the vibrations get stronger and the engine mounts cannot absorbe them all
From the 'Project 928' book, it is also well known that Porsche did many test regarding eliminating vibrations from the trans unit during the development of the car
As I said above, as a test, I installed the two small engine shocks from my 1980 model, and the result is great but still not 100% - Just now I am wondering how to install one more set of engine shocks on the gearbox - But maybe, that like placing a bucket under the leaking roof!
As Rufus, I would like to get the 'real answer'
Regards from Erik in Denmark
10-15-2003, 12:29 PM
#47
Burning Brakes
Join Date: Jan 2003
Location: Minneapolis MN
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Yes it seems the solution or problem lies between the clamps or torque converter. I too have a vibration like this, but it may be due to my RMB. I'm having the muffler put back on, and we'll see what happens.
If the vib. is still there, I'll check the clamps, but not Loctite them for the same reasons you say. - Ruf
If the vib. is still there, I'll check the clamps, but not Loctite them for the same reasons you say. - Ruf