Vibration after torque tube bearing job
03-31-2018, 01:13 AM
#46
Former Sponsor
I am a big picture guy too and have always looked at the whole of a system when designing our products, which as you may know encompass other Porsche models with torque tubes.
Porsche placed a heavy weight in the torque tube to add weight since it is a lightweight assembly without it. The OE bearing units are light weight and do nothing to quell the harmonics of the solid steel shaft that it absorbs from the engine through the flywheel and front flex plate. As you know, the automatic versions have very little weight at their flywheel to absorb engine harmonics. That's why when we designed our Super Clamps, we decided to give it some weight to help calm the harmonics down at the flex plate besides clamping onto the drive shaft and keeping it in place.
The Super Bearings were designed to add back the weight of the vibration dampener which we strongly advocate against re-using due to their age and failure rate. Three Super Bearings replace the weight of the OE dampener that was figured out by Porsche through its research. We didn't change that. The Super Bearings also help to control/absorb the drive shaft harmonics coming from the engine. This is done by the increased rubber both on the outside and inside of each Super Bearing. They each are harmonic sinks that also help support the long drive shaft throughout its entire length. This is something that is our design and a departure from Porsche since there is no downside to controlling more vibrations.
The problems you are seeing in the engine seems like more of an outcome of the hardening of the front dampener you have noticed since that is it's main purpose and is attached to the crank. Completely understand looking down range to other possible causes, but our Super Bearings are better at controlling more vibrations than the OE dampener.
Don't believe any of the above will change your mind, but understand that a lot of research went into their design than just doodling something on a piece of paper because it looked cool.
"Bully" might have been a strong term, however from this side of the computer screen, it does come across that way at times.
Porsche placed a heavy weight in the torque tube to add weight since it is a lightweight assembly without it. The OE bearing units are light weight and do nothing to quell the harmonics of the solid steel shaft that it absorbs from the engine through the flywheel and front flex plate. As you know, the automatic versions have very little weight at their flywheel to absorb engine harmonics. That's why when we designed our Super Clamps, we decided to give it some weight to help calm the harmonics down at the flex plate besides clamping onto the drive shaft and keeping it in place.
The Super Bearings were designed to add back the weight of the vibration dampener which we strongly advocate against re-using due to their age and failure rate. Three Super Bearings replace the weight of the OE dampener that was figured out by Porsche through its research. We didn't change that. The Super Bearings also help to control/absorb the drive shaft harmonics coming from the engine. This is done by the increased rubber both on the outside and inside of each Super Bearing. They each are harmonic sinks that also help support the long drive shaft throughout its entire length. This is something that is our design and a departure from Porsche since there is no downside to controlling more vibrations.
The problems you are seeing in the engine seems like more of an outcome of the hardening of the front dampener you have noticed since that is it's main purpose and is attached to the crank. Completely understand looking down range to other possible causes, but our Super Bearings are better at controlling more vibrations than the OE dampener.
Don't believe any of the above will change your mind, but understand that a lot of research went into their design than just doodling something on a piece of paper because it looked cool.
"Bully" might have been a strong term, however from this side of the computer screen, it does come across that way at times.
You, however, have always seemed like a "straight shooter"', to me.
One last question, before I move on and do what I do....and you can do what you do.
When you originally designed and made the first of these bearings, they were aluminum.
Which brings up the obvious point and obvious questions.
You recommended removing the counterweight with your aluminum bearings also.
Isn't this a bit inconsistent with what you are saying above? What raw engineering data/what were you seeing that made you go to a heavier material? (In truth, I always assumed it was a pure economy of production decision....which is one of the really big reasons I decided to leave the counterweight mass in!)
03-31-2018, 08:28 AM
#48
Greg and Karsten were answered.
Information removed to lighten load of this thread after it fell to second page of forum.
Cheers.
Information removed to lighten load of this thread after it fell to second page of forum.
Cheers.
Last edited by Constantine; 04-01-2018 at 10:57 PM.
04-03-2018, 01:58 AM
#49
Rennlist Member
I actually thought it was a good discussion of some of the issues. My 928 has just recently developed a very mild harmonic between 2500 & 3000 rpm under moderate acceleration and I've been thinking it might be time to re-build the torque tube. I used your bearings on my 944 S2 a couple of years back and I'm very happy with them but I've never done anything to the 928 drive line and didn't even know there was a harmonic balancer on that side. I know there's one on the front of the crank. I suppose it's time to get out the PET and check this out.
04-03-2018, 09:00 AM
#50
Hi Scott,
The TT induced harmonics usually exist through the whole RPM range and are usually worse the higher you go up. Severe cases when the bearings have moved from their positions results in very pronounced vibrations when it shifts. The vibration dampener can also come apart and you can usually hear it sliding up and down with application of brakes or gas.
The kind you describe are usually from the engine and or/transmission mounts going away. All of the 928s are at the age where most of the rubber parts in the suspension and those which help dampen the driveline harmonics, are no longer up to their task.
The TT induced harmonics usually exist through the whole RPM range and are usually worse the higher you go up. Severe cases when the bearings have moved from their positions results in very pronounced vibrations when it shifts. The vibration dampener can also come apart and you can usually hear it sliding up and down with application of brakes or gas.
The kind you describe are usually from the engine and or/transmission mounts going away. All of the 928s are at the age where most of the rubber parts in the suspension and those which help dampen the driveline harmonics, are no longer up to their task.
04-03-2018, 02:54 PM
#51
Rennlist Member
I actually thought it was a good discussion of some of the issues. My 928 has just recently developed a very mild harmonic between 2500 & 3000 rpm under moderate acceleration and I've been thinking it might be time to re-build the torque tube. I used your bearings on my 944 S2 a couple of years back and I'm very happy with them but I've never done anything to the 928 drive line and didn't even know there was a harmonic balancer on that side. I know there's one on the front of the crank. I suppose it's time to get out the PET and check this out.
Also note that most of those old weights have hard shrunken rubber and will most likely start to move around, unless you want to start pinning things down.
Just my 2 cents, no affiliation, I'm just a satisfied customer.
Dave K
Last edited by davek9; 04-07-2018 at 08:54 AM.
04-07-2018, 06:55 AM
#52
Rennlist Member
Scott I've done several over the years (auto and manual) and have always removed the "weight" as suggested by the manufacture of the bearings, and have never had a vibration issue, none.
Also note that most of those old weights have hard shrunken rubber and will most likely start to move around, unless you want to state pinning things down.
Just my 2 cents, no affiliation, I'm just a satisfied customer.
Dave K
Also note that most of those old weights have hard shrunken rubber and will most likely start to move around, unless you want to state pinning things down.
Just my 2 cents, no affiliation, I'm just a satisfied customer.
Dave K
04-07-2018, 06:59 AM
#53
Rennlist Member
Hi Scott,
The kind [of vibration] you describe are usually from the engine and or/transmission mounts going away. All of the 928s are at the age where most of the rubber parts in the suspension and those which help dampen the driveline harmonics, are no longer up to their task.
The kind [of vibration] you describe are usually from the engine and or/transmission mounts going away. All of the 928s are at the age where most of the rubber parts in the suspension and those which help dampen the driveline harmonics, are no longer up to their task.
Best Regards,