Black Sea R&D 5 super bearing TT
03-13-2017, 06:42 PM
#16
Rainman
Rennlist Member
Rennlist Member
Been a while since I had a TT apart but I seem to remember the bearings being more or less "evenly spaced out" between the flywheel end and the transmission end.
Not saying there weren't harmonics to consider but that's how they appeared (based on measuring depth to re-install new bearings later).
I can stick a tape measure in my spare TT later and see...
That said, I would like to eventually get the Constantine bearings but would only do 3 as he has suggested previously.
Not saying there weren't harmonics to consider but that's how they appeared (based on measuring depth to re-install new bearings later).
I can stick a tape measure in my spare TT later and see...
That said, I would like to eventually get the Constantine bearings but would only do 3 as he has suggested previously.
03-13-2017, 08:28 PM
#17
So how about if a new driveshaft is installed and is made of better quality materials which I would think would have an effect on harmonics? If so that meterial has never been tested by Porsche. So I'm thinking the R&D after the name Black Sea hold some truth? I don't mind researching for them. I highly dought I will have any issues, but in 30 years if I'm still alive all let you know what I have found.
I don't know the formula for the 1E mode of a simply supported cylinder off the top of my head, but the effect of the length term is going to be exponential whereas the E (modulus) is going to be linear and might change by 10% if you're lucky. So the spacing is a much larger driver to controlling vibrational response than anything else.
Since you can only have integer numbers of supports, somewhere along the line Porsche likely tested 2, 3, 4, and 5 supports and settled on 3. I suspect going from 3 to 4 showed enough diminishing return that it wasn't selected for the cost/benefit ratio.
03-13-2017, 08:30 PM
#18
Been a while since I had a TT apart but I seem to remember the bearings being more or less "evenly spaced out" between the flywheel end and the transmission end.
Not saying there weren't harmonics to consider but that's how they appeared (based on measuring depth to re-install new bearings later).
I can stick a tape measure in my spare TT later and see...
That said, I would like to eventually get the Constantine bearings but would only do 3 as he has suggested previously.
Not saying there weren't harmonics to consider but that's how they appeared (based on measuring depth to re-install new bearings later).
I can stick a tape measure in my spare TT later and see...
That said, I would like to eventually get the Constantine bearings but would only do 3 as he has suggested previously.
03-13-2017, 08:35 PM
#19
I had a long look at this and chatted to an automotive engineering guru who said exactly as above. The positioning of the bearings would have been in part designed to align and negate with waves in the drive shaft. Random positioning was not in his view a good idea. Interestingly the 928 TT runs with 3 bearings and a dampener unit which is a different approach again.
The number of bearings chosen may have been on the edge between 3 and 4 for effectiveness and the 'entry level' car got 3 and the premium badge got 4. I dunno. I would love to know the testing that went into the decision.
03-14-2017, 08:10 AM
#21
Through the research and work we've done on Porsche torque tubes (TTs) here is some of what we've found concerning 944 and 928 TTs:
Porsche used four bearing units in all 944 torque tubes.
Porsche used three bearing units in all 928 5-speed TTs.
The 928 5-speed two part drive shaft is about the same length as a 944 5-speed drive shaft.
Porsche used three bearing units in early 928 automatic TTs and just two in later TTs.
The original bearing units do move from their assigned positions sometimes which can induce drive line vibrations. One would think if Porsche was worried about keeping the bearing units in specific areas of the TT, they would have secured them better than just a friction fit, like Ferrari had done in some of their TTs.
From our tests, the material used in all the drive shafts is unremarkable, but care was taken to heat treat the splined areas which would be exposed to increased loads on the 944 drive shafts. The 928 5-speed two part drive shaft has a heat treated short shaft which lives in the clutch.
And finally, our products have been pretty well vetted over years of use by hundreds of owners/racers worldwide and we are constantly tweaking them. We try to provide the very best products and services to our customers to help keep these fine Porsches on the roads and tracks around the world.
Cheers,
Constantine
Porsche used four bearing units in all 944 torque tubes.
Porsche used three bearing units in all 928 5-speed TTs.
The 928 5-speed two part drive shaft is about the same length as a 944 5-speed drive shaft.
Porsche used three bearing units in early 928 automatic TTs and just two in later TTs.
The original bearing units do move from their assigned positions sometimes which can induce drive line vibrations. One would think if Porsche was worried about keeping the bearing units in specific areas of the TT, they would have secured them better than just a friction fit, like Ferrari had done in some of their TTs.
From our tests, the material used in all the drive shafts is unremarkable, but care was taken to heat treat the splined areas which would be exposed to increased loads on the 944 drive shafts. The 928 5-speed two part drive shaft has a heat treated short shaft which lives in the clutch.
And finally, our products have been pretty well vetted over years of use by hundreds of owners/racers worldwide and we are constantly tweaking them. We try to provide the very best products and services to our customers to help keep these fine Porsches on the roads and tracks around the world.
Cheers,
Constantine
03-14-2017, 10:46 AM
#23
Addict
Rennlist Member
Rennlist Member
So, is 5 or even 6 bearings good addition or not? What about 4 double bearings? 
03-24-2017, 12:49 PM
#28
New torque tube shaft I see. Very nice. Constantine was just in the process of making the drive shaft when he built mine. I have a stock unit that he built. Still works great.
03-25-2017, 12:49 AM
#30
Drifting
Thread Starter
Well it started with UPS breaking the bell housing on the unit I sent due to poor packing on my behalf and mishandling on UPS's part, so that was a loss on the value of the part and the $209 that was a loss due to UPS shipping cost not insuring at least the shipping cost, or sending another TT for half price for breaking mine and admiting fault. UPS didn't want to work with me at all because my packing did not meet their guide lines. So I paid the core charge which was less then shipping. The total cost of the rebuilt torque tube w/new drive shaft and 5 super bearings was $1925 shipped to my friend company. The grand total to include my losses is close to $2400. If you decide to use UPS follow there guide lines on packing or they will not cover any losses.