TBF clamp fix offer - long
03-05-2005, 10:51 PM
#16
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Originally Posted by Bill Ball
The TT shaft is said to twist 90-180 degree under torque. This causes it to shorten and pull back on the flex plate. You'd think the plate, being flexible, would accommodate the shortening, but it isn't flexible enough, I suppose, under sudden shortening. Others have proposed that the shaft actually moves forward over time due to "ballooning" of the torque converter. But so many people have documented that the TT actually pulls back though the front clamp, that that is more commonly accepted. That said, my TT does seem to be further forward (or longer) than before. Each time I release the forward tension and the clamp moves back I seem to have less of the splines exposed behind the clamp than I used to several adjustments ago. Hmmm... If that is true, then the better clamp would not be the answer. I tend to discount my observation and the ballooning TC hypothesis as the earlier cars, with the end shims and circlip to prevent the TT shaft from pulling back through the front clamp, are not known to suffer from TBF. So, I'm very interested in Constatine's clamp, especially since I am going to install an SC soon.
03-05-2005, 11:21 PM
#17
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I think this is some excellent work. I intend on becoming a 5spd only 928 owner but I am strongly considering this device, thank you for offering it.
03-06-2005, 03:26 AM
#18
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Originally Posted by bigs
See, I find that interesting. It sounds like either your drive shaft is getting longer over time (?) or maybe it's pulling out from the rear attachment and moving forward. Have you made any observations over time regarding the rear end of the shaft?
03-06-2005, 06:32 AM
#19
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Very interesting design.
If '84 and earlier cars do not have problem no matter how much HP and TQ is run through TT that early design has to be answer to TBF. Seems to me Constantines clamp will do this. Perhaps little expensive way of dealing it but sure fix none the less. Now all automatic owners go and buy one to make price drop to reasonable level.
If '84 and earlier cars do not have problem no matter how much HP and TQ is run through TT that early design has to be answer to TBF. Seems to me Constantines clamp will do this. Perhaps little expensive way of dealing it but sure fix none the less. Now all automatic owners go and buy one to make price drop to reasonable level.
03-06-2005, 09:39 AM
#20
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Bill,
If your drive shaft is getting longer, maybe your torque converter bearings are wearing?
Constantine, Great work.
Late automatic owners, Save your engine from TBF and install Constantine's clamp or do the "LoctiteFix".
If anyone is interested in some TBF history and results of the "loctite Fix", I tried to put all the info (or pointers to) on my site.
http://members.rennlist.com/captearlg/
If your drive shaft is getting longer, maybe your torque converter bearings are wearing?
Constantine, Great work.
Late automatic owners, Save your engine from TBF and install Constantine's clamp or do the "LoctiteFix".
If anyone is interested in some TBF history and results of the "loctite Fix", I tried to put all the info (or pointers to) on my site.
http://members.rennlist.com/captearlg/
03-06-2005, 10:42 AM
#21
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Hi Capt. Earl,
Thank you for the kind words! Hopefully I get enough interest to get this out. Would be nice for 928 AT owners to have a few choices to combat the dreaded TBF.
Hope all is well,
Constantine
Thank you for the kind words! Hopefully I get enough interest to get this out. Would be nice for 928 AT owners to have a few choices to combat the dreaded TBF.
Hope all is well,
Constantine
03-06-2005, 12:42 PM
#22
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There are some frightening stories from people who have experienced TBF first hand, but just how common is it? My impression is that it's very rare. Does anyone have an overview of the situation in terms of proportion of cars that are at risk and at what sort of age / mileage?
Thanks
Mark
Thanks
Mark
03-06-2005, 01:17 PM
#23
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I don't own an automatic 928, but if I did, I would purchase/install Constantine's device in a heartbeat. Constantine is as honest as they come, and his dedication to researching and finding a solution to TBF is impressive. As far as I know, he's been working on this for at least 2 years. Definitely not shooting from the hip. Thanks Constantine for helping to save a few more precious 928's. 
03-06-2005, 02:00 PM
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I am not questioning Constantine's integrity in any way - quite the opposite. I am plan to post the fix on UK sites - awareness of TBF failure is poor here (I don't know of any cars affected, although we have a much smaller 928 fraternity than the US) - and it would help if I had some idea of the scale of the threat. There is so much I need to do to my S4, and limited resources - mind you it will largely be a waste of time if the engine goes pop due to TBF!
Mark
Mark
03-06-2005, 02:29 PM
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Hi Chris,
Thank you for such a glowing endorsement! Hope to see you and your lovely wife at the upcoming Sharks in the Mountains.
Kind regards,
Constantine
Thank you for such a glowing endorsement! Hope to see you and your lovely wife at the upcoming Sharks in the Mountains.
Kind regards,
Constantine
Originally Posted by Chris Lockhart
I don't own an automatic 928, but if I did, I would purchase/install Constantine's device in a heartbeat. Constantine is as honest as they come, and his dedication to researching and finding a solution to TBF is impressive. As far as I know, he's been working on this for at least 2 years. Definitely not shooting from the hip. Thanks Constantine for helping to save a few more precious 928's.
03-06-2005, 02:43 PM
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Hello Dr Mark,
I don't know if anyone really knows. I personally know of a TBF suffering car that was loctited and sold to a used car lot. I'm sure the new owner would find out during a long drive since the car would be fine for short trips, but would suffer low oil warnings during extended drives. Scary part is that when I drove it, it felt fine!
Our clamp stops the driveshaft pullout at the front flexplates which could lead to TBF. The forward pressure pressing onto the flexplates, to the flywheel, to the crankshaft and ultimately the thrust bearing, is what this is supposed to stop. I'm willing to bet if you check your front flexplates you will see a forward bow to them if you place a straight edge against them. Hopefully not. I could go on but i'm hoping this helped a bit.
Kind regards,
Constantine
I don't know if anyone really knows. I personally know of a TBF suffering car that was loctited and sold to a used car lot. I'm sure the new owner would find out during a long drive since the car would be fine for short trips, but would suffer low oil warnings during extended drives. Scary part is that when I drove it, it felt fine!
Our clamp stops the driveshaft pullout at the front flexplates which could lead to TBF. The forward pressure pressing onto the flexplates, to the flywheel, to the crankshaft and ultimately the thrust bearing, is what this is supposed to stop. I'm willing to bet if you check your front flexplates you will see a forward bow to them if you place a straight edge against them. Hopefully not. I could go on but i'm hoping this helped a bit.
Kind regards,
Constantine
Originally Posted by Drmark
There are some frightening stories from people who have experienced TBF first hand, but just how common is it? My impression is that it's very rare. Does anyone have an overview of the situation in terms of proportion of cars that are at risk and at what sort of age / mileage?
Thanks
Mark
Thanks
Mark
03-06-2005, 04:02 PM
#27
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To get it straight. Most feasible theory of what causes TBF is:
1. TT's center shaft shortens when it's strained
2. This causes forward flex plate clamp to move forward on shaft
3. Shaft don't return back to it's original place when it's again in it's normal lenght due to tight (but not tight enough) clamp.
Now changing clamp to design what don't allow flex plate forward movement will solve this problem. While doing it will it create other one by 'solidly' relaying center shaft shortening to crank? Will this be problem and do thrust bearing wear from forward side then? Probably will not be as quick as on TBF but will it wear more than without solid clamp? I think ultimate solution would be to have sliding joint but this fixed version is much better than factory.
1. TT's center shaft shortens when it's strained
2. This causes forward flex plate clamp to move forward on shaft
3. Shaft don't return back to it's original place when it's again in it's normal lenght due to tight (but not tight enough) clamp.
Now changing clamp to design what don't allow flex plate forward movement will solve this problem. While doing it will it create other one by 'solidly' relaying center shaft shortening to crank? Will this be problem and do thrust bearing wear from forward side then? Probably will not be as quick as on TBF but will it wear more than without solid clamp? I think ultimate solution would be to have sliding joint but this fixed version is much better than factory.
03-06-2005, 04:51 PM
#28
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I'm in for one!!
Constantine,
I saw your design at SITM 2 years ago and was wondering if/when it would be available. It was great looking. Put me down for one, I have a 1985 and 2 years ago when I found out about TBF, I checked my flex plate. Sure enough, it was bowed forward, when I released the tension on the clamping bolt, it snapped back. I checked the end play and luckily it was within specs. I then did the loctite fix and it seems to have stopped the problem But, why chance it, only thing is that it sounds like the torque tube must be removed to replace the coupling. A project for next winter.
Glen McCartney
I saw your design at SITM 2 years ago and was wondering if/when it would be available. It was great looking. Put me down for one, I have a 1985 and 2 years ago when I found out about TBF, I checked my flex plate. Sure enough, it was bowed forward, when I released the tension on the clamping bolt, it snapped back. I checked the end play and luckily it was within specs. I then did the loctite fix and it seems to have stopped the problem But, why chance it, only thing is that it sounds like the torque tube must be removed to replace the coupling. A project for next winter.
Glen McCartney
03-06-2005, 07:22 PM
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Hi Glen,
Would you mind sending me a pm if you still want one. It would make it easier to keep track with who wants one. Hope to see you at this years SITM!
Cheers,
Constantine
Would you mind sending me a pm if you still want one. It would make it easier to keep track with who wants one. Hope to see you at this years SITM!
Cheers,
Constantine
Originally Posted by Glen McCartney
Constantine,
I saw your design at SITM 2 years ago and was wondering if/when it would be available. It was great looking. Put me down for one, I have a 1985 and 2 years ago when I found out about TBF, I checked my flex plate. Sure enough, it was bowed forward, when I released the tension on the clamping bolt, it snapped back. I checked the end play and luckily it was within specs. I then did the loctite fix and it seems to have stopped the problem But, why chance it, only thing is that it sounds like the torque tube must be removed to replace the coupling. A project for next winter.
Glen McCartney
I saw your design at SITM 2 years ago and was wondering if/when it would be available. It was great looking. Put me down for one, I have a 1985 and 2 years ago when I found out about TBF, I checked my flex plate. Sure enough, it was bowed forward, when I released the tension on the clamping bolt, it snapped back. I checked the end play and luckily it was within specs. I then did the loctite fix and it seems to have stopped the problem But, why chance it, only thing is that it sounds like the torque tube must be removed to replace the coupling. A project for next winter.
Glen McCartney
03-06-2005, 07:32 PM
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Hi Erkka,
My very first TBF fix was a sliding coupler mounted to custom made flexplates. Problem was the vibration from the drivetrain caused it to rattle within itself. Very noisy but got quieter with higher RPM.
After much thought and designing a brand new torque tube assembly on paper, I figured the product would be very exspensive for anyone to buy one. So I looked at this whole problem again and devised this clamp set up. If you study the manuals you can see Porsche did not want a hint of forward pressure at the front flexplates.
Regards,
Constantine
My very first TBF fix was a sliding coupler mounted to custom made flexplates. Problem was the vibration from the drivetrain caused it to rattle within itself. Very noisy but got quieter with higher RPM.
After much thought and designing a brand new torque tube assembly on paper, I figured the product would be very exspensive for anyone to buy one. So I looked at this whole problem again and devised this clamp set up. If you study the manuals you can see Porsche did not want a hint of forward pressure at the front flexplates.
Regards,
Constantine
Originally Posted by Vilhuer
To get it straight. Most feasible theory of what causes TBF is:
1. TT's center shaft shortens when it's strained
2. This causes forward flex plate clamp to move forward on shaft
3. Shaft don't return back to it's original place when it's again in it's normal lenght due to tight (but not tight enough) clamp.
Now changing clamp to design what don't allow flex plate forward movement will solve this problem. While doing it will it create other one by 'solidly' relaying center shaft shortening to crank? Will this be problem and do thrust bearing wear from forward side then? Probably will not be as quick as on TBF but will it wear more than without solid clamp? I think ultimate solution would be to have sliding joint but this fixed version is much better than factory.
1. TT's center shaft shortens when it's strained
2. This causes forward flex plate clamp to move forward on shaft
3. Shaft don't return back to it's original place when it's again in it's normal lenght due to tight (but not tight enough) clamp.
Now changing clamp to design what don't allow flex plate forward movement will solve this problem. While doing it will it create other one by 'solidly' relaying center shaft shortening to crank? Will this be problem and do thrust bearing wear from forward side then? Probably will not be as quick as on TBF but will it wear more than without solid clamp? I think ultimate solution would be to have sliding joint but this fixed version is much better than factory.