Flexplate secured with Loctite 290 experience (6 months later)
08-13-2006, 11:30 AM
#16
Three Wheelin'
Originally Posted by Constantine
the 928 Intl. method of re-introducing the circlip,
Can you provide some more info or a link about this? I tried searching and checking the tips link at 928 Intl, but didn't see anything. Thanks!
08-13-2006, 12:07 PM
#17
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Hi Chris,
Actually this is found in the 928 shop manuals and was the intial way to "preload"the flexplate in its relation to the flywheel to ensure there was no forward pressure at all against the flywheel. The early style driveshafts have the area and groove needed to place these items ahead of the flexplate after careful measurements area taken to find the measurement needed which would be accomplished by placing different shims onto the driveshaft. Porsche stopped using this method since, from my limited research into this matter, it was found to be difficult for the procedure to be done by Porsche techs in the field who would sometimes get it wrong and TBF would pop up in the 928 customer cars. Porsche then went to the simpler but less efective way of just sliding the crank backwards and pinching the flexplate clamp at that point.
Call 928 Intl and ask about this for further information for your application. But your driveshaft, unless it was changed, will not have the groove and area needed to place these items on it. If you do go this route pay very careful attention to the shop maunuals for the correct installation procedures!
Cheers,
Constantine
Actually this is found in the 928 shop manuals and was the intial way to "preload"the flexplate in its relation to the flywheel to ensure there was no forward pressure at all against the flywheel. The early style driveshafts have the area and groove needed to place these items ahead of the flexplate after careful measurements area taken to find the measurement needed which would be accomplished by placing different shims onto the driveshaft. Porsche stopped using this method since, from my limited research into this matter, it was found to be difficult for the procedure to be done by Porsche techs in the field who would sometimes get it wrong and TBF would pop up in the 928 customer cars. Porsche then went to the simpler but less efective way of just sliding the crank backwards and pinching the flexplate clamp at that point.
Call 928 Intl and ask about this for further information for your application. But your driveshaft, unless it was changed, will not have the groove and area needed to place these items on it. If you do go this route pay very careful attention to the shop maunuals for the correct installation procedures!
Cheers,
Constantine
08-13-2006, 04:29 PM
#18
Three Wheelin'
Originally Posted by Constantine
Hi Chris,
Actually this is found in the 928 shop manuals and was the intial way to "preload"the flexplate in its relation to the flywheel to ensure there was no forward pressure at all against the flywheel. The early style driveshafts have the area and groove needed to place these items ahead of the flexplate after careful measurements area taken to find the measurement needed which would be accomplished by placing different shims onto the driveshaft. Porsche stopped using this method since, from my limited research into this matter, it was found to be difficult for the procedure to be done by Porsche techs in the field who would sometimes get it wrong and TBF would pop up in the 928 customer cars. Porsche then went to the simpler but less efective way of just sliding the crank backwards and pinching the flexplate clamp at that point.
Call 928 Intl and ask about this for further information for your application. But your driveshaft, unless it was changed, will not have the groove and area needed to place these items on it. If you do go this route pay very careful attention to the shop maunuals for the correct installation procedures!
Cheers,
Constantine
Actually this is found in the 928 shop manuals and was the intial way to "preload"the flexplate in its relation to the flywheel to ensure there was no forward pressure at all against the flywheel. The early style driveshafts have the area and groove needed to place these items ahead of the flexplate after careful measurements area taken to find the measurement needed which would be accomplished by placing different shims onto the driveshaft. Porsche stopped using this method since, from my limited research into this matter, it was found to be difficult for the procedure to be done by Porsche techs in the field who would sometimes get it wrong and TBF would pop up in the 928 customer cars. Porsche then went to the simpler but less efective way of just sliding the crank backwards and pinching the flexplate clamp at that point.
Call 928 Intl and ask about this for further information for your application. But your driveshaft, unless it was changed, will not have the groove and area needed to place these items on it. If you do go this route pay very careful attention to the shop maunuals for the correct installation procedures!
Cheers,
Constantine
Thanks Constantine. I still have the original TT, so sounds like this wouldn't be an option until replacement. Sounds like I"ll just go with periodic checks and adjustments.
08-13-2006, 05:49 PM
#19
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Did factory change TT center shaft for '85 MY when shims were deleted? If not they could be installed. '89+ shaft is most likely different as it's 3mm thicker everywhere except at mounting points at ends.
08-13-2006, 10:30 PM
#20
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Constantine, I've tried to keep up to date with this isssue but I must have missed something about your different clamp that can be used with S4 drive shafts. Please explain.
08-13-2006, 10:44 PM
#21
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Porsche used the old shafts until they ran out and then they were changed to larger diameter shafts to better withstand the higher torque of the S4 engines. So said one of the 928 driveline engineers I had the pleasure of trading emials with about this subject.
The best way to make sure if your driveshaft can accept the discontinued pieces is to drop the lower bellhousing and visually check it. So many 928s have had TT changes done to them one will never know what they really have. Heck, one local shop I know ran across a welded front clamp and driveshaft!
Hope that helps,
Constantine
The best way to make sure if your driveshaft can accept the discontinued pieces is to drop the lower bellhousing and visually check it. So many 928s have had TT changes done to them one will never know what they really have. Heck, one local shop I know ran across a welded front clamp and driveshaft!
Hope that helps,
Constantine
Originally Posted by Vilhuer
Did factory change TT center shaft for '85 MY when shims were deleted? If not they could be installed. '89+ shaft is most likely different as it's 3mm thicker everywhere except at mounting points at ends.
08-13-2006, 11:00 PM
#22
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Please do a search in this forum for "TBF fix" and you'll see a few posts from me about the new front flexplate clamp we designed and had made to stop the movement of the driveshaft within the front flexplate. In short it replaces the OE front flexplate clamp and clamps onto the driveshaft with much greater force. Been tested in my track car for a few years and no movement whatsoever but easily unclamped when needed. There are pictures of it on two threads by me on this subject. Too much to do again on this thread. Or email me at dicongo@earthlink.net and I will forward you a picture of it and more detailed explanation.
Very proud of it since it looks and works like Porsche made it for the 928 in the first place. Or at least they should have.
Cheers,
Constantine
Very proud of it since it looks and works like Porsche made it for the 928 in the first place. Or at least they should have.
Cheers,
Constantine
Originally Posted by Chazz
Constantine, I've tried to keep up to date with this isssue but I must have missed something about your different clamp that can be used with S4 drive shafts. Please explain.
08-13-2006, 11:13 PM
#23
Burning Brakes
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I just shortened the bolts on my ex S4 as opposed to leaving them out.
Originally Posted by fabric
As Schocki said, yes - you just need to drop it where the manifolds attach to the rest of the exhaust. Once you've done this, leave off the back 2 bolts holding the bell housing on, as those are the only 2 you can't get at, and in the future you won't have to touch the exhaust.
08-14-2006, 12:17 AM
#24
Under the Lift
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We just did the early type shaft replacement on a 91 S4 using the shim kit. The early shaft may be thinner overall, but the neck-down at the end in the later shaft creates a stress point that goes snap sometimes. I don't know if the later shaft is more or less susceptable, since this break is so very rare, but there have been 3 reports of snapped TT shafts in late model cars here in the last 6 months.
Regardless, the early shaft substitution can be accomplished. Getting the circlip that holds the shim pack in place onto the shaft looks tricky, but we did it with a simple circlip tool approaching from behind the flywheel. You need a cheap, thin circlip too, not a beefy, expensive one, due to small space. It's tricky establishing the 0.3mm free play. We approximated it. I'm not sure how critical it is, as long as there is some freeplay, but not so much that the shaft can creep back a lot.
Regardless, the early shaft substitution can be accomplished. Getting the circlip that holds the shim pack in place onto the shaft looks tricky, but we did it with a simple circlip tool approaching from behind the flywheel. You need a cheap, thin circlip too, not a beefy, expensive one, due to small space. It's tricky establishing the 0.3mm free play. We approximated it. I'm not sure how critical it is, as long as there is some freeplay, but not so much that the shaft can creep back a lot.
Last edited by Bill Ball; 08-14-2006 at 01:22 AM.
08-14-2006, 08:17 AM
#25
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Shaft substitution involves replacing the TT with another that has this style shaft in it. 928 Intl. sell rebuilt TTs with the older style shafts. However, replacing the OE front flexplate clamp at the same time with one of ours then gives you the freedom to use any style driveshaft and be able to take care of the problem of driveshaft migration. The new style clamp only costs $380.00 plus shipping and will last the life of the car, probably longer.
Installing the circlip, shims and washer, although cheaper, needs to be done after careful measurements are taken and can only be done with the older style driveshafts. The distance needed between the flexplate and flywheel will always be different and is why Porsche provided shims of different thickness to get this distance just right. It's interesting that Porsche discontinued their use... That's why we designed the new style clamp, to give 928 owners a fix to this whole problem that's easy to use.
As far as driveshaft breakage, driveshafts of both varieties have been known to break, some due to being run in a 928 that had one bank of cylinders shutting down during operation. This creates a shock load that fractures the driveshaft that might not become apparent for a while.
Constantine
Installing the circlip, shims and washer, although cheaper, needs to be done after careful measurements are taken and can only be done with the older style driveshafts. The distance needed between the flexplate and flywheel will always be different and is why Porsche provided shims of different thickness to get this distance just right. It's interesting that Porsche discontinued their use... That's why we designed the new style clamp, to give 928 owners a fix to this whole problem that's easy to use.
As far as driveshaft breakage, driveshafts of both varieties have been known to break, some due to being run in a 928 that had one bank of cylinders shutting down during operation. This creates a shock load that fractures the driveshaft that might not become apparent for a while.
Constantine
08-14-2006, 11:11 AM
#26
Three Wheelin'
Originally Posted by Constantine
...However, replacing the OE front flexplate clamp at the same time with one of ours then gives you the freedom to use any style driveshaft and be able to take care of the problem of driveshaft migration. The new style clamp only costs $380.00 plus shipping and will last the life of the car, probably longer.
...
Constantine
...
Constantine
Ahh, that was a piece of info I was missing, I thought you only made X clamps and were out. Now the details are coming back - you were hoping to get a larger order or vendor support to bring the price down with volume, and $380 is just how much it costs to do it in small numbers?
I'll definitely do this when the TT comes out, if you're still making them whenever that happens. I'm at 81K, so it may be around the corner, or in several years.
08-14-2006, 05:29 PM
#27
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Chris,
I will be probably ordering another batch soon, currently working on another project for our beloved 928s driveline.
I have one clamp left that was due to go into our 1989 928S4, but since the track car will be converted to a 5 speed, I will be placing the prototype currently in the track car into our 89S4.
Cheers,
Constantine
I will be probably ordering another batch soon, currently working on another project for our beloved 928s driveline.
I have one clamp left that was due to go into our 1989 928S4, but since the track car will be converted to a 5 speed, I will be placing the prototype currently in the track car into our 89S4.
Cheers,
Constantine
