releasing the tension on the flexplate, '91 GT, instructions pleeeease!

low miler · 01:58 AM

I am in dire need of the exact instructions for releasing the tension of the flexplate on a '91 GT. I need the specific numbers and measurements, please. If someone has these, can you please post them asap. I would be forever greatful.

The symptoms found so far are the following; 4 times the spec movement on the crank, rub marks around the edge of the flywheel, grumbling on the car while under load near redline (probably causing the rub marks around the flywheel). Thanks.

Thank you, Todd

Danglerb · 08-21-2008, 09:22 AM

Not the latest version, but its mostly in this.
http://members.rennlist.com/v1uhoh/928TechFlexPlatearticleTH.pdf

Newer faster simpler write up I think from Bill Ball, but didn't find it.

low miler · 09:41 AM

I'm not a mechanic, so this is probably an ingnorant question, but is there tension that can be released on a 5 speed GT?

Todd

Danglerb · 08-21-2008, 09:45 AM

Not really, strictly a slushbox disease.

low miler · 08-21-2008, 09:50 AM

Quote:

Originally Posted by Danglerb

Not really, strictly a slushbox disease.

Dammit!

Thanks anyway, Todd

911blex · 08-21-2008, 10:09 AM

Can anyone please confirm that the transmission should be in neutral when adjusting the flexplate tension?

Danglerb · 08-21-2008, 11:28 AM

http://www.nichols.nu/tip598.htm

Landseer · 05:46 AM

Todd,

Cut open the oil filter and hope for the best.
There is a lot of surface area for contact, if contact has been made, so likely a lot of mainly aluminum particles.

Some of the past threads suggest that a 5 speed could also have the contact, but it is less likely.

lizard928s · 08-22-2008, 08:05 AM

I had to laugh when I saw this, I have to admit that.

The changes of this happening on a 5 speed are pretty NIL.

good luck though

AOlson · 08-22-2008, 09:05 AM

There is no flex plate on 5-speeds, however, you can still measure crank end play which is a surrogate for thrust bearing health.

low miler · 01:57 AM

Quote:

Originally Posted by lizard928s

I had to laugh when I saw this, I have to admit that.

The changes of this happening on a 5 speed are pretty NIL.

good luck though

After talking with the Master 928 Guru Advisor, Jim Bailey, I'll admit I took one huge deep breath and felt very relieved afterwards (I'm mechanically ignorant at best, so TBF sounded logical to me?). Jim confirmed your comments and went on to say that if indeed this were a thrust bearing failure, that it would go on record as being the very first stock GT in the U.S. to experience this. Those words made me feel alot better I'll have to admit.

I'm not out of the woods yet, but I'll have a more specific answer today. From talking with Jim and my tech, the probable culprit looks like it's going to be the bolts that support the starter bracket which apparentely goes into the bellhousing. Let's hope anyway.

I'll keep everyone posted.

Todd

SeanR · 08-22-2008, 09:23 PM

Todd, I almost called you when you posted this thread. I laughed and then thought. "wait, what am I missing, could my thought process be wrong?"

Then when I got back to the thread, it was discussed, and I just had a smile.

lizard928s · 08-23-2008, 08:07 AM

Sean, I thought about posting right away, and then figured, I want to see some of the responces for a day or so :P

Danglerb · 08-23-2008, 09:30 AM

The GT part just flew right over my head.

rhjames · rhjames's Garage

Quote:

Originally Posted by Danglerb

The GT part just flew right over my head.

Sorry I couldn't help, been busy with truck show in Big D....

and now that I'm awake, yep, they're right----it's a slushbox disease.

breathe a sigh of relief.

--Russ

low miler · 06:49 PM

Let me preface this post by reminding everyone that I'm 99.5% mechanically challenged at best and that anything I say or talk about is relayed third party info and may need translation by an expert to be fully understood. This is easily verified by my GT flexplate question in the first place.

. Okay, my tech is not a 928 guru, though he is still very good, and cheap. He said on Friday just before he closed that he turned the crank and found it to be about three times the spec movement, or something like that anyway. He said regardless, it wasn't enough to be thrust bearing failure. He was then thinking out loud and said he would consider machining the flywheel? But then, while speaking out loud again, said to himself that the flywheel is honed to the crank (thereagain, he's speaking Chinese to me?

) He then said, to me this time, that I've already replaced the throw out bearing, the release bearing and installed the updated guide tube? (again?), and that to him it would appear the disc or pressure plate is out of balance or something. I do recall Jim Bailey saying something about there being flawed pressure plates or discs out there and that this might just be the culprit as well.

Sooooo, should I have him just skip the machining of the flywheel entirely (sounds risky to me?) and just replace the disc and pressure plate instead, thus making it a completely new clutch assembly? Oh, and he also measured the distance of the bearing in the torque tube and said it was about 6 inches down in there. Jim Bailey previously said it should be checked while apart and be 6 inches down. So it appears that I've at least got one thing right!

This damn GT has turned into a freakin' 4 month long project, make that full rotisserie restoration!

You name it, it's new! Yep, even that.

My doors are completely open to your valued opinions, suggestions or simple conjecture.

Thanks in advance....

Todd.......thoroughly confused and frustrated at this point.

rhjames · rhjames's Garage

Quote:

Originally Posted by low miler

Let me preface this post by reminding everyone that I'm 99.5% mechanically challenged at best and that anything I say or talk about is relayed third party info and may need translation by an expert to be fully understood. This is easily verified by my GT flexplate question in the first place.

. Okay, my tech is not a 928 guru, though he is still very good, and cheap. He said on Friday just before he closed that he turned the crank and found it to be about three times the spec movement, or something like that anyway. He said regardless, it wasn't enough to be thrust bearing failure. He was then thinking out loud and said he would consider machining the flywheel? But then, while speaking out lous again, said to himself that the flywheel is honed to the crank (thereagain, he's speaking Chinese to me?

) He then said, to me this time, that I've already replaced the throw out bearing, the release bearing and installed the updated guide tube? (again?), and that to him it would appear the disc or pressure plate is out of balance or something. I do recall Jim Bailey saying something about there being flawed pressure plates or discs out there and that that might be the culprit as well.

Sooooo, should I have him just skip the machining of the flywheel entirely (sounds risky to me?) and just replace the disc and pressure plate instead, thus making it a completely new clutch assembly? Oh, and he also measured the distance of the bearing in the torque tube and said it was about 6 inches down in there. Jim Bailey previously said it should be checked while apart and be 6 inches down. So it appears that I've at least got one thing right!

This damn GT has turned into a freakin' 4 month long project, make that full rotisserie restoration!

You name it, it's new! Yep, even that.

My doors are completely open to your valued opinions, suggestions or simple conjecture.

Thanks in advance....

Todd.......thoroughly confused and frustrated at this point.

the further I read about this, it leaves me wondering still how the marks got on the flywheel, much less the grumbling you are experiencing....

the flywheel is easy enough to check if it's out of the car. same goes for the clutch/pressure plate etc...

the sleeve doesn't look like a contributor to the problem, as you have removed and replaced it.....

too much crank end play isn't good, regardless of opinions that it would be the first for a stick car.

keep searching-----

--Russ

low miler · 08-24-2008, 07:06 PM

Quote:

Originally Posted by rhjames

the further I read about this, it leaves me wondering still how the marks got on the flywheel, much less the grumbling you are experiencing....

the flywheel is easy enough to check if it's out of the car. same goes for the clutch/pressure plate etc...

the sleeve doesn't look like a contributor to the problem, as you have removed and replaced it.....

too much crank end play isn't good, regardless of opinions that it would be the first for a stick car.

keep searching-----

--Russ

But I don't want to be the first on this issue!

Todd

Danglerb · 08-24-2008, 07:55 PM

Thrust bearing failure is from force applied against the crank pushing it forward in the block and wearing the bearing down. Nothing in a 5 spd can apply much force, except when the clutch is pressed in, and thats not enough force or for much time.

Repeating the end play measurements is where I would start, maybe pull the oil filter and cut it open to check for bearing or other metal.

****

The flywheel is a round disc of metal about 16" across, that bolts to the back end of the crank. If the flat area that contacts the clutch isn't smooth or flat enough sometimes the flywheel is turned, more or less like a disc brake rotor, except just one side.

low miler · 08-24-2008, 08:02 PM

Quote:

Originally Posted by Danglerb

Thrust bearing failure is from force applied against the crank pushing it forward in the block and wearing the bearing down. Nothing in a 5 spd can apply much force, except when the clutch is pressed in, and thats not enough force or for much time.

Repeating the end play measurements is where I would start, maybe pull the oil filter and cut it open to check for bearing or other metal.

****

The flywheel is a round disc of metal about 16" across, that bolts to the back end of the crank. If the flat area that contacts the clutch isn't smooth or flat enough sometimes the flywheel is turned, more or less like a disc brake rotor, except just one side.

So machining the flywheel WOULD be an acceptable measure?

I mean, it wouldn't do anything that could make things worse?

Todd