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Discussion Starter · #1 ·
Here's the skinny, PART I:

new 331 stroker installed. The mechanic did the initial break in for 20 mins. The car was driven approx 20 feet in and out of the garage. The oil filter was removed and brass filings were seen - crank end play increased to .025 from .006 - result thrust bearing failure.

Transmission T5
Mcleod scattershield
JMC hydraulic clutch
Spec flywheel and pressure plate.

At about this time, I'm extremely frustrated as I'm losing a chunk of the driving season which is pretty short up here.

PART II:

SO, the engine is torn apart, cleaned, new thrust
bearing, all measurements redone in spec, scattershield indexed, tranny depth measured.

The engine was re-installed, and the second attempt began. The engine ran while the car was still, no problem, broke in fine, no filings in the filter - 2 oil changes no problems.

The car was then taken for a test drive, drove very well. Opened up the filter -FRICKIN FILINGS AGAIN!!!!!! The bearing is toast.

I can't get this engine to work!!!!

What has been ruled out:
tranny is not pushing against the crank,
Driveshaft play is fine.
Clutch fork and pivot - fine

The only things left are the scattershield and the JMC clutch or some weird ghost in the block

Could the JMC hydraulic clutch not be bleeding back and exerting pressure on the clutch/flywheel/crank??

Should I try a cable clutch?

Could it be a problem with the scattershield?? Note, it has been repeatedly measured and checked and is within spec.

The mechanic has exhausted his resources and is as frustrated as I (well not quite)

PLEASE HELP, I"M DESPARATE!!!!!!
 

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time for a new builder-i know its easy for me to sit here and say that,but hell,he has to be missing something-i feel your pain.best of luck getting it sorted.
 

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You mean the crank end play Decreased from .025 to .006 right?.....

What you may have ment was an increase from .025 to .060?

Anyhow.... You should measure the clutch fork travel that comes from useing the hydraulic, it may seem to be within specs but it might be off in as much as when pushing the fork there is too much pressure applied...

I doubt that is the issue though... But it could happen I guess...

I'll drop a word in on this after I do a few mental measurements and tolerances tonight while I am sleeping and racing my falcon and let you know what the morning brings...

FE
 

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A buddy of mine had a custom clutch made for his twin turbo supra. after the clutch install he had a thrust bearing failure and it turned out the pressure plate was so stiff that the force it took to release the clutch (clutch fork pushing forward on the crank) is what caused the failure.

If your hydraulic clutch is not adjusted correctly, it could be over extending the clutch fork and be applying more pressure on the crank than what is required to actually release the pressure plate. This is the only thing I can think of. What side of the thrust bearing was damaged more?
 

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On 2006-07-12 23:56, FEandGoingBroke wrote:
You mean the crank end play Decreased from .025 to .006 right?.....

What you may have ment was an increase from .025 to .060?
From what i read, it started at .006 and after worn, it ended up at .025 clearance.
If possible, get another similar motor to get ALL sizes and reference points from. There must be a simple answer to this, so good luck finding it.(it is there though)
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<font size=-1>[ This Message was edited by: xdclevo on 7/13/06 5:31pm ]</font>

<font size=-1>[ This Message was edited by: xdclevo on 7/13/06 5:33pm ]</font>
 

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You mentioned the the hydro clutch setup, I run one, be sure there is some free travel at the pedal like with the old mechanical setup so that the thrust is not constantly engaged. Adjust it for atleast 1/2 to 1" free travel at mid rpm (neutral, of course).

Always have the car in neutral and foot off clutch when starting the motor and until there is ample oil pressure. Learned this the hard way long ago with a hays racing plate, somewhere around 3200 lbs, on a small ford.

I have had best luck with the thrusts and high-pressure plates by providing additional oil to the rear bearing half by adding a slight chamfer at the both parting lines back of the rear bearing shell. This will provide more oil under pressure to the rear of the bearing.

Make sure that the crank thrust surface is perfectly smooth and true.

If you were closer I'd take this one on.
 

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Discussion Starter · #7 ·
Thank you fo the responses. Yes, crank end play increased from the accepted .006 to .025 because of the loss of bearing thickness.

The bearing scored pretty evenly on the backside.

Could the heavy duty clutch be the problem? It's only a SPEC stage 2 and they have up to a stage 5 - so it's not extreme.

I don't recall the play in the clutch, could that be enough to toast a bearing?

The clutch fork pivot angle was similar to stock, but I'll ask the mechanic again.

Could it be that scattershield for some odd reason? It was indexed at the crank.

Modifying the thrust bearing for increased oiling sounds iinteresting, I'll forward it to the builder.



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<font size=-1>[ This Message was edited by: DrStang on 7/13/06 9:18pm ]</font>
 

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I had a similar problem once. One of the pressure plate fingers jammed requiring extra effort to push in and disengage the clutch. In the 20 mile drive back home endplay went from .005" to over .090".
 

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Discussion Starter · #9 ·
On 2006-07-13 06:52, bmcd66250 wrote:
I had a similar problem once. One of the pressure plate fingers jammed requiring extra effort to push in and disengage the clutch. In the 20 mile drive back home endplay went from .005" to over .090".
Interesting... I'll ask the mechanic if extra force was needed to engage the clutch, since I didn't road test it.
 

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I would say the problem lies in the clutching setup. I would definately focus my attention there. You will find it
 

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Discussion Starter · #11 ·
On 2006-07-13 08:11, woody1 wrote:
I would say the problem lies in the clutching setup. I would definately focus my attention there. You will find it
Do you think I should concentrate more on the clutch itself of more on the engagment linkage (hydraulic clutch setup).
 

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well my first observations would be the hyd engagement and see if its fully disengaged when shifting from gear to gear. It's terribly hard sometimes to envision what is happening on someones car 3000 miles away but it sounds just like an old lady riding the brakes and wondering why she needs brakes every 2000 miles
 

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Discussion Starter · #13 ·
On 2006-07-13 08:56, woody1 wrote:
well my first observations would be the hyd engagement and see if its fully disengaged when shifting from gear to gear. It's terribly hard sometimes to envision what is happening on someones car 3000 miles away but it sounds just like an old lady riding the brakes and wondering why she needs brakes every 2000 miles
Sometimes I feel like a little old lady
especially after a hard weekend of football.

Note: the first time the thrust bearing went, the car was only driven 20 feet.
 

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If the engine ran ok, in neutral, then chewed up the thrust bearing after driving he car, I suspect the issue has to be with the clutch.

Was the crankshaft checked for burrs in the area of the thrust bearing after the first failure?

Frank
 

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Can you check the crank end play with everything assembled and in the car? I had a couple of my pressure plate bolts work their way out a little bit a while back... didn't realize what the problem was, but the clutch had to be all the way to the floor to even start disengaging, so I tightened up the slave cylinder until the clutch worked right... which made it put constant pressure on the clutch fork all the time. Drove it for probably at least a month that way before the bolts worked loose so far that I started to fee a vibration. Started checking around and finally Holy Sh1t, the bolts are loose! So I tightenend them up, re-adjusted the slave cylinder, and have put probably 10K-15K miles and a few dozen 7000rpm shifts on it since then. There was never a change in oil pressure, and I didn't check the filter, just tossed it during oil changes... but now this thread has me wondering if having the clutch fork pre-loaded for that long caused any thrust wear.

Given all this though, I can't see it possible that 10-15 miles with a clutch that is a little on the heavy side would ever cause THAT much wear on the thrust bearing. If it did, then my crank would have ground all the way through the bearing LONG ago! I think your problem has to be something like the crank's thrust surface not being prepped right.

Also 66408stang: Every single manual transmission car I've ever driven required the clutch pedal to be pushed in during startup... it's a safety feature, and obviously never caused any excessive wear on the thousands (millions?) of cars that come like that from the factory... so I can't see why that would cause any problems here.
 

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Discussion Starter · #16 ·
Thanks guys,

Well the crank surface has been checked and double checked and is true.

Crank end play was checked with everything still attached. Showed up at .025 from the initial and accepted .006.

The next step is to disassemble, clean, reassemble and put it on the engine dyno. That will give me a definitive answer on the status of the engine build.

If it survives, it's gotta be the clutch/bellhousing/hydraulic setup.
 

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On 2006-07-12 22:23, DrStang wrote:
What has been ruled out:
tranny is not pushing against the crank,
Driveshaft play is fine.
Clutch fork and pivot - fine
Flywheel side of thrust bearing is worn out? Right?

Walk us through your check method for each of the items in the list. It's one of them...
 

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Discussion Starter · #18 ·
Flywheel side of thrust bearing is worn out? Right?

Walk us through your check method for each of the items in the list. It's one of them...
Flywheel side, yes.

Transmission - Shaft length is stock T5 specs , nothing special here.

Bellhousing has been measured and is within stock specs, also has been indexed to acceptable specs to the crank.

Clutch pivot is at stock height

Play in the hydraulic clutch - the clutch has been adjusted so in engages closer to the end of the down stroke so there should be sufficient play.

thank you,

Steve


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<font size=-1>[ This Message was edited by: DrStang on 7/14/06 10:31pm ]</font>
 

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Ummm...those aren't exactly measurement techniques.

I would back the tranny to bellhousing bolts out about 0.250" and with the oil pan off check the end play.

Next cinch down the trans and check it again. I bet your endplay goes to zero. You have to be having thrust on the flywheel from the trans....


This of course implies you have a 'correct' thrust to start with which implies pulling the whole thing apart again...and checking the crank and replacing the thrust bearing.

HTH

Oh...and don't run it with the oil pan off.
 
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