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Discussion Starter · #1 ·
I read a lot. But my first fiasco, maybe.
2005 T56 120,000k a bit sloppy. Took too south Florida A+ shop that only does manuals. $1700 new synchros, steel shift fork. Couple bearings and input shaft.
Bolting got to about an inch away. Used guide bolts. Lined ‘er up and inched in and torqued
Notice output triangle very stiff. But two hands could move.
hooked up and fired up with driveline attached after clutch bleed.
Ran for 5 minutes and kinda stalled. Tried to start and kind of bound.
Thought it thru. Removed trans. Called shop. Turns out input shaft is 1/2” too long. Meant for GTO orC06. Not V.
Crossing fingers. Has anyone had this happen and any engine internal / tranny damage from spring loading the crank about 7/16” ?? (New ls7 flywheel/clutch)
 

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Hmm. Any chance you damaged the thrust bearing?


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Check the oil filter for metal flakes. Sounds like the thrust bearing could have been murdered. If so......time to throw in forged internals. :( but also :)
 

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Bolting got to about an inch away. Used guide bolts. Lined ‘er up and inched in and torqued
You know this is NOT on the transmission shop, right?
Yeah, they used the wrong parts, yeah that was wrong....
but there's no install procedure, anywhere that treats this as a press-fit operation.
Any time you are installing a trans to engine ~~manual OR automatic~~ the mechanic has to verify that the bell housing mates to the engine fully without pulling down with bolts.
If it will not mate up, the next step is detective work, not force-fitting.

The trans shop should fix the box but even that isn't certain (there could be snap ring/case/bearing or other damage in the trans) but I wonder if there may be damage in the engine.
The great likelihood (just my opinion) is that the locking up that occurred is possibly in the trans and your engine is likely OK.
You could measure (with a dial indicator) the crank end play while the trans is out and compare to the spec (?) but even that may not reveal all.
 
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I would think measuring endplay WOULD say if the thrust bearing is chewed up in the engine. "Kinda" stalled?? What does that mean? "Kind of" bound? What does THAT mean? It either stalled or didn't, and it is either seized up (bound) or not. That would be like "kinda" pregnant. That's not an option.
 

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Have the oil sent out and analyzed. The filter probably has some metal bits inside.


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Agree about the vague wording.
Not really useful when diagnosing


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Discussion Starter · #8 ·
The engine stalled. Started but with much starter torque, almost thought it was a low battery. And stalled again. Stopped there.

The 8 trans bolts did NOT turn with any more force than seemed normal.

Great idea on looking at oil, definitely will do. We have not attempted to move engine since last stall and subsequent transmission removal.

And will search the endplay procedure.
 

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The 8 trans bolts did NOT turn with any more force than seemed normal.
Let's explore this a bit.
Did the bell housing (once it was aligned on the pins) slide up to the block without bolts being used to pull it up?
"Normal" in this case would be the effort it takes to run the bolts into the threads with your fingers, until the head contacts metal, with the bell housing mated up. If the bell housing will not mate up to the block, ANY effort using tools to make it so is NOT normal force.
When you have a large number of bolts on an assembly like that, as you move from snugging one to snugging the next and the next, it can seem that it couldn't be excessive as no ONE fastener was extreme. The cumulative 'stepping effect' can be substantial, though.
 

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Bottom line, the crank is not designed to be pushed on axially. I don't see how you could put 1/2" of compressive "preload" on the crank and gear box input shaft both, that the thrust bearings could survive. Just think about it. 1/2" too long. Steel doesn't compress very well. Where did that 1/2" go? In all likelihood the bell housing deformed and the result was the same as if a huge/stiff spring had been put between the crank and transmission shaft. Run for 5 minutes before it died? That's how long it took the bearing to fail. :(
 

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Discussion Starter · #11 ·
With old Pontiac’s I could “listen” for spun or bad bearings. The LS6, we are not accustomed to lower end r&r. The engine was not seized. Rolled a few revolutions by rotating flywheel. Engine fired easily/ quickly. Did a few 20 second cycles. Next is to drain oil and analyze
Thrust measurement search results are inconclusive on results. Tranny shop will open box so WE can see any shaving, deformations.
Any other NDE checks suggested??
 

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I am of the opinion that the crank thrust bearing is likely fine and the trans is potentially more seriously damaged.

Along those lines, just for study purposes let’s say the crank thrust surface WAS damaged some in this short run time.
Once the cause of the loading was removed, how critical would the thrust bearing clearance be, if every thing else is fine with the main bearing?
Of course the metal shavings that might result from the event might themselves become an issue if not filtered out, but, again the actual cause of the thrust load is gone.... the thrust bearing surface had some wear. Thrust bearing damage doesn’t automatically lead to main journal damage. Is the engine going to grenade, due to the thrust bearing having some wear? The only direct axial loading it’s going to see is clutch operation. I would do oil analysis, at least three times over say, 1500mi to see if it ‘cleans up’. If oil pressure stays good, oil cleans up and no odd noises?
I probably wouldn’t lose any sleep over the engine unless the main has spun (oil pressure tanks) or crank end play is huge.


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Thrust bearing damage doesn’t automatically lead to main journal damage.
But it can lead to other damage. When the crank moves fore/aft, the connecting rods have to tilt so the big end can follow the crank while the top remains held in its vertical orientation by the wrist pin. Pulling the bottom of the rod towards the front of the motor is going to put side loads on rod bearings, pistons and rings... none of which are designed to move with that kind of load.
 

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The effect of the pistons tilting in their bores and the rod bearings rocking slightly would certainly not be a positive but again, back to the numbers and how much movement are we talking about? As with everything else mechanical, there are allowable tolerances for every dimension, so it's a matter of degree...literally.
If the crank shifted 0.025 the rod and piston tilt would be 0.234degree. Again, not preferred, but would less than a quarter of a degree kill an engine? I’ve taken apart old well worn (but still running quietly) SBCs with more end play than that.
I don’t know, I’m hoping someone has some tolerance numbers for us and also hoping the OP can tell us what he measures on his.


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Did you pull the filter and cut it open?
 

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I would check crankshaft end play with a dial indicator applying light pressure to the balancer with a pry bay to check the thrust bearing clearance. Very easy to do and eliminates all of the guessing.

I have done this before in another car I owned that “ballooned” the torque converter. Worked very well.
 

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Discussion Starter · #17 ·
We have not changed the oil yet. Still sitting and waiting for the correct input shaft to come in. I will do both the thrust measurement and the oil change.
 

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Any update?


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