Thrust Bearing failure,Only 1 ?

[LikeMySix]

Got a thrust failure, I'm aware of all the possibilities of why. My question is this.
Max end play is .007 so in the event of a thrust failure you end up with .064 what is the chances your crank is junk?

Thats all I want to ask, get some idea before I pull the motor and tear it down. Just really pissed and wanted some thoughts. Motor only had 300 miles on it,with zero passes. Really sad! This might get ugly in the coming weeks.

TIA

Frank

 

[LikeMySix]

NoOne has any opinions?

Just for kicks I will throw this out there.
This is a $20k engine Oncenter TA aluminum Block. Crower 2.5" Billet crank Oliver Billet Rods. Had a well known engine builder (Sponser here) assemble it, the failure at this time doesnt appear to be his fault. That doesnt go without saying he was mistake free. The thrust failure would have been indentified immediately had he not made the mistake he did. The Thrust failure at this time seems to be caused by the T400 coverter/cooler pressure output. It was measured at 80psi. Took for granted the transmission was built/modified by the trans guy that builds the transmissions for another big name sponser/member of this site, and that I was refered to this shop by him.The trans shop was instructed to build the tranny to the specs just like the above mentioned members tranny. Its quite obvious his tranny isnt killing his thrust bearing since hes running 8 seconds without issue. Guess the needed pump mod slipped this tranny guys mind building my trans. So again I see another american charging a premium price for a half ass job,and we all wonder why our country is going to crap. NoOne wants to take pride in there work anymore, hence why everything is being built in China. If you cant do it yourself then your pretty much screwed anymore.

 

[cool 84]

My dad had a thrust failure in similar conditions. The motor had never been over 10psi because it was being broken in. Less than 300 miles. It started with a knock, a deep knock that was definately a bottom end problem. We tore it apart and the crank had shifted so far forward that the counterweights were hitting on the main webbing. We rebuilt it with the same crank and block and all was well with many 10 and 11 second passses for years. It only killed the bearing, crank was fine. The original builder had set it up at .002". I would say you definately have a chance of the crank still being good.

Oh, and China junk is just that, junk. At least give the builder good parts so he has a chance to build a good motor/tranny.

 

[S2V6RACER]

I am scared at what you are going to find. I'm pretty sure the crank can be repaired however, but I understand your frustration. 80psi fill PSI is pretty high, I know of a few that smoked thrust bearings because of that. I was scared to death with all this kind of crap going on and I log that PSI on my racepak so at least I know what works for me and it isn't 80psi.

Good luck and I'm sorry for your problems.

 

[LikeMySix]

My engine was in the break in period as well, too bad it really broke. Boost was at 9#. But realize 9# is still moving alot of air with what I'm using. TA street eliminators with larger valves and full port and polish(mike @ TA personally built these) 1.75:1 rockers. Cam is a 236/236 with 650" lift. Turbo is a GT4276 so theres alot of air moving even at 9#. THE ONLY positive is there hasnt been any type of abnormal engine noise at all. All the way up until I confirmed excessive endplay still no knock. Engine Ran smooth and sounded perfectly normal. Oil pressure at hot idle 12# was the 1st thing that rose my suspicion using 20/50 or even straight 50. Then of course the gold flakes in the oil.

As for china products, yea mostly junk. The problem is there willing to do the work for little money. What hurts them isnt the workmanship its the quality of the material. Here it the USA we have good/excellent quality of materials but poor workmanship. The inability to follow thru (no pride/shortcuts) with work.

 

[Alky V6]

80 psi from a 400 at the cooler line is a crank killer. End of story.

The pump mod for the 400 is largely unknown or ignored by a very high percentage of transmission builders (in the 90s percentile). You'd think it should be a common procedure. It is not. And most tranny guys will argue that it's not necessary. Mainly because they don't understand the physics of the situation.

It is!!!

When did you find out you had 80 psi? I sure hope you didn't start that engine knowing it had 80 psi.

You're headed down the wrong road if you're suggesting the engine builder caused this failure. You could have had the best, and it actually sounds like you did, and still kill that thrust with a 80 psi cooler pressure reading.

I'm surprised that I'm still reading about crank thrust failures on this board. I thought I educated everyone on this problem. Dang! I feel for you guys.

 

[Alky V6]

I have to tell you this story.

I very well known Turbo Buick specialist (not transmission) on the west coast called me up to ask me why he just took out the 3rd crankshaft in his Stage II, twin turbo Buick race car. Of course, the first question out of my mouth is, "You're using a 400, right?" He was. Built by a legendary tranny builder on the west coast. I explained what I felt was happening, even though I had not been able to do any testing myself. I explained to him what had to happen. He went back to his tranny guy and, as usual and expected, the guy was adamant that the pump mod would cause problems with the T/C. Cavitation is what I think it was. The person with the engine problem called me back for more clarification. I gave it to him. He went back to the tranny guy. The tranny guy was unyielding. I mean, what would you think. Here's this legendary tranny man telling you one thing, and then on the other hand, this 'Don Wang guy' telling you he's wrong in his thinking. Finally, I just told the guy, "Just tell him to do the mod or do it yourself."

The mod was done and a happy ending ensued. The End.

Three crankshafts. Three ruined high dollar engines. It just turns my stomach.

 

[83ttypecooled]

Hi,
I don't know much about Hi end turbo Buicks, or race caliber thm400s,but the first thing that came to mind was torque converter surge,or balooning.As you are running a race converter,with subsequent reinforcement,the latter is out of the question.I'm a grunt;I work in the trenches of auto repair,where 20 psi cooler pressure is the norm. Why would 80 psi cooler pressure be necessary? Usually, that pressure would be reserved for line,at rest.If you are running that much,then line pressure must be astronomical. Anyway, Wong is right and I would imagine a restrictor of some sort is in order.
By the way, regarding Chinese parts,it is an ongoing thing here in the trenches. I see an significant rate of failure with parts in the jobs I perform,and it irritates me.I try to do MY best,and don't think you are being fair regarding American workers. Sure, there is some slipshod, bad attitude crap being put out there, but it is balanced by a lot of fine craftmanship. TA performance is a perfect example.That must be SOME machine you have there,and Americans built it.You have a few glitches, but do you think the Chinese could have done a better job?
That's it, good luck with your issue!

 

[Alky V6]

Be careful about the Chinese stuff. I'm old enough to remember people saying the exact same thing about Japanese stuff. Look at what happened with that.

 

[Alky V6]

When I was first testing 400s to determine why 400s seemed to always be paired with crankshaft failures (late 1980s), it was not for race cars or race engines. This was a very common occurrence in simple motorhomes and HD trucks with a BBC and turbo 400 drivetrain.

 

[83ttypecooled]

Hi Donnie,
And what was your conclusion? This is interesting, as I have never seen a 400 cause this problem.I go way back also,though in the earlier days my experience was limited.Did a lot of racers back in the 60s and up have this issue? Very interesting about the motorhomes and such. Thanks,in advance, for light you can shed on this issue. By the way, sorry I misused your name, should have been Wang.

 

[Alky V6]

Hi Donnie,
And what was your conclusion? This is interesting, as I have never seen a 400 cause this problem.I go way back also,though in the earlier days my experience was limited.Did a lot of racers back in the 60s and up have this issue? Very interesting about the motorhomes and such. Thanks,in advance, for light you can shed on this issue. By the way, sorry I misused your name, should have been Wang.

That's OK. A lot of people say, and mis-spell it wong all the time. In China, Wang is actually pronounced Wong. So Wong is actually the wight way to say it, not spell it.

Anyway. Starting with transmissions in the early 80s, I had always heard of BBCs killing the cranks in MH or HD trucks. It didn't dawn on me until I had more experience under my belt that this always occurred with 400s in the picture. Being that I worked at the only shop in San Diego that was using a transmission dyno to test transmissions, I had the chance to observe normal pressure characteristics of different transmissions. One of the pressures always monitored during testing was cooler line pressure. 40 psi was by far the average standard for just about all models of transmissions. One day during testing of a 400 that was known to have come from a job that involved a crank thrust failure in a MH with a BBC, the dyno operator called me over to observe the cooler line pressure. It was 100 psi! Being that we were used to seeing 40 psi on most everything including 400s, this was very alarming. I was also very excited since we had just discovered the cause for the crank thrust failures.

Imagine a plastic coke bottle filled with water and one person is squeezing the bottle, while another person is trying to keep the cap from blowing off. Imagine the cap is not screwed on, but is slipped on, just like a torque converter slips into the front of the transmission. Squeezing the bottle creates pressure on the cap, which tries to blow the cap off the front of the bottle. The more you squeeze, the more pressure on the cap. This pressure is pushing the cap forward, just like the T/C pushes forward on the crank thrust. The crank thrust is designed to take some loading. The active word here is 'some'. Too much load and the oil film overheats, breaks down and metal to metal contact occurs. The rest is history.

The pressure exerted on the crankshaft is the inside area of the torque converter hub times the pressure of the fluid feeding the torque converter.

A more detailed description and the fix has been explained in past posts. Do a search for crank thrust failures.

 

[83ttypecooled]

Hi Danny,
Thanks for your elucidation on this issue. I hope to speak with you again in the future. You are a gentleman and a scholar!
Dale

 

[LikeMySix]

Don I caught this problem hopelully in time the engine hasnt started knocking yet and my engine builder tried to give me some hope in that the crank was nitrided and hard chromed on the bearing surfaces to supossedly give it a very high rockwell rating.We will see when I get the time to tear into it. My above statements didnt accuse the builder of the failure but the transmission. Like you stated 90% of the trans builders dont mod the pump or check for this pressure, I took for granted this guy was building T400's for TSO buicks and thought it was taken care of. I can only hope the thrust bearing is the only casualty. Oh and the T400 in question happens to be a Truck/RV trans.

As for the China statement you get what you pay for is what I was referring to. Here in the US it seems more like you never get what you pay for anymore unless you supervise the progress of what your buying even then its still marginal.