Excessive crankshaft end play

[lost2a6]

I just pulled my tranny to get the converter restalled and happened to grab my flexplate to see if I could get some fore and aft movement. What I discovered was HOLLY S**T, I've got approx .030-.040 movement. The engine has about 7000 miles and about 30 1/8 mile passes since major rebuild. The only thing that I can think of that would have caused this is converter. I have run two converters on this engine since rebuild. First was the Vigilante multi disc and now the billet 9X11. I had a lot of trouble out of the Vigilante; it wouldn't surprise me if it caused the damage. Would it hurt anything to run as is, or could I get away with just replacing all of the main bearings without removing the crank, providing that the crank still looks good. The oil press is still about the same as it was since I first fired it up.
Thanks

 

[Blown&Injected]

The book says .003 to .009 so it sounds like the thrust bearing is dead. How much play between the flex plate and converter?

 

[750H.P.V6]

Steve,

Sorry to hear about your problem. I came across a similar issue in my friends high mileage GN with an old style AC 9" convertor. In his case we found that the thrust bearing and the crank were bad. We put another bearing in there to take up part of the clearance. The car ran long enough to get the new motor on line. When we disassembled the old motor the crank was toast and we tossed it out. I hope yours isn't this bad.

Good Luck

Neal

 

[REDS HOT AIR]

http://www.turbobuick.com/forums/showthread.php?s=&threadid=144845

 

[lost2a6]

Thanks Guys, I did think about the issue with the converters bolting flat against the flex plate. I'll put it back together with some washers. I hope this is what caused it, and then just maybe I can get away with replacing the bearings. I have about 3/16-1/4 play between the converter and flex plate when unbolted and converter pushed all the way back. The crank was good when I had installed it. It was turned .010-.010; it had been balanced and checked for run out. The block has the center billet steel caps, ARP studs, and was align bored. With the Vigilante, I always had issues with the converter not wanting to go all the way forward until it hit the flex plate, had to pry, fight cuss etc. Come to think of it, I do recall being at the GS Nationals one year, and some guy was at the Vigilante booth bitching how their converter had caused his thrust bearing to fail. Who knows?

 

[Reaper]

cough thrust bearing cough cough

 

[JDEstill]

also check out this article, it talks about how excessive trans pressures can cause thrust failures.

http://www.atra.com/crankshaft/

John

 

[lost2a6]

Originally posted by JDEstill
also check out this article, it talks about how excessive trans pressures can cause thrust failures.

http://www.atra.com/crankshaft/

John

Wow, that was very interesting. Once when I was running the Vigilante, I was in third at WFO and for no apparent reason the rotor in the front pump just broke! I wonder if this was from the converter balloning.

 

[lazaris]

I would T into the your trans line that goes out to the cooler and see what the pressure is. This is the pressure the converter sees and what pushes it out into the crank. Report what you find.

 

[lost2a6]

Originally posted by lazaris
I would T into the your trans line that goes out to the cooler and see what the pressure is. This is the pressure the converter sees and what pushes it out into the crank. Report what you find.

I'll do, however I don't think that there's a problem now. I feel like this happened a while back and I have just now discovered it. When I first installed the vigilante, they had me put a .030 restrictor in the cooler line. I didn't like the idea, but I figured they knew what they where doing. I took the restrictor out and ended up chunking it, after I put 2-3000 miles on the car and several WOT passes.

 

[lazaris]

Dont assume its ok untill you check the pressure. I was suppose to have a modded pump with the unit I bought to reduce the converter feed pressure and after I checked it it allot more than the thrust bearing would take..........

 

[S2V6RACER]

Originally posted by lazaris
Dont assume its ok untill you check the pressure. I was suppose to have a modded pump with the unit I bought to reduce the converter feed pressure and after I checked it it allot more than the thrust bearing would take..........

Give this man a cigar.

 

[lost2a6]

So what should the max press be?

 

[lazaris]

Thanks Ted. From the information i have gathered, if your runnig a turbo 400 then no more than 50psi. With a 200r4 you can get away with slightly more because the inner surface area of the converter snout is smaller thus producing overall less force.

 

[JDEstill]

I seem to remember reading somewhere or another that running two coolers in series (such as the one in the radiator followed by an external cooler) might restrict the flow some, which then raises the pressure, which could then cause a thrust problem. Can anyone confirm that is a real possibility?

John

 

[lazaris]

John,

I ran tests on that as well. The result was that the more coolers you ran in series the more the backpressure went up, leading to more coverter thrust force. I would not run the stock cooler combined with a an external on a 400 or even a 2004r for that matter, especially if converter feed pressures have not be modified. The size of the external cooler along with inlet and outlet size will play a role in how restrictive the cooler is and thus how much backpressure it creates.

 

[lost2a6]

Another question, it just dawned on me, how are you guys checking the press on the 2004r? The reason why I ask is because on the 200's that still retain the lockup, there is very little fluid that goes through the cooler until the converter locks up. If I remember correctly, it's like only 20-30% flow goes through the cooler when the converter is unlocked.

 

[lost2a6]

Update: Just pulled the main/thrust bearing. The rear thrust side of the bearing is trashed. The crank isn't too bad. It has around a .005 wear groove in it. But what really concerns me is on the lower bearing, looking from the front of the engine, at about the 7:00 O'clock position; there is some brass showing. I'm thinking that this is from detonation, or it busting up, as I'm not going to lie, I've detonated, over-revved the sh$t out of this engine. One good thing is that the center billet main caps are still very tight. I purposely didn’t O-ring my heads for the simple reason of using the head gasket as a relief valve sort of speaking. I would rather it to blow a head gasket than to drive over the crank. I guess that the good ole GM head gaskets held a little too good.

 

[2 SLOW]

I have had thrust problems before too. Two years ago I had my motor rebuilt. After 50 miles the thrust started to go bad. Pulled the motor and had it fixed before it caused any serious problems. The engine guy blamed the tranny guy and the tranny guy blamed the engine guy, leaving me, the customer in the middle. I believed the tranny guy and left the same converter in when it went back together. There were no further problems. It would take a lot of pressure in the converter to hurt the thrust. It is just another bearing like a rod or main, and look at the pressure when you are making 400 or 500 HP. Now if it baloons thats another thing. Thats when the converter grows so much it takes up the 3/16ths play and starts to jam the crank forward. So be careful about putting washers in.

And how did I know there was a problem after 50 miles? When you rebuild a motor you should always take the filter apart after 50 miles and then again after another 500 miles to see if there is any copper on the paper element in the filter. The thrust is the only place copper will come from. And of course you should be looking for any other metal as well.

We never did figure out why the thrust went bad, and a converter can cause a problem, but my tranny guy says a turbo 400 tranny puts out a lot more pressure than a 200 so it is less likely to be a problem.

HTH

 

[lost2a6]

Originally posted by 2 SLOW
I have had thrust problems before too. Two years ago I had my motor rebuilt. After 50 miles the thrust started to go bad. Pulled the motor and had it fixed before it caused any serious problems. The engine guy blamed the tranny guy and the tranny guy blamed the engine guy, leaving me, the customer in the middle. I believed the tranny guy and left the same converter in when it went back together. There were no further problems. It would take a lot of pressure in the converter to hurt the thrust. It is just another bearing like a rod or main, and look at the pressure when you are making 400 or 500 HP. Now if it baloons thats another thing. Thats when the converter grows so much it takes up the 3/16ths play and starts to jam the crank forward. So be careful about putting washers in.

And how did I know there was a problem after 50 miles? When you rebuild a motor you should always take the filter apart after 50 miles and then again after another 500 miles to see if there is any copper on the paper element in the filter. The thrust is the only place copper will come from. And of course you should be looking for any other metal as well.

We never did figure out why the thrust went bad, and a converter can cause a problem, but my tranny guy says a turbo 400 tranny puts out a lot more pressure than a 200 so it is less likely to be a problem.

HTH

Thanks; I just got back from the machine shop. He looked at my bearings. Of course the thrust is bad but the brass that was showing on the mains wasn't bad at all. He said that being as they were racing bearings,(V-series) the tin layer is very thin and any wear at all would show brass. The bearing surface is very smooth, which he is saying is good.

Yea, I might as well not worry with the washers. Without the washers, that is just that much more growing room for the converter. The way I look at it is, what if I had a standard shift trans. then the so called flex plate wouldn't exist. It would be called a "Flywheel" which doesn't flex at all.