Bad thrust bearing in 370 miles?

[RKHiPerformance]

Check this thread:

http://www.turbobuicks.com/forums/showthread.php?t=32584

 

[Joe Tiano]

Converter drops back and the pump engages.
__________________
Umm..I dont think this is your problem...if that was the case the pump & tangs on the converter would chewd all to f%#! it sounds to me like the switch on the brake pedal needs some adjustment or the TCC selonid is about shot..good luck joe

 

[Silver 'T' Top]

It would explain why my lockup only works going uphill. Converter drops back and the pump engages.

If the pump is not engaged till this point, how'd you get through your first 3 gears?? Sorry, don't buy this one!

 

[Silver 'T' Top]

Anyone else with "proof" that a converter took out a thrust bearing ? Sorry, I still don't see how that can happen even after reading Ken's article.

 

[Bryan Weber]

Steel Cap Installation

What commenly happens when caps are installed the cap is not square to the main bores. This is because the cap mating surface on the block is broached in the GM production process. The cap is then bolted in place and the main bores and thrust surface machined. If when the steel caps are installed and the mating surface is not machined square to the main bores the cap will be out of square. This is why we always machine the main registers when installing caps.

 

[getchasum]

What commenly happens when caps are installed the cap is not square to the main bores. This is because the cap mating surface on the block is broached in the GM production process. The cap is then bolted in place and the main bores and thrust surface machined. If when the steel caps are installed and the mating surface is not machined square to the main bores the cap will be out of square. This is why we always machine the main registers when installing caps.

Bryan, welcome and glad your here sharing you knowledge.
Two questions.
1. what is broached?
2. Can this type of error happen with a a simple line hone and stock caps?

 

[Bryan Weber]

Broaching is not as common in engine production as it used to be thankfully. There is different type of broaching but the type used for main registers is rotary broaching. If you picture a circular saw blade but much wider this would be the type of broached used. The problem is that when the cutters get a little dull and it goes over a hole the load (psi)on the cutter changes and it cuts deeper at that point.

Can the problem happen from just doing an align hone job? Absolutely. The side of the thrust cap has two different machining operations done and are not necessarily parallel to each other. When grinding the bottom of the cap it is clamped against the side of the cap in the fixture. The cap grinder if it is set up properly the wheel cuts exactly 90 degrees from the from the surface of the fixture that contacts the side of the cap. The part of the cap that protrudes the farthest is what will contact the fixture. On this engine that is not the thrust surface. So basically if a machinist just cuts the cap like they would any other (non-thrust), the thrust surface of the cap will likely be out of square to the crank and cause the bottom edge of the thrust bearing to be where the contact is made. This greatly reduces the bearing surface area and will cause thrust bearing failure.

I hope my attempt at explaining this is understandable.

 

[Silver 'T' Top]

Yes Brian, thanks for your input on this matter! Keep it coming, I know I ain't the only one out there!

 

[Marc87GN]

You guys are worrying me with some of these posts.

 

[Scott Atk]

Mark, Here's a good read for you.

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

 

[Marc87GN]

Mark, Here's a good read for you.

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

Thanks alot. Interesting article.

 

[Bryan Weber]

That's a great article. Thanks. I am however suprised they didn't mention thrust cap misalignment caused by improper main cap installation or improper cutting prior to align honing or boring. These are posibilities that are 100% factual and should not be overlooked.

 

[stretch]

Update

The machine shop didn't find anything wrong in my motor..they suspect the convertor as well.

The cam bearings look good..we're replacing the rings, rod & main bearings & of course cleaning the block up.

I have no choice but to swap out that 9/11 convertor & see what happens.

I'm going to have to check out this line pressure I keep hearing about.

I can't afford to have this happen again.

 

[Marc87GN]

The machine shop didn't find anything wrong in my motor..they suspect the convertor as well.

The cam bearings look good..we're replacing the rings, rod & main bearings & of course cleaning the block up.

I have no choice but to swap out that 9/11 convertor & see what happens.

I'm going to have to check out this line pressure I keep hearing about.

I can't afford to have this happen again.

I hope you get a few 100K out of the next one. I hear you on that last comment.

 

[Silver 'T' Top]

Keep us posted, we are putting a stock converter back in mine for the time being. Will be checking LP also, whats the magic # we are looking for in regards to LP?

 

[ijames]

Remember, this line pressure is the pressure in the cooling line going from trans to trans cooler, NOT the internal line pressure. Tee a gauge into the line up by the radiator. I've read that on a 200-4R this pressure needs to be under 100 psi. Do some searches in the trans forum and maybe here; there's been some discussion of this a few times with people giving pressures. With a TH400 this needs to be under 75 psi for sure and hopefully closer to 50 psi since that input shaft is bigger so it is a bigger piston, generating more force with less pressure.