Torque Converter Flex Plate Question

[Tinkerer]

Can anyone explain why a flex plate would turn into such a total disaster ? I removed the engine in my Case tractor/loader/backhoe for a major overhaul and this what I found. There was a lot of rust in the flywheel hub and on the converter nose.
I had no idea that the flex plate was failing. The machine still ran OK with no vibration or noise. If you look closely at the metal around the bolt holes they are cracked to the point of breaking off like the others that are broken.

 

[willie59]

I've seen flex plates destroyed like that as well tinkerer, for no rhyme or reason, and no faulty components, have no idea why they do that. Possibly just age, since the flex plate is tempered steel, constant flexing over long period of time simply causes metal fatigue and it begins to break up. Just my best guess.

 

[MitchSA]

I've seen them do that aswell. Changed some the other day on a Tadano crane, this one had multiple plates though. 4 I think?

 

[grandpa]

Going into gear at too high idle..... check idle adjustment

 

[Tinkerer]

It isn't the idle speed. It has a good working tachometer and the idle speed is well within factory specs. Also, always a complete stop before changing direction with the shuttle. I believe ATCO is right --- no rhyme or reason it just sometimes happens. Maybe we will hear about some more experiences with this kind of failure.

 

[alan cox]

were the bolts tight, are the two housings machined to be perfectly paralell.. no loose bolts or something under one side so the flex plate is working too much.
the flex plate is just that. a plate that flexes because things are not lined up perfectly. that is what it does. i am thinking this is the part that sacrafices itself and the purpouse is to stop a thing called fretting.. this really should be called a fret protector..
when a female spline is inside a male spline and the two transferr power. the splines develope a chatter. (fretting ) and it starts to fatigue the two surfaces.
some newer john deer tractors have a shaft inside the transmission that is in the back of the flyweel. it is dry. no lubrication. these are failing rather rapidly. no flex plate.
i think there is something here that is perfectly normal and expecting the flex plate to last forever is not the answer. it is for saving wear and tear on the torque converter.
i have changed dozens of these. few were like this. most are not.

 

[alrman]

I'm also with ATCO on this, but I must say I've never seen one so rusty - do you clear snow with it?
It is possible to fit the plates on the Case convertors, with them being not truely in the centre. There is an aligning tool for the job - never seen one, always nipped a couple of bolts & centralized the plate to convertor with verniers & then tightened bolts.

 

[Tinkerer]

Yes it has cleared its share of snow. But the snow was never that deep! The converter housing inspection panel was still in place and all the bolts were tight. I have the original shop manual. There is nothing in it in regards to centering it on the flywheel. It doe's explain about shimming the flex plate to give the converter shaft the correct amount of insertion onto the shuttle input shaft.

 

[John C.]

There any number of reasons that flex plate looks as it does. First and foremost is the amount of hours on the machine. The fact that it is rusty means the rear main seal in the engine is good.

Hard shifting, lots of high travel speeds, ramming the loader bucket into piles and so on and so forth. If there is lots of time on this machine I would consider tearing down the torque converter since you have it out of the machine. Bearings and seals are probably in order for high hours. You probably won't find anything wrong but just in case you might find something that could cause you grief down the road. If the transmission oil temperature has been running high you definitely need to take it down.

Other than all this, I agree completely with Atco. These things just happen to fail in this manner, sometimes for no apparent reason.

 

[Tinkerer]

Alan, Yes the bolts were all tight. Maybe the rust in the hub of the flywheel and on the converter knob contributed to the failure. The converter and flywheel had to be wriggled a lot to get them to separate. No pounding just a lot of gentle prying around and around.
John C, Yes it is a very high hour machine. The transmission temperature has never been high. I baby that old (1974 model) tractor as if it were made out of egg shells.Thanks for the heads up about looking inside the converter. I think I may look into it.

 

[mitch504]

We used to have a couple of Ford industrial tractor-loaders w/ manual transmissions. When my father semi-retired, the first one I bought was a used 4500 with a torque convertor. My father used it on his home place for a while in the off-season, and I stopped him and had arguements several times. Our old tractors had only hand throttles, and when loading, you just set the throttle and stopped, mashed the clutch, and shifted gears. My father kept running the 4500 this way, ignoring the foot throttle. Frequently, when the bucket was full, the back wheels would come off the ground when he reversed direction. After a few weeks of this, my new tractor's flex-plate looked just like this one.

 

[Tinkerer]

I determined yesterday that the converter is not serviceable. It is welded together. I cleaned both the flywheel and converter. The two are definitely centered up because of the close fit of the flywheel hub and the nose on the converter when they are assembled. Now I am waiting for parts which include a new flywheel ring gear. The ring gear has six nasty looking teeth in one place on it. Thanks to everyone for their input to my question. On a side note- I removed the cylinder sleeves from the engine yesterday. Amazingly they are stenciled with yellow paint 03-29-73. The coolant cavity was painted with what appears to be primer red and looks as if it is almost new.

 

[alrman]

Tinkerer,
I have those convertors repaired all the time - find an auto transmission shop & they should be able to tell you where to get it done, if you needed to that is.
The shop I use does convertors & nothing else, automotive, industrial, drag cars, everything - cuts them open on a lathe, fits new bits & then welds them shut.

 

[Tinkerer]

Another example of the amazing information that is shared here on HEF ! Thanks alrman . I had no idea they could be opened up.
When I saw that it was welded I thought ,replacement only. As of now it has been working ok. I will deal with it when and if it gives me A problem. The shuttle may need work done on it before then. At least I can thoroughly flush it out now and put all new oil in it.