A few years back I saw a video of a Torque Convertor bolted to a flex plate with the engine running. The flex plate was really flattening out as the engine revved up...Anyone recall that vid or have a link...Discussion with a buddy on how much the plate moves...Thanks

Hence “flex” plate

I think if you see the flex plate, flex more than .075, it might be too late.

You're thinking of the video that shows the red converter which had already taken out the thrust on the running engine.

Yes, in that scenario, it'll flex A LOT

I think it can not move much because of how the converter is attached. My visualizer [mind] feels if it moves much, something is a miss.

Converter without a balloon plate can do it. I'm in the process of replacing a rear block plate, flex plate, and transmission on a dodge pickup from that very thing. Truck is tuned, owner brought it in with a complaint of tcc lockup issues. Found the converter ballooned enough it bent the flex plate inward enough to wipe out the rear block plate on the engine....it sticks out from the mounting face of the trans almost 2" more than it should.

quote:

Originally posted by Larry Woodfin:
I think it can not move much because of how the converter is attached. My visualizer [mind] feels if it moves much, something is a miss.

https://www.youtube.com/watch?v=YEfqKoilLkI
Larry someone from YB posted this link from a YouTube Video...The Convertor can move fore and aft easily within the Pump assembly. The convertor is bolted to the flex plate so it appears movement is regulated by how by how much flex is built into the flex plate.. I believe charge pressure?? within the convertor is causing it to move away or out of the pump, although I'm not sure why that is...What is the relationship between Ballooning and Flexing ??

Crankshaft thrust face or bearing is junk in that video. Seen some junk machined thrust. Took off too much. First thing first. Check the crank end play .004 - .006.

This message has been edited. Last edited by: TD3550,

I understand about the converter moving freely in the pump.

To be clear, I am visualizing a drag race Powerglide with a drag race converter and quality [thicker] flex plate.

Maybe my visualizer needs updating.

The amount of flattening out of the flywheel,depends on the length of the pilot ring on the back of the converter.They are different lenghts and interchangeable for different applications...The ring fits inside the end of the crankshaft and stops the converter from pushing out..Anything running a midplate usually require a longer pilot ring...

quote:

Originally posted by 1800gb:
The amount of flattening out of the flywheel,depends on the length of the pilot ring on the back of the converter.They are different lenghts and interchangeable for different applications...The ring fits inside the end of the crankshaft and stops the converter from pushing out..Anything running a midplate usually require a longer pilot ring...

No Sir

You want the pin to barely engage the crank, no matter mid plate or no mid plate.

So that no matter how much flex occurs in the flexplate, the pin won't touch down on the crank.

If you were to put a mid plate converter in a no mid plate car and the pin touched down on the crank, it could hurt the thrust on the crankshaft.

Any converter you put in your car, you should always check the clearance from the end of the pin to the backside of the crank.

Check even a new converter, you gave all the info to its builder.

Modern converters have a bronze pin to make it impossible for the pin to micro weld itself to the crankshaft, for this same reason.

Bronze pin torque converter.

Modern

Soon as I get this 71 split bumper done. I'll go 6.41 113 mph with this converter Super Pro Bracket racing. 71 is hogging the lift up.

If it is too short,it might not reach the crank.Mid plates in the past came with the longer pilot ring also...If it was purposely built,it was built with the longer pilot ring...

ATI's crank pilot rings are threaded, removable and replaceable. They are used on ATI's 8" and 9" Ford and GM converters.
GM Converter Crank Pilot Rings
Part Number

Price
STD. GM, .450” LONG, USE W/NO MIDPLATE OR UP TO .125” MIDPLATE
451340

$22.95
MIDPLATE GM, .638” LONG USE WITH .125” TO .250” MIDPLATE
451350

$22.95
MIDPLATE GM, .765” LONG USE WITH .375” MIDPLATE
451351

$20.66
MIDPLATE GM, .865” LONG EXTRA LONG FOR SPECIAL APPLICATIONS
451352

$20.66
STANDARD GM – LS1, .765” LONG, NO MIDPLATE
451342

$22.95

quote:

Originally posted by 1800gb:
If it is too short,it might not reach the crank.Mid plates in the past came with the longer pilot ring also...If it was purposely built,it was built with the longer pilot ring...

I'll give ya a clarification of what I already said.

No matter how much the flex plate flex's, you don't want any part of the converter to touchdown on the crank, like converter to the flex plate bolts, or the pin to crank.

The pin is long enough if it barely engages the crank once the converter drive is pulled out a minimum of .125" off the tongs on the transmission inner pump gear. You need .100' to .125" pin to crank engagement. The less the pin engages the crank, the safer.

The pin engagement to the crank is to center the converter drive on the transmission pump gears.

You don't want the pin touching the crank due to the flex plate flexing.

You read that in the description on the video posted on this page, it's wrong.

I already know all this, I'm trying to help YOU or ANYONE who reads this.

guess I've just been lucky. I've installed torque converters and flexplates in my street/strip cars and race cars for about 4 decades and ain't wiped out the thrust on any engine maybe because I don't use junk converters nor chinese shyt flexplates and most of these engines make/made far my power than our resident retard's nothing special junk. Nobody is impressed in the year 2021 by a 3200 lb. cutup shyt box sporting triple chrome plated bumpers that runs 6.40s

After all these years of racing and building, I never considered watching the flexplate "bending" under load. The video, to me, seems excessive so at my next opportunity I will check one of my cars. I know my builds are properly set up with the recommended clearances.

As posted above by Ed, I also have never experienced any thrust bearing problem or flexplate breakage.

Larry Woodfin...KNOWS!

You mention "Crank walk". Some guys will look like they have seen a ghost. Many don't even check end play. Only had one back in the day on a SB. Used engine. Crank thrust was junk. Cut too thin on the repair. Well sure the *** converter is going to push forward.

quote:

Originally posted by 1320racer:
guess I've just been lucky. I've installed torque converters and flexplates in my street/strip cars and race cars for about 4 decades and ain't wiped out the thrust on any engine maybe because I don't use junk converters nor chinese shyt flexplates and most of these engines make/made far my power than our resident retard's nothing special junk. Nobody is impressed in the year 2021 by a 3200 lb. cutup shyt box sporting triple chrome plated bumpers that runs 6.40s

Ed you're a crate engine buying know nothing parts changer, you don't know how to check anything because you haven't a clue how anything works.

If you do ever hurt anything, you'll be on the phone blaming someone else for these very reasons.

Now go breast feed your driver with those man boob milker's of yours, he's hungry.

quote:

Originally posted by Larry Woodfin:
After all these years of racing and building, I never considered watching the flexplate "bending" under load. The video, to me, seems excessive so at my next opportunity I will check one of my cars. I know my builds are properly set up with the recommended clearances.

As posted above by Ed, I also have never experienced any thrust bearing problem or flexplate breakage.

If you don't check the clearance from the front side of the pin,to the back side of the crank, all it would take is for the converter sales rep to hear and/or write down the info incorrectly, or the shipping clerk to ship you the wrong converter, by mistake.

Then you could be like Ed, on the phone blaming someone else hundreds of miles away, for your lack of experience.

Never assume the electricity is turned off when you're working on it, either, just because someone else told you it was.