Flex Plate Questions

[AZDeuce]

Gentlemen

About 2 years ago my M1009 had the flex plate come apart, it tore off at the center leaving the center still bolted to the crank, but the rest of the flex plate (FP) was completely disengaged from the center.

Fortunately it still ran and started, but I knew this was NOT a good thing! I bought a replacement FP from then Checkers, now O'Rielly auto parts, I installed it, and all was well, I drove it for abou 6-8 months until I went through a series of electrical issues that kept her inoporable for almost 10 months.

So about a month and a half ago I finally got the electrics sorted out and drove it for about 2 weeks when one morning when going down the off ramp, it started screaming/howling, but when I accelerated it would get quiet until it got to speed then it would start screaming again.

Having gone through this several years ago, I was "pretty sure" it was the flex plate, either that, or I ran my transfercase out of oil! (Don't ask!)

Well this morning I pulled the torque converter pan, and sure enough the flex plate was broken just like it did the first time, all the way around the crank shaft.

WHAT IN THE WORLD!!??

At first I thought it might be due to a sub-standard after market flex plate, probably made in Mexico or China. I saw the post on NOS GM flex plates and I WILL buy one of those for this project.

However, I read anoither article on SS where it was stated a broken motor/tranmission mount might cause the FP to break, then a friend told me the Crank could be moving back and forth, but I find that hard to believe as the engine would probably bind up if this was happening and I'd have excessive oil leaking.

So I was wondering if any of you have encountered this issue with the FP, and was it something other than a sub-standard FP that was causing the issue?

I hate to go thru all the work of installing the FP to have it do the same thing in 6 months or so....if there is some other issues I should investigate, I'd like to know what they are.

I will look at the engine/trans mounts I'd like to find polyurathene replacements if anybody knows where to get them from. please let me know.

THANKS in advance!

 

[Cucvnut]

how are your motor mounts ? when you flex the motor and transmission and a motor mount is bad you will crack the flex plate.

 

[Coal Cracker]

Check that your trans is fully against the motor, and that the bolts are tight and no rust pushing them apart, also make shure that the bellhosing of the trans isn't cracked.
Also your torque conver might not have been rebuilt correctly, it might not have been welded together correctly, I would imagine it has been rebuilt at least once in it's life.

When you bolt the converter to the flexplate, does the converter have any freeplay?, you have to have at least 1/8 th to 1/4 in. freeplay before you bolt it up.

 

[AZDeuce]

I know nothing about the torque converter, how can I tell if it's bad? Where do I get one NAPA, AutoZone?

If I remember correctly there was play between the convertor and the FP before I tightened up the bolts......and yes, I torqued every thing to specs.

 

[sschaefer3]

Poly Mounts, Energy Suspension:

Engine: 3-1116G
T-Case: 3-1106G

I recently installed these on my truck. The t-case bolts right up the engine mounts you pull the original mount open up the shell and replace the rubber insert with the poly insert. The 2 rivets are drilled out, I tac-welded the shells back together with the poly inside so they were held together like when the rivets were installed.

I bought these from Summit Racing.

 

[Coal Cracker]

Another thing you should check for, is your Crankshaft is walking back and forth?
Stay well away from the autozone rebuilds,they are nothing but trouble, I can tell you why but it would be too big a writeup. Stick with Dacco converters, don't bother with high performance or low or high stall, just get a stock rebuild converter if need be.

A trans parts supplier like Transtar Industries 800-445-6700 will have rebuild kits, converters, hardparts etc, anything trans related you'd need.

 

[AZDeuce]

Ok.....how can I tell if the crank moves forward and backwards....a pry bar of some sort? What is required to fix that? Rebuild the engine?

I got the CUCV up on stands, but that's as far as it has gotten. I've been working 7 days, 8 to 10 hours per day, and I'm too tired to fool around with the truck.......but I will get to it in the next couple of weeks.......I HOPE!

Also, how can I tell if the torque converter is no good? Is there a way to test it, or should they just automatically be changed out every "X" miles?

I know I need a flex plate, but would like to know how to check these other parts that could potentionally cause my plate to crack. I've already bought the new motor/transmission mounts, because I've had the truck 8 years and they've never been changed out, and it's a high-mileage M1009! So I figured it needs new mounts whether that is the culprit or not.

 

[sschaefer3]

Engine: 3-1116G

The t-case mounts bolt right on, these engine mounts do need a bit of tweeking. The poly chunk matches the factory rubber but the side tabs are a bit off. I had to cut the side tabs off and re-drill the mount holes.

They work, but maybe look for a product from another company that will work easier. Like a fully assembled mount with poly inside. These you cut open and rebuild your stock mount.