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ekaz 06-29-2010 12:53 AM

(long) story and flex plate comparison
This is on my 09 GCSRT
First off, a little background....I was using an allen wrench to secure my BT coilpack covers and dropped the wrench, no big deal, it'll fall out. Anyway, a few days later, I hear some rattling under the hood and figure the wrench is stuck somewhere in the headers and remind myself to dig it out. I do hear the rattle when starting and occasionally when shifting into gear, again, still thinking the wrench is rattling against the frame or something. (again remind myself to get under there and start hunting). So, as we al have done before, I forget to look until one day I do a part throttle (maybe 30-40% pedal) launch and hear the dreaded BANG and the everything goes dead.
I pull the Jeep over to the side of the street, put it in park and try starting it..nothing. OH FCUK! My Dad and I get out and search for leaks or anything hanging, nothing. Try starting it again and she tries a bit, but nothing. Thinking I broke the 426 and going over everything in my head, and everything checks out. Give the Jeep one more try and she starts! Idles perfectly with no codes or anything! However, there is an awful racket from underneath, and from location, it sounds like the torque converter kicked the bucket. Put the Jeep in ANY gear and NOTHING happens, even if I try revving it. Admit defeat and call the flatbed. Get her home, jacked up and let her sleep.
Next morning, I have to work but Dad comes over and crawls under. He removes the inspection plate and out falls a torque converter bolt. WTF? He digs around and finds a couple more. I come out to help spin the engine and 5 of the 6 bolts are snapped in half! Looking back, I guess it wasn't the allen wrench rattling around. :blam::roll:
So we drop the trans and notice the following carnage:
So after seeing all that fun stuff, I pull the trans pan off and notice all the shaving in the corner of the pan and faced with a I rebuild the stock one knowing that I'll need a new beefed up trans later or do I bite the bullet and get the trans now? Well I decide on a new trans and call Andy to order me up a trans from SHR. (It won't be in until the end of this week so no impressions on that yet). Also, a note of another observation, I did not have a crank bushing in for the torque converter. Not sure how that was missed, but it was, and has been already corrected.
All bolts were torqued to the proper spec when installed.
As for the torque converter, it is a PI 2800 and I sent it to them to have it checked out. They replaced the cover (has the broken bolts in it) and impeller hub for no charge! All I had to pay for was the return shipping. Now that is awesome customer service. Their product wasn't even the cause and they fixed it, no questions asked.
Now on to the flexplate replacement:
I also need a new flexplate and Andy says that he has one from ATI and sends it my way. The differences between the Paramount Performance plate and the ATI plate are as follows (again, not bashing anything, not promoting anything, just posting my personal experience), for those that may be interested. The ATI is just under 2 pounds heavier (6.4lbs vs. 4.6lbs). There seems to be twice as many welds on the ATI unit, the ATI ships with actual bolts for the torque converter vs. the allen head bolts that came with the plate from Paramount Performance. Both plates are SFI certified, the ATI is black, the PP is not.
Here are the pics I took of the 2 flexplates:
Now all that being said, I like the additional weight and stage 8 bolts that come with the ATI plate. Also, is it possible that some of this was caused by the allen head screws that were not grade 8? I understand that the crank bushing is needed, but would it missing cause this type of failure if all 6 bolts were correctly installed and torqued?
This is a first for me, so looking for insight.
Thanks guys!

05wkguy 06-29-2010 01:32 AM

Re: (long) story and flex plate comparison
IMHO, the lack of crank bushing allowed to much fore/aft movement of the torque converter which added undue stress on the bolts and plate. Most cars and trucks do just fine with only 3-5 bolts holding them to the flexplate (most any chevy or ford small block for example) and this type of failure is almost unheard of, even in extreme high performance/ high hp applications. If they had been grade 8 screws would this have happened? I think yes, but it would have taken longer.

Escape 06-29-2010 02:49 AM

Re: (long) story and flex plate comparison

Not having that little crank bushing and those allen head bolts screwed it up bad. To much play in there and those allen head bolts had to be crap to shear like that.

Put a bit of liquid blue locktite on those bolts and make sure to seat that torque converter perfectly and you shouldn't have any issues ever.

Once you have the torque converter seated to the trans and the trans bolted and torqued to the block I use this procedure to mate the plate to the converter.

Don't forget your blue locktite. Line the holes up and thread your first bolt till it just touches the plate. Using a paint marker/sharpie put a 1 by it. Count your holes and go to the opposite side of the plate and put a 2 by it and hand thread until it just touches the plate. Do the opposites all the way around until they are all threaded in, numbered and just touching the plate.

Now slowly 1 turn each work your way around the plate following your numbered sequence. Do this again and again until they are snug/tight and you have pulled the converter flush with the plate. Then following your numbered sequence torque to spec.

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