Thread: WTF Flexplate broke/damaged Updated

So almost 2 months ago I took my fuel rails off to make a set for when I installed my intercooler. Long story short, I got sidetracked with house projects/new baby/family visiting. Last week family left and I started back on the car... Made custom fuel rails, installed AN fuel lines, Ported LIM installed, IC installed, bunch of custom brackets and stuff. I am still waiting on my trans coolers(had to remove the old bulky one for the FMHE) I have just about everything but them done so I decided to just start it up and run it for a few and check for leaks and all that good stuff. So I start it, had forgot to put the EGR blockoff plate on the LIM and it ran for just a few seconds but rather rough cause of the giant vac leak. So I fix that and start it again, idles perfect and smooth like she should and no leaks. I rev it a bit, nothing past 2k and I hear this horrible loud ticking but as it idles back down it goes away. I grab my stethoscope and rev it again and it gets louder and now will not go away. First I thought crank/rod but after a little looking around I think its coming from flexplate, pull inspection cover and it is LOUD. So I turn it around a few times with the screwdriver looking all over for cracks and I see none. Unbolt TC from flex and nothing changes, still no cracks. But with it running and TC unbolted I can see the flex wobbling like its bent... Here's a couple videos I took, and the one where I use the screwdriver is just so you can see the wobble a little better:

Broken flexplate Grand Prix GTP - YouTube

IMG 2507 - YouTube

Flexplates break.

They tend to develop a hairline fracture, that will, over time, lengthen. Eventually, that fracture will reach either the end of the flexplate (where the teeth are) or one of the balance holes, and then turn into a full blown crack.


Mine did it one day, just driving down the road. Came to a stop, and all of a sudden that terrible racket started.

Even after pulling the engine, and checking the flex over with a magnifier, I still couldnt find the crack. But replacing it with a new flexplate sure did fix it.


Long story short. It's mechanical. Nothing mechanical will last forever, it will eventually break.

You guys make me worry about mine now.

if you think about it, the flex plate takes all the abuse, its what transfers all the power to the trans.

Originally Posted by scottydoggs

if you think about it, the flex plate takes all the abuse, its what transfers all the power to the trans.

Sorta. It also takes a piss ton of abuse from years upon years of start-up.

I understand that mechanical things break but just seems like a really really odd time for it to make itself evident ya know? After sitting 2 months, then never going above 2k rpm just seems really really strange to me... I rotated it all around and pried it side to side and never saw anything as far as cracks. I'm either gonna demod and sell it off over the winter or just buy me an l26 and use my ported heads and cam on it cause I sure as **** ain't pulling a motor for a ****ing flexplate.

my flexplate broke in the inspection line. had the ebrake on and she said try to move, and i did and then clack clack clack.

it happens. just replace it.

EDIT: and i was STOCK, bone stock.

Before people start getting their panties too far up their ass to get back out.

cop is right, stock parts are gonna break, especially on modded cars.

But, the exact same thing happened to me Kejross...and I took the opportunity to completely clean the engine bay and detail the motor while the engine was out. Yes, it's a total PITA to have to pull the motor for a few bolts. But it is really worth parting out something you love over something so little?

And to be honest, pulling the motor doesn't take a real long time. I had mine out, cleaned, detailed, and back in (save for the wiring, and the belts) in a little over 12hours, and that was at night.

So just take a deep breath, grab a 6pack (any more and you'll start misplacing parts) and just get to work.

Anyone else in to tell the OP to get a Billet one...JUST BECAUSE.

Originally Posted by copgtp

You're pretty extensively modded dude...how could you be so horrified that your STOCK flex plate broke??? LMAO, you guys crack me up sometimes. You need to pay to play my friend, modify your car, stock **** is goin break. Either pony up and put a new one in, or get on the demod.

I'm horrified because before I had it down it was just a rockered 3.6 setup with no symptoms and NO drive time on the IC and 3.0 You tell me you wouldn't be really super pissed if you just got done hand making a set of fuel rails and installing an IC setup just to find that upon startup with no explanation.

Originally Posted by machinegunsquid

But, the exact same thing happened to me Kejross...and I took the opportunity to completely clean the engine bay and detail the motor while the engine was out. Yes, it's a total PITA to have to pull the motor for a few bolts. But it is really worth parting out something you love over something so little?

And to be honest, pulling the motor doesn't take a real long time. I had mine out, cleaned, detailed, and back in (save for the wiring, and the belts) in a little over 12hours, and that was at night.

So just take a deep breath, grab a 6pack (any more and you'll start misplacing parts) and just get to work.

Your right, I've calmed down a bit now and even though I still don't get why it broke when it did I will just start on pulling the motor a few hours a day before work when the kids let me and its not too cold over the next couple of weeks.

Originally Posted by bluegtp91

Anyone else in to tell the OP to get a Billet one...JUST BECAUSE.

Originally Posted by copgtp

+1, but I'm sure he'll complain about how expensive it is.......

Originally Posted by Pure2sin

There is on for sale on here but good luck getting the dude to respond.

For the price they want I would rather pull the motor again... Motor pulling and parts from my shelves are nearly free save for a gallon of antifreeze. If it happens again will I be pissed and complain??? You better believe it...lol

do you really have to pull the whole engine out? cant you just hang the engine in the engine bay, separate the trans and get into the bolts.

i used to do clutches on my old 77 gmc sorta the same way, we just unbolted everything and slid the trans back and left it on the jack, (those old 3 speeds with the low creeper gear, weighed like a ton) and just work in between the 3 or 4 inch space we left.

and if you dont touch the lift (engine hoist) it should go right back together, well easier that if you took it all the way out, at least it will be close.

Originally Posted by scottydoggs

do you really have to pull the whole engine out? cant you just hang the engine in the engine bay, separate the trans and get into the bolts.

i used to do clutches on my old 77 gmc sorta the same way, we just unbolted everything and slid the trans back and left it on the jack, (those old 3 speeds with the low creeper gear, weighed like a ton) and just work in between the 3 or 4 inch space we left.

and if you dont touch the lift (engine hoist) it should go right back together, well easier that if you took it all the way out, at least it will be close.

I found this: ClubGP Message Forum troubleshooting

It really isn't hard or too time consuming to just pull the motor, I may try that though.

Think on the bright side, now would be a good time to ditch the rockers and put in a cam.

Originally Posted by AjL227

Think on the bright side, now would be a good time to ditch the rockers and put in a cam.

I was thinking that cause I have a set of IS2 heads w/YT 1.61 rollers and an IS3 cam I been saving for an L26 bottom... But I was hoping it would be summer after next project so I could buy my timing chain, gasket set, arp head studs, and of course the motor in stages. After I buy a built trans that is just too bad this IS3 cam is too big for stock heads