Three flex plates in 5 months

[ZachAubin]

Alright guys, so…the title pretty much says it all lol.
I am on my third flex plate going out in 5 months.
One initially went out because of reason unknown. Had that fixed and the mechanic didn’t tighten the bolts all the way which managed to make another break down the middle pretty much right when I heard the bolt start to make its little ticking noise. Had that fixed, and two weeks later, when everything is squared away, the new flex plate makes an awful grinding noise against the starter. Had it brought in to a different shop and these guys said they put a whole new flex plate and starter in, and now the gears are grinding down again on their test drive.
Of course they recommend I replace the whole block because they think there’s a slight wobble in the crankshaft, but I feel like this problem is easier solved than buying a new 6.2 L99. I have a 6L80E trans on a 2011 2SS.
Can y’all help me figure out what’s going on here?

PS: if this isn’t the right place to be posting this, please let me know so I can post it elsewhere.

Thanks in advance.

[gtstorey]

Did they try shimming the starter?

[fz4k98]

"they think there is a wobble " is not something i would use for deciding. If there is an issue with the crankshaft wobbling they would be able to measure it with dial indicators.

[fz4k98]

To help figure it out you could measure the flexplate wobble of the current flexplate before taking it apart by rotating the engine while using a dial indicator. Mark the current flexplate location on crank and log the measurement while marking the high and low spots on the flexplate.

Then remove the flexplate, rotate the flexplate only 180 degrees and reinstall it. If the high and low spots stay close to the same location on the flexplate, it is the flexplate. If the high and low spots move 180 degrees it is somehow in the crank surface to flexplate surface.

[InFiD3ViL]

Originally Posted by gtstorey

Did they try shimming the starter?

Yeah, this is what I am wondering. Why would they immediately place the blame on the engine/crank rather than looking at the starter?

I feel like we are missing some important information here, but still...'You need a new engine' sounds like some lazy diagnosing to me - and that's a major understatement.

[ZachAubin]

Originally Posted by gtstorey

Did they try shimming the starter?

I have not asked about the shimming on the starter. That’s a good place to begin with them.

[ZachAubin]

Originally Posted by fz4k98

To help figure it out you could measure the flexplate wobble of the current flexplate before taking it apart by rotating the engine while using a dial indicator. Mark the current flexplate location on crank and log the measurement while marking the high and low spots on the flexplate.

Then remove the flexplate, rotate the flexplate only 180 degrees and reinstall it. If the high and low spots stay close to the same location on the flexplate, it is the flexplate. If the high and low spots move 180 degrees it is somehow in the crank surface to flexplate surface.

THANK YOU! I just got back to you guys and I apologize. Life has been a little crazy recently. I’m going to get on them about this and see if they did even measure using a dial indicator. This is all new to me. I can do engine work but, anything underneath is beyond me which is why I came here.

[ZachAubin]

Originally Posted by fz4k98

"they think there is a wobble " is not something i would use for deciding. If there is an issue with the crankshaft wobbling they would be able to measure it with dial indicators.

This is what I’m saying…immediately jumping to “replace the engine!” turned me way off to them.

[HOJO]

Umm yeah, a crank just doesn’t suddenly develop a wobble. Shims should be easily installed, I’d start there. If that doesn’t work then move to a dial indicator.

[fz4k98]

There should be some witness marks or grind marks on the flexplate gear to point toward the issue. Can you get pics of the flexplate damage?

Visualize a quarter, damage on the knurling of the edge of the quarter would be different than damage on the face edge of the quarter.

face edge grinding and only in certain spots (not all the way around) would point toward wobble.

[ZachAubin]

Originally Posted by HOJO

Umm yeah, a crank just doesn’t suddenly develop a wobble. Shims should be easily installed, I’d start there. If that doesn’t work then move to a dial indicator.

These guys are saying they don’t need to use a dial indicator because they can see the flex plate moving almost an inch which (if I’m wrong please correct me) sounds like a torque converter or maybe a thrust bearing issue…I feel like they have no idea what they’re doing or are just trying to pull one over on me which is not working out well for them.

[bayarea408]

The flex plate changed out could be the problem, OEM? Racing? TCi? B&M? Meziere? JEGs? dealing with mechanics and not knowing exactly what they put in can be an issue.

So with this up in the air, when you throw an aftermarket flex plate against a aftermarket OR OEM torque converter it needs to be shimmed correctly. It sounds like a bunch of rookie shops have been playing hot potato and just tightening the bolts up with no shimming to account for the play. I bet there isnt a stock flex plate in there.

[G8One2]

I've seen this before, when the torque converter isn't fully seated on the pump, because people think its ok to pull the trans together to the engine, with the bolts instead of fully seating the bellhousing BEFORE installing bolts. Happens all the time with hack mechanics. You'd be surprised how many people don't know how to properly seat a torque converter, and think that it is. And when the trans wont glide right in, the force it together with the bolts.

[G8One2]

One other thing too, if there was originally a spacer plate between the engine and trans, that has to go back in, but I dont think LS engines have that. Missing that would cause the same thing to happen.