Assploded 2nd flex plate......

Rent Free

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Jan 26, 2015
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got one coming for 50 bucks from parts store. I wanted to order a meziere from intense racing but I cant justify the price difference at the moment when ill be leaving for overseas again middle of april the car just needs to be drive able while im gone for my wife. meziere plates are like 450 shipped to my house.

Thanks anyways. If anyone does have a meziere plate laying around i'd be interested in buying it so I have it stocked.......
 

Rent Free

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Appreciate it! Just need to kind of get by now. Its going to be sitting in my garage under a cover while im gone since my kids bikes and crap are in there too. Just needs to be fixed so wife has a spare vehicle to drive while im gone.

I got a stock replacement for 50 dollars. The price difference between stock replacement and a billet can go towards a new cherry picker and a few other odds and ends I need.

I guess this will have to do for now.
 

Turbocharged400sbc

3800 & 4T80E > ALL
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they eliminated the 5 window "na" flexplate somewhere after 01/02 and just used a dual patttern 3 window with the counterweights different.

from measuring an old L67 all the way to the new junk you have a 22-19 oz/in imbalance.

later sc are 21 L26 ive had both 19 and 20

so it does pay to pay attention

im going to be tossing the oe flexplates i have on a mill when i machine both out meziere's for the 4 bolt 80e pattern
 

Rent Free

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Got 6 of the sheared bolts out of the crank still have 2 left that are being a whore I might have to heat them a little or take a dremmel to them. From the flex plate spinning in there when the bolts broke they almost look friction welded to the crank. I also need to get a tap and chase the threads before I put the new flexplate on.

The 6 I got out was cake with left hand drill bits. Screw using easy outs them left hand bits are the sh1t!
 

Rent Free

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in case 1quick didnt see in the chat.

i didnt put the arp bolts in the crank. i bought the car modded and already had them in it. the 1st flex i broke was cracked between the windows and i could at least limp it to the shop. 1st time around i just reused the arp bolts and didnt see any reason not to.

i didnt know the arp bolts were from a different application and that the crank had to be taped or grind the bolts down a bit.

this all makes sense now since arp doesnt list flex plate bolts for a 3800 application.

i think id be best off going back to stealership sourced oem flex plate bolts and hope those last along with a new oem flexplate.

i appreciate the insight and hope this puts an end to the madness.
 

Turbocharged400sbc

3800 & 4T80E > ALL
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the intense arp bolts are just arp's std 5/16 x 3/4" uhl bolt.

the ford pressure late bolts are longer with a shoulder for the flexplate to sit against.
these are 1" uhl with the 1/4" tall shoulder. they have a washer but even with the thicker meziere flexplate you still have to counterbore the crank holes ~ 3/16ths.

counterboring the holes with a 5/16ths step drill is quite easy (i used the HF one with ~3/16ths/1/4" tall steps) but if your a shitty driller make sure to file the 1/4" cutting edges so that the bit wont cut away your valuable threads.

the the TR's build thread i went through alot of this, even down to a pic of all the various hardware thats usable
 

Rent Free

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11 ftlbs?!! Really is that it for stock oem TTY bolts?

Been looking for tq specs on this so tomorrow and I can put the engine back in.

11 ftlbs seems really low? That and red locktite correct?

GM 3.8L-231ci-V6 Torque Specifications - TorkSpec - Knowledge for the Motorhead

(edit: disclaimer not using god damn arp bolts using TTY oem bolts this time around so for the love of god I hope I don't have to do this again!)
 

b4black

before black
Jun 6, 2008
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What's the problem with the ARP bolts from intense? I just used them on my flexplate. I had it done at a shop - they planned to reuse the TTY bolts.

I didn't see anything on Intense's website about drilling the crank or grinding the bolts. I'm amazed that you were able to shear off all eight bolts!
 

Rent Free

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If you would like to send me a pm of your phone number id be more than happy to send you pics. Just my 2 cents here.

If the damn bolts aren't made for this application which ARP doesn't list them for a 3800 flex plate then the crank has to be modified or bolts shortened or use a washer or something like James has been talking about.

My feeling is that the bolts were bottomed out in the threads and the flex plate still had room to wiggle around since it wasn't tight against the crank. My car has s1x cam E85 blah blah blah makes about 330whp and 400wtq from when previous owner had it dyno'd
I wont hide that I don't drive it nice but this is pretty unexpected to be a failure point twice now.

I cracked a flex plate about 6 months ago while I was in Washington DC. That plate cracked between the "window" in the plate. The last one was demolished, and I lost a damn race to a G8 that I was out in front of. FML. A new TQ convertor from TEP was put in last time I had to replace the flex plate too.

My view from this mess is use the right damn bolts for the application. So I went back to stock flex plate and new TTY oem bolts.

If this happens again I'll be forced to bite the bullet and buy a billet flexplate and reevaluate what bolts to use with a billet plate. I'd likely just spend the money on a new dampner too for added insurance/piece of mind.

All of the broken bolts came out pretty good with left hand drill bits. I had to fight one that was stuck pretty bad and Im not to thrilled with the threads that are left. I think it will be ok but time will tell.
 

GTPpower

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Jun 5, 2012
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I sort of went through this same deal about a year ago on my car. I believe I ended up just using the arp bolts that zzp sells after I snapped a few GM bolts off in the crank. I've got pretty close to 20k miles on it since then, but it's not making the power that you are, and most of my miles are pretty gentle. I've only taken it to the track once since then.
 
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