I have a TCI flexplate I would like to swap in when I change my converter. I am looking for the correct ARP Bolts for this flexplate, but there are two types listed for GM:

Internal Balance - 3/4 socket UHL .680 7/16-20
External Balance - 5/8 socket UHL .725 7/16-20 (1Pc. Rear Seal)

I am assuming I need the External balance with 1Pc. Rear Seal, can someone verify this for me? I called ARP and the guy was like "Uhh, I only show two kinds for the chevrolet....."

Also, has anyone had any interference issues with ARP Bolts. I have a friend in my car club who's converter bolts actually hit the back of the motor when installed.

Thanks,
Ken

 

5/8 the 3/4 is a bitch to tighten down (it rubs against the crank flange) i used the 3/4 first then switched to the 5/8

 

I had the ARP bolts w/ the large 12 point heads and there was a bolt head clearance problem with the crank hub (no room for the socket). So, I went back with a new set of OEM (GM) flex-plate bolts w/ thread-locker.

Also, make sure your TCI flex-plate isn't powder-coated. If it is, you'll need to sand down the coating on both sides of the plate to ensure the coating doesn't crush under the torque load and the plate become loose. That has happened to several people.

WD

 

Thanks for the tip, I will check on the OEM bolts.

So basically both sides of the flexplate where it is bolted to the crank, and where the converter bolts are located the powdercoat should be ground?

 

Here are some photos of the TCI flex-plate with powder-coating that the bolts loosened (powder-coating crushed). Notice the bolt holes are oblonged which ruined the flex-plate.

WD

 

Wow, thanks for the pictures, I will definatley be removing the powder coat off those areas. I hope it isn't too difficult, I don't have a grinder, just a orbital sander or a dremel tool.

 

so will a factory th350 converter work with the factory lt1 flexplate?

 

Yes, the three torque converter bolt holes are somewhat of a strandard pattern on GMs as far as I know.

WD