80 TH400 Torque Converter-Bolt Size? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

trukman1 · 03-21-2002, 01:57 AM

Picked up a 1980 (supposedly) TH400 and the torque converter bolts were missing. Installing 3/8-NC bolts by hand seemed loose. Tried to insert 10mm tap, also by hand, and it seemed to fit better. Did GM switch to metric bolts in the 1980 versions, or at all? Or do I have a different year? Thanks for any help, Gary

gchemist · 03-21-2002, 07:32 AM

The VIN number will tell you the model year. You do have round headlights right? If they are square then its an 81 or newer model. I don't know when GM went to metric bolts on some items. I know some bolts on my '83 are metric. I'm pretty sure the converter bolts are too. Best bet is to buy converter bolts from a catalogue. The bolts need to be very strong to hold the flextplate and torque converter together. You can get bolts from www.jegs.com www.summitracing.com

------------------
Gerardo
1983 Custom Truck
TX Plates: "BAD BOW"

trukman1 · 03-21-2002, 11:14 AM

Problem is I don't have the VIN just bought the tranny from a guy who said it was out a 1980 truck. I bought bolts from Jeg's that were too large for the holes in the flexplate I got from Summit...Go Figure! Will call a tranny shop today and will post findings later.

trukman1 · 03-28-2002, 03:17 AM

Turns out they're 10mm! Yech! And I wanted to keep it all SAE. Fellow I used to work for owns a tranny shop now and he's getting some for me. He said '80's can be either. Go figure.

03-21-2002, 01:57 AM	#1
trukman1 Registered User Join Date: Apr 2001 Location: Beavercreek, Ohio 45431 Posts: 737	80 TH400 Torque Converter-Bolt Size? Picked up a 1980 (supposedly) TH400 and the torque converter bolts were missing. Installing 3/8-NC bolts by hand seemed loose. Tried to insert 10mm tap, also by hand, and it seemed to fit better. Did GM switch to metric bolts in the 1980 versions, or at all? Or do I have a different year? Thanks for any help, Gary __________________ 1967 K30 461/TH400/Np205/D60/14FF/BDS MTZ 375/75/16 on 16x10 Pro Comps

03-21-2002, 07:32 AM	#2
gchemist BAD BOW-Silverado XST Join Date: May 2000 Location: Senior Member from Austin, TX Posts: 6,431	The VIN number will tell you the model year. You do have round headlights right? If they are square then its an 81 or newer model. I don't know when GM went to metric bolts on some items. I know some bolts on my '83 are metric. I'm pretty sure the converter bolts are too. Best bet is to buy converter bolts from a catalogue. The bolts need to be very strong to hold the flextplate and torque converter together. You can get bolts from www.jegs.com www.summitracing.com ------------------ Gerardo 1983 Custom Truck TX Plates: "BAD BOW" __________________ Gerardo a.k.a. Mad Chemist Silverado XST videos

03-21-2002, 11:14 AM	#3
trukman1 Registered User Join Date: Apr 2001 Location: Beavercreek, Ohio 45431 Posts: 737	Problem is I don't have the VIN just bought the tranny from a guy who said it was out a 1980 truck. I bought bolts from Jeg's that were too large for the holes in the flexplate I got from Summit...Go Figure! Will call a tranny shop today and will post findings later. __________________ 1967 K30 461/TH400/Np205/D60/14FF/BDS MTZ 375/75/16 on 16x10 Pro Comps

03-28-2002, 03:17 AM	#4
trukman1 Registered User Join Date: Apr 2001 Location: Beavercreek, Ohio 45431 Posts: 737	Turns out they're 10mm! Yech! And I wanted to keep it all SAE. Fellow I used to work for owns a tranny shop now and he's getting some for me. He said '80's can be either. Go figure. __________________ 1967 K30 461/TH400/Np205/D60/14FF/BDS MTZ 375/75/16 on 16x10 Pro Comps



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