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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: bake315 on August 19, 2018, 03:35:06 PM

Title: Flex plate to torque converter bolts - half appear to be missing??
Post by: bake315 on August 19, 2018, 03:35:06 PM

Hi guys,

I was under my R30 (sigline below) hunting leaks last night, and when I pulled the dust cover underneath, I noticed what appeared to be half of the bolts missing.  It seemed like there should have been six, but there were only three.  Those three were all properly tight, and were in every other hole.  So thinking that someone lost three and just decided to skate by on the remaining three, I picked up some more today.

So when I went to install them, I discovered that none of the holes lined up.  Not by a longshot.  What am I seeing here?  Did someone install the wrong flex plate?

Thanks as usual, for any insight you are able to offer!

Title: Re: Flex plate to torque converter bolts - half appear to be missing??
Post by: Stewart G Griffin on August 19, 2018, 08:22:02 PM

Pretty sure there are only supposed to be three.   What trans you got?

Title: Re: Flex plate to torque converter bolts - half appear to be missing??
Post by: Stewart G Griffin on August 19, 2018, 08:40:00 PM

Also, it's likely that you have a dual-pattern flexplate-----to allow different sized converters to be able to be bolted to the flexplate.  Which is why the other 3 holes didn't line up.  Although i'm confused on that as well;  Most converters only have 3 places to put bolts.  What type of converter do you have?

Title: Re: Flex plate to torque converter bolts - half appear to be missing??
Post by: Stewart G Griffin on August 20, 2018, 07:37:19 AM

Nevermind----your signature says TH-400.   There are only three converter bolts.   3/8"

Title: Re: Flex plate to torque converter bolts - half appear to be missing??
Post by: bake315 on August 20, 2018, 10:01:03 AM

That's what I needed to know!  Thanks, SG!

Title: Re: Flex plate to torque converter bolts - half appear to be missing??
Post by: Irish_Alley on August 21, 2018, 07:58:48 AM

youre thinking of the flexplate to crankshaft bolts.

Title: Re: Flex plate to torque converter bolts - half appear to be missing??
Post by: bake315 on August 21, 2018, 03:41:45 PM

Quote from: Irish_Alley on August 21, 2018, 07:58:48 AM

youre thinking of the flexplate to crankshaft bolts.

Hey, Tim.  Actually I wasn't.  The torque converter had a total of what appeared to be six fastening points, along its outer edge, where one would expect to bolt up the flex plate.  The flex plate was bolted to it using basically every other point, leaving the rest free.  The flex plate also had three empty holes, but none of them lined up (off by maybe a 1/8') with the corresponding holes on the converter.  I will try to find some pics to illustrate what I'm describing - I definitely know the difference between these, and the flexplate to crankshaft bolts.  Not a complete imbecile, but I'm sure there have been rumors flying around...

Thanks again.

Title: Re: Flex plate to torque converter bolts - half appear to be missing??
Post by: VileZambonie on August 21, 2018, 04:38:31 PM

It is correctly installed. There are different torque converter mounting holes for different applications.

Title: Re: Flex plate to torque converter bolts - half appear to be missing??
Post by: Irish_Alley on August 21, 2018, 10:48:07 PM

Gotcha, I know the 700r4 uses a slightly different pattern then a th400/4l80e. One has slightly a larger diameter than the other

Title: Re: Flex plate to torque converter bolts - half appear to be missing??
Post by: Stewart G Griffin on August 26, 2018, 08:21:32 PM

Side note:
i learned, because i had to install a transmission recently, that it's ok and even normal for the flexplate to flex a little-----hence the name-----FLEXPLATE.

Do you think i deserve a cookie?