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73-87 Chevy _ GMC Trucks => Interior & Equipment => Seats and Restraints => Topic started by: mizozuman2 on May 21, 2014, 10:48:02 PM

Title: Bench seat bolt sizes?
Post by: mizozuman2 on May 21, 2014, 10:48:02 PM

What are the bolt sizes that connect the bench seat to the floor of the cab?

Size, thread pitch, Length?

Thanks!

Title: Re: Bench seat bolt sizes?
Post by: rich weyand on May 22, 2014, 12:32:48 AM

Parts book says 3/8"-16 x 1-1/4", which jives with my memory from replacing them a couple years back.  Note: I believe they are grade 5 or 8; I used grade 8 bolts to replace them.  DO NOT USE LONGER BOLTS OR YOU CAN PENETRATE THE GAS TANK.  I also used a 3/8"-16 tap to clean up the threads in the hard points in the floor before I put in the new bolts.  Again, do not go deep enough with the tap to contact the fuel tank(s).  I had a problem where some of the bolts had threads worn enough that they would not pull up tight.  New bolts solved that.

Note: you did not mention the model year (I don't remember from the other thread we are chatting in).  This info is from the 1973-1978 parts book.

Title: Re: Bench seat bolt sizes?
Post by: mizozuman2 on May 22, 2014, 03:04:56 AM

Quote from: rich weyand on May 22, 2014, 12:32:48 AM

Parts book says 3/8"-16 x 1-1/4", which jives with my memory from replacing them a couple years back.  Note: I believe they are grade 5 or 8; I used grade 8 bolts to replace them.  DO NOT USE LONGER BOLTS OR YOU CAN PENETRATE THE GAS TANK.  I also used a 3/8"-16 tap to clean up the threads in the hard points in the floor before I put in the new bolts.  Again, do not go deep enough with the tap to contact the fuel tank(s).  I had a problem where some of the bolts had threads worn enough that they would not pull up tight.  New bolts solved that.

Note: you did not mention the model year (I don't remember from the other thread we are chatting in).  This info is from the 1973-1978 parts book.

I just need to make the truck my signature... LOL

Thanks. I'll check around some more. a guy gave me a link for an '86 Service manual. That should help me out quite a bit. Now, to find a printer..........

Title: Re: Bench seat bolt sizes?
Post by: rich weyand on May 22, 2014, 03:29:25 AM

That bolt probably did not change unless the seat belt mounts migrated to the seats.  You can always pull one out and check it.  If you pull one, pull out one of the front ones.

Title: Re: Bench seat bolt sizes?
Post by: zieg85 on May 22, 2014, 05:34:09 AM

I can confirm that the bolts throughout the 73-87(91) is all the same

Title: Re: Bench seat bolt sizes?
Post by: mizozuman2 on May 22, 2014, 06:50:41 AM

Quote from: zieg85 on May 22, 2014, 05:34:09 AM

I can confirm that the bolts throughout the 73-87(91) is all the same

Awesome! Thanks!

Title: Re: Bench seat bolt sizes?
Post by: 87 ChevyVan on October 04, 2020, 09:01:21 PM

Pretty funny.

I was trying to take the bench seat out of my 87 G20 Van, and did not have the right size deep well socket.  Seems that it is a 3/8 bolt with a 9/16 head.  9/16 deep well is the only size I did not have.