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| | | | Joined: Dec 2018 Posts: 473 Shop Shark | | Shop Shark Joined: Dec 2018 Posts: 473 | Why did GM opt to use this type of washer when securing the bed planks? What exactly is the purpose and how do they relate to the underside crossmembers? Is an offset countersink and special tool required?
Last edited by Apache1; 03/31/2019 9:07 PM.
| | | | | Joined: May 2007 Posts: 1,718 Moderator: 60-66 Trucks; North Eastern Bolters | | Moderator: 60-66 Trucks; North Eastern Bolters Joined: May 2007 Posts: 1,718 | My guess is to stop the washer from spinning when tighening the nut. All other bolt holes are square to shoulder the bolt.
Last edited by Hambone; 03/31/2019 9:36 PM.
| | | | | Joined: Dec 2018 Posts: 473 Shop Shark | | Shop Shark Joined: Dec 2018 Posts: 473 | Sounds logical....but how much spinning can be expected when tightening against wood? | | | | | Joined: May 2005 Posts: 8,983 Sir Searchalot | | Sir Searchalot Joined: May 2005 Posts: 8,983 | They are not for securing planks, they are the holes for attaching "bed" to the frame. As HB says, the counterbore (not countersink) hole locks the washer from spinning, the square on the bolt fits into square in washer to keep bolt from spinning.
Without the counterbore the washer would still spin. Bed wood companies can drill these for you. They are only used at the locations for tying to truck frame. You can buy a counterbore bit and do it yourself if you use the correct technique or a template.
Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn
| | | | | Joined: Dec 2018 Posts: 473 Shop Shark | | Shop Shark Joined: Dec 2018 Posts: 473 | Still doesn't explain why they were designed with an offset. | | | | | Joined: May 2015 Posts: 10,997 Housekeeping (Moderator) Making a Stovebolt Bed & Paint and Body Shop Forums | | Housekeeping (Moderator) Making a Stovebolt Bed & Paint and Body Shop Forums Joined: May 2015 Posts: 10,997 | Still doesn't explain why they were designed with an offset. Sure it does. If the bolt hole was centered, the washer could rotate in the counterbore. With the bolt hole offset, the outer rim of the washer immediately bumps up against the side of the wood counterbore and can't rotate any farther. They have a square hole for the carriage bolts so that the nut on the bottom of the frame can be tightened.
Kevin 1951 Chevy 3100 work truckFollow this saga in Project JournalPhotos 1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car) Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together. | | | | | Joined: Dec 2018 Posts: 473 Shop Shark | | Shop Shark Joined: Dec 2018 Posts: 473 | OK...that cam action thing...got it! | | |
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