Bed Bolt Hole Size

JimsGlad

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I saw several days ago where someone ordered some eyebolts for tie downs using the factory threaded holes in the bed. I searched but cannot find it. My question is what size are these bolt holes? 1/4 is too big and 3/8s is too small. Is it metric? Thanks



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ShadowsPapa

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I saw several days ago where someone ordered some eyebolts for tie downs using the factory threaded holes in the bed. I searched but cannot find it. My question is what size are these bolt holes? 1/4 is too big and 3/8s is too small. Is it metric? Thanks
M6 1.0
6 is the diameter, 1.0 is the pitch.
They are METRIC (like other stuff in these trucks.......)
 
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JimsGlad

JimsGlad

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I found a thread that says these bolts are M6
 
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JimsGlad

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Thanks for the replies
 

ShadowsPapa

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The trick is getting the spray-in bedliner out of the threads on a truck like mine so I can mount rails! That stuff is as hard as the metal behind it and using a tap may simply cut new threads - cutting the metal threads and weakening them. I cleaned two holes, one of them the tap had METAL on it so I stopped.
 

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Uppers are M6, lowers (tiedowns) are M8.

Reason I always suggest using a tap to clean out the threads, most people don't understand what a thread chaser is and that they can REALLY F*@K up their threads with a chaser.

With a tap, if you go slow, in a little, out all the way, in a little more, out all the way, it's not as easy to screw up the threads.

By all rights, if the threaded inserts are of correct size and pitch, you should never be able to remove base, material. But we all know that tolerances are all over the place.

Chasing threads, or for that matter tapping threads, is an art. It takes touch and feel. Too many people believe in the bear down and crank it in mentality. Those people then get to learn how to drill out and install nutserts.


OEM fasteners have all pretty much gone to metric on all domestic vehicles. With parts and hardware being outsourced to other countries it's just cheaper for them to be made in metric which is all of the world except the U.S.

Here is an inexpensive set of thread chasers, both male and female of each size. Can't speak for their quality. https://www.amazon.com/Lang-Metric-...ywords=M6+thread+chaser&qid=1606081523&sr=8-5
 

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Machine shop background thanks to automotive training...... no trouble with the various types of tap (taper, plug, etc.) or chasers.
The issue in my case is that the bed liner itself is as hard as the base material it's sprayed on. There are no threads for all practical purposes. It's a hole, with rock-hard bed liner in it, You literally risk starting NEW threads since there's no thread to start a tap into.
Example - let's assume for sake of argument that originally the beginning of the thread is near the top, the "groove" is at the top. When you use a tap, since there's no exposed thread at all, it may as well be a hole in the steel, your tap may start the cut at the bottom. So you are in effect cross-threading and cutting your existing threads out with the bed liner.
You can't assume your tap will start where the threads start since it's a hole without threads.
You could also compare it to a hole where you've drilled out the old bolt that broke off - perfectly centered, but the old bolt is still stuck in the threads by corrosion, whatever.
Running a tap into it may actually cut NEW threads and not pull the remains of the bolt out.
Or, consider a hole that someone has filled with bronze - brazing rod. If you run a tap into that, will you follow existing threads? Unlikely

Anyway, taking a tap into those holes you may well end up cutting all new threads, removing halfe the existing threads and threading the bed liner instead.

Best way is to try to soften in some way the bed liner material, otherwise, there are no threads for a chase OR a tap to find and clean! It's a hole filled with concrete in a way.
The only 100% safe way is to start from the BACK SIDE, assuming the bed liner didn't hit the back end of the hole (one of mine it did, so there's no thread for the tap to catch and clean) or to soften and pick out some of the bed liner ensuring you are removing it and not steel.
 

kevman65

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Machine shop background thanks to automotive training...... no trouble with the various types of tap (taper, plug, etc.) or chasers.
The issue in my case is that the bed liner itself is as hard as the base material it's sprayed on. There are no threads for all practical purposes. It's a hole, with rock-hard bed liner in it, You literally risk starting NEW threads since there's no thread to start a tap into.
Example - let's assume for sake of argument that originally the beginning of the thread is near the top, the "groove" is at the top. When you use a tap, since there's no exposed thread at all, it may as well be a hole in the steel, your tap may start the cut at the bottom. So you are in effect cross-threading and cutting your existing threads out with the bed liner.
You can't assume your tap will start where the threads start since it's a hole without threads.
You could also compare it to a hole where you've drilled out the old bolt that broke off - perfectly centered, but the old bolt is still stuck in the threads by corrosion, whatever.
Running a tap into it may actually cut NEW threads and not pull the remains of the bolt out.
Or, consider a hole that someone has filled with bronze - brazing rod. If you run a tap into that, will you follow existing threads? Unlikely

Anyway, taking a tap into those holes you may well end up cutting all new threads, removing halfe the existing threads and threading the bed liner instead.

Best way is to try to soften in some way the bed liner material, otherwise, there are no threads for a chase OR a tap to find and clean! It's a hole filled with concrete in a way.
The only 100% safe way is to start from the BACK SIDE, assuming the bed liner didn't hit the back end of the hole (one of mine it did, so there's no thread for the tap to catch and clean) or to soften and pick out some of the bed liner ensuring you are removing it and not steel.

You have the background, have you thought about trying an M5 drill to clean the hole?
I know I've had to do it on heat exchanger bundle heads to clean out broken studs and retap the threads.
 

Krafcik

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Can someone confirm what the two threaded holes on the back of the cab are? I found somewhere that they are m6x1.25, but those don't fit. I know the trail rail bolts are all m6x1.0.
 

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You have the background, have you thought about trying an M5 drill to clean the hole?
I know I've had to do it on heat exchanger bundle heads to clean out broken studs and retap the threads.
You were reading my mind - not sure I have that size but I did collect some metric bits a while back when getting into swapping engines around in 90s vehicles - and they are good for door hinge restoration.
That was indeed my next consideration seeing how the liner literally hides the threads completely in this truck. Got one perfect but then the tap was actually able to find a peak to catch on and it removed 100% liner, not a spec of thread.
 

Gladiator847

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I cleaned out the bed liner debris the best I could a couple of days ago but the bolts only would go half way. I tried to back them out but I stripped one the bolts slightly trying to do so. I sat on my chair in the garage in disbelief for about ten minutes and eventually went to all the bolts with my electric hand drill with proper attachments. It was a dumb thing to do but I diddnt really think oiling the bolts would of worked anyway.
 

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