Demersus
Well-Known Member
- Joined
- Feb 13, 2011
- Messages
- 47
- Vehicle Year
- 1990
- Engine
- 2.9 V6
- Transmission
- Automatic
Hello everyone and Merry Christmas!
I'm working on my A4LD and noticed that a few of the bolt holes for the pan are stripped. I plan to use some helicoil type thread inserts to repair them. But, I'm not exactly sure of the bolt size and thread pitch.
Using a drill bit gauge I measure the shaft as 5/16". The head size is 1/2", which does correspond to a 5/16 bolt according to standards. But the thread pitch is 20, whereas the standards state it should either be 18 or 24 TPI. The standards also state that a 1/4" bolt can have a 20 thread pitch, but the head size will either be 7/16" or 3/8".
I wonder if using a drill bit gauge is giving me the wrong measurement of the bolt shaft. I seem to recall that you don't measure the outside diameter of the threads. So maybe they are actually 1/4" shaft. That would explain the 20 TPI, but not the 5/16" head.
So, are they 1/4" bolts with an oddball head size? Or, are they 5/16" bolts with an oddball TPI?
Now, the other thing I have read is that M8 1.25 matches up with 5/16-20. So that makes me even more confused.
I have noticed on my Ranger that there is a very weird assortment of standard and metric fasteners used, and they they are even sometimes blended on certain parts of the rig.
I'm working on my A4LD and noticed that a few of the bolt holes for the pan are stripped. I plan to use some helicoil type thread inserts to repair them. But, I'm not exactly sure of the bolt size and thread pitch.
Using a drill bit gauge I measure the shaft as 5/16". The head size is 1/2", which does correspond to a 5/16 bolt according to standards. But the thread pitch is 20, whereas the standards state it should either be 18 or 24 TPI. The standards also state that a 1/4" bolt can have a 20 thread pitch, but the head size will either be 7/16" or 3/8".
I wonder if using a drill bit gauge is giving me the wrong measurement of the bolt shaft. I seem to recall that you don't measure the outside diameter of the threads. So maybe they are actually 1/4" shaft. That would explain the 20 TPI, but not the 5/16" head.
So, are they 1/4" bolts with an oddball head size? Or, are they 5/16" bolts with an oddball TPI?
Now, the other thing I have read is that M8 1.25 matches up with 5/16-20. So that makes me even more confused.
I have noticed on my Ranger that there is a very weird assortment of standard and metric fasteners used, and they they are even sometimes blended on certain parts of the rig.