A4LD Pan Bolt Size - Thread Repair Question

[Demersus]

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.

 

[mplummer08]

I don't recall the exact size of the bolts but when I rebuilt my A4LD I used a slightly longer bolt on the pan where it was stripped and was able to catch the threads a little further back.

Sent from my SPH-L720T using Tapatalk

 

[Transman304]

8x1.25 is the correct size and pitch for pan bolts. Longer bolts as mentioned will also work in some cases. Good luck.

 

[Demersus]

Thanks for the suggestion and size confirmation!