Topic: Drive Shaft to Pinion Flange Fasteners

[Atazman]

My question is "what is so special about Toyota driveline bolts........the ones that connect the driveshaft to the pinion and Transfer case flanges?  I would like to understand why it is so important that the Toyota bolts be purchased.

Example........my FJ-40 driveline calls for 10 mm bolts (0.394" diameter).  What is wrong with either (1) getting hard, 10 mm bolts of the right length with fine threads, or (2) using off-the- shelf Grade 8, SAE 3/8" diameter X 24 threads?  Yes.....the 3/8 bolts are slightly smaller in diameter than the 10 mm bolts.  Is this a big deal?  True, I don't like mixing SAE with metric bolting either; just trying to figure out what fasteners are required and why??

I'm looking for technical responses more so than "just buy the Toyota hardware and be done with it".

Many thanks.......

Don Evans
Pleasanton, Ca

[Toyoballs]

 :psss:If you look at the Yota bolts they have a smooth shoulder on them I wouldn't want the drive shaft twisting force on the threads of a bolt because they will wear down and cause problems, like coming loose just my  

[Marlin]

Don, the factory bolts have an extended shank (the part of the bolt between the head and the thread) and are a special 10x1.00 mm thread. This is a special very fine metric thread that resists unloosening and has a special grade 11 hardness.
I have never found a quality bolt assm like this anywhere else.
Marlin

[WHITE_TRASH]

I'll vouch for them being tuff.  when I first got my truck done origionally I had just swapped a 83 rearend into it and couldnt get the flange off for the life of me so I drilled 2 of the bolt holes to 3/8 and drove it.  Well I forgot about the missing bolts thing and when it had about 1500 miles on it I went mudding pretty heavily.  The dang things never even loosened up let alone broke!

[Atazman [OP]]

Thanks, guys, for your responses. I am glad to  know that there are "logitimate" differences in the drive line fasteners.  I will order a complete new set from Toyota.

Appreciate yor responses.......

Don Evans
Pleasanton, Ca