babyfood1217

Began losing pressure at the pedal on my '93 4runner (22re), and found the reservoir was bone dry. It was pouring in the Puget Sound region when I first noticed this all, so I topped it up and vowed to check on it later. It drove fine for a few days, and then my girl came home after using it and said it was difficult to shift, and the pedal didn't seem to do anything. Vowed to look at it sooner.

After the undercarriage dried out from the rain a couple of days ago, I jacked it up and crawled underneath. Sure enough, the only wet area was the slave. Nothing suspicious around the lines (hard or soft), just coming from the boot. After pulling the failed slave and installing the replacement, I found, to my dismay, that one of the slave mounting bolts was stripped. I could make out quite clearly that the bolt itself was stripped (don't ask me how, I know that it threads into an aluminum transmission housing and aluminum should never trump steel), so I became quite worried the hole was stripped too.

A little research yielded the appropriate bolt size: M8x1.25 and an eyeball comparison revealed 25mm was the correct length. I was bummed at the notion of this replacement bolt needing a 13mm wrench instead of the 12mm OE bolt, but I would rather have a secured slave than uniform bolt-head size.

However...

To my surprise, I saw another drawer with assorted M8x1.25 bolts. Curious how they differed, I pulled the drawer out, grabbed a 25mm length bolt, and compared to the first replacement I had grabbed. Same grade, same pitch, same zinc (?) coating, but it had a smaller head size!!! I compared it to the original with stripped threads, and it was a match! The key was...

It was JIS: Japanese Industrial Standard. I knew about JIS vs. ASTM because of work I have done on my old Honda motorcycle, but I never even thought about my trucks! Using JIS hardware will be a much better match in terms of a suitable OE replacement, as the wrench size needed will be more inline with what these trucks were designed/built with (typically 8, 10, 12, 14mm and a few various larger sizes (maybe a couple smaller too...)

JIS crosshead screwdrivers exist too (these are the godsend tool for old Japanese bikes.) ASTM philips drivers ramp out of screws early and quickly, leading to stripping. JIS drivers, which the screws were designed for, don't (or perhaps, only do under tremendous effort!)

Long story short: Seek out JIS hardware, if you can, when replacing hardware to ensure a fit and uniformity more consistent with OE hardware.

Love,

Chris "babyfood1217"

wyoming9

iTrader: (1)

I have a bolt bin filled with JIS hardware nothing worse to me then having the correct size wrench or socket in hand only to find someone was in to much of a hurry to get the correct hardware.

Terrys87

iTrader: (1)

Every trip to the bone yard, I come out with as many nuts and bolts as I can. Has saved me many frustrations. Yard owners even let me carry a coffee can and have charged me $5 for a full can. Thanks for the info on the JIS.