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What is the thread size on a AC Bolt?

I was driving around one day and heard a bang. Stopped and found the ac clutch rolling around on the under body. Thankfully the spacer was stuck on the shaft (magnetism worked for me). Unfortunately, I was unable to find the screw.

I went to the junk yard and the oldest thing I could find was a 2003 toyota camry. The engine looked very similar. I took the bolt from that AC compressor shaft.

Before I twist this bolt in there, I figure I should ask someone more intelligent than me a question. What is the proper thread sizing my AC shaft on a 2006 Toyota Camry 2.4L engine?

If you used a 10 mm wrench/socket to remove the bolt, figure the thread size to be 6mm.

The question is, is it a 1.25 mm pitch or a 1.50 mm pitch?

If there’s an ACE hardware store nearby, they’ll have the correct bolt.


That’s pretty coarse. Wouldn’t it more likely be an 6mm bolt x 1mm pitch? I always considered that to be the standard size.

I know my metric sizes pretty well by eyeball. I sold Volkswagen parts for many years. :wink:

However, if I didn’t know what size or thread pitch, I’d try some, first.

Can you see another bolt or two holding something non-critical under the hood that looks about right?

Borrow it for a minute and try to carefully thread it into the hole you’re working on, BY HAND. I like to put it in a socket and perhaps use an extension, but NO handle! Don’t force it. Don’t go wrenching on anything until you are sure it is correct!

Another idea would be to have the parts guy/gal at a Toyota dealer look up the bolt and see if it gives the specs or see if they stock the part.

before you get too far, I’d stick a tiny screwdriver or something up in the bolt hole and make sure the old bolt didn’t snap off. This all may be for naught if the old bolt is broken off in the a/c compressor.


Is this a bolt or nut on the shaft? I’m picturing a nut on the shaft, not a bolt. At any rate, I’m with Eddo and proceed with caution. These things usually don’t just come loose unless something locked up and that’s what spun the clutch off.

My son had a nut come off the shaft of his alternator some years ago. I had a spare one in the junk pile so put that one. We made it about 5 miles and the thing was off again until we could get a new alternator in the morning. Never really found out why but I always thought the thing locked up for some reason and spun the nut off.

The more threads within one millimeter of length, the finer the thread.


I know that. The more threads per any length means a finer thread, the fewer means the coarser.

However, unlike an SAE pitch (1/4-20) where the count per length is given (20 threads per inch), metric pitch gives the distance between threads!

A 3/8"-16 bolt is a coarser thread than a 3/8"-24. The larger the pitch (count) number, the finer the thread. A 1.5 mm pitch is coarser than a 1.0 mm pitch. The larger the pitch, the coarser the thread.

A 1.5 mm thread pitch = 16.93 threads per inch.
A 1.25 mm thread pitch = 20.32 threads per inch.
A 1.0 mm thread pitch = 25.40 threads per inch.

You can see that a 1mm pitch is a finer thread than a 1.25 or 1.5 pitch.

"Metric fasteners are specified with a thread pitch instead of a thread count. The thread pitch is the distance between threads expressed in millimeters (measured along the length of the fastener). For example a thread pitch of 1.5 means that the distance between one thread and the next is 1.5mm".

6mm bolts generally don’t have a 1.25mm or 1.5mm pitch. That’s too coarse.

I stand corrected.