Bolts and Nuts question

[scottherbert]

I am looking into Koni strut cartridges for my vehicle and they indicate that the top end of the cartridge is (normally) 5/8" and that the user needs to identify the desired thread and pitch -- here are the options:

THREAD & PITCH
M48 x 1.50
M48 x 1.00
M51 x 1.25
M51 x 1.50
M52 x 1.50
52.8WW

The stock strut has a 1/2" top bolt size. Would someone be so kind as to educate me about the thread and pitch options?

Thanks, Scott

[Matt Leicester]

The quick and cheap way to check thread pitch is to use a known bolt and see if the threads line up. Almost all 6mm bolts (10mm heads) have 1.0 pitch, almost all 8mm bolts (12mm head for Japanese, 13mm head for European) have 1.25 pitch. 10mm bolts are commonly 1.25 or 1.50 pitch, here the Europeans like 1.50 and the Japanese like 1.25. The Japanese 10mm bolts typically have 14mm heads, the European stuff has 17mm heads. The pitch is the number of millimeters per thread, so if you have 10 or 15 mm of threaded area, you could count the threads and divide by the length of the threaded area. Or you could cheat and get a thread pitch gauge at a tool store... The big number is the diameter in mm.

Matt Leicester