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M85: means standard metric thread with nominal major dia. of 85 mm. Nominal dia does not mean that it will measure exactly 85mm... I've found a maximum reference in my local standard for M64, did you check the iso standard ? Maybe you can find more information there.

2.5: lenght of thread. Seems here to be informed in inches, or would not make sense.

6G: is the tolerance between the bolt and the hole where it will be bolted. It's the standard tolerance for diameters over M1,4

Thank you for the information.

Hi,

As you have written it, this appears to be a metric thread as defined in BS3643 (probably an ISO standard by now):

M85 = the nominal O/D of the thread

2.5 = the pitch of the thread

6g = the normal tolerance class for an external thread

I don't know if this is an actual size that you're quoting, but 2.5 is a non-standard pitch for M85 thread.

Drew

Hi again,

I've just checked the BSI site and BS3643:1981 parts 1 & 2 is a current standard.

If you have a look in the standard it will tell you all you need to know about this type of thread.

Hope that this helps.

Drew

Thank you for the information.

Thank you for the information.