Re: tapping e50 cylinder stud holes to m7

Born to be WillD /
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there are two ways to make threads, cutting them or pressing/rolling them. cutting them leaves sharp bottoms and stresses that actually weaken the threads so they're much easier to strip. Some of that can be recouped by heat treating, but its not often done. I think alotta these convenience aftermarket studs are made by machine shops just by cutting and not treating because those are the tools available to the machinist. They will strip more easily and most of the time probably wont hold up to factory torques. You can remedy that somewhat by using long coupler nuts or brass nuts to distribute the load over more threads. Cutting also means the shaft diameter is the same as the max OD of the threads, so theyre wider (and heavier)

the OEM ones and most proper studs and higher grade hardware, the threads are pressed or rolled in, which creates stresses that strengthen the threads. They also have by default a thinner shaft because the threads are swuished out and pressed in, the main body diameter is halfway between the outer diameter and the bottom diameter of the threads. Its also cheaper, but requires specialty tools.

The end result? when you buy aftermarket or machineshop made studs they're cut threads and much weaker threading. The factory and OEM are almost always rolled and both stronger and have thinner body shaft diameter.

TLDR: Get the tomos, they'll fit. the other ones are less likely to fit and also weaker.

In my personal experience I've had luck with using an M7 to m6 helicoil after tapping out the cases (this is my goto) and you can also easily drill out the hole in the cylinder and head to 7mm if needed for a full M7 stud. but those tomos ones should work as is.

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