Suspension Top Mount block has no threaded holes for the bolts, just smooth holes

[Submariner1]

I bought Bilstein Top Suspension Mounts (coil spring retaining plate, bearing block, and bump stop and gaitor) because MB no longer make them for a 2002 car.

The OE ones look similar except the 2 holes for the bolts do not have a thread inside. They are possibly slightly tapered holes.
Looking carefully at the old blocks, the thread seems to start faintly at the top and then get progressivly deeper cut near the end. The cleaned up bolt is also stiff inside this thread. Plus even on the genuine MB part the thread does not look perfect.

Q. Are these self cutting bolts and it is meant that you cut the thread on install?

Note both top mounts were smooth inside the holes. And the “self cutting bolt?” Does go in about 1/3 of the way before biting.
Impatiently I did screw in the bolts on one mount and it did seem to cut a similar ‘poor’ thread, (but it does work) looks pretty much like the original mounts hole now.

Only asking as I could cannibalise this mount and reuse the block of the old MB one, but although the rubber bush looks OK, it might be near end of life.

Q. Just checking do Mercedes ever use these self cutting bolts on parts like this?

NB when I replaced my Professional Honda I rang Honda and asked why was mine £1400 and the lower range was £700. One of the reasons he gave was they used self cutting bolts to stick on the carb and other parts. He said they were good for about 7 to 10 remounts. Whereas if torqued correctly, the tap and die threads on my Professional Engine and deck were good for hundreds if not thousands of remounts .

 

[onefortheroad]

I bought Bilstein Top Suspension Mounts (coil spring retaining plate, bearing block, and bump stop and gaitor) because MB no longer make them for a 2002 car.

The OE ones look similar except the 2 holes for the bolts do not have a thread inside. They are possibly slightly tapered holes.
Looking carefully at the old blocks, the thread seems to start faintly at the top and then get progressivly deeper cut near the end. The cleaned up bolt is also stiff inside this thread. Plus even on the genuine MB part the thread does not look perfect.

Q. Are these self cutting bolts and it is meant that you cut the thread on install?

Note both top mounts were smooth inside the holes. And the “self cutting bolt?” Does go in about 1/3 of the way before biting.
Impatiently I did screw in the bolts on one mount and it did seem to cut a similar ‘poor’ thread, (but it does work) looks pretty much like the original mounts hole now.

Only asking as I could cannibalise this mount and reuse the block of the old MB one, but although the rubber bush looks OK, it might be near end of life.

Q. Just checking do Mercedes ever use these self cutting bolts on parts like this?

NB when I replaced my Professional Honda I rang Honda and asked why was mine £1400 and the lower range was £700. One of the reasons he gave was they used self cutting bolts to stick on the carb and other parts. He said they were good for about 7 to 10 remounts. Whereas if torqued correctly, the tap and die threads on my Professional Engine and deck were good for hundreds if not thousands of remounts .

I've had a thermostat that had similar holes ,where the bolt cut it's own thread as you drive it home.

 

[AndySlade]

I've had a thermostat that had similar holes ,where the bolt cut it's own thread as you drive it home.

I also had a thermostat like that, thought it had missed quality control. I tapped the holes before fitting. There were blind holes for the bracket that held flexible hoses, so taper tap and bottom tap!