Coil Mount

Hi All,

I replaced my coil today (thanks for the manuals @richard-7 - donation coming your way) with a genuine bosch item. The coil that was in my bike (a 2015, Australian delivered 961 Sport) was a "no name" with no marking on it.

The coil itself is used in a number of Mercedes vehicles, and In replacing it, I noted that the way the coil is mounted is oriented upside down as compared to those.

Where (at least in my bike) the flat face goes towards the flat surface of the mount, in a Mercedes, the coil mounts on a spigot, with the bolt head recessing in the whole.

This is it mounted in a e55, effectively on top of the rocker cover:



Whereas in our bikes:



Whilst it may not be the end of the world, and I don't know how many actual coil failures are experienced, has anyone flapped their coil over to what appears to be the correct way? I'm guessing if that's the way the manufacturer intended it to be oriented (and how Mercedes does it) its likely the better way.

It will need a spigot of some kind spun up to flip - but any thoughts?

Gojuu said:

Hi All,

I replaced my coil today (thanks for the manuals @richard-7 - donation coming your way) with a genuine bosch item. The coil that was in my bike (a 2015, Australian delivered 961 Sport) was a "no name" with no marking on it.

The coil itself is used in a number of Mercedes vehicles, and In replacing it, I noted that the way the coil is mounted is oriented upside down as compared to those.

Where (at least in my bike) the flat face goes towards the flat surface of the mount, in a Mercedes, the coil mounts on a spigot, with the bolt head recessing in the whole.

This is it mounted in a e55, effectively on top of the rocker cover:

View attachment 83968

Whereas in our bikes:

View attachment 83969

Whilst it may not be the end of the world, and I don't know how many actual coil failures are experienced, has anyone flapped their coil over to what appears to be the correct way? I'm guessing if that's the way the manufacturer intended it to be oriented (and how Mercedes does it) its likely the better way.

It will need a spigot of some kind spun up to flip - but any thoughts?

Click to expand...

Won’t make any difference how it’s mounted.

Interesting read.
The only change I have made is to cut a cork gasket to soften the contact between the coil and the bracket.

ntst8 said:

Interesting read.
The only change I have made is to cut a cork gasket to soften the contact between the coil and the bracket.

Click to expand...

And that's kind of how I started. I looked at it and thought it was odd that was just mounted solid - especially when I've read threads on here where people have repaired stress fractures - so wanted to see what other manufacturers did.

I’ve seen these types of coil mounted in a number of ways. They are a solid state device and manufacturers are free to mount them in any way convenient to them. My car versions are mounted with the flat face down and typically these coils they are mounted with their flat face to their mounting surface/ component. They are fairly heavy and mounting them where all that weight is on a single spacer is not the best idea in my view. I would not say the Mercedes example is the correct way, but ‘a’ way, and not a very good one, but it suits their application. Ntst8’s suggestion of a gasket might not be a bad idea though.

Coils don't care which way they are mounted as long as the connectors are not getting filled with water.

The real issue with the coil mount is if your boots are weak, you will actually get some contact(spark from coil to bracket) through the bottom boot. We check this on every 961 that comes in. Easy to check with the lights off. It is even more noticeable when the plugs are pulled. You can actually hear the contact of the spark before you see it.

City Garage said:

Coils don't care which way they are mounted as long as the connectors are not getting filled with water.

The real issue with the coil mount is if your boots are weak, you will actually get some contact(spark from coil to bracket) through the bottom boot. We check this on every 961 that comes in. Easy to check with the lights off. It is even more noticeable when the plugs are pulled. You can actually hear the contact of the spark before you see it.

Click to expand...

That’s useful to know