Exhaust Mounts

As part of driving a Mini with a solid mounted subframe, sporty cam, and lightweight flywheel, I’ve naturally become interested in the art of vehicle refinement, and specifically the isolation of engine noise and harmonics from the passenger compartment.

It turns out to be an exceedingly complex science when done properly, and effective solutions tend to be extremely specific, but there are a few broad principles to start with. Like this one concerning rubber mounts on vibrating components: the brackets supporting the rubber mount should be as rigid as possible, and the rubber as soft as possible.

So, the exact opposite of standard 1960’s Mini exhaust mounts then. Right. Where’s my welder. Let’s start with the rear mount:

Those rubber cotton reel mounts are rock solid. Modern exhaust mounts are little more than a couple of rubber straps, designed to stretch and move. So that’s what I’ll use, and make up a couple of brackets to bolt it to the existing mount holes. (Minis from around 1990 used this style of hanger, but with welded-on brackets.)

Interestingly, the exhaust gets about 8mm longer when it’s hot. I’m going to need to align this mount carefully so it doesn’t hit anything.

And now the middle mount. Same deal:

That’s the standard mount in the front- just a big block of solid rubber. It really doesn’t move much.

And there we go! All fixed. The loud booming from the rear cabin has completely gone, and the exhaust is free to expand and move about a bit without stressing the mountings. We’ll see how long it lasts…