Scooterotica

Please ignore above comment from me. I completely bolloxed it up and don't know how to delete...

My understanding is that they used brass nuts (a lot of cars use brass nuts on the exhaust as well) because brass expands a lot with very little heat so the nuts tend to lock themselves on to a running motor as it warms up.

so which way is correct?

Put them on anyway you like, if they fall off you got it wrong!

Personally, spring washer then round side of nut against the washer.

round side down, there is no point in having a machined diameter on the top of the nut, if it is on the bottom it ensures the hexagon cant catch on welds, we use similar nuts on race car exhaust flanges for that reason

sunrisemac wrote:round side down, there is no point in having a machined diameter on the top of the nut, if it is on the bottom it ensures the hexagon cant catch on welds, we use similar nuts on race car exhaust flanges for that reason

Aren't you more likely to have a proud weld where the flange is welded to the downpipe, therefore it would make sense to have the round bit upwards.



With a spring washer and a flat washer between its round bit and the flange of course.

I think we may be getting "Up" and "Down" confused now.......

Rounded bit next to exhaust flange.

The round end of the nut has a larger surface area to place pressure and contact on the flange. If used the other way what is the purpose of the rounded end? It may not be there.

here's a sketch of what I mean

sunrisemac wrote:here's a sketch of what I mean

Same as me, but my exhaust bolts the other way up