Sump & nappies

[Newbie57]

Oil change today. First time since I had the engine replaced.

Yet another bolt decided to give up the ghost whilst removing the nappie. Is it really worth fitting them back on? I guess they are there fo some reason. Reduced drag or just to stop road dirt in the engine bay?

Other thing I noticed is there is a lot of surface corrosion on the sum pan on the vertical face sump nut side facing the wheel. Still seems solid. Wire brushed it and Hammerite to hopefully avoid it rusting through. Is this corrosion usual?

[Carolyn]

A lot of people run without them, I do.   I'm always tinkering with mine, so they would just be a total pain. 

It must be an aero thing, 'cos they don't seem to prevent corrosion (witness the rust on your sump!) and, in the case of sub-frames, they can hide it until it's too late to correct.

Mind you a lot of people prefer to have them in place, in which case they tend to be held on, at least in part, with tie-wraps.

While they're off, it's worth wire brushing anything that looks rusty and priming and painting.  It's surprising how spots of rust get going underneath and a once-yearly brush-up under your car will really preserve it.

[Joesson]

@Carolyn , The under trays could be "an aero thing", but also, I am sure you remember when cars did not have wheel arch liners. Do you also remember the road detritus that found it's way into all the crooks and nannies and acted like a sponge to hold water and road salt to eventually cause rusting through at the top of the wing.
I suggest that our under trays/ nappies offer a similar protection to the wheel arch liners.
As for cable ties, my 2 had a sufficiency of them but I drilled and tapped out all the broken screws and replaced them with hex. head stainless when I de catted my 2.

[Carolyn]

@Carolyn , The under trays could be "an aero thing", but also, I am sure you remember when cars did not have wheel arch liners. Do you also remember the road detritus that found it's way into all the crooks and nannies and acted like a sponge to hold water and road salt to eventually cause rusting through at the top of the wing.
I suggest that our under trays/ nappies offer a similar protection to the wheel arch liners.
As for cable ties, my 2 had a sufficiency of them but I drilled and tapped out all the broken screws and replaced them with hex. head stainless when I de catted my 2.

There are definitely good arguments on both sides on this one!!  I would be in the 'drill and tap' school too, if I had nappies, that is.

[Joesson]

@Carolyn - I don't think the underside of your 2 would dare attract dirt or rust.

[Ardent]

@Newbie57

Surface corrosion is quite common. Many 2s look like they have been parked in the north sea of an evening.

Nappies
Aero - cooling or otherwise. No idea.
But sabine is quite happy going commando.
No sheared bolts, iffy clips or zip ties.

Edit.
And no risk if the under tray catching fire due to being zip tied too snugly to the zorst.

[Newbie57]

They are back on again with a few more cable ties.
I think I'd want it on a 4 post lift to drill and tap all the holes.
A few of the holes in the plastic have pulled through but that's an easy repair.
The nappies were caked on the inside with road dirt. Scraped that out so a bit lighter:)

[Ardent]

Lighter is good.
Lighter still without.

Just be mindful not to zip tie or otherwise, too tightly. A smouldering nappy, is not a happy nappy.

Been there done that. Or more accuratley, been there, after someone else done that.

[Petrus]

Nappies
Aero - cooling or otherwise. No idea.

There is also yhe noise containment. This is whu the engine bottom covers/shields started.
The aero benefits of a closed, flatter underside came later. F1 came up with this first and the industry trailed for surprisingly long.
The sound insulation predated the aero by at least a decade.

I would lóve to ditch the one under mine as it collects an amazing amount of vegetation. I rate the aero effect too high though. Currently trying to fit a diffuser to it without taking removal to the next level of annoying.

But sabine is quite happy going commando.

Got the girls for that ;-)