Switch fitment

[rhattersley]

I'm putting together the dashboard for my 289 roadster and most of it is going great, but I'm having trouble with the Lucas style toggle switches and the fog light switch. They don't have a long enough thread and/or nut to attach the two without it pulling through the vinyl and foam covering. (They worked fine on a test piece of the fibreglass-foam-vinyl combination, but that was on a flat section. The recesses in the IVA dashboard add just enough extra thickness to spoil my fun.)

I can see two options: remove some of the foam around the hole or use a longer nut.

The dash is looking reasonably flat at the moment and not too spongy, so I'm reluctant to just dig holes for the switches, but perhaps it won't be as bad as I think. Anyone got any pictures they can share? Perhaps I just need to make a mock-up of the recess.

This photo shows an early test fit to give an idea of what the other fittings look like.

dash.png

The fog light switch uses a very fine M12x0.75 thread, so I've not been able to find any longer nuts. That just leaves getting some hexagon brass bar, drilling and tapping a hole in the centre, machining it down to give a barrel/T-nut profile, and getting it plated! The Lucas switches seem to be M14x1, so the same sort of thing applies.

Has anyone else had this problem and solved it?

[rhattersley]

The mock up of the recess doesn't seem very promising. The nut is so far back that the leaves of the vinyl aren't long enough to stay behind.... add to which, the whole thing looks somewhat silly tucked so far back.

recess.png

Adding a longer nut could have its own problems. It wouldn't take very much extra length before it starts to foul the action of the switch.

It might be possible to hack away at the reverse side of the fibreglass so that the switch can sit further forward ... ?!

[Migge]

Why have you padded it? Originals were not, problem solved.

[rhattersley]

Why have you padded it? Originals were not, problem solved.

I thought it was an IVA requirement, based on things like Stuart's use of 6 mm foam and the mentions of non-rigid coverings in the "Interior Fittings" section of the IVA manual... but I've just been back to the IVA manual to find the specific wording and I can't find anything that says the face of the dashboard needs to be padded! It actually just talks about padding for:

1. the lower edge of the dash (possibly not relevant as it's only necessary if you don't already have a 19 mm radius),
2. the backs of the seats (not relevant),
3. and shelves (not relevant).

My world has just turned upside-down! Does the IVA really not require a padded dashboard?!

[StuBaker]

It certainly didn't 3 years ago.
There are some IVA regs that are often, it seems, misinterpreted.
There is for instance no definition of the softness/hardness of any padding. (IMHO and last time I read.)
This thread should perhaps be on the IVA section to get a better response...?

[StuBaker]

This is from .gov today:
https://www.gov.uk/government/publicati ... orfittings
Note the solid carbon dash and solid wood dash. The Hawk dash should have the correct 19mm radius.

[clive]

My dash was bare fibreglass and wasn't covered with anything when I had it SVA'd back in the day. Can you grind back some of the fibreglass at the back of the dash to allow the switch to protrude more?

[rhattersley]

There is for instance no definition of the softness/hardness of any padding. (IMHO and last time I read.)

That part has at least had some clarification. For example, in the current IVA manual it states:

Note 6: A "non-rigid material" is a material which has a hardness of less than 50 shore A. For the purposes of this examination it will be deemed to be a
material which is capable of depression under thumb pressure and when deformed retains a degree of protection against contact with any structure
which it is covering and when released returns to its original form.

I hadn't come across the Shore A hardness scale before, but it's easy enough to find references and an engineer I spoke to was certainly familiar.

This thread should perhaps be on the IVA section to get a better response...?

Now that it's become about IVA regulations rather than switch fitment, you might be right!

[rhattersley]

Can you grind back some of the fibreglass at the back of the dash to allow the switch to protrude more?

From my playing around with removing material from the back this afternoon, I don't think it'll work without also making up a small plate for the switch to fix to, otherwise there's nothing left for the nut to grab hold of.

If I can ditch the foam instead then life will get a whole lot simpler!

[StuBaker]

Ditch the foam!
Are your switches inside the safe zone on the steering wheel?
PS, you may need to put a hole in for the steering column!!