Chassis Bracing + Flat Floor. Rigidity & Aero

[DirtyHabit]

I’ve been probing around for a while, planning a for something a bit ‘unconventional’ next for my ND. (probably more common on earlier models…?)

having had some ‘test’ runs with the OEM underbracing off, and the front strut off and seeing/feeling the difference i have had an eye / plan to fully stiffen the underbody.
thats part 1…

secondly the single best driving improvement for me was fitting the flat floor which really helped stabilise the rear at high speed corners. so functional aero under there has solid functional use
thats part 2.

so, how do i do both? (and do them both better?)

Below is a sample pic of how my ND looks from below, as i have the full Verus kit fitted. I dont have an angled view from the front, but i can tell you now - it may be ‘flat’, but its far from smooth or uniform.

What i would like to do, is to custom fabricate a fully flat sheet(s) to make a flat floor like a typical sports marque may do. example below).

of course… i have some ventilation to think so, so understand my example are just a guide not a final product.
Fabricating this and fixing will be, to be honest, easy. theres a choice of materials. dozens of mounting points. and its fully function not fashion - so doesnt matter how it looks.

But, lets factor in those braces again…
I have been looking at either the goodwin aluminium set, or the Hardrace. (both about the same price). in terms of benefit gained i image both will be of similar improvement. the goodwin may be lighter (and not bloody blue!) BUT, i cant weld to aluminium. which might be a requirement…

The conundrum i have at the moment is as follows, and i think i have 3 options:

a) The bracing kits are not a uniform height on the ground side. meaning, applying a flat-floor on the ground side will require alot of spacers in other areas and massively reduce ground clearance, while also creating an airflow issue with closing gaps on the front and sides so not to create a sort of wing under there. this is due to the mounting points having immense skirts for the bolts.
b) i could weld (hence Hardrace option) tabs or sheets to fill the shapes. effectively making all the hollow triangles, squares etc a solid object, and this will also leave the bolt holes clear for easy removal.
c) use the new bracing kits as an exoskeleton. i will need longer fixing bolts, but this will be a very easy cut of various sized sheets which will be held in place by the bracing kits. but, this wont make a true flat underfloor.

Has anyone else had a go with this sort of thing? internet doesnt have too much info, on any car. especially when it comes to a convertible where i want to improve rigidity at the same time.

thoughts, ideas, discussions welcome :))

[DirtyHabit]

found a black hardrace! nice

this angle should show what i mean about it being difficult to get a flat / clearence on the ground side.

as such, excuse the crude drawing, but this is what i mean by ‘exoskeleton’: use the new bracing to sandwich and support sheets to make a flat bottom. in principle should be dead easy. (will add some cut outs for the exhaust, gearbox, diff ofc). but will this ‘‘count as a flat floor’’? or will this be a complete detached flow.

[BlueAgave]

An awful lot of work and money for how much gain for essentially a road car doing 70 miles per hour. You also need to consider heat - cooling of the diff, gearbox and exhaust .

[Force_9]

If you do this, first dibs on the redundant verus engineering panels

[DirtyHabit]

yea, i know. but its all in the name of ‘fun’

i think it might be easier to image (especially for me) if i had some bits in my hand and while being under the car.
but now ive had a better look (at the pics), im not so sure on the Hardrace kit at all. looking at the triangulation points, its bolted connections at the points of torsion. hmmm…

i think i may try some mix and match. some kits seem to have far better sections than others.
eg - the center X brace on hardrace may as well be the OEM. but the Goodwin has torsion levers built in.
the rear section, Beatrush seems to be the only one with a rear sub-to-sub connection (left to right side) wheras the others just triangulate within the same section.

as for the verus - yea i have been looking at that. i think no matter what i do, the rear covers and the diffuser will be fine/compatible. it will be the 2x center ones which will be obsolete.

[exiled-viking]

Nice work a lot of strength mods there, doing somthing in this line but just using ally plate as I am a cheapskate , and the cars use is Road only but l am doing just 3 panels one large at the front and two small further up with air flow vents, and making a new gearbox ram vent the old one will find a new home at sometime on here this is this years winter project I will be testing this home made project ramps with electric lift plate as well to get under the car….

will be replacing this ram air vent with a new lighter version

[DirtyHabit]

what did you make that out of? if you made yourself a set like that youll be onto a winner

[DirtyHabit]

so after more digging. i think i’ll take a punt on 3x beatrush products

X brace & rear brace:
These look like they wont interfere with the Verus panels. at the rear sub frame, there is a shared hole for booth, so a longer thread will be needed. that will be minimal cost.
ths rear bar is also the only product ive found that creates a tie left to right on the rear frame.

and the front member bar.
again, because this looks like it wont be affected by the verus bits, and will be an additional left to right tie.

because of the verus, i wont be getting the ‘K’ oem relacement, as that has tabs both sides for the flat panels.

…. more crude drawings. but, that will give me something like this:

which means, because i keep the verus flat panels, i think i only need to exoskeleton one section of ally under this, to get something like this:

it should really join together the rear + middle verus peices, while giving some structure.

well. i’ll sleep on it. but i think this will be the next ND mini task

[BlueAgave]

I’ve used a front member bar that goes into the engine cover and provides the same support

[DirtyHabit]

thank you @BlueAgave , completely forgot - ive already got that fitted too got the ClearR one.

ok, thats a few quid saved. X and Rear only then

[exiled-viking]

Well I saw the one on BlueAgave car and being a tight wad decided to make my own around two years back out of 1.5 mm ally plate

I have now put the red fancy washers and bolts on edge’d it in some split rubber a few hours work but I have loads of ally to do projects with …are local metal smith keeps me in with all there off cuts at cheep prices

[exiled-viking]

I wonder if you could use metal tubing and flatten and drill the ends to make some of these brace’s or would that be a little bit of a mod ???

[DirtyHabit]

Little price comparision chart.

i noticed that the MX-5 parts (superlight/ iL motosport) braces have the OEM tabs fitted… which is great. thats what the verus panels connect to. plus, very cheap! so added these in.

looking at shapes, designs, mounting points i think theres ability here to mix and match products. yes, i might have some blue, and gold, and red parts on the underside, but noones going to see it

by mixing the parts, i should be able to

• improve rigidity front to rear
• keep all the verus flat panels
• be most cost effective

the odd-choice on the table (cost wise) in the rear Beatrush. i think that is the far superior design compared to the others for the rear tie, hence why thats made the list.

the other mention is the Hardrace front lower… this will add a new left to right tie in (blue bar) and will allow me to keep the CleaR lower front chassis brace. double win. wheras the goodwin would replace that left right tie in the same location.

[ian.prossor]

I feel like you will appreciate these pictures…

Before

Halfway

After

No comments on the state of the underside, it has had a hard life and A LOT of miles!
And note that a lot of aftermarket chassis bracing doesn’t have captive nuts to mount the floor sections too like the OEM stuff does.

[DirtyHabit]

thank you for this!!
i didnt think this pic would exist very helpful. i noticed the tabs on the Superlight seemed further from the brace than oem, suggesting it was a bit leaner.

on the bracing side, hapy with the red bits?

[BlueAgave]

The ILMotorsport red braces are far stronger than the oem ones

[Bol]

I’ve got the red bits on mine and am very happy with them. Nice and light too, which is a consideration, as it all adds up.

Very pleased to see the Verus stuff fits with them too, as that’s something I’m hoping to add at some point.

[DirtyHabit]

I’ve decided - im going for the full hardrace set. tried getting it in black, but the UK suppliers had extra markup on it. so sticking with blue. (i’ll probably give it a dirty spray before fitting just to hide the colour)

i’ll wait for the black friday sales at the end of the month and get it ordered.

i’ve got some ideas for fitting the fully flat underbody to go with it. once ive got parts in my hand i’ll get to work on templates and jigs.

[Bol]

Can I join the queue for any left-over Verus bits please

[DirtyHabit]

with what ive got planned, the center panels and side skirts will be obsolete for me.
deending on ‘creativity’ and ease of making, possibly the rear suspension covers too.
Will then look to join the front splitter to the rear dffuser