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MG Midget and Sprite Technical - Bodywork measurements - Bamboozled :-(

Grab yourself a cup of tea, this could be a long one!

Last summer/autumn I finished replacing the floor/footwell/sill etc. on the passenger side. I was going to fit the heelboard in the bottom of the footwell and found it didn't fit. The footwell appeared to be 8 - 10 mm too narrow. I was pissed off for a while thinking I had welded everything in squint but resolved just to live with having ill fitting carpets and to only carry passengers with narrow legs. I will make sure I line things up better when I put the drivers floor in...

Over the past few days I have been trying to line the floor up. Using the passenger side heelboard as a reference to make sure things will fit once welded up. Whatever I did I seemingly couldn't get things to fit right. So I measured everything...

Firstly the floor is 467 mm wide (I know it's an imperial car but mm are easier!) see pic...

Malcolm Le Chevalier

the rail + one flange is 70 mm. see pic...

Malcolm Le Chevalier

and the heelboard is 412 mm wide at the bottom. (see pic I know this is the passenger side one, but they are the same right?! The dirvers side one is in the post). so the heelboard + the width of the chassis rail should be the width of the floor right?

heelboard + chassis rail = 482 mm
width of floor = 467 mm

NOT EVEN CLOSE?!

The only other reference I have is the width of the footwell carpet, this is 392 mm. Plus the width of the chassis rail = 462. Which looks about right for fitting in the footwell (floor is 467, so 5 mm "space").

So confused... :-(

Malcolm Le Chevalier

Comparing the old and new heelboards they look quite similar... (albeit they are from opposite sides)



Malcolm Le Chevalier

but the sill/footwell side and it poked out with a gap. It wasn't welded in, it was just glued to the sill with mastick or something!

See last pic of mangled metal before old heelboard was cut out...

Note 4 footwell fronts! bonkers!

So, anyone know what is going on? This really has got me down... :-(

Thanks all,
Malcolm

Malcolm Le Chevalier

Hi Malcolm,

My Sprite is in a not dissimilar state to yours, and up on a rotisserie so easy to measure.
I know that you think metric is easier, but since the parts were made to logical imperial measure I still prefer to measure in inches and 1/8"ths..
My floor panels measured across the width at the front are 18 1/2" = 470mm
The chassis rails, across the flanges are 3" = 76mm

Does that account for some of the difference?

I am not sure what the "heelboard" thing is you are measuring - even from the photo! It doesn't look like a heelboard to me. But I suspect we are using different nomenclature. I always thought the heelboard was the front face of the rear box section behind the seats?
Guy

Ah, got it from your later photos which appeared whilst I was typing! Your Heelboard is what I would call a Toe board! The rearward face of the front triangular box section forming the angle between the floor and the front of the footwell? I just made those out of flat sheet steel to fit the space I had available - so had no fitting problems! If you need to adjust anything, I would modify that flat panel rather than anything else. It just needs to fill the width available and be welded all around.

Guy
Guy

Doesnt the flange on the Toeboard (AKA heelboard!) that you have measured to but against the inside face of the chassis rail ? - It doesn't extend the full width of the floor panel as measured does it?

I suspect that the vertical sides of your chassis rail that you measure as 70 mm are folded inwards slightly with the base plate missing,, rather than properly vertical and parallel.
Guy

You are adding the full width of the chassis rail to your Toeboard measure. Yoo need to subrtract one of the flanges of the chassis rail.

On mine this would mean that the toeboard would be floor width of 18 1/2" - chassis rail of 2 1/2" ( Top hat chassis rail of 3" less one flange of 1/2") Answer = 16" (408mm) Close enough to your 412mm ?
Guy

Hi guy, heel/toe are the both part of the foot! ;-) why would the heelboard be behing your back?! Anyway, thanks for getting back so quickly.

I can't add up in inch fractions, especially when you end up with 1/4 + 3/16 + 7/8 etc...

Floor looks the right width.

The measurement was for the rail + 1 flange. Across both flanges its about 84 mm not 76?!... (see pic) this is 1500 were they different?

I ignored one of the flanges because the heel/toe/foot board buts up against the side of the rail. (If that makes sense).

Might just do what you did and just make something that fits. Just a bit unnerved and disappointed that 'new' panels dont fit... and the panic that I must have made an all mighty cock up for them not to fit!

Cheers,

Malcolm



Malcolm Le Chevalier

typing as you were typing! my chassis rail measure was 70mm minus one flange. 84 mm with both, are they that far out?!

Malcolm
Malcolm Le Chevalier

I think Malcolm must have gone for a pint to assist his brain in working things out!

Just noticed that you say the chassis rail less one flange is 70mm. But then your drawing is dimensioned as showing 70mm across both flanges.

If less one flange is 70mm, maybe the sides are splayed slightly, rather than folded inwards as I stated. Or maybe when I rebuilt mine I have built in slightly wider flanges, maybe that should be 2 78" not 3".
Guy

Sorry, was a bit of a crap camera phone picture.

A bit of a paint diagram to summarise... Not to scale of course!

I will go and investigate my rails... Might post again shortly from my phone cheers guy

Malcolm

Malcolm Le Chevalier

Ah so you hadn't gone for a pint!

Mine is a Frog. I didn't think the shells were different in these respects. But mine is at least as rusty as yours - rather more so you will be amazed to hear! So possibly my dimensions are a bit distorted.

The reason I measure in inches isn't just to be pedantic! It is because if there is any doubt (e.g when measuring to frilly rusted edges) I interpolate to the nearest logical imperial measurement. Seems safer than making it to a random metric figure. But whichever scales are used, the physical dimensions should be (near enough) the same shouldn't they.

The floors are in mine now, so I am measuring the chassis rails width immediately forward of the footwell. I made up new base plates for the forward pointing chassis rails and I made these pieces exactly 3" wide. The chassis rail upper surface - which is original and sound - is exactly 2" OD
Guy

Yep, in garage now and agree with the 3 inch and 2 inch measures. Rail is slightly splayed but not enough to cause all the discrepancy I don't think.

If you reckon the floors are about right I might just go from there!
Malcolm Le Chevalier

Malcolm,
I agree your logic. So it looks like either the Toe board is made oversized so that you can adjust the width to suit you car ( this is the happier answer!)
OR, your floor is too narrow!

Don't get diverted by my measurements. I ma have made my chassis rail baseplates too narrow, although they lo9ok right to me.! From your last photo with the tape measure it looks like yours has 5/8" flanges giving an overall width of 3 1/2" whilst the actual box section remains the same as mine at 2" ( 2" + 5/8" + 5/8" = 3 1/4")

If mine had the wider flanges, I would be subtracting 2 5/8" from my 18 1/2" floor panel, giving a Toe board width of 15" 7/8". Checking on my tape measure this = 403mm. Meaning that your Toeboard is supplied at around 9mm too wide (to allow for adjustment?

I know that some replacement panels ate not that accurately made. It will be interesting to see if the other one ordered is the same size!
Guy

My floor panel is definitely 18 1/2" = 470mm. So yours is within 3mm of mine (1/8") It does look like your new Toeboard is oversized.

What width is the square front of the footwell? Mine is 15 1/4", external. But then I made those too!
( I am secretly checking my dimensions against yours! )
Guy

And how does your new Toeboard fit across the main part that connects to the side of the transmission tunnel rather than the wider bit to the chassis rail? Is the whole piece too wide, or is it just that extension bit at the bottom which is longer?
Guy

Pass... Can't really measure that at the moment.

What really confuses me is comparing the new board to old. They look very similar... I'm sure its original as it has original paint and spot welds. Ho hum... Might just forget about it all...

Malcolm
Malcolm Le Chevalier

Whole thing appears too wide
Malcolm Le Chevalier

Yes, I looked at that photo - which is why I wondered if it is just that little extension bit that is too wide. The bit missing from your old one so you cannot compare!
Guy

Remember the "Two Ronnies" sketch on Mastermind with the subject of answering the question before the one just asked !!?

Looks like our floor panels are the same width anyway, +/- 3mm. So it is more likely that panel that is oversized a bit.

Guy

Thanks for your help guy, I have resolved never to think about it again and just make my own toeboards. As long as everything else is straight and solid (give or take) I think I will be able to call it a victory!

Thanks for being a sounding board for my woes!

I should buy you a beer next time I'm in Cumbria! I am down there quite often as my girls mum lives in Wigton.

Malcolm
Malcolm Le Chevalier

Wigton.
Home of the famous motorclub!
T'other end of Cumbria though. Maybe next time I am in Scotland, although I don't get up0 to Aberdeen so often these days.
Guy

Still there Guy? Driver side toe board arrived today. See pic for scale of the problem!

These toe boards seem way out, will just cut them down to size and be done with it. Floor/rail can't be that far out!

(yes there is a bit of the rail missing, but with my repair patch in it buts up to the rail and side of the footwell fine)

Cheers,
Malcolm

Malcolm Le Chevalier

Weird!
Its got to be the toe boards that are wrong. Persisting with my imperial measurements, the floor panels are 18 1/2" wide each = 37" and the engine/ gearbox gap between the chassis rails is 11" giving a total floor width between the inner edges of the cills of 48".

Get those dimensions right then all you have to do is "adjust" the toe boards to fit! As I said, I made my own so it didn't occur to me to do it any other way. Its much cheaper at least making all of the flat panels yourself. I found metal fabricators who let me plunder their offcut skip for free. Why pay good money for parts like that when they aren't even made to the proper size anyway!
Guy

This thread was discussed between 19/05/2012 and 21/05/2012

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