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MG Midget and Sprite Technical - Sills and chassis alignment

Hi all,

New here, in the process of rebuilding a 1975 midget.

All of the welding has been complete by my father-in-law. However the original was in a right state, and it needed a lot of panels and metal.

So, with all work done, when I looked at the car on some tressels something seemed wrong by my eye.

So I chose to have the shell put on a jig and measured up by a local company. 3 days later it was ready, but I was told one sill was half an inch lower than the other.

WHen we came to attaching the wings, one wing needed adjusting, by cutting about 2cm's out of it to get it to line up.

Now, being the perfectionist I am, I want this sorting out. But I also want to check which sill it is.

Obviously, I can't go moaning to the father in law, so, I'm on my own on this one.

Can anyone give me any advice as to what to do next?
IR Ryde

Ian, that's a tricky one as it sounds like errors have been "locked in" to the main body frame and then worsened by altering things like the front wing which otherwise might have provided a datum. It is likely to be difficult to correct, and at only 1/2" discrepancy it may not be worth the effort, assuming it still "looks right"

You really need to try and find the root cause of the problem and this will take a lot of measurements. You don't necessarily need to have absolute measurements, but compare one side with the other. That said, some dimensions from a known good shell might help. Measure dimensions that clearly should be the same on both sides. Top of the sill up the curve of the A post and scuttle to the edge of the screen, or to the rear corner of the bonnet opening - that sort of thing.

If one side is lower than the other, do you know which is the correct one, or are they both out? Do the doors fit both sides correctly - they are a useful guide unless they too have been altered to fit to the "wrong" door opening? Is the distance down between the underside of the floor pan and the underside of the sill the same on both sides?
Guy Weller

What Guy says!

Check if the doors fit or measure up door holes. i.e. height of top of sill to top of A- post etc.

Measure inside floor to top of sill.

You might be able to get away with cutting out and replacing the outer sill. Although this would involve cutting into the A and B posts too for access.

Been there and done it myself! As the sill is so long a tiny angular misalignment means quite a big error at either end of the sill.

If you measure and consider the above, the bits that are at fault will hopefully become clearer.

Cheers,
Malc.
M Le Chevalier

X3 all the above

The sill is the concrete foundation of your house ....

if its off, then everything else becomes off more and more till you reach the peak of the roof and nothing fits correct

Because this so serious and can even effect things like car balance and handling, I woould not be embarresed or ashamed to get the old man back into the shop for a 2nd go

If you wont reinlist the old man, for what ever raeson, then the best advice is to sell the car as parts and buy another with out rust issue

Another thought... ask the frame machine company that measured it for you if they cant pull it into spec....it might be priccy but worth it if they have the capabilities

Prop
Prop and the Blackhole Midget

As the guys say, its probably too late to 'bend it' easily. If the doors fit then to some degree you got away with it.

The essence of a good build is to have the floor flat and go up from there. No easy alternative.

So as a starting point I would say you need to find a datum point and measure both sides from it. Like the tops of the foot wells. Are they original? Is it possible to measure down on each side of the car to the floor or sill and compare the measurements? Then come back to someone like Guy or Malcolm who have pretty accurate motors and see how theirs compare with yours. (Mine is definitely not perfect).
Dave Squire

Just following on from Prop's comments. I wouldn't worry overly about it. If it were mine I would want to identify where exactly the error lies, and if possible I would want to correct it. But I wouldn't be panicking into selling it for parts. "one sill 1/2" higher than the other sounds quite a lot, but 1/4" down on one side and 1/4" up on the other is really not that far out for a car of this type of construction. Its not like a modern car assembled with computer controlled tolerances where bodywork accuracy is much tighter. External bodywork on a Spridget is more about what looks right.

Much more important is the accuracy of the suspension pick up points and I would be checking these. The way to do that is to park the car on a known flat and level surface and to use a plumb line from pairs of suspension mounting points to mark on the ground below. Measure and note the vertical heights. Then roll the car out of the way and use a chalk line or straight edge to connect diagonal pairs of matching points. These lines should all bisect on a single longitudinal central line which will confirm that the floor pan and suspension points are all accurate. Around that, the external body panels are really just about looking right, with constant body panel gaps. Unless of course your name is Gary
Guy Weller

Ain't that a fact :0) It's all about self respect, and I have none.
G Lazarus

Gary, it was a tribute to your free- thinking attitude, unbound from staid convention, you alone are permitted to expose your gaps in public, to the unbridled adoration of all your true followers
Guy Weller

Hi all,

Just had time to come and check your posts, and I am amazing at how active this forum is, i can't thankyou enough. My mind is put at ease a little.

Tho doors do fit fairly well (alittle tight on the bottom of the a-pillars), but nothing that can't be rectified.

I going to measure the what Malc says and return here with some photos in hand.

Thanks again guys,
Ian
IR Ryde

Someone taking my advice, Wow, you are obviously new :-D

Yes, it is active on here, although quite a lot of the time it isn't about Spridget related stuff! It is a quiet and forgotten corner of the internet here (just look at the design of the site, 1990s or what?) that the internet janitors have long since forgotten about. Both a good thing and a bad thing depending on your mood at the time! :-)

Cheers,
Malcolm
M Le Chevalier

Congrats malc

Now your somebody special...today the prognosticator of spridgrt advice, tomarrow prime minister of new soviet Europe

Prop
Prop and the Blackhole Midget

This thread was discussed between 18/09/2014 and 23/09/2014

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