MG-Cars.info

Welcome to our Site for MG, Triumph and Austin-Healey Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG Midget and Sprite Technical - MGB door fitting NMC

Anyone any experience of fitting second hand MGB doors?
The 2 photos show the first 'fit' of the passenger door.

The wing (also second hand) is a good fit at all points but the door is too tight at the bottom leading edge whilst also being too high at the top rear edge.
Moving the door so the leading edge gap is improved makes the rear edge even worse.
Juggling it around using the limited amount of movement allowed by the hinges doesn't resolve the problem.

A PO had welded (now ground down) the hinges to the A post 😱 and one of the captive tapped plates is missing. Is that a possible contributing factor?

The hinges are handed and according to Moss, they have different part numbers for upper and lower - that may have something to do with the catch/stop mechanism fitted to the lower hinge, rather than them being different in construction.

Any thoughts?
Thanks.





Jeremy MkIII

Irrespective of door hinges, surely the door skin should correctly fit the hole,allowing for correct gaps all round. Your contrary fit suggests either the door or the hole is the wrong shape. Has it had work on the sills, A or B posts?
GuyW

Has the door had a new skin?
Dave O'Neill 2

Looking at your photos again, I may have misunderstood your explanation. The fit is hard to tell in the photos other than the top is too far out and the bottom too far in, at least at the front of the door. It also looks as if the door may be twisted but hard to tell until the hinge end by the A post is set correctly.

In-out and up-down of the front edge is by adjusting where the hinge is bolted to the body. Back-forth is where the hinge is bolted to the door. But it also works diagonally, so moving the top hinge out will shift the bottom rear corner inwards.

Clear as a London 1950's pea souper!
GuyW

Worth first trying the door in the aperture to see if actually fits especially if it’s been reskinned. Try laying the door on a flat surface to see if it has twist in it - often after repairs or reskinning - frame down.

It’s a long time since I fitted new doors to a ‘B’ - the hinge boxes into the A post give a fair amount of adjustment when slackened off and as guy has noted for/aft is by the hinge straps.

The trailing edge especially the bottom was often an issue at the factory and the rectification tool was a length of 3x2 through the door openings into the bottom and physically twisting it back. I have resorted to that technique ISTR.

Did the old door fit correctly ?
richard b

Thanks

The friend whose B it is, is concerned it may be twisted.
Not sure whether it has been reskinned as it's from Andy Jennings. It came in primer so it may well have had a reskin.

We've adjusted it using the hinge screws and tried shimming the hinges at the A post.

To answer your helpful comments in sequence:

Guy - yes it's had new sills in the past but the old door fitted. No work AFAIK on A or B pillars.
Good point about the skin/door fitting the aperture. Will try try and see if it does.

Dave - don't know but possibly see above.

Guy - no, you've understood it well. The photos aren't the best as room is limited but as well as the issues you describe the rear top of the door is well proud of the B post, in height terms.

Edit - yes the old door fitted well, sorry missed that.

Richard - think that's a good place to start. We'd assumed it would fit but we all know what assume does 🤭 Trying it flat - will do and just trying it unattached just in the door gap, thanks, will do.

Thanks again, really helpful.
Jeremy MkIII

Yep, our old mate assume has a lot to answer for!
Twist is a not uncommon result of poor fitting of a new doorskin.
It could be the replacement door, but could also be the previous one with the body adjusted to suit when opened up to do the sills.
So if the replacement passes the lying flat check, have a look at the old one.
Paul Walbran

Will do that Paul, thanks.
The whole car is an interesting challenge!!
Jeremy MkIII

Jeremy
Just wondering, would it be easier to repair the old door?
Bill B

The other check on the fit is the swage line across the door aligning with the body. On the photos this looks pretty good but you also said:

"the rear top of the door is well proud of the B post, in height terms." That suggests a dimensional mismatch between door and B post.

I wonder how much variance there was in MGB doors over the production life? I have read that the big steel presses wore significantly over the years, producing variations in the larger Spridget panels like wings and bonnets.
GuyW

There is also a difference between Heritage and repro panel's
Paul Walbran

Bill, between the PO and corrosion, the lower hinge bracketry (in the door) was in a very poor state - it was welded in places MG never intended, so was the reason the door was replaced...

Guy, there's nothing wrong with your powers of observation! Well spotted. The swage line isn't too bad considering how poor the door fits - which is a concern.
The Hindustan Ambassador used Morris Oxford(?) tooling well past its use by date and needed lumps of lead to make good, so more than likely the B had very worn tooling by the end of its production run.

Paul, there is. A couple of the Heritage repair panels fitted like a glove, others required some work to make a good fit. But it's a 52 year old, fire damaged shell!
Jeremy MkIII

This thread was discussed between 08/08/2025 and 09/08/2025

MG Midget and Sprite Technical index

This thread is from the archives. Join the live MG Midget and Sprite Technical BBS now