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MGB MGB door skins and the infamous crack

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drooartz

drooartz

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When I was reading the Original MGB book, the author mentioned that MGB doors tend to develop a crack right below the little quarter windows. Sure enough, when I looked at my first MGB last week, both doors had this crack. Small, to be sure, but there.

So I have 2 questions on this:

1. Is this really common, and is it something I should be worried about as I search out my LBC?

2. If it comes to replacing the door skin, is there a fix for this that would prevent it in the future?

Thanks,
-Drew
 
This is extremely common BUT it is possible to find an MGB without a crack(all 3 of our MGB's are clackless)but we've owned many in the past that have had cracks...it's caused in the rubber bumper B's because the placement of the mirror puts stress on the skin between the mirror and side vent whenever someone slams the door. One thing some people have done is moved the mirror up a bit to cover the crack...with the mirror moved up it should releave the stress and prevent the crack from getting any bigger. Another way would be to replace the door skin and add some type of renforcemanet to the back of it in the crack area. If the crack doesn't really bother you and your careful with closing the doors gentle then it shouldn't grow to much. Basically be careful, make sure you get one with little or no crack.....I've seen some that have cracked right down the the chrome trim!
I hope this helps!

Zack
 
I don't know the best fix, but you're smart to attend to it now:


crack_of_doom.gif
 
My MG also has "the crack" in both doors. Cracks of this sort tend to propagate if nothing is done, but welding repair is a bugger and a lot of down time accumulates if that is the repair you decide on.

A simpler repair is to just drill a small hole at the very end of the crack, then use a punch to slightly indent all around the hole and then Bondo and finish. The round hole distributes the stresses that cause the crack to propagate in such a way that usually the cracking is stopped. (That is why it is called a stop-drilled crack. /ubbthreads/images/graemlins/lol.gif)

I learned this in the AF and again when working for the Boeing Co.

By the way: no guarantees as to how long the fix works if you insist on driving over wash-board roads!!
/ubbthreads/images/graemlins/cheers.gif
Guinn Hudon
 
One critical thing after you fix it is to never ever pull the door shut by grabbing the vent wing. It flexes the doorskin and the crack WILL reappear. I have been known to lecture passengers on this topic... /ubbthreads/images/graemlins/nonono.gif
 
Thanks all for your comments. If I wind up looking at more MGBs in my quest, I'm not going to be all that concerned about the cracks. I'll still try to find a car without them, but they don't seem to be all that hard to deal with. The link posted above had some good ideas for reinforcing the door.

Since this LBC wouldn't be my only ride, I'm not too worried about long stretches off the road for repairs. Doing this sort of work is one of the reasons I'm looking into getting an old car anyways.

-Drew
 
people closer 'B doors by pushing on the vent wings?!? OY! Ah well, I've been guilty of closing my doors by pushing on the side glass... but not the vent wing; I normally only do so with enough force just to set the door in motion to barely close the door.
 
Hate to break the bubble - but the root cause of the crack [fatigue not stress] is the result of an improper aligned windshield. The doors should be aligned for fit to the body first, then the vent windows installed in the doors. Now adjust the windshield to the vent windows so it is parallel and not putting too great a pressure on the vent windows via. the rubber seal. I checked many MGB's and I've made particular note of the gap of the vent window/windshield. Cars with cracks usually have the rubber pinched at the top of the joint. Moving the mirror as suggested hids the problem - doesnot fix the root cause.
If the seal pressure is too high every time you open & shut the door this pressure flexes the door skin and eventually that fatigue produces the 'crack'.

Regards, Bob
 
I had it on the passenger side. Had it welded up, sanded down, and painted over. No more crack, no more problem.
 
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