|The MGA With An Attitude
DOOR ALIGNMENT During Reassembly -- BD-103D
At 07:38 AM 5/19/2007 -0600, Mike Bane of New Brunswick Canada wrote:
>"Having a real problem refitting the doors - referring to the shims behind the hinges - what are the average thickness and roughly how many? I have made a few shims but still need more? The door originally fit okay, but ....".
Ah, the perpetual perplexing problem. Origin of the problem is that the hinges are likely to be all different. Before disassembly you need to mark each hinge for original position and note all original shimming, then put it all back in the same places during reassembly. Stating from scratch can be a big chore. If the shim setup was bad before (too many shims or the wrong kind of shims), it may be better to start from scratch anyway.
>"I seem to remember removing several washers and not shims."
Washers would be a DPO bodge, not factory issue.
>"I have tried resetting the hinges on the door - not much no real change. I have also checked for previous body damage - none seen. Also done dimension checks between posts - okay. It all seems to do with amount of shims that you fit. How many is right?
Original body assembly was jig welded, but 50 years ago the manner of fixturing parts in the jig was not particularly accurate. Dimensions specified for frame and body alignment can vary up to +/- 3/8-inch in some places. If you were lucky the original door posts might be aligned within +/- 1/8-inch (space between the posts) , but that sill leaves up to 1/4-inch total range to be adjusted out at final assembly. Factory assembly workers would commonly bend the hinges to get the alignment "close" before starting with the shims.
I used to think that keeping the original alignment of the door posts and hinges and shims was critical to reassembly, until the day that I had to replace a broken hinge with a new one, and it was not the same as the old one. With further experience, I think it may be easier to start with the body in two pieces with no sills so you can carefully realign the door posts, and do a better job than the factory issue. If you do that, the ideal starting place would be exactly one shim on each hinge and one shim on the latch striker plate, and then adjust from there +/- one shim if necessary.
If the body posts and sills are already fixed in place, it may be necessary to bend the hinges to get to the desired starting condition of one shim (if you think it is worth the time to do this to eliminate extra shims). If you have the hinges installed with a stack of shims, and the door is closing and latching, then you know how much shims you want to eliminate. Dismount the hinge, position it with the plates parallel, and measure the overall thickness. Add or subtract the thickness of shims you wish to change or eliminate to get the desired overall thickness of the hinge.
The hinge plates are likely stronger than the hinge pin, so it may be best to use heat to soften the metal prior to bending. You would want to keep the plates flat where they attach to the body post and door, so the appropriate place for the bend would be very near to the hinge pin on the front plate (the side that attaches to the body post). You need an acetylene torch to heat the plate for full height along a line in this area. Heat to cherry red to make it easy to bend. To bring the plates closer together, simple squeeze the hinge in a vice. To push the plates farther apart, place a round steel rod inside the hinge near the hinge pin, and then squeeze the hinge in a vice.
As stated, the ideal condition is to have the door mounted, closing and latching with one shim for each hinge, and that shim should be between the hinge and the door post. Be careful with the fit of the top front corner of the door near the end of the top body cowling. There is a neat trick to fine adjustment of these shims. The original type shims are a soft fiber material and fairly thick. They have a large surface area, so they do not change thickness much from tightening all four screws. They can however be re-formed during assembly into a slight wedge shape, coming to be thinner at one edge.
For instance, if you need the tail end of the door to come slightly higher, you want to move the top hinge slightly forward. Loosen the four screws on the top hinge, make the two inboard screws very loose, then tighten the two outboard screws firmly. This will compress the outboard end of the soft shim, providing a slight wedge shape and moving the hinge pin forward a bit. Then tighten the inboard screws last, and maybe not quite a tight as the outboard screws.
If that is not enough movement, you can repeat the process making the shim even more wedge shaped. If still not enough you can move on to the bottom hinge, intending to move that one slightly rearward. Loosen all four screw on the bottom hinge, then tighten the inboard screws first, smashing a slight wedge shape onto the shim to bring the hinge pin rearward, then tighten the outboard screws. With a little fiddling around in this manner you may be able to properly align the doors with exactly one shim for each hinge. If necessary you might go back to reform one of the hinges (again).
In factory production I suspect they had various boxes of hinges which had already been formed to various over all thickness, so rather than stacking additional shims they might just grab another hinge with different thickness. Perhaps half the cars might have been assembled with nominal dimension hinges, 1/4 needing a thicker hinge and 1/4 needing a thinner hinge somewhere. Then maybe up to 80% of the hinges could be nominal, with 10% needing to be thicker and 10% needing to be thinner. This would not be too much problem in production, with 20% of the hinges having been reformed en-mass prior to final assembly. They also likely didn't need or use heat to bend the new hinges.
For body assembly of the MGA you need to build the car around the doors, starting in the middle and working forward and back from there. Get the doors mounted and working first. They should be easy enough to align with the original body sill, shooting for about 1/4" gap at the bottom. If you are replacing the outer rocker panel, you should install the door first, and then figure out how to align the rocker panel to the bottom of the door to provide the desired clearance.
With sills and doors in place it should be a relatively simple matter to install the fenders, starting with the desired gap between door and fender, tightening the fender attachment screws along that edge to keep that alignment, then following up with alignment and attachment of the rest of the fender farther away from the door.
I have another hinge alignment trick I used during reassembly after body sill replacement in 2008. In this case I managed to eliminate all shims for the hinges, and hinge alignment took minutes rather than hours. Having just replaced body sills and substantial parts of the B-posts, the prior hinge alignment was no longer valid, but there was enough space here front to back to allow for installation of at least one shim for each hinge (as described in a prior article).
I assembled the hinges securely with all screws but with no shims, leaving the door slightly farther forward than the desired final position. I tied/taped a thin steel wire to a piece of drill rod, suspended the drill rod between the hinge plates near the hinge pin, then pushed the door shut slowly, a little at a time, for the desired result. The steel rod holds the hinge slightly open while the force on the door pushes the hinge plates together. This bends the hinge plates a bit resulting in more space between the hinge plates. This gives a result similar to adding a shim(s) to the hinge but without needing a shim. It worked like a charm, but before you ask, I was prepared to buy a new hinge if I happened to break one.