RM Riley A-Post Repair in Steel

The design of the A-post (windsreen pillar) in RM Rileys (and earlier Rileys) leaves a lot to be desired. The main problem is that the pillar is made of wood and the lower end protrudes into the front wheel arch behind the wheel where is is regularly soaked by water thrown up from the wheel. Since the end grain of the wood is exposed the water is sucked up into the wood. The wood then rots from the bottom upwards. Of course as the wood rots so the metal in contact with it rusts in sympathy. On most RMs the front door lock striker plate is screwed to the wooden pillar and as the wood rots the plate loosens. A temporary fix often found for this problem is the use of Rawl plugs to hold the screws more firmly. However this does not work for long and everything becomes loose again. The worst case scenario is where the striker plate pulls off and the suicide door flies open at speed.


With the outer metal removed the wooden pillar usually looks this or worse.

The wooden structure behind the panel containing the ventilator is also prone to rot again due to the water thrown up by the front wheel. Usually the first signs are rust bubbles around the edges of the ventilator panel. The only way to find out how bad things really is to remove the panel and see what lurks inside. Usually the easiest way to remove the panel is to remove the screws holding the wing and running board to the wood beneath the panel, remove the striker plate and cut through the door shut face behind the striker plate, cut through the weld holding the rear bottom of the panel to the cill vertical face and remove the nails holding the front and top of the panel. To play safe remove the short chrome trim at the top of the panel. In theory the main panel and the shut face are nailed to the wooden frame and the heads are covered with solder. Usually the wood is well rotted and the nails will pull out easily. With all the visible fixings removed, a firm pull on the panel should get it off.

New wooden sections are available but a viable alternative which will avoid all future wood rot and give a stiffer structure is to replace the wooden A-post with a steel one.

Pictured here is the same car as above fitted with a new steel A-post. It has been made from 6mm steel and all the welds were done with a cheap arc welder.

Note that the new pillar finishes at the striker plate which is screwed to it. To allow for later adjustment of the striker plate to get a good door fit, the holes in the A-post have been drilled well oversize and a nut plate has been fitted behind it. In order to hide the striker plate behind the shut face, the bracket holding the striker plate is 3mm thick.

Another thinner bracket (not easily visible) is welded to the top of the A-post (just above the striker plate) to make a attachement point for the wooden member which runs beneath the windscreen.

This picture shows the difference between the original chassis mounting plate and the new one. The new plate is welded to the main A-post and is bolted to the inner panel just as the original was. Again it is made of 6mm thick steel.

When complete the final structure is much more rigid than the original and effectively rot free.

Depending on how severely the wood is rotted, the original A-post above the striker plate may still be serviceable. If it is, just cut through the post above the striker plate and leave the top part of the post in place. This part of the post does little more than provide an inner fixing for the trim. However if it is rotted it should be removed as the rot will spread to the roof timbers. This part of the post also provides a home for the nails which again join the door shut face to the main body and, of course, the nail heads are covered with solder. If the wood is very rotten it can got out while leaving the remains of the rusty nails in place. If you are lucky the solder will be strong enough to attach the shut face firmly to the main body in which case will that is needed is a small plate welded in the provide rigidity and somewhere to attach the inner trim.

The panel containing the ventilator will almost certainly be well rusted along the bottom edge and around the shut face where it was nailed to the wood. Here there is a choice between replacing the wood and repairing the panel to its original design or continuing with removal of the wood and replacing it with steel. Whichever path is chosen the panel will have to be repaired with new metal being welded in. If the wood is to be replaced completely it will be necessary to weld the shut face to the outer panel and to extend the lower lip so that it almost reaches the inner panel. Brackets can then be welded onto the inner panel either side of the A-post to provide an attachment for the panel and also the front wing and running board. It will also be necessary to weld a strip of steel to the inner edge of the shut face to provide an attachment for the inner trim.

Finally after everything has been reassembled completely seal the underside with silicon mastic (not the cheap stuff) so that the water thrown up by the front wheel can never get inside again.

How long does this repair take? When I did this job on my RMB and I did not want to car off the road for longer than necessary. I knew that the ventilator panels were very rust by the shut faces so before starting work on the car I made two repair section. These comprised the new shut face welded to the rear part of a new outer panel. The shape of these was got simply by using the door as a template. I also cut the steel to be used roughly to size. With everything to hand I started on one side on a Friday evening by removing the outer panel and the lower half of the old A-post. The inner panel was then given a good clean and a coat of rust killer and left for the night. Saturday was spent making the new A-post an exact fit by cutting it to size and tack welding the bits together while they were held in position on the car by clamps. When I was sure that the fit was correct, the clamps were removed, the post lifted away and then welded up on the bench. The post was then refitted and held in place by a couple of clamps while holes were drill for the fixing screws. With the screws in place the clamps were removed. Next the bracket to hold the striker plate was made and clamped roughly in place on the new post. The door was closed onto the striker plate and the clamp moved until the door fitted correctly above the striker plate. The striker plate bracket was the welded in place.

The outer panel was cleaned up and the old rusty metal was cut away leaving an overlap where the new rear section would be joined. The new stronger bottom lip was then welded on. The panel was then fitted to the car and held in place with clamps. The rear repair section was clamped roughly in place and the door closed. The repair section was moved as necessary to get a good fit against the door. The position of the front edge of the repair section was then marked on the outer panel ready for the two to be welded together. At the same time the position of the lower edge of the outer panel was marked on the inner panel ready for the fixing brackets to be fitted. The panel was removed from the car and the repair section was welded in. The fixing brackets were attached to the inner panel and everything was ready for a trial assembly. This being satisfactory the panel was refitted after the welds had been ground back and the surface made smooth with a little filler.

Sunday was spent in final fitting, attaching the trim and painting. By Sunday evening everything was back together and the undercoat was dry. The car was driven to work Monday morning. During the week the undercoat was rubbed down and top coats were applied. The following weekend the same procedure was followed on the other side of the car. In this instance the top parts of the A-posts were is good condition and were left in place.

I carried out this repair on 3 RMs about 30 ears ago. I still own 2 of these and neither shows any signs of rot around the A-posts and the whole front structure remains very rigid. I have lost contact with the RMB but when last seen it too had no problems. I know of 2 other cars which have been repaired by their owners using this method with no reported problems.