RP Sliding Roof

[Hugh Barnes]

My apologies for what may turn into a lengthy thread and I crave your indulgence...

When I bought my trusty Box Saloon in 1970, It had a sliding roof panel, but the rear portion of the rails, behind the panel, had been cut off and a galvanised plate screwed over the whole rear portion. I ran the car for a couple of years before the late, much missed Ray Walker declared he coudn't stand it any longer and we removed the galvanised panel (to find the original roof covering still intact underneath), Ray made up the missing portion of the rails and I had an opening roof. However, the rather quick restoration of the roof was never really satisfactory and the roof was always a struggle to use and leaked from the rear. As with many others, this period of house arrest is leading us to tasks that we have put off for a number of years - in my case, 50.

I was fortunate in that the original sliding panel seemed in good-ish order and, remarkably, the original metal 'plate' that goes on the back of the panel, came with the car. I attempted to re-instate this, along with a wooden fillet I crudely made, but it never seemed to work correctly. For those of you who are unfamiliar, the design at the rear of the roof is this..

   

So, I am going back to basics and will make certain everything is as it should be at every stage. I am fortunate in that I also have under the bench, another portion of rails that goes from the front of the car round the open portion, so I can 'rehearse' all this on the bench. The first thing I want to check is that all is well with the panel. A series of 3 photos hopefully will illustrate where I'm starting from..

   

   

   

   

My first questions. From what you can see with the panel fitted to my spare rails, does this look right and, is the measurement from front to back of the panel correct? I have always wondered whether it is short, which leads to the issues with the metal pressing and wooden fillet not seeming to behave as expected...

Thanks for reading this far!!

[Martin Prior]

Hi Hugh.

As you may know, we make these horrible things!

With reference to your sketch, almost everything looks exactly as we make them.  Only two minor details stand out;  I've not seen an original roof with the metal strip below the rubber seal at the back, but it looks sensible enough.  Secondly, where you have Hidem banding on the internal vertical surface, there should be a headlining-covered shaped timber strip (of that I'm certain).


The overhang of the back of your sliding panel, beyond the transverse rail looks generous.  Off the top of my head, it should be about 1 1/4".  I can check, if you like.

[Hugh Barnes]

Hi Martin, I hoped I might attract your attention... ;o)

Yes, I agree, Hidem banding is an error on the drawing and it should be a piece of ply (or thin ash?) covered in headlining material. Again, the drawing is perhaps mis-leading in regard to the overhang. Having measured from the very rear of the panel into the depth of the transverse rail behind the opening, I get an inch. That almost seems to tie up with the metal strip, which 1 1/4" in width. When you make the panels, what length are they, front to back? Or anyone else? I'd like to check that measurement first if I can.

   

   

   

[Martin Prior]

My own RP still has its original sliding panel and track set. The overall front-to-back measurement of the panel, over the curve and allowing for the thickness of the fabric covering is 30 7/8". The distance from the extreme back edge of the sliding panel into the base of the transverse track channel is 1 5/8", but in a perfect world, the panel should probably slide forward by another 1/4", so 1 3/8" is probably nearer the mark.

The metal strip looks original.....interesting.

The interior strips on my car are ash and are 3/8" thick on the back and the nearside, but only 3/16" on the offside (?something to do with the locking bar?). I've seen some Rubies (possibly all Mk2s) with ply strips, but we generally supply them in ash.

[Hugh Barnes]

Thanks for taking the time to do that, Martin. So, herein lies the first problem, my panel appears to be some 3/8" short. Doesn't sound a lot but when there is a lot to get in there withought fouling the transverse rail, I suspect that is significant. The panel structure I believe is original - I may well have to strip the underside to check - certainly the final wooden rail looks original where I can see it through a small reveal in the material - and is also the right size...

That discrepancy is also borne by your measurement between the rear of the panel and the depth of the transverse channel of 1 5/8" (or even 1 3/8") whereas mine in the earlier photo can be seen as 1"

Hmmm...

   

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Martin - may I trouble you for two further measurements, please. Having been a little more 'invasive' I can now say that the outlines of my roof frame at 28 15/16" long and 31 1/2" wide. May I ask what dimensions you put on your newly made frames, please?

   

   

   

I still think this is original structure, but may be wrong. Obviously it has all been recovered etc and I distinctly remember fiddling with the rather odd joints between the transverse rails and the side rails when sorting it out, 25 years ago.

[Martin Prior]

Ours are 28 7/8" x 31 3/8" as the crow flies, so near enough identical to yours over the curve. Everything in your photos looks OK. Is there any possibility that your track set has been fitted too far back? On early RPs the wind deflector at the front is separate from the track and so incorrect positioning is possible. On later cars they're a single pressing which, if set correctly into the front rebate in the roof, can't go wrong.

[Hugh Barnes]

Well, after 50 years, I may have got to the bottom of this. After a lengthy phone call with Martin Prior yesterday, it became apparent that the sliding panel on my car appears to be short by 1/2" or so. How this has come about, I have no idea. It may date back to when the roof was sealed up in the 1950s. However, I have finally got to the bottom of the problem and the resolution was simple, whilst on the phone to Martin, I simply ordered one of his replacements!