Causes behind hinge post bottom rot

[Mark McCombs]

Here's one to ponder for those who have rebuilt their tubs:

One thing it seems all tubs that have had the side panels removed in the course of restoration have in common is the rotted bottom of the hinge post where it fits into the main rail. Interestingly, main rails many times seems OK, as do the bottoms of the latch posts up front.

So what causes this?

The easy answer is water ingress, but from where? The rear arch overlaps the side panels in this area but from the outside (like a shingle). There is no real opening above it...Unless it is sneaking in at the bottom folded edge of the side panel and works its way to the rear of the side, but that bottom lip is a tight fit (and firmly nailed) again the bottom of the main rail.
The same with the hinges; They are a tight fit into the hinge post, with the sheet metal a tight fit against the hinge bottoms.

Any thoughts? It seems like a repetitive and serious ingress that I would like to seal-up if possible.

[i.thomson]

My experience of wood rot tells me that it is not so much water ingress that is the problem as water exit. If water is able to get in, probably from some way away, it will puddle where it cannot escape and it is the constant wetness of the wood which causes the problem. If it can dry out any rot takes much longer to develop. Thus the various watertight overlaps may actually be part of the problem.
Ian Thomson.

[Mark McCombs]

Interesting thoughts, Ian. I am suspecting the original ingress would then likely be from the inside of the tub itself.

[stephen stierman]

Mark, it probably comes in around those hinges or seeps in under the nailed sheet metal. All these timber bodied cars suffer from wood rot low down "below the water line". My Morgans suffered the same way. I use plenty of wood preservative, oil base paint, urethane or whatever you like to give some additional life expectancy something the factory never did. I also run a bead of silicone latex caulk around the body panels and over the timber joints before I nail them on to try and keep the damp out. Remember these cars are quite old and many were used day in day out for regular transportation, I doubt your car will see that sort of duty.

[Duncan M]

Is it just a coincidence that area of rot on the upright you guys are talking about is in the back corners of the floorboards? Not sure where water would collect on a rainy day, but it seems like a likely spot. Perhaps an argument for loose fitting floorboards back there?

Does anybody use "ethylene glycol" on wood?

[stephen stierman]

Duncan, I do not caulk my floorboards to allow any rain water that might collect a way to exit. This is not a problem with the TC as it really does not go out in the rain, but it is with my Morgan which may get caught on a club run or weekend club meet. When water gets in from the side curtains or various windshield seals it will run out via the floorboards.

I used ethylene glycol on the TC timbers as a matter of fact after reading about it somewhere and also painted them as mentioned above. I am really not too concerned about timber rot on this car considering its use. It will easily out live me at this point.

[Duncan M]

Hi Stephen, I was replying to Mark's original question with an observation.