'anti drum' door brackets

[markattard]

Found this bracket inside my split screen front door, it has rubber attached to the tip, apparently to cut vibration sounds from the outer door skin.

however it does not touch the skin at the rubber end! is this the way it should be or is there something missing?

[geoberni]

It just so happens that I have my Drivers Door card removed.
Here's what I've got in my SII.
I can't guarantee the doors are the originals, since when I got the car, 3 of the 4 items of glass in the 2 doors were etched with a late sixties registration, so had been donated. The donor car was also black, so no way to distinguish.

Looking at that gap, I doubt it's supposed to touch.

20200712_173701.jpg (566.03 KiB) Viewed 2149 times

[jagnut66]

Hi,
I believe Mk 2 Jags had something similar, which did come into contact with the door skin and, in the long run, caused it to rot through at that point, as it trapped moisture.
So maybe it's just as well there's a gap........
Best wishes,
Mike.

[markattard]

It just so happens that I have my Drivers Door card removed.
Here's what I've got in my SII.
I can't guarantee the doors are the originals, since when I got the car, 3 of the 4 items of glass in the 2 doors were etched with a late sixties registration, so had been donated. The donor car was also black, so no way to distinguish.

Looking at that gap, I doubt it's supposed to touch.
20200712_173701.jpg

thank you so much!!

[markattard]

Hi,
I believe Mk 2 Jags had something similar, which did come into contact with the door skin and, in the long run, caused it to rot through at that point, as it trapped moisture.
So maybe it's just as well there's a gap........
Best wishes,
Mike.

thank you I'm also thinking its some kind of crash buffer?!!!

[geoberni]

thank you I'm also thinking its some kind of crash buffer?!!!

About the only good it might be is to stop a small dink to the middle of the door breaking the drop glass if it were lowered at the time.
It does seem to be quite valueless at first glance.....
Any collision to the side isn't going to be stopped by something that small....

[markattard]

yes I agree just on ocd approach for something that could happen one in 10 million lol

[philthehill]

I am going to stick my neck out here and say that it has nothing to do with the outer door skin but is related to the inner door skin.

I am of the opinion that the anti drumming door brackets are there as an absorber of the inner door skin resonance. That is why it does not touch the outer door skin. The bracket just hangs there and vibrates counter to the vibrations of the inner door skin. It acts in a similar way to white noise. The rubber is the counterweight and being rubber and dense is a good absorber of resonance.

[geoberni]

By Jove Phil, I think you may well have it.
That sounds perfectly feasible.
I'm not sure the actual inner skin would resonate as such, due to all the cut outs and bends in it, unlike the outer skin, but it could well be an overall door resonator suppressor. Certainly a better proposition that any other suggestions.

[markattard]

Sound deadening doesnt work exactly like that but who knows what was the science about it back then!!

[geoberni]

Sound deadening doesnt work exactly like that but who knows what was the science about it back then!!

Exactly.
From the same era, look what happened to DeHaviland and their Comet experience.
You'd think anyone would know about the structural stresses of squared windows....., but in fact, the 'square windows' took the blame unnecessarily.
It wasn't the design of the Square windows that was the fault at all. If was the manufacturing process.
The square windows got the blame because of testing/investigation errors following the crashes.
There's a brief 11 min video on it here if anyone's interested: https://www.youtube.com/watch?v=2rvx-r2itrE
If you already know about the crashes and the blame being on the square window design for the past 60+yrs, you can skip to the 7 minute point....

[philthehill]

The bracket does not deaden sound. The problem is the drumming/resonance of the panel which is completely different to noise.

The bracket does not appear in the BMC 1/4 ton commercial parts catalogue.

[johngrigg]

Its sole purpose,for which it is brilliantly designed ,is to get in the way and annoy you when working on the door interior .it is best fitted in the box where you keep one day parts ,that is parts you are going to replace one day when you can remember where they go.......

[ian.mcdougall]

Hi some modern cars have lumps of heavy metal bolted to panels to stop unwelcome noises intruding into the car .One i remember was an audi TT with one bolted to the rear panel behind the bumper ,another one bolted to the bulkhead of a Honda, one like a round rod in rubber mountings on the front panel of a ( I think ) toyota. So your theory has some credence there Phil