What are the structural bits of the bumper made of? Like the big heavy parts behind the rubber dressing bits.

 

On the big-bumper cars (USA and Canada primarily) there's a hefty aluminum beam behind the rubber pad, #3 in the illustration

Bumper-Rear-Energy Absorbing - Parts For Series III Saloon | Jaguar Heritage Parts UK


On the slim-bumper cars there's a less substantial beam....probably aluminum but I' not sure about that

Bumper-Rear-Non Energy Absorbing - Parts For Series III Saloon | Jaguar Heritage Parts UK


In either case there's nothing of substance along the sides.....where the chrome blades and rubber pads wrap around the sides of the car


Cheers
DD

 

Iv got mine apart at the moment and I'm pretty sure that it's steel. The steel beam under the rubber was rusted and I needed to replace it. Mine is a slim bummer

 

Definitely steel beams on the ROW slim bumpers, pretty heavy gauge too. I just drilled my front one today to hang driving lights underneath and it took some getting through. Yes, they they do rust.

 

I want to say mine were aluminum/aluminium, dont recall it being very heavy, but dont take that as gospel, i dont remember what i had for lunch yesterday!

 

Ah, thats different from mine, Ill upload a photo of the old one. Its rusted as anything though.

Your one certainly looks like ali