R107 – So The Hood Is Aluminum?

[WINTS]

Just giving this thread a bump after going through the archives here for info.

My 81 280 SL trunk is very light, and I was sure it was aluminum, but a magnet just about sticks to it. The hood however, which I thought would be steel, is aluminum. The magnet just slipped off it...

[JimFreeh]

Originally Posted by Greg in Oz

My understanding is that the early 107s (such as my '73 350SLC) used steel but with the introduction of the 107026 (5.0) they switched to aluminium. Where I believe the confusion comes from is the fact that on the 107026 in addition to using aluminium for the bonnet (hood), they also used it for the boot (trunk) lid, lower bumper sections and bumper mounting brackets. I have been able to confirm that all these items are aluminium on my 107026 ('81 500SLC). An interesting bit of information I have heard that the rear spoiler on the 107026 was a "delete" option and in the instances where it was not fitted the boot (trunk) lid was steel rather than aluminium. I have seen some other 107s (eg. 500SL) fitted with the rear spoiler but I do not know whether these used aluminium or steel for the boot lid. What I do know is that according to the owner's manual for my 500SLC, it is lighter than every other 107 model which presumably can only result from greater use of aluminium in the body (since all post '80 models with V8 engines used alloy engine blocks).

Greg

This aligns with my experience.

I've got a 73 450SL with a steel hood, the 81 and 85 380SLs have aluminum and the 84 280SL is also aluminum.

As a side note, on W126 cars, the diesels (300SD, SDL) had aluminum hood and trunk panels, the others did used steel.

Jim

[London380sl]

The aluminium hood became standard in 1981 as part of their corporate drive to make their cars more fuel efficient. I wish they had made the hardtop roof aluminium instead. That's one part that could use losing weight.

[jplinville]

Originally Posted by London380sl

The aluminium hood became standard in 1981 as part of their corporate drive to make their cars more fuel efficient. I wish they had made the hardtop roof aluminium instead. That's one part that could use losing weight.

To do that would have severely lessened the strength needed to survive a roll-over. With the steel top on, it is as safe as a coupe.

[unavita]

The aluminum bonnet and rear deck lid appeared on the 450 SLC 5.0. It became standard on all SL's beginning with the 1981 380 SL.
The reason was for weight saving but also with the 380 Mercedes left the all cast iron (read: high heat retention) engines behind. The unfortunate result was the alloy version was less reliable in the are of cylinder head and pistons.
Mercedes changed it's process for making the cars as well. Steel hold form much better as well as retains a better paint job over time. It was also easier for the crafters to stamp out. It is more forgiving.
Aluminum is lighter, dents more easily denting even under heavy hand pressure and is thought to not hold as deep a luster.

[rowdie]

Only the block on the 3.5 and 4.5 engines was cast iron. Heads, intake, TC cover and pan were aluminum. The 2.8L was a cast iron block throughout production. You are correct that all model 107s had aluminum hoods beginning with the 1981 model year. After the stock of steel hoods was depleted the aluminum hood became the only replacement available from MB.