230 SL Brake Drums same as..... ?

[scoot]

I salvage parts and sell them.    I looked up the cost of a new brake drum and it's insane.   I looked at the cross reference for the part and it appears to be the same drum as on the front axel of a 111.012 220 S sedan.   So I got a pair and had them turned etc.   But when I look on ebay, I see other drums that look exactly the same but say that they are for a 190 SL. 

So my question is...   Are all of the ALFIN drums from this period the same, even if they have different part numbers in EPC?   And is getting a pair of drums cheap a big deal, or are they all over to be had?

thanks
Scott

[badali]

The drums on my car are light weight.  I think the outer part is aluminum.  I have one NOS drum with the bluish coating on the inside.  The guy I bought it from said he had another but has not found it yet.  I think later finback sedans with front discs have the same drums but the others are different.

[ja17]

Hello Scoot,

These aluminum finned drums are the same on the fronts of 190SLs, some Ponton sedan, and the finback sedans with drum brakes. The aluminum finned drums have steel sleeves where the shoes contact them.

Earliest  190SLs had all steel finned drums. After a couple years they used the aluminum finned drums in front and the steel finned drums in the rear. I always used to replace the rear steel drums on my 190SLs with the aluminum finned drums to save weight and improve cooling. Most likely this could be done on the W113 cars also.

[scoot]

...so even if the different cars have different part numbers for the drums, it sounds like generally speaking the ALFIN drums can be used on all applications where this period Mercedes had drum brakes, is that correct?  If so, what I should be look for is drums with very little wear.   I have seen the price of a new drum from MB - something like $1800 per drum....   I wonder if they can be re-sleaved...

[Benz Dr.]

The 190SL and 230SL use the same brake drums. Some early sedans use a brake drum that is both narrow and has no fins on them.

The alfin drums have cast iron sleeves - they're not steel. Watch what happens when you put them on on a brake lathe. The material crumbles as it's removed - steel machines in long curly pieces. You could have new inserts installed. I know that they do that on 365 Porsche.

[ja17]

Hello Scoot,

They do turn these drums down and there is a minimum specification. Dan is correct about cast iron. They do chatter and carry on in a drum lathe.

I do not know of any alfin drums which are different except those on the 300SLs which are larger.

For your information scoot, the expensive aluminum shoes found on the fronts of some of the Finback sedans and some ponton sedans are also the same as 190-SL aluminum shoes.

[J. Huber]

Hey Joe or others  -- let me ask the question a different way: if I need to do my back brakes tomorrow and my drums are too thin to re-use, what would I be looking at? How available are ones I could use - and what would they run me?

Sadly, that time will come -- I redid the rears about 5 years ago -- and mechanic mentioned I was getting close to minimum. 

[Jordan]

James, Dan (Benz Dr) can send you another set of brake drums, but he will need you to send him the cores if you want to save a bit of money.  He reuses the cores for the next person.  There might also be someone in the US but I got mine from Dan last year.

[J. Huber]

Thanks Jordan. I actually got my last set of brake shoes from Dan -- just as you say, with a core exchange. I wouldn't see the point in sending the drums though as they will be too worn for the next guy. I am thinking they will make a nice centerpiece for the dining room table... 

[Benz Dr.]

I never throw anything away which is why I have so much  stuff around here. I have quite a few alfin brake drums around here. Some of them may be worn out but I'm sure some are good.
Anyone have the minimum spec handy?  Once they get thin they tend to warp easily but that's not a big problem on 230SL's because the rear brakes don't work as hard as the front ones on a 190SL. As long as they're round the brakes will work OK and there's a lot more adjustment on the 230 rear brakes as compared to a 190SL.

 It's the brake shoes that have a core return. The brake drums would be a direct sale.

[scoot]

OK, then what do I have...   I took the drums off the FRONT of a 230 Sedan, I think 1961.  They are definitely finned and aluminum.  They do _not_ look like cast iron inside - they look like steel.    When I look in EPC it shows the front drum from this car being the same as the rear drum on a 113.  (and gives a 113 part number).    Cast iron???  Does cast iron look like steel when it has been turned?

[George Des]

Dan,

I believe the minimum size is stamped on the inner edge of the drum. 245mm rings a bell but it's been a while

George

[ja17]

Hello scoot,

Cast iron and steel are related and both are ferrous metals (contain iron and attract a magnet). They look nearly the same but the strength and hardness vary a lot between the two. As Dan has indicated, the inserts are cast iron. I recall reading this somewhere in factory literature.

[DaveB]

According to the '66 technical spec book, maximum drum internal diameter is 231mm for the Alfin and 232 for the all steel drum. New spec is 230mm so you would need an accurate gauge to assess used drums (wow, 0.5mm between new and junk). Out-of-round spec is only 0.02mm, that would seem hard to measure without serious equipment. Ovality can apparently occur if very hot drums are left to cool with the handbrake on tight.