The brake booster has been gone through by me before, during the end of the eighties when I did the whole brake system and changed to silicone fluid. At that time I didn't find new rubber, diaphragms etc to a reasonable price. Since it worked as it should I only checked and cleaned everything thoroughly before re-assembly. The paint on the slave cylinder in the first picture is from that time. I didn't spend time to find the dark blue - actually shifting in violet - color that it had. But I can still remember it. Well, more of that later and let's proceed to what I did this time (do also see Mercedes-Benz Ponton Page's booster article).
The second picture shows one - probably rude - way to remove the large piston; squeeze it with the help of a vice so that you can remove the rivet that holds it in place. From that point and onwards it's very simple and it won't take you many minutes until you have everything in front of you (picture three - five). The vacuum can was polished on the inside and - don't ask me where my brain was when I made this decision - the outside sandblasted. If I only had glass beaded it or even better, grinded and polished it!
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When restoring the can I did not only do one unbelievable mistake, I made two. I tried to polish the sandblasted surface but gave up and hoped that the surface would look like new after the metal finishing, in this case white cadmium. I don't remember but I assume that I wanted to do too many parts/items with a far too short schedule. A couple of micro millimeters of white cadmium don't hide anything, which I already new from earlier mistakes. Anyway, the can came back and looked quite awful, with the marks of the sandblasting still visible. I didn't want to polish it again and have it re-finished since I'm a little bit too scared of hydrogen embrittleness caused by the electroplating. So, in my next life I'll try to find a new can, restore it to perfection and put it into the car. Meanwhile I put a couple of layers of car wax on it in order to make the small "pits" in it more easy to clean. On the other hand, the can won't be easy to see under the hood.
Next step was to get the cover back in shape. First I covered all holes and threads, glass beaded it and then had it tumbled at Trumlingsaktiebolaget. The second photo shows you the result - perfect!
All parts were ordered from Will Samples (see Acknowledgements for e-mail address). I could have bought most of the parts new in Europe too but not all of them and then from 2-3 different suppliers incl Mercedes-Benz. But ordering everything from Will was much more simple, probably cheaper and above all, I could send him my questions and got answers within a couple of hours! That is more than invaluable. First I didn't really know who he was but looking through some old american Mercedes-Benz articles I found out that he's been in the business for quite some time. And the quality of the parts were - of course - very high! Hence, the next photo is an almost complete booster (paint on slave cylinder not there yet and the non-return valve I chose isn't black cad'ed here).
Then we came to the piston with its leather sleeve. During my previous booster "restoration" I dismantled and cleaned it totally. This time I only spent half an hour on cleaning the leather with Acetone and then soaking it with oil (the "rope" that's "distributing" oil all around the sleeve is my invention, I don't remember what was there from the beginning). Some sources have told me to use Calipsol on the leather and then fill the can with castor oil. However, the manual I got from Will said "mineral oil with viscosity 5-6 Engler at 20 degrees celsius". The product support at Shell told me that today you measure it in centistoke (cSt or mm2/sec) at 40 degrees celsius. This conversion gives you ISO VG 15. Shell had two suitable products which could stand cold weather, Clavus 15 and Tellus T15. The previous is a pure mineral oil without any additives. It's however some sort of cooling compressor oil and can be hard to find, especially in my quantities. Tellus T15 is a thin, hydraulic oil with no additives which can spoil your leather sleeve (at least not according to Shell). So I spent some days tracking these oils down and ended with 2 litres (!) of Tellus T15 from SGA in Stockholm. They've dealt with Shell oils for a looong time and confirmed that either of the oils would work and Tellus T15 they had in stock.
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And now to the color of the slave cylinder. From my memory as well as some input from Will I found a color that is almost perfect - Auto K Multona's #0800. On the picture the color looks a little bit too light blue and glossy. Reality is better but yes, it ought to be more lilac in its tone and a little bit more semi-gloss. Right now I think it's enough. In my next life though...
The rest of the row shows you something that I'm quite proud of - the end result. One funny thing happened this week. Even though it worked like it should when I dismantled it and I'm 100% sure everything is assembled correctly I wanted to have it pressure tested. So I went to a very reputable and old brake shop in Stockholm who has helped me before. We first had a long conversation about old Mercedes-Benz in general and what I'm doing with my 219. Then I showed them the booster and asked them to test it. They refused to do it, it was too nice looking and they didn't want to have on their responsibility to damage the like-new finish! Their comment was, if it looks like that on the outside and you've accomplished the same on the inside and it worked as it should before the restoration there's no reason to test it. The functionality is so simple so you can/will test it as well during the first drive. If it doesn't work you'll notice but you can still brake "manually". My father's comment was the same so I skip it (any comments from you, dear reader?). It's partly flattering but partly annoying not to have it tested, I've restored fully functional parts before with a bad result...
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Under construction
The can was glass beaded, grinded and finished with white cad, only rust protection only. At that time I planned to putty the rust pits on top of the can and then paint it black all over. From an old factory photograph I however realized that the top of the can, the rusty part was supposed to be white cad'ed or something similar. The can isn't finished yet but here you can see the status of it per August 2003, grinded tin covering the pits.
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Under construction
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