Welding zamak/zamac parts on r1200rt

[dan cata]

I have noticed that especially after the year 2000, bmw makes some parts out of zamac and not aluminum. Not sure the reason why, it cannot be weight since it's close to the one of aluminum. Perhaps bmw wants their customers to buy the new part instead of repairing/welding it.

 

the issue I had was with a friend's r1200rt windshield frame, especially the parts that keep the plastic windshield. I have replaced the upper brackets but one of the plastic mounts was cracked. I took it to a welder, he tried to get it back together and as far as I can tell, so far, so good. Not sure how long it's going to last, though...

 

Has anyone else try to repair zamac parts instead of swapping them with new parts? If so, some input would be greatly appreciated.

 

Thanks,

Dan Cata

[dirtrider]

Morning Dan

 

Repairing Zamak by welding is real crap shoot as it is basically what we in the USA call a Pot Metal. Because of the alloy type content of Zmak = Zinc/Aluminum/Magnesium/Copper, finding a filler rod that is compatible runs from about impossible to trial & error until something sort of sticks.

 

Zamak is basically used because it is cheap & easy to cast into intricate forms. Not much final machining required except for hole placement, finished size in some areas, & some possible hole threading.

 

Over the years I have welded some types of Pot Metal or Zamak castings with limited success. It really depends on the stress that the re-welded part is subject to & the area that is available to weld. If possible adding keyed welds or across-break stitches works better than just V'eing the part & attempting a conventional TIG weld.

 

On high loading/ high stress parts like those windshield arms I usually just toss them out & buy new (if available) or machine up new out of 6061 or 7075 as welding the OEM is usually a waste of time & effort.

 

[dan cata]

What would you do in this case? Another new part will last as long as this one. Having another one machined... hmm... that can be done, just not as nice as the OEM one, as it has some shapes that are extremely hard to reproduce.

 

Will consider machining new parts...

 

Dan.

[dirtrider]

Morning Dan

 

I'm not sure exactly what part you are working with but if the lower arms look at Beemer Boneyard as I (think) 10over is now making lower (aluminum) replacement arms for them to sell.

 

[Guest Kakugo]

Hi Dan.

ZAMAK was pretty heavily used on Vespa scooters (flywheel, brakes etc) and small Italian and German motorcycles from the '40s to the '70s so there's a bit of knowledge around about welding it.

There are a few soldering products around.

I don't remember the exact name but is sometimes marketed as Malloy 52. It's an alloy specifically developed for "dissimilar metals" like pewter and ZAMAK. Don't know where you can find it in the US but around here at every vintage bike fair there's at least a stall selling it. When fixing the part is worth a shot that's what people "in the business" around here use.

 

Some people have also employed Dura Fix to repair ZAMAK, though Malloy 52 is usually more widely available and hence more used. You should have no problem finding this in the US as it's made in South Carolina. Apparently it works as well as Malloy 52 and is a tad easier to work once cooled.

[w2ge]

Pot metal is such crap... Really disappointing that a company like BMW would use this sh*t on their bikes anywhere is very disappointing..

 

It's what I expect to see on a Pep-Boys POS Asian special

[dirtrider]

Morning Kakugo

 

Yes, in the USA there are also some soldering/brazing type products for repairing Pot Metal & Zmak type castings. Problem is, they are low temperature & very low strength, mainly used to repair cosmetic type Pot Metal breaks.

Not much available to weld on Zmac & give it back original strength & that strength is marginal even with the unmolested original Zmak parts.

 

[David R]

They taught me in school to take another part identical, melt some of it and pour it into a piece of angle Iron. This makes filler rod that matches. This was also referenced to welding zink carb with an oxy acet torch.

 

I would never screw with windshield mounts made out of cake batter. Chuck em and buy aftermarket.

 

Think about it when you are going *** Mph.

[biometrics]

How about making a mold from a good part and then casting one out of aluminum? Probably would only take a beer can or two to have enough metal to make one eh?