cracked hubs

[penton117]

Hi Guys,

I have a question regarding magnesium hubs. I just removed the front wheel from my 77MC5 and noticed that inside the hub, the part that holds the bearings  has two big cracks, about 180 degrees apart from each other. Not good. I quickly grabbed an extra wheel I had laying around and looking at it, same deal. Two big cracks! Was this common on the magnesium hubs? Also, can they be welded or do they go out with the trash next week?

[firstturn]

Penton117,
Not unusual at all.  Magnesium is great when it starts out, but can age and become unusable depending on the climate.  It might be wise to hang on to them for future restorations if they are OK other wise.  I always put a note on the inside of the brake area that states the hubs are cracked.  Just a thought.

Ron Carbaugh

[Rain Man]

this may not be any help to your specific problem,  I had the same problem with my rear magnesium hub on my Jackpiner back in 1979:D.
 I replaced it, but... I'm the type of guy that will run things into the ground, If.. and only if , I can limp it on home on the rims, when it finally pukes out.   Replacing a hub can be tough, especially if all the spokes are rusted solid too..
If you try to weld magnesium, it will not work,It may catch fire or do some weird things. ( fire works kinda) I dont remember the specifics, Good Luck

[penton117]

Well, since we have determined that I own two front wheels for my 1976 250cc Penton, which are both junk, I must ask, does anyone have a good, used front wheel available? Thanks and happy new year to all.[^]

[Rain Man]

I spoke with Mr. Jake Fischer in Ohio last week, and he said he had 8 complete wheels left in stock. I'm Not sure of the applicaton, he's listed in the suppliers.  
   You could always ride it like a unicycle, which, depending on the terrain...
R

[jj]

I'm curious as to the vintage of you hubs. Do they have the 6 similar fins (look like the Aluminum models) or are they the newer and improved 4 large + 2 small fin models?

John J Slivka

[penton117]

Hi John,

For some reason, mine are the older looking, six similar fins, style. Odd because this bike is a 1977 MC5 (although it has a big tank and a VDO speedo drive) I thought by '77 all the hubs were the newer style, but maybe just the MX versions? Anyway, thanks for any input and any leads on a replacement front wheel. I am pretty good at riding wheelies, but I may have to put the front end down at some point . . .

[Mike Lenz]

Larry, I have had success welding mag hubs...if the welder is good.
Mike

[Randy Kirkbride]

Mike,
Did you weld them yourself or have them done locally?  I have three I would like to get repaired but can't find anyone to do them here.  Could you email the name & phone # of the shop that did them for you?
I could ship them if they are interested in fixing them.
Thanks

[Steve Minor]

Bobby Lucas in Arlington, TX has a certified aviation magnesium  welder "on call". Get in touch with him if your other welders don't come through.

[Kip Kern]

"Ditto" on the aircraft certified welder.  They can weld anything Magnesium and very well indeed.  That is the same route I go!

[tomale]

According to my welding manual Magnesium can be welded. You need to have a Tig welder with the right gas and the right welding rod. The danger in fire is the shavings that are left near an open flame. To do it safely you need to keep the welding area clean of all dust etc.
I would think that welding around a bearing surface would be tricky. Once is is welded you would need to remove enough material to allow for the bearing to seat again. I think that is the tricky part.
Good luck

Thom Green,I own and ride a 76 250 MC5 MX which I bought new.