Spanish/Montesa brains trust.

[mx250]

I'm going to swap over the VA's internals to the VB cases. I've got access to a press, how do you best get the bearings out? Is heat required?

I've got the VB's cases apart with the ign side crank pulling out of the ign side mains leaving the ign side main in the cases and the rest of the crank still attached to the cases at the primary side mains. Should I use heat or give it over to an experienced Spanish mechanic.

[mx250]

http://www.southwestmontesa.com/montesa/frmst1.htm

"Then heat the crankcase half on a hotplate until the bearings fall out". 

[Hoony]

get a small blow torch like a burnzamatic or primus and gently heat around the bearing housing quickly (but not the bearing) and then pick up the housing and quickly give the housing a sharp tap on a block of wood on the bench (bearing side facing downwards) and the bearing will fall out. aluminum expands a lot quicker than steel so you need to apply the heat fast before it penetrates the bearing.

works for me every time !

[cyclegod]

get a small blow torch like a burnzamatic or primus and gently heat around the bearing housing quickly (but not the bearing) and then pick up the housing and quickly give the housing a sharp tap on a block of wood on the bench (bearing side facing downwards) and the bearing will fall out. aluminum expands a lot quicker than steel so you need to apply the heat fast before it penetrates the bearing.

works for me every time !

Read the manual !!!!!!!! page 39 section 3. DO NOT use a torch for heating the crankcase halves

[Hoony]

Read the manual !!!!!!!! page 39 section 3. DO NOT use a torch for heating the crankcase halves

 does it realy say that Cyclegod? i would have thought a small amount fof heat would not distort case, well the press would be the go then.

[cyclegod]

From watching my brother in action, flame + magnesium cases = pile of magnesium oxide where case once was

[Hoony]

Oh, didn't know they were magnesium cases !

[cappra]

Centre cases are aluminum!  A hot plate is the best, but a propane torch is ok.  Never drive them out!
Heat the cases to remove the bearings and heat the cases to install them.  Put the bearings in the freezer over night
to shrink a bit.  You don't want to remove any aluminum when removing or replacing.

[mx250]

Worked like a charm; hotplate for about 10mins, dropped it on the carpet from about 200mm and all bearings popped out  .

Starting to love working on these Monties  .

The manual does say "no special tools required" (except 3 prong puller on f/sprocket  , and reverse thread nuts on ign side  ).

Thanks for the help guys 

[YUMASTEPSIDE]

        I'm always replacing crank bearings in bikes for different people and I've found the best thing is one of those hot air paint stripper guns,like an extra hot hair dryer.The one I use is just a cheap RYOBI one and its had a floggin' for years in the workshop.
    Keep the heat moving around the case until a drop of water sizzles when dropped on the heated area.The best thing is there is no naked flameand its also handy for heating and removing old tank stickers..........again,no flame!

                         Roger