Husqvarna 550 Mark 2 keep destroying bearings

[Maxchaos]

Hi
I've got a 550 Mk 2 with broken bearings,the owner already changed It two times,the clutch side keep shattering after 20 minutes of light work,note the nylon cage is shattering not melting,using original Husqvarna bearings BB1-3023. He gifted to me and I'm waiting for the delivery,he had already done bearings on other saws so this seems strange, crank seems good and balanced,what can cause this effect?
Pics when the saw come,it's fairly new with like 100 hours on It.Piston and cylinder look good.

 

[Motorka]

Buy new short block ....

 

[farminkarman]

Buy new short block ....

This

 

[Stump Shot]

...crank seems good and balanced, what can cause this effect?

Side tension from installation not being relieved.

 

[hacskaroly]

Buy new short block ....

For those who don't know, what will a short block do that the current block won't (or doesn't) - seriously asking here, because I don't know.

 

[Maxchaos]

For those who don't know, what will a short block do that the current block won't (or doesn't) - seriously asking here, because I don't know.

Short block is crankcase and crankshaft already assembled by factory and full new
This is what I want to do because the price is really low for Short block ~200€ here,not bad paying that price to get an almost new 550mk2 then

 

[Maxchaos]

Side tension from installation not being relieved.

Sorry I don't know how to multi-quote in one message,but this is something I tought,infact I already have new bearings,can be worth one last try with tension relieving of the crankshaft.
You only blow It on the sides until It move freely or you measure the distance of the crankshaft shoulders over the crankcase inner and put It centered? What's better?

 

[hacskaroly]

Short block is crankcase and crankshaft already assembled by factory and full new

Ok, thanks! That makes sense, at first I was thinking that it might be a shorter cylinder than the original or something like that.

 

[Stump Shot]

Sorry I don't know how to multi-quote in one message,but this is something I tought,infact I already have new bearings,can be worth one last try with tension relieving of the crankshaft.
You only blow It on the sides until It move freely or you measure the distance of the crankshaft shoulders over the crankcase inner and put It centered? What's better?

Index the crank by installing in the flywheel side first. I use the heat method and working fast tapping the two halves together when they meet at the alignment pins. Still working fast get a couple few bolts started and tightened, check the crank by giving the rod a flip and if free will roll back and forth on its own, if not it will stop abruptly. Still working fast before the heat is gone, tap the end of the crankshaft with a brass hammer to alleviate the tension until the crank will roll freely on its own. Here's a couple vids showing how free the bearings should be.

 

[hacskaroly]

Index the crank by installing in the flywheel side first. I use the heat method and working fast tapping the two halves together when they meet at the alignment pins. Still working fast get a couple few bolts started and tightened, check the crank by giving the rod a flip and if free will roll back and forth on its own, if not it will stop abruptly. Still working fast before the heat is gone, tap the end of the crankshaft with a brass hammer to alleviate the tension until the crank will roll freely on its own. Here's a couple vids showing how free the bearings should be.

This is good to know and thank for the videos that helps me understand better what you were saying. So if you don't alleviate that pressure, you are basically shortening the lifespan of the bearings?

 

[Stump Shot]

This is good to know and thank for the videos that helps me understand better what you were saying. So if you don't alleviate that pressure, you are basically shortening the lifespan of the bearings?

Yes, the inner and outer race are not in alignment with one another, which places undue stress, friction and heat on the bearing.

 

[hacskaroly]

Yes, the inner and outer race are not in alignment with one another, which places undue stress, friction and heat on the bearing.

I am learning all sorts of new things today including I have two saws that I need to readjust. I could not figure out why it was much tighter to turn the crank after reinstalling everything compared to ones that come from the factory. Now I know. At least I can get to these before I blow out the bearings!

 

[Stump Shot]

I am learning all sorts of new things today including I have two saws that I need to readjust. I could not figure out why it was much tighter to turn the crank after reinstalling everything compared to ones that come from the factory. Now I know. At least I can get to these before I blow out the bearings!

Here's some good vids, by a top builder on the subject.
Bearings install on crank

Crank install in case halves and bearing stress relief.

 

[hacskaroly]

Here's some good vids, by a top builder on the subject.
Bearings install on crank

Nice, I like how he pulls the bearing out of the oil, drops it on the floor, blows it off and installs it! I like how freely it spun when he got done, something for me to definitely work on!

 

[Maxchaos]

Here's some good vids, by a top builder on the subject.
Bearings install on crank

Crank install in case halves and bearing stress relief.

That's exactly how I usually install them,or by using the puller,then i blow the crank with copper hammer until it's right in the middle of the case by measuring with feeler gauge,check for free spin and if it's a little bit hard to turn I smack It to the most free turnover,when It come to me I will try to see if it spin good,but the bearing are already damaged,don't think I can see better if it was stress relieved or not

 

[Stump Shot]

Nice, I like how he pulls the bearing out of the oil, drops it on the floor, blows it off and installs it! I like how freely it spun when he got done, something for me to definitely work on!

That's why I use the microwave to heat them.

 

[Stump Shot]

That's exactly how I usually install them,or by using the puller,then i blow the crank with copper hammer until it's right in the middle of the case by measuring with feeler gauge,check for free spin and if it's a little bit hard to turn I smack It to the most free turnover,when It come to me I will try to see if it spin good,but the bearing are already damaged,don't think I can see better if it was stress relieved or not

Again, all the way into the flywheel side first will automatically center(index) the crankshaft orientation.
Also, if too much of your disassembly/assembly process involves a hammer, it is possible to bend a crankshaft.
Just a few light taps with a brass hammer should be all that is necessary to relieve any side tension from the installation process.

 

[Rich Fife]

So beat it into the case, beat it while it's in the case, drop it, bath it in oil and add heat. Did I get that right!?

 

[Maxchaos]

Again, all the way into the flywheel side first will automatically center(index) the crankshaft orientation.
Also, if too much of your disassembly/assembly process involves a hammer, it is possible to bend a crankshaft.
Just a few light taps with a brass hammer should be all that is necessary to relieve any side tension from the installation process.

Will see how It is when It come and then try your method,I don't start from a precise side,one thing to note is that with the puller I don't heat the case halves,will heat them from now on.
I do small taps to relieve the tension and move It inside the crankcase

 

[Sloughfoot]

Here's some good vids, by a top builder on the subject.
Bearings install on crank

Crank install in case halves and bearing stress relief.

I need a better vise.