stuck crank bearings

[wedge]

im in the middle of a crank swap on an 066 stihl, ive got the case apart but the bearings are froze on the shaft.theyre both good so id like to reuse em but im kinda clueless as to how to get em off cause theyre so close to the conterweights of the crank. any ideas?

 

[Al Smith]

May work,may not

This method will work but I don't know how well the bearing will be.Put the whole thing in the freezer for a day.Have ready several hard wood slats about 1" square and 8 to 12" long,a wooden mallet or deadblow hammer and an industrial heat gun.Heat the bearing as quickly as possible and drive them off with the hardwood and mallet.The crankshaft is a larger mass of metal and will not expand as rapidly as the bearing with the heat.I've used this method,but never tried to reuse the bearings so I don't know if it will be entirely successfull in what you want to do.

 

[raybow1]

There are a couple ways to do it and niether is good. You can use a puller to pull them off the crank and there are a couple different kinds made for this. One sandwiches together under the bearing and the other has two arms that go around the outside of the bearing while pushing on the end of the crank with the center threaded shaft. There is one more way if you do not have access to a puller and that is to use a vise and narrow it up to fit the outside of the bearing and then use something like a plastic fallers wedge to put at the end of the crank and then hit the wedge with a hammer. This is very crude but will work. The only problem with reusing the bearings is that you have put a lot of side stress on the outside cage and could damage them. It's always better to replace them but if not those ways will work.

 

[Lakeside53]

You should be able to get a two leg puller onto the bearing outer ring between the counter weights. hold the counter weight in a soft jaw vice, clamp the twom legs togther (to stop them spreading) and gently but very firmly turn the puller with a big wrench. Using an air tool will mess up the bearing innner race (you aren't supposed to pull aganst the balls even with a wrench, but you have little choice). There are special pullers with bearing plates, but the bearing is so close to the crank you probaly won't be able to slip one in behind it.

 

[Fish]

Put a few drops of new, synthetic, marvel mystery oil on them, and they will fall off!

No, just joking. I have never tried, but the freezer idea would be my first try, but
why would you want to take a chance if the bearings might be damaged, and you did
notice?
Why are you replacing the crank?

 

[wedge]

as usual you folks came across with some great ideas. im gonna try the freezer trick.how hard to find are used bearings? im changing out the crank because the old one broke just inside the flywheel.

 

[thompson1600]

Used bearings can be found, I may have some around. However, you only need to buy the clutch side bearing from Stihl, because the oil seal fits into it. The flywheel side bearing is just a common 6203 ABEC C3 bearing. They can be found at any bearing shop for about $5-8 bucks. I like to use FAG or NSK unshielded, but other brands are good too. So you can change your bearings out with new ones for about $35 bucks. Cheap insurance since you have the case torn all the way down.

Also make sure you order the Gasket kit from Stihl for the 066. Runs about $30 bucks but includes all the gaskets and oil seals. Part # 1122 007 1053 I believe.

Tom

 

[wedge]

ive already got the gasget kit, so all i would need to get from stihl is the one bearing and both seals. how much do good used bearings go 4?

 

[thompson1600]

The oil seals come in the gasket kit. All you would need from Stihl is the clutch side bearing, about $25 bucks new. Then just get one of the ABEC 6203 C3 bearings at a bearing shop for $5-8 bucks. That way you have new.

Normally used bearings go for about $20-25 a pair, about half of what new Stihl bearings run.

 

[oakman]

if you enjoy tearing stuff apart, like i do, go ahead and re-use or put used bearings in. however if you actually wanna use the saw, and have it perform and last awhile, nix the used bearing idea. as has already been said, heavy side load/ hammering on the outer race will damage the bearing. you won't find out till ya got it up on the pipe in the cut. also when installing the new ones you need a driver that slips over the crank and drives on the inner race not the outer one. sometimes if you freeze the crank first, the new ones will slip right on. sometimes....................

 

[Al Smith]

Another method

This may or may not work.First,I've never torn down an 066,but have taken 048,042 ,038's down,so I would assume they are all about the same.Because the clearance is real close to the crank counter weights a regular puller won't work.If you are familiar with Jacobs chucks,used on drill motors mills,lathes etc,they mount on a special taper.To remove those chucks a special tapered split wedge is used,in pairs.I have never tried it but a pair of Jacobs taper wedges #3 or 4 might span the crank and wedge those bearings off.These wedges a relatively cheap.If you do a Google search on Jacobs chuck,you will see what I mean.If you do a search of this site you will see the proper procedure to reinstall the crank and bearings into the crankcase halves.The Stihl co most likely has special tools for bearing removal but I didn't feel like going through about 1000 pages to find them.

 

[wedge]

the freezer idea worked great,i pulled the crank out of the freezer and it slipped out of my hand and hit the floor and much to my suprise they fell off just from that

 

[Al Smith]

Good

 

[Lawn Masters]

this is good info. I'll have to remember that next time I do crank bearings.

 

[Fish]

Admit it, you have a "synthetic" freezer, don't you?

 

[wedge]

i did throw a chunk of dry ice in with it too.after i was done with it i put a sizeable piece in my buddys hot pocket box. it took him 15 min. to nuke em they where so froze.

 

[ErrolC]

more good info and feed back...he he he..synthetic freezer..yea, plesant dreams

 

[Lakeside53]

If you want a real quick freeze, and MUCH colder than a freezer, just hit it with a CO2 fire extinguisher very close up. Use gloves though, 'cos your fingers will stick to the crank.

Two things on using "generic" bearings. Be careful.... particularly on high performance saws. Stihl bearings have a custom chamfer on the inside edge to guarantee fit up to the crank (generally not a problem, but I have had one that wouldn't pull up to the crank far enough enough because of the radius at the crank lobes), and, Stihl bearings are specified with a high temerature cage construction. This is often TN9 or TVH suffixes for SKF or FAQ brands. Generic C3 fit bearings are medium temperature only. You can get the temperature stabilized version for a few bucks more, but often they aren't stocked locally and take a week or two to get.

As much as I don't like paying another $10-15 for the genuine bearing, I often do . It's a balance between "a few bucks saved" and the cost of tearing it all down again with possibly greater damage the second time. Same for second hand bearings... is it "really" worth the savings? Many of the "second hand" bearings have been removed with less than desirable care (like pullining or hammering on the outer ring).

I see about two saws a month with broken bearing cages (saw locks up when the crank gets pinched). Usually these are the polyamide (plastic) caged bearings. Seen LOTs of bad TS400 bearing from concrete dust ingestion but no broken cages - these have a rivited metal cage and expanded temperature range. Consider replacing the orginal Stihl bearing on big saws with the same type used their cut-off saws.

 

[Al Smith]

You might note that many bearings used on Stihl products are OEM.In other words.like it or not,Stihl controls the distribution of those parts.I,ve tried to cross reference them through leading bearing companys in it all comes back to that fact.You just got to bite the bullet,so to speak.