Installing crank bearings using heat

[kev1n]

Great post Jerry, I've got some 026s that have been sitting until I read enough good info to rebuild them. Your info gives me enough confidence that I think I can tackle the job.
Thanks Kevin

 

[pioneerguy600]

Great post Jerry, I've got some 026s that have been sitting until I read enough good info to rebuild them. Your info gives me enough confidence that I think I can tackle the job.
Thanks Kevin

Good for you, it is not really all that hard to do. Did you make a case splitter yet?

Pioneerguy600

 

[Cliffhanger9]

Sorry Matt, I answered your question but I see it did not post, this has been happening off and on now for a while, I see many times where it just gets hung up and times out.
You can use anything that is softer than the steel in the crank, it may take a good bump to move the bearing aside, this is what you want to happen, it moves outward just a tiny bit and when done in both directions it relieves the stress of the balls on the sides of the races so you are actually trying to get the ball bearings exactly centered on the races.
Pioneerguy600

First time changing bearings and seals for me.. This thread was of tremendous help. I got nervous once I had the case halves bolted down and the crank didnt spin without lots of effort. I relieved the stress with [quite a] few raps to both side of the crank and she spun smooth like butter. Until I put the oil seals in and now it's really stiff again. Is that normal? I know the seals are supposed to seal and be tight but I have another saw that passes a pressure test (indicating that the seals on it are good too) and spins way smoother.

Maybe these new ones just need to break in? Or should I perform another rap session on the crank?
Again, first time doing this and any insight appreciated.

Cheers,
Dan

 

[Mastermind]

First time changing bearings and seals for me.. This thread was of tremendous help. I got nervous once I had the case halves bolted down and the crank didnt spin without lots of effort. I relieved the stress with [quite a] few raps to both side of the crank and she spun smooth like butter. Until I put the oil seals in and now it's really stiff again. Is that normal? I know the seals are supposed to seal and be tight but I have another saw that passes a pressure test (indicating that the seals on it are good too) and spins way smoother.

Maybe these new ones just need to break in? Or should I perform another rap session on the crank?
Again, first time doing this and any insight appreciated.

Cheers,
Dan

It sounds fine to me. The new seals are fairly stiff.....

 

[67L36Driver]

Time to fire up the Vidal-Sasoon 1600...............................................................................daughter's ol blow dryer.

 

[bcaarms]

FYI aviation uses dry ice and ovens to install bearings and races while overhauling transmissions, rotor head assemblies, and drive shafts. They actually have time and temperature requirements to ensure consistency of results.

Nice thread.

 

[tdi-rick]

I heat cases to about 350 in an oven, hit the bearings with a CO2 extinguisher and they drop right into the cases. I then use a factory assembly tool to pull the crank into the bearings. The advantage of the factory tool is two fold 1) it is designed to prevent side thrust on the bearings and 2) the tool can make VERY precise adjustments necessary to center the crank in the cases.

350*F is too high IMO.

In another lifetime I worked with mag and aluminium race car castings (transaxles/uprights) and only ever used the water 'pop' test outlined way back in the thread which means just above boiling, (100*C/212*F) no more.

At that casting temp interference fit bearings at room temp fall in, there's more than enough expansion in the casting.

The reason for holding the heat to a minimum is that if something you are assembling has been heat treated you haven't started to anneal it, which is easy to do with HT aluminium.

 

[StihlNAlberta]

Awesome post! Great info.

Cheers!!

:msp_thumbup:

 

[half_full]

I just completed the bearing install a few days ago. I followed the advise here about not freezing the crank/bearings. All went very well.

I used this to heat the cases - RO188BR - Rival® 18 Quart White Roaster Oven w/ Bonus Buffet Server - Rival Products - Rival 18 QT roaster oven. Dialed it to 240 degrees.
Found it on CL for $10. Kept me out of the dog house. Last time I used the oven in the house it smelled like kerosene for a few heat cycles. Plus, the roaster oven can be filled with fluid and heat parts as they soak.

 

[pioneerguy600]

I still build 8-10 Stihl chainsaws each year, everything from 026`s up to 088`s and I am still installing crank bearings using this method. Some of the bigger Stihls that have the steel insert on the clutch side require a little more heat to expand the case enough for a smooth effortless fit. I have soaked the case halves at 350F for 10 minutes on these saws and the bearings will slip right in, the cool bearings and crank will immediately shrink the case clamping the bearing in place. It takes a good sharp rap with a brass hammer to relieve the side load on each bearing. I have done this so often it usually only takes one rap on each side for me to get the bearings relieved and the crank centered.

 

[briantutt]

I still build 8-10 Stihl chainsaws each year, everything from 026`s up to 088`s and I am still installing crank bearings using this method. Some of the bigger Stihls that have the steel insert on the clutch side require a little more heat to expand the case enough for a smooth effortless fit. I have soaked the case halves at 350F for 10 minutes on these saws and the bearings will slip right in, the cool bearings and crank will immediately shrink the case clamping the bearing in place. It takes a good sharp rap with a brass hammer to relieve the side load on each bearing. I have done this so often it usually only takes one rap on each side for me to get the bearings relieved and the crank centered.

How big of a brass hammer? I was using a rubber mallet. Need to get a brass hammer to "adjust" my Frankensaws.

Brian

 

[pioneerguy600]

It doesn`t take a very big hammer, one less than a lb will do the job easily, its the sharp rap that works best for me, no need to use the big swing and hit. Usually one or two raps will work for me. others will find differences in the amount of times they need to strike the crank as we all hit differently. A person gets a feeling for this type of chore if done plenty of times over a lifespan. Been driving bearings and seals in and out since the early 60`s so the feel has had time to develop.

 

[Rubber duck]

Installing crank bearings using heat may not be for you!
If you have to follow a manual word for word then this method may not be for you, this thread is just for info. I have used the method described here for over 45 years now and had no problems show up by doing the install this way.
A source of heat is required, a hot plate with a piece of plate steel on it, a hot air heat gun ,a oven of any sort or even a torch will do.
Have the two bearings and the crank cleaned and ready.
I place a heavy piece of angle iron and clamp it in the vice, mine is 3/8"X4X4X 12" long and leave 6" of it stick out from the vice jaws. The throw of the crank sits on over the end of the angle iron and supports the crank, either end up will do.
Heat the bearing up to 200-220*F and with a welding glove I pick it up and drop it over the end of the crank that is sticking up, it will almost fall into place but if it does not I have a length of 3/4" black iron water pipe cut to length and a hammer ready, slide the pipe over the crank end and a light tap will seat the bearing. The pipe must contact the inner race only.
Do both bearings this way and let them cool.
Next heat the PTO crankcase half up, the heat gun will do but an oven is better, 210-220 *F is plenty hot. I have a set of blocks set up that supports the case half up about 6" off the bench.
When the case half is hot pick it up with the welding gloves on, sit it on the blocks and then drop the crank with the bearings already on it into place, you won`t have to hit it.
Let that side start to cool down and start heating the opposite side up to 210-220*F . Turn the crankcase open side up. Place the case gasket on the case half and I use the dowel pins for the Stihls or a couple of long case bolts with the heads cut off, these need to be long enough so that they can be removed later, threaded rod pieces work well also. These studs work very well as a guide to help guide the case halves together.
After the case gasket is in place put the gloves on and pick up the the hot flywheel side case and drop it down over the upended crank. They will usually go all the way into place with a hollow clunk sound if done right. Once in a while I have to bap the case with the side of my fist to settle it but not always.
I now install the case bolts and draw the cases tight. Let the assembly cool for 5-10 mins and then try the crank for axial stress, if it needs relief then tap each end a good rap with a brass hammer. That usually relieves the stress and if the assembly is now cool enough start to put the seals in place. I have pieces of pipe cut to length that clears the end of the crank by at least an inch and fits the outside diameter of the seal, very easy to drive the seals this way.
Now reassemble the rest of the saw as required. Happy sawing.
Pioneerguy600

I really like you style I do it similar I use a gas grill sometimes oven or toaster oven for crankcase half but I put my bearings in deep freeze and crank then use assembly lube or 2 cycle oil a lot of people worry about constitution from putting bearings in deep freezer but assembly oil will pull that out or can use heat gun or hair dyer I do use the aliment pins and I do use a little sealant on gasket to just hold it in place with pins and for a little extra seal please tell me if this is wrong because any one who has been doing saw repair for 45 years I am only 48 and wisdom comes with age I know everyone does things different but always looking to improve I rebuild vintage saws as a hobby and for friends and family anyways really like just the heat ideal because I have always dropped bearings out of freezer into a heated crank case half I found by trial and error if you heat crankcase half to 350 degrees for 30 mins in oven bearings will just fall right in place and crank will go in by hand and I heat each half separate I am doing a sthil 038 av right now I believe I will try your heat method man I love this site. The rubber duck over and out.