385xp bearings.... alternatives?

[fatboycowen]

I just got finished doing the clutch side of my 385. New OE crank and bearings. Here's what i did:
First i read the workshop manual. The manual says to heat the case side to 200C (almost 400F), and to insert the bearing, and let it cool (this goes for each side). Then, use special tools to pull the crank through the bearing, one at a time. 400, holy moly.

I tried the Mastermind method. I heated the clutch side case with my heat gun. It took quite a while. I got the inside part of the case to 250F on my IR gun. I set the case down, crank side down, on top of an old, but clean piston, so that the bearing had a surface to stop at. The manual says to put the bearing flush with the inside of the case. The piston provided the stop.
At that temp, the bearing went right in, just as mastermind suggested.
I waited a few moments and tried inserting the crank. Not sure if i didn't get it hot enough or what, but the crank did not go in all the way. It went in about half way. I tapped gently the other direction, and it popped out. Tried again, no go. It was getting stuck just as the bearing got to the surface it will finally be on. It seems that this is a very tight fit.

So, i had the bearing in the case, now pretty much cool. Given that it's a plastic cage, i didn't want to heat the bearing. I was kind of freaked out, as i didn't want to do anything to damage the new 200 dollar crank, or expensive bearing.

So, I put the crank back through the bearing as far as it would go by hand. I took some appropriately sized washers and used them as spacers. The washers rest against the inner race of the bearing, and the ID of the washers is large enough to fit over the crank. I threaded the (clean) clutch onto the crank, and started turning the clutch with the clutch removal tool and wrench. As the clutch was tightening onto the crank, it presses against the washers, and pulls the crank into the bearing very effectively. I had to stop a few times to add washers, so that the clutch didn't bottom out. This worked extremely well, and was quite easy. As far as i can tell, this is the redneck version of the shop manual method.

I'm wondering if i should try the same method on the flywheel side. I'll have to be a little more creative with the washers, but it should work. On the other hand, the opposite bearing has a metal cage, so i could heat the bearing inside the case. But, i sort of like the idea of doing it the factory way.

Also, don't put the bearing in the wrong way, or the crank!

Thoughts?

 

[nmurph]

I just use the case bolts to pull the halves together. BTW, you heat the case to put bearings in. Then, you need to chill the case halves and crank so that you shrink everything and make it slip together easier.

 

[blsnelling]

I always install one bearing on the crankshaft, then install that in the case. I install the other bearing in the other case half. I then use the case bolt to pull the two halves together.

 

[fatboycowen]

The shop manual method puts no bending force on the crank. I'm betting that's why they say to do it that way.

 

[nmurph]

.. Given that it's a plastic cage, i didn't want to heat the bearing. I was kind of freaked out, as i didn't want to do anything to damage the new 200 dollar crank, or expensive bearing... so i could heat the bearing inside the case...

If you heat the bearing, the inner race grows inward and makes the crank a tighter fit.

I heat both halves and slide the bearings in, then chill the halves with the bearing installed and the crank, slip them together, and use the case bolts to pull the case together. I use the clutch and the FW nut to help ease things along-tension the case bolts, bump the clutch and FW, and repeat until the halves are together. Bumping the FW nut and clutch (doesn't take much) really takes advantage of the tension created by the case bolts.

 

[Mattyo]

Heating the case halves doesn't damage the oil seal? ...especially the one on flywheel side? ....that's what I would be concerned about.....how about the gasket too? ....loctite 515 on gasket? ....or leave it dry?

 

[nmurph]

You don't want to heat the bearings or you decrease the diameter of the inner race and make it harder to slip the crank in. When the bearings don't have the integral seal like the 385, don't put the seals in until you have the halves together.

I usually run a little Yamabond on the case gasket, but that's a recent change for me and they don't have anything on most of them from factory

 

[angelo c]

If you heat the bearing, the inner race grows inward and makes the crank a tighter fit.

I heat both halves and slide the bearings in, then chill the halves with the bearing installed and the crank, slip them together, and use the case bolts to pull the case together. I use the clutch and the FW nut to help ease things along-tension the case bolts, bump the clutch and FW, and repeat until the halves are together. Bumping the FW nut and clutch (doesn't take much) really takes advantage of the tension created by the case bolts.

Neal,
Have you ever tried to leave the cases (and installed bearings) "warm" and just chill the crank ?
And does your procedure change for the Stihl cases that do not have the plastic in the bearings. 066-460-440
Thanks buddy.

 

[Mattyo]

Man....I got a Lotta reading to do....

 

[angelo c]

Man....I got a Lotta reading to do....

Save me a chair in the library...


Do they still have libraries ?
Are the still called libraries ?

Man it seems like yesterday I was studying for finals...

 

[Mattyo]

Putting this stupid thing together is going to be my final exam....and I finished the 21st grade

 

[nmurph]

Neal,
Have you ever tried to leave the cases (and installed bearings) "warm" and just chill the crank ?
And does your procedure change for the Stihl cases that do not have the plastic in the bearings. 066-460-440
Thanks buddy.

No, it doesn't have anything to do with a bearing cage, just physics.

I wish I had some liquid nitrogen I could blast the crank and drop it in!!! (would have to be careful and not make the crank brittle).

 

[fatboycowen]

nmurph, I'm having trouble believing that heating the inner race reduces the inner diameter. I think it's the opposite. Do you have any supporting information?

 

[fatboycowen]

http://www.maintenanceresources.com/referencelibrary/bearings/morb.htm

If that link works, read the 3rd paragraph down under temperature mounting. It suggests that the inside diameter of the inner race increases with temperature.

 

[husqvarnaxpman]

So can you use a 6203 c3 on the flywheel side?

 

[fordf150]

I use a toaster oven set to 250 degrees. Put crank and bearings in the freezer. Heat case half up and drop bearing in. Immediately throw case half with bearing installed back into the oven. Leaving it in there for just a couple minutes. That ensures that the bearing is up to the same 250 degrees. The cold crank drops right in. Throw the case half with crank installed in the freezer. Repeat bearing install on the other case half. By the time you get the other half heated up and bearing installed the case half with bearing and crank installed will have cooled down enough that everything will slip right together. No pulling halves together with case bolts with the exception of some stihl saws that the alignment dowels are a really tight fit. So far this method has worked for me every time. I have tried the heat gun method and either I'm impatient or I need a bigger heat gun

 

[Mattyo]

So far, flywheel half has bearing installed.... and crank. The bearing didn't quite want to drop in....a little extra heat w/ a torch and a large socket and hammer and it went home.... now waiting on the clutch side bearing to chill out again after a failed attempt.... gotta get that case a little hotter....and bearing cooler. We're getting there! I'm taking video along the way so everyone here can see how incompetent I am!

Thanks to VIKING for sending me some clean case halves.... they'll work out fine!

 

[angelo c]

So far, flywheel half has bearing installed.... and crank. The bearing didn't quite want to drop in....a little extra heat w/ a torch and a large socket and hammer and it went home.... now waiting on the clutch side bearing to chill out again after a failed attempt.... gotta get that case a little hotter....and bearing cooler. We're getting there! I'm taking video along the way so everyone here can see how incompetent I am!

Thanks to VIKING for sending me some clean case halves.... they'll work out fine!

What temps are ya using ? Maybe not hot enough ?
Waiting for the vids

 

[Mattyo]

Not hot enough... 250 doesn't cut it......

Had to use the torch to get clutch side bearing in... case was likely 300F or so.... eventually it just tapped in.... it was stuck about 3/16 or 1/4" up and eventually it just dropped. i'll keep working on the build and get video up eventually.

 

[Mattyo]

then I tapped in the oil seal on the flywheel side...and the rubber part wanted to invert itself... need lube next time....used the tip of a pen to coax it back.