rc4j

My Feedback: (103)

Hi all,

I've just recently purchased a used OS 40 Surpass that needs new bearings. I successfully got the front and rear bearings out by heating them in the oven ( 15-20 min. @ 250 deg.) and knocking them out on a piece of soft wood. The cam gear bearings, on the other hand, are giving me a fit. I've never changed these bearings before and I'm having trouble getting them out. They don't want to budge even after heating, and I'm afraid to pry on them much. I tried a wooden dowel, and a small pick, with no luck.

Surely, someone here has run into this before. HELP!!!

Jai

Moderator added "40" to title.....

jsn

My Feedback: (8)

I've never had to do them either... after looking at the book how bout this. Are they stuck on the cam shaft itself? can you pull it out? if so how about one of the small cheap battery terminal puller's? you'll probably have to mod the jaws to work much like when using them as a drive washer puller...should be able to grip the bearing and press out the shaft... a good soaking in yield, PB blaster or the like should help also.

Hope this helps

John

w8ye

My Feedback: (16)

My experience is that they are stuck in the crankcase and the cap.

I've heated the cases up to 300 F and couldn't shake them out.

One guy had a expanding mandrel type bearing puller to get his out.

http://www.skatelog.com/bearings/bearing-tools.htm

proptop

My Feedback: (8)

I've been thinking this over for a while , as I have some O.S. cam bearings to change too...

How about a nut pick...you know, the ones that come with nutcrackers? Or maybe a small flat bladed screwdriver...
Bend the tip 90 degrees and reach in to hook the inner race and pull on it after heating?

A small expanding mandrel or collet would be nice though...

lrb75

My Feedback: (12)

WAX! Take little pieces of candle wax or the wax used for sealing jars and fill up the bearing center. Take a drill bit or a dowl that is just slightly smaller than the inside diameter of the bearing and hammer it into the wax. After about 5 or 6 times the cavity behind the bearing fills up and the hydraulic pressure behind the bearing will force it out. If the bearings are sealed you can apparently use a very think grease instead. Heat the case up and allow any remaining wax to flow out and push the new bearings in. Make sure you only push on the outer race. Good luck.

rc4j

My Feedback: (103)

Thanks for all the suggestions, the bearings are stuck in the crankcase and cap. I've tried heating and pulling them with various things, but they're not budging. I haven't tried soaking them in anything however. What is this yield and PB blaster that you speak of? Maybe the gumming of the old fuel oil has them glued in?

w8ye- I think the skate bearing puller would be the way to go. It needs to be a fairly even pressure to pull them straight out without binding. But, I doubt that puller would reach into the crankcase far enough. Modification possibly? It seems there should already be a tool made for this job, I wonder what OS uses?

lrb75- It was suggested to me to use some kind of oil and hydraulic pressure them out as you say, but these bearings have no seals. Wouldn't the wax flow out through the race as well?

Has to be some way of doing this, still ciphering!

rc4j

My Feedback: (103)

Here's the tool! A blind hole bearing puller. It's just too big. It needs to fit inside a 4mm ID bearing, and the kit has Four collet sizes: 3/8" to 1/2", 9/16" to 11/16", 5/8" to 1", 1" to 1-1/4". Set includes a 2-1/2 pound slide hammer with T-handle. Maybe there's a version of this made for model engines somewhere?

w8ye

My Feedback: (16)

I tried the plunger/grease and wax trick without success.

If you heat the parts at all, the grease and wax will both be so thin as to be useless.

Pepe J

My Feedback: (2)

This is a slide hammer that I made up. It was made from a 6" long #8 bolt. The lip is turned -.002" under the bearing bore and is +.002" on the bearing width. The lip is only about .020" wide. Just hook it in behind the bearing and a couple of whack's at 180... Never Failed Yet!

lrb75

My Feedback: (12)

Don't heat the case when using the wax use it cold. Trust me it works. The stock bearings used in OS and YS have shields which will contain the wax even the bearing cage will hold it enough. Just try it. It can't hurt anything and its alot cheaper than buying or making a bearing puller.

jsn

My Feedback: (8)

Here's PB blaster http://www.pbblaster.com/store/morei...m?Product_ID=1 you can usually find it at your local auto parts store... it the BEST stuff I've ever used for loosening stuck, rusted, corroded parts of any metal type. Yield is about as good but not as good... you could also try liquid wrench but Yield and PB blaster are FAR better for the job.

John

lrb75

My Feedback: (12)

The bearings aren't rusted they are installed with a light press fit.

proptop

My Feedback: (8)

Well...I tried the wax trick...
I lit a small candle and dripped the wax in until I couldn't get any more in there. Then I used a small drift and lightly tapped with a small hammer, (using a wood block behind the case for back-up ) and the hardened wax pushed the bearing up a little...then I had to reach in with my bent over screwdriver and it came out

(I warmed the case a little before dripping the wax in there, so it would flow better...then let it cool )

That wax trick (actually, thick grease ) is the same techinque used to get a pilot bushing out of a (1:1 ) car's crankshaft...

Thanks for the reminder lrb75

rc4j

My Feedback: (103)

Well, I finally got my bearings out and the new ones back in!!!
I made me a poor man's puller out of music wire and a prop drill guide as a slide hammer. I cut and bent 3 equal lengths of music wire with a small enough hook to get inside the bearing. I had to grind them slightly flat to fit under the bearings also. I needed to spread the wires out once inserted, so I cut slots in a piece of wood dowel, and once pushed into place, I taped it to keep it from moving. Here's the most important part I learned. I used a propane torch instead of the oven, slowly heating the general area of the bearings. The one inside the cap fell out from the weight of the puller, and the bearing inside the crankcase only needed a slight knock to get it out. I guess the torch does a better job, but careful not to over do it! I cleaned everthing good, re-oiled, re-heated and pressed the new bearings back in with my drill press and a hollow pipe that I ground down to fit the outer race perfectly. Everything fit great, and the 40 will be ready to go in a Falcon 56 I'm getting ready to build soon.
Thanks everyone for all the help and great suggestions.

proptop

My Feedback: (8)

Ingenuity! [8D]
So now we gotz 2 ways to do it...and all it took was a little time and a few cents worth of materials...[sm=thumbup.gif]

rc4j

My Feedback: (103)

video

http://www.youtube.com/watch?v=EPpFgVI6-tU

sj3cub

My Feedback: (9)

Good Job Jai !!!!!!!!!!!!. There have been few things that I have not seen you be able to fix. Now,
come on over and replace the bearing in my .72. What did you say the sorce for the bearings was?

Scott

rc4j

My Feedback: (103)

http://rc-bearings.com/


I emailed Paul and he was very helpful in locating exactly which bearings I needed, and his prices were the best. Compare for yourself to bocabearings.com