boxbeam

My Feedback: (188)

I am getting ready to do a rear bearing in a saito 45. I don't have a press, how do I get the prop thrust plate off the shaft? This is a first for me. Gotta be walked through that one. I understand the installation of the bearing.

Ron

Ernie Misner

When you tap the crank out the thrust washer will come off at the same time. Put the prop nut on part ways, put the washer on in front of that, and use an old oversize prop or a piece of hard wood as protection for the front threads of the crank. Then tap it right out. Put the case in the oven at 350 and the old bearings will fall right out with tapping on the backplate area. Put the new bearings in the freezer and install them while the case is still hot. Get the rear bearing fully seated while the case is still hot.... ask me how I know... Suck the crank back in using the oversized prop and by tightening the prop nut on the front threads. Good luck!

Ernie

Flyboy Dave

My Feedback: (21)

Ernie...whatever way you decide....you'll set the case
in a vise....not clamped, like this. Strike the outer race
ONLY....1/3 the way around....that is to say....at 12, 4,
and the 8 o'clock position looking at the bearing.
Keep tapping around like that till the bearing seats home.
You'll feel it, and hear it when it does.

If you look inside the crankcase with the back-plate off...
you can see the outer race. I would heat only the area
around the bearing, on the outside, and seat it with a small drift....rotating the crank after eack blow....and using the
12, 4, and 8 technique.

Ernie Misner

Hi Dave,

I was curious so I just sent an email off to Boca Bearing asking them at what temp I could safely put the phenolic bearings in the oven. 350 degrees is fine for regular bearings. We'll see what they say next week. I like your idea of using the torch on the outer part better though. Thanks a million for all your help here, and everyone else's too!

Ernie

Flyboy Dave

My Feedback: (21)

....get a battery terminal puller at the local Auto parts
store for a couple dollars....and pull the collar off.

boxbeam

My Feedback: (188)

Thanks guys, both sound like they will work. And the oven and fridge tools are the real secret!!

Flyboy Dave

My Feedback: (21)

One thing you guys need to know about bumpin'
crankshafts to remove the front collar....this is why a
puller is used. In an older engine...99 times out of a
hundred....the crank will be corroded onto the inner race
of the rear bearing.

When you start hammerin' on the prop-stud to remove
the collar....your trying to move three parts at the same
time....the collar (off) ,and the crankshaft (out the back),
BUT....more often than not....your pushing the rear bearing
out with the crank....especially if the case is still hot from
removing the liner....because it is stuck to it.

If the rear bearing is stuck to the crank...it can be very
difficult to remove it....mainly because there's no bearing
puller that small....with the reach necessary to do the job.

So here's my drill....after you remove the back-plate, and
the front collar....squirt this "knocker-loose" into the rear
bearing, the front bearing, and up into the wrist pin area.
This will give you a head start on the crank removal, if it
is corroded. Get this stuff at Napa Auto....it is a savior....

Then pull the head....heat it up, and remove the liner,
piston, rod, ect. Now....WATCH the rear bearing as you
bump out the crank....if the bearing is coming out with it,
STOP...let it cool....and give it another squirt of juice.

The whole deal is to try and get the crank out....without a
frozen bearing attached to it. Once the crank is out....the
bearing is easy to remove.

Also....pulling the crank in with the prop-stud is fine....but
make sure you give it a nice bump from the back to make
darned sure it is home.....if you have removed all the
corrosion from the crank, and with new bearings....it should
slip back in real nice....with some gentle taps of a wooden
dowel.

Ernie Misner

Many thanks to Dave and all the others. You have given me some great ideas like the battery puller and the Knock Loose spray. I should be hearing back from Boca about how much heat a phenolic race can actually take.

Ernie Oh, thanks for the great photos too!

Slinger

I have been looking online for books or videos on 'how to rebuild rc engines' and am drawing a blank, specifically a .46 Max SF. Does anyone have a OS .pdf on the rebuilding process? I am pretty mechanically inclined and just need the steps basically 1-100 or what ever lined out to follow. I also am looking for a parts source for this motor bearings, crank, piston, sleave, ect...

Any suggestions would be helpful

Thanks,

Slinger

Ernie Misner

Hi Slinger - the two strokes are pretty darned easy. Not much need for a book. I have a .46 SF also. Is yours abc or ringed? Mine is ringed. Did you know that at Just Engines you can purchase an ABC Leo liner and piston that will be a drop in fit for your older SF??? More power and rpms are acheived also I think.

After pulling the backplate, remove the sleeve. Mine came right out without any heat. Once the sleeve is out the rod can be gently pulled off of the crankpin. Lots of good info above about removing the crank and bearings. I did have a slight problem getting my ring to line up with the piston pin on re-assembly. Just took a few tries as I slid the liner back into place. Best of luck!

Ernie

wolf152

My Feedback: (13)

Wrap wire around bearing for ease of removal from pan. Place bearing in pan with enough oil to cover. Heat to 200 degrees. Put on gloves. Remove bearing from oil and slide on shaft quickly. Press bearing to shoulder until cool. Oil will prevent any damage to hardness of bearing.

wolf152

Slinger

I do not know the type of motor, how can I tell the difference? I did look at the piston and I am sure that it had a ring, only one. The motor was a given to me by a friend that said if I could get it running right to make him a fair deal. Looking at the motor with the end cap and head off and trying to bench run the motor, the crankshaft will stick in place like the bearings have a flat spot. It is not the compression stroke of the motor, and it sticks in the same spot every time. I have experiance with motors with bearings and this is usually the problem. A quick swap of the bearings, and back in business. If I am going to swap the front and rear bearing, would it be adviseable to change the sleave and piston as well? I see no visible cracks or plateing flake, ect.


Thanks

Slinger

Ernie Misner

Hi Slinger,

If there is a ring on the piston, it will be only one ring. If it is an ABC type there will be no ring at all but there will be a "tight" spot at the very top of the compression stroke. A tight spot anywhere else would be something else as you said I think. If this motor has been sitting for a long period it might have congealed oil in it that has hardened. If that is the case putting the block in the oven should loosen it up. You could further clean it up by putting it in hot antifreeze for a few hours. Best of luck!

Ernie

Slinger

can you give me an idea of where ican get replacement piston and sleave to convert my SF to ABC.


Thanks

Ernie Misner

Hi Slinger,

Just Engines is the place to go. They have the ABC piston and sleeve (made by Leo). There is one that fits the OS 46 SF's and one that fits the OS 46 FX's.

Paul will fix you up real quick! Havta have a Visa Card I think....

Ernie

Slinger

Hey thanks Ernie, did not realize the parts would have to come across the pond; however ; I think it would be worth it. I did get the motor apart, cleaned up, and running again "as is". Thanks for the experienced advise!


Senor Member of "Lawn Dart ASSOC." :idea:

Slinger

Ernie Misner

You are welcome Slinger. Did you find the article for swapping Leo parts?? (at Just Engines) I am VERY interested in this too since I have an older, ringed OS SF .46.

Ernie

neversink

Hey guys, while were pulling apart our 46 SF's, does the front drive hub really just pop off when you apply a small gear puller or terminal puller to it? There appears to be a small captive steel snap ring of sorts in the hub. I've been afraid to put a puller on it with the ring but can't pry the ring out either. Any info would be appreciated!
Rich

Flyboy Dave

My Feedback: (21)

Use the puller, and it will pop right off. That piece you
see inside is the tapered cone that binds down on yhe
crank, and keeps it from turning.

Get a puller....don't try to pry it off.

Dave.

neversink

Thanks Dave - thats a big help. With extra bits like the tapered cone and machined head it must have cost OS a bit more to make an SF than the FX's they currently are banging out!
Rich

Flyboy Dave

My Feedback: (21)

They used to use a woodruff key in the prop collar....
but I think everyone now uses the tapered collar. Works
just as well, and cost's less to produce.

Slinger

Hey Ernie,

I did not see that article I think. What is this about 'swapping parts' ? I would be interested, I di do the math and the expense of the parts leave a little to be desired, is he will to discount or trade?


Senior Member 'Lawn Dart Assoc.' :stupid:

fastlash

My Feedback: (7)

When doing a bearing swap never drive it in using the inner race you will do damage to the bearing, The way I do it is to take the old bearing and shave the outer race down with a belt sander or even a bench grinder just enough that it will slide in to the housing and I use this with a C-clamp and press the new bearing in using the old bearing as a driver, the surface mates perfect with the outer race, of the new bearing,and if you really want it perfect grind a little of the face off the inner race and face that against the new bearing and this will allow for the little stretch you get with the pressure being applied by the C-clamp

Ernie Misner

Okay Slinger, here's the Just Engines website page that shows swapping Leo parts of OS parts. It is VERY interesting, even shows the rpm increases with the new parts...

http://www.justengines.unseen.org/os1.htm

Ernie