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Old Feb 15, 2013, 05:23 PM
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Originally Posted by DarZeelon View Post
Hey, was this thread not about removal of the bearings of an OS.55AX?
Yes it is, so why did you show that puller back in post #8 which isn't required for a 55AX?

Personally I think it's a good thing when others show various methods for removing bearings because sometimes they can be a real pain to remove when the normal methods fail. Just because the topic title happens to mention a particular engine shouldn't limit the replies. I had extreme trouble trying to remove the gritty feeling rear bearing in a Moki M5 and finally resorted to using a Dynabolt to grip the inner race and act as a puller with lots of heat. Unfortunately even that didn't work so in desperation I threw the whole lot in my US cleaner. The bearing cleaned up silky smooth so I put the engine back together again .
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Old Feb 15, 2013, 09:25 PM
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Plus heating up the engine good lets you remove the crank, bearings and prop driver/washer all at once too. So you do not really have to have a puller for the prop driver/washer. If you do use the hammer method, do not just wack on the threaded end of the crankshaft directly. You have to hit straight and level down on the crank end and use something like a prop nut and a block of wood so you don't shock the crankshaft (it could shatter or break off the end). i prefer using a brass hammer as it does the same thing without shocking the crankshaft or bearings so they crack or break.

Ideally using a press is the best method, but not everyone has access to one.
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Old Feb 16, 2013, 02:37 AM
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Originally Posted by earlwb View Post
Plus heating up the engine good lets you remove the crank, bearings and prop driver/washer all at once too. So you do not really have to have a puller for the prop driver/washer. If you do use the hammer method, do not just wack on the threaded end of the crankshaft directly. You have to hit straight and level down on the crank end and use something like a prop nut and a block of wood so you don't shock the crankshaft (it could shatter or break off the end). i prefer using a brass hammer as it does the same thing without shocking the crankshaft or bearings so they crack or break.

Ideally using a press is the best method, but not everyone has access to one.
Downunder and Earl you both are way out of this OS topic so go, appologise like I did
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Old Feb 16, 2013, 12:48 PM
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This does not apply to OS engines, but the suitability of a hammer depends on your intentions.
If you take your engine apart, just to thoroughly clean it, or to replace a specific part (but not the front bearing!); using a hammer is a no-no!

If you do intend to replace a faulty front bearing anyway; a hammer *can* be used, but the puller is still the better option.

When you use a hammer; even if the tip of the shaft is protected, the strike will directly blow the inner race backward and cause the balls of the bearing to Brinnel both races.

Even if that bearing was good and reusable, it would just have become rough junk that needs to be replaced...

I don't care how much money one has, but model engine parts are not replaced just for the heck of it! You don't destroy parts on purpose; and using a hammer to remove the prop-drive washer is exactly that!
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Old Feb 16, 2013, 09:31 PM
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Some one should make a video to show us all how it really should be done instead of criticizing those who did make videos.
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Last edited by earlwb; Feb 16, 2013 at 09:35 PM. Reason: typo correction
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Old Feb 17, 2013, 02:14 AM
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Here you go, Earl.

It's from Dan Stegall.

Here it is...
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Old Feb 17, 2013, 08:50 AM
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That is a great video clip of how to remove the prop/drive washer. The puller tool works pretty good for that. But some engines have a tapered groove that cam be a problem as the tool's jaws tend to slip out. I have used a old water hose clamp or a clamp to keep the jaws in the groove in that case. If there is room for it, a small bearing splitter tool works great too.

But if you have a engine with a prop/drive washer that does not have a groove for a puller tool on it. Plus the part has a thin skirt that overlaps the front bearing housing on the crankcase so that you can't get a grip on it with the puller tool either. So then what would you do?

As soon as I need to replace some bearings on a engine again, I'll endeavor to make a video myself. But don't anyone hold their breath. I don't have any engines at the moment that need repairing.
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Old Feb 17, 2013, 12:01 PM
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Earl,


A terminal puller can also be engaged against the rear of the prop-drive washer (with a thick rear), if it does not have a groove like the TT Pro version (or Saito, MVVS, Etc...).
It is the best method because it applies force only to the parts that need to be separated.

A small bearing splitter would do the same, if used with a puller that presses against the crankshaft.
But if this tools clamping bolts are used to clamp its jaws together; essentially separating the prop-drive washer from the crankcase, to which it is not connected; some damage can happen.

...I'd never understand a manufacturer that would use a 'smooth' drive-washer with a paper-thin dust-shield rear... unless it is intended never to be reused...
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Old Feb 17, 2013, 07:49 PM
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Well I do have a few engines and there are more like it, that have a smooth drive washer with a thin skirt that just fits over the front bearing housing on the crankcase. Even better the front bearing housing is recessed so the drive-washer skirt fits into it nicely, like it is streamlined. Thus no way to get a puller tool onto it. Even if you could the drive washer would be badly damaged as the thin skirt folded upon you.

I have a couple of old SuperTigre engines that are like that, plus some older model Fox engines that do it too.

But if the bearings are bad, there isn't any reason to not heat up the engine good and use a brass hammer on the crank and drive washer to get it apart. Or better a press on it, if you have one. Damaging bad bearings doesn't hurt anything.

Granted using bearing pullers is the better way and or a press too. But most people aren't going to have a set of expensive bearing pullers to fit or a large press either. Nor access to the tools as well. So they either give up on the engine, pay someone with the tools to do it, or use more primitive methods.
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Last edited by earlwb; Feb 17, 2013 at 07:56 PM. Reason: typo correction
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Old Feb 17, 2013, 10:14 PM
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Hammer beatings!!!!
Yea !!
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Old Feb 17, 2013, 10:57 PM
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Quote:
Originally Posted by earlwb View Post
But if you have a engine with a prop/drive washer that does not have a groove for a puller tool on it. Plus the part has a thin skirt that overlaps the front bearing housing on the crankcase so that you can't get a grip on it with the puller tool either. So then what would you do?
Heat and pressure is about the only way to do it. The ST prop driver is bad for this, particularly seeing it's a casting and not as strong as a fully machined driver (overtightening a prop can cause this casting to crack). My Moki M5 is even worse with less than a 1mm gap and it's machined to match the crankcase.

For pressure I use a drill press with the (closed) jaws of the chuck against a nut on the crankshaft and a piece of flat wood to protect the rear face of the crankcase. A vice or even a G clamp could be substituted for the drill press but, particularly with a vice, you'd have to be a little careful not to put on too much load. With pressure applied I use a small gas torch to heat the prop driver.
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Old Feb 18, 2013, 08:10 AM
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Yeah the cast prop drivers are quite fragile in that sense too. Fox made a number of "Deluxe" engines that had a integrated prop driver and spinner backplate. You could not use a puller on that type of prop/driver/spinner backplate without damaging it.

I also noticed that quite a few of the .15 (2.5cc) engines also have very fragile prop driver washers too, that do not have a groove in them and have a recessed close fitting skirt as well. My Para engines is one example.
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Old Feb 18, 2013, 10:06 AM
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What the heck? It runs. Who cares?! No?
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Old Feb 19, 2013, 03:38 AM
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Quote:
Originally Posted by earlwb View Post
That is a great video clip of how to remove the prop/drive washer. The puller tool works pretty good for that. But some engines have a tapered groove that cam be a problem as the tool's jaws tend to slip out. I have used a old water hose clamp or a clamp to keep the jaws in the groove in that case. If there is room for it, a small bearing splitter tool works great too.

But if you have a engine with a prop/drive washer that does not have a groove for a puller tool on it. Plus the part has a thin skirt that overlaps the front bearing housing on the crankcase so that you can't get a grip on it with the puller tool either. So then what would you do?

As soon as I need to replace some bearings on a engine again, I'll endeavor to make a video myself. But don't anyone hold their breath. I don't have any engines at the moment that need repairing.
Picture of that OS pulling device but it only can manage the smaller engines, maeby they do have one for the larger ones. I have put some different drive washers in line, the left one (Fox?) causes no problem, the middle ones will have damage if really tightened hard due to the conical shape (fe Webra) because the puller's feet will slip outward, and the one on the right is Super Tigre and almost impossible to remove with a standard puller. Last pictures show two out of the shop pullers, I did remove excess material underneath as to be able to grip onto drivers like the Super Tigre ones. If you skip on those there is no repairing since the material is so thin.
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Old Feb 19, 2013, 10:35 AM
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Originally Posted by DarZeelon View Post
What the heck? It runs. Who cares?! No?
This helps how ?
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