stuck bearing

[MikeS]

I tried to remove the bearings in my asp fs 1.20 today that I am rebuilding but no joy. I've changed a few over the years in various engines and do not normally encounter a problem.

Tried heating for 20 mins at 325 but no joy and then a further 20 mins at 350. Then tried cooling then heating but still not coming out.

The engine was second hand and I think the bearings have been in the there for a while. Does anyone know if you can get a bearing puller for our engines. Think that might be they way forward.

Mike

[Keith Evans 3]

Hi Mike

I have not tried this idea out myself but my son uses Rawlbolts fom B&Q when he needs to extract bearings from his very expensive bi cycles . These are the type that expand a collar when you screw the nut down the threaded shaft and are usually used to secure wooden posts into brick walls . I believe he uses sockets as spacers .

Let me know if this works.

Keith

[MikeS]

Keith, thanks for that. I was thinking along these lines but this rawlbolt looks better than what I had in mind. Will pop out after xmas and get one.

Mike

[MikeS]

Well the idea is a sound one but it did not work, the bearing still will not pop out. I think it must be stuck in with old castor varnish.

Maybe a solvent to break down the castor gunk first would help, any ideas

Thanks Mike.

Edited By MikeS on 28/12/2014 08:25:55

[Peter Miller]

I think that you could afford to go quite a bit hotter. I stick my crankcases over a gas burner or use a butane gas torch.

[cymaz]

I use a heat gun and welding gloves...when the case is smoking give it 5 more mins. Make sure the heat is even all the way around the case

Edited By cymaz on 28/12/2014 08:34:38

[Graham Bowers]

Posted by MikeS on 23/12/2014 16:27:34:

I tried to remove the bearings in my asp fs 1.20 today that I am rebuilding but no joy. I've changed a few over the years in various engines and do not normally encounter a problem.

Tried heating for 20 mins at 325 but no joy and then a further 20 mins at 350. Then tried cooling then heating but still not coming out.

The engine was second hand and I think the bearings have been in the there for a while. Does anyone know if you can get a bearing puller for our engines. Think that might be they way forward.

Mike

Farenheit or Celcius?

Graham

[MikeS]

Graham I tend use gas mark 3 325 f if that does not work then gas mark 4 350 f for 20 minutes. How hot should I go. The engine is smoking when I take it out. Never normally have this problem

Mike

[Engine Doctor]

Strange . I have never had a bearing resist extraction even with really old engines . I use a hot air gun (decorators Type not the modelling type)and a pair of welding gloves . Heat all round until "smokin" then some more . The test I was shown back in the !960's when rebuilding motorcycle engines was to spit on it and if hot enough the spit would bubble and bounce off the casing .If it just bubbles then its not hot enough. Once hot enough simply tap the case on a smooth piece of wood and bearing usually falls out .

Just a long shot but Is there any sign of the bearing being held in place by punching/peening ? if there is its usually due to bearing turning in housing and becoming a loose fit or a badly machined crank case. an old bodge on motorcycles was to coat the outer race of the bearing with solder . Smaller bearings were fitted and the alloy punched to tighten the fit Definitely not recommended for model engines though. I have come across a couple of engines with loose bearings over the years both chinese 4 strokes . The modern fix without the expense of a new crank case isbearing fit adhesive"and that will release with heat .

[Hannes Koekemoer]

If caster oil varnish is the problem, the best I can think of is to use thinners or acetone to try and dissolve the varnish, but to me it sounds more likely that the alloy was punched to tighten the fit as the Engine Doctor states.

[MikeS]

Thanks for all the replies, what should I look for to confirm if the bearing is punched or peening in the case.

Mike

[Graham Bowers]

Mike

To be honest, I'd have thought 350F would be hot enough. I've had lots of old Brit motorcycle crankcases in the oven up to gas mark 6 which is 200C / 390F but they were aluminium alloy. I don't know for sure but I'm guessing the intricate shapes of model engines require an alloy based on Zinc, which has a lower melting point than Aluminium.

http://s174.photobucket.com/user/greenbacking/media/PICT08782_zps28129a9e.jpg.html

This pic shows what I'd describe as a staked bearing but peened / punched would probably be good descriptions - I only add the word "staked" as you may wish to search on it. The key characteristic of a punched / staked / peened bearing is that the crankcase will have been deformed by a blow to provide a local lip to retain the bearing. I've never seen this on a model engine but I've not stripped many down - and those I have were not problematic. If you've had the engine from new then you can probably discount that. If it was used then who knows what bodges it may have suffered. Was it new to you please?

If its not staked then I would suggest making sure the way out for the bearing is free of gunge and trying again with the heat. Also, is it possible to tap the back of the bearings with a soft rod to drift them out?

Finally, where are you?

Graham

[MikeS]

Graham.

Well looking at your photo I cannot see anything like those punch holes on mine. It looks like all the other engines I have changed bearings in. The engine was second hand around a year ago and has been running until a few weeks ago.

I can only imagine that either the bearing is being held in by solder/glue or gummed up fuel. The crack case I believe is die cast alloy.

If I can get the front bearing out the then I might be possible to drift out the rear bearing.

I am near Kingston apon thames.

Mike

[Shaunie]

I can't believe they won't let go but if you need to get really extreme:-

Pull out the lip seal if there is one, break up the cage, pull out the balls and race inner. You can then get a really good grip with a Rawlbolt or take your trusty Dremel and grind a slot into the outer until it collapses. Extreme care is required to avoid damaging the housing.

There are special tools to pull races which either grip the inner race or will grip into the race area after breaking up the cage. Bit expensive for single use though.

Shaunie.

[Graham Bowers]

Mike

I'm in the Midlands, so a bit far to "pop round" I'm afraid.

You may be right that "something" is holding the bearing in rather than the grip of the housing as designed. I think all of the possible techniques have been discussed in this thread. If it's any consolation, I have a mountain bike component that needs the dremel treatment Shaunie presented.

I think the order I'd go for is:

1) Form an opinion on whether the engine has been apart before. If you know who you got it from you could ask, otherwise you'll have to look at the engine for clues. Condition of screws, prise marks on casings, condition of gaskets. If the engine hasn't been apart before then it can't have been bodged so you know that the crankcase is suitable for further use. If you get the bearings out of a crankcase with a damaged bearing housing you then have to decide if its fit for further use.

2) Clean as best as you can, heat and try to drift the bearings out.

3) Improvise collet puller https://www.youtube.com/watch?v=bUOkEtQ8iSw

4) Dremel

Good luck, and let us know how you get on please.

Graham

[Bob Cotsford]

I had a Magnum 91FS that I bought second-hand where the rear bearing had spun in the crankcase raising a bur at it's rear that stopped the bearing dropping out. Brute force and careful use of a sharp edged drift through the front of the case got it out at a cost. New bearings were a free fit in the housing and even stud'n'bearing Locktite didn't hold for long. I ended up putting everything into a new ASP crankcase from Just Engines.

[MikeS]

OK. Bit of a delay in the update of the bearing saga due to the Mrs being off. Decided to soak the engine in acetone for an hour then put the rawlbolt in and back in the oven for 20 mins at gas mark 4. Rear bearing fell out in the oven.

Can you belive it!!!. Front bearing needed a little help but came out. Finally.

Ok New bearings, front has the plastic covers on both sides and rear has only one on one side. I'm think rear should not have any and front should have one on the outside.

Mike

[cymaz]

Someone will correct me , but I usually have no covers on rear bearing and only the outside cover on the front one.

Congatrulations on getting the bearings out...all Good.

[Engine Doctor]

I now fit sealed front bearings on my engines especially four strokes that don't always get proper lubricant supply from crankcase. These bearings are used in car alternators with a significant load put on them by the driving belt and they last for thousands of miles . The ones I've fitted have/are all still fine after a few years of use. I did strip an OS 90 for rebuild a couple of years ago and that had a front seal left in the rear bearing ? This engine had never been stripped from new so seal was left in presumably by OS . The only down side to this seal being fitted as far as I can make out is that it prevents oil being drawn into the can shaft and cam followers as was evident on the stripped engine with a rusty gunge formed on the cam gear . The top of the engine also needed at good oil as rust had started to form on the rocker arms. I couldn't find reference to a sealed bearing in the parts list ? Perhaps some one on here can shed some light ?

[Martin Harris - Moderator]

I've seen some engines with a single shield on the rear bearing but never a sealed one. As a general rule I change like for like but have toyed with the idea of leaving both seals in place on front ones as I've had Irvines with them from the factory.

Incidentally, Irvines that refuse to cut can often be cured by a light application of Bearing Fit when assembling the front bearing - I've found several that leak air between the sealed front bearing and its housing...

[MikeS]

Reading all the advice I removed the cover off the front bearing leaving one in place. The rear bearing however is not a cover my mistake. It is the bearing race but looks different from the old one. Both new bearings were sourced from Just Engines.

The engine is now rebuilt, however my mind is rusty on the timing, from memory I think it is piston at tdc with the timing dot on the six o'clock.

Mike

[cymaz]

I've found a Magnum picture of the timing marks, should be the same

magnum

[William Morrison]

Saito engines have sealed bearings in the front. I have not run into other engines that did so. Some would retain shields on the main bearing fearing debris getting into or out of the bearing. Personally, I remove the shields on the main bearings to enhance the flow through of lubricant to the cam area. I do not think the shields will totally interrupt the flow of lubricant to the cam box but I would rather have more than less.

[Erfolg]

I assume that you have had the bearing under tension/being pulled, whilst heating?

From experience of industrial scale situations, often a lot of tension and a lot of heat can be required.

I have seen fitters almost giving up, when nothing is happening, when a sudden crack and the pullers falling of, brings a smile to the face.

Another approach I have seen, is to pull so hard that the cage and inner track, disassemble themselves. Where upon the fitters have resorted to grinding stones in Desoutter air drill, to grind a grove in the outer track, until suddenly the race just comes loose. Seems to take time and some skill and above all patience.

[MikeS]

Yep Erfolg I had the rawlbolt hanging out the bearing adding weight which helped.

Cymaz I read through the post and set up my timing as per the photo. Will see how it runs when I next get down the club.

Mike