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ASP prop driver stuck!

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Keith Miles 211/08/2019 10:20:32
301 forum posts
6 photos

Cymaz, Oh, Yes, that idea has been put to me! Not my preference at the moment!

Still struggling to work out how to post some pictures!

Have created an album, can view the pictures but the heading says “Start a discussion” and there are drop down boxes etc.

My brain hurts!

Keith Miles 211/08/2019 10:32:37
301 forum posts
6 photos
Posted by Engine Doctor on 11/08/2019 08:56:23:

Hello Keith . You will probably find that the prop driver has split allowing it to go further onto the tapered collet and foul the crankcase. It happens quite a lot on ASP etc as the prop driver seems to be made of varying hardness of alloy . It will need a replacement. Just engines apparently still stock parts for them .

Ah- ha!

Indeed?

Now that is interesting. Mind you, whilst I was thinking along similar lines, I would have thought, as others have said, that the prop driver would have come off relatively easy rather than the reverse!

Yes, I was going to give JE a call, anyway. I’ve dealt with them on a number occasions. Very helpful. In fact, I bought the engine from them five years ago and they managed to sort out a replacement silencer for me recently when the tail piece loosened allowing it be rotated with finger and thumb!

Keith Miles 211/08/2019 10:33:57
301 forum posts
6 photos
Posted by bert baker on 11/08/2019 09:57:48:

Or you could set the nut on the crankshaft at the end And gently tap it in slightly with a mallet,

oh is that the time

Already tried that.

bert baker11/08/2019 10:51:49
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1524 forum posts
317 photos

Is the piston out

Jonathan W11/08/2019 11:01:09
111 forum posts
11 photos

Having looked at the picture in your gallery, the puller is not effective due to the bending of the metal plate you have used to adapt it to the prop driver. I think your best bet would be the bearing separator, as previously suggested by Martin Harris.. I also use a separator and the extra rigidity provided works wonders.

PatMc11/08/2019 13:50:53
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4326 forum posts
524 photos

Is it possible that it isn't the prop driver that's moved back a on the crankshaft but that the crankshaft has moved back a fraction in it's bearings ?
This could have been done accidentally whilst in the process of refitting the cowl, prop & spinner after the test fight.

Martin Harris11/08/2019 14:46:53
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9171 forum posts
242 photos

Wouldn't that simply introduce end float on the crank?

Keith Miles 211/08/2019 15:33:58
301 forum posts
6 photos

In response to latest comments.

Bert,

No, the piston is not out. The engine is fully assembled.

Jonathan,

I am glad that you can see the picture in my album. Still trying to figure out how to pop it into this thread on my I-pad!

As said earlier, the plate was somebody’s home brew which I borrowed. It has apparently worked on at least one other engine, but, as you have noticed, not this one!

Yes, the bearing separator seems like a good idea that SHOULD work and I am now considering buying one, or a set, if necessary! My own experience, albeit limited, tends to support the view that having the proper tools makes life much easier!

PatMc,

My view, and a majority one, is that it is extremely unlikely that the crankshaft has moved backwards for numerous reasons. Everything was fine prior to removing and refitting the prop immediately after a test flight. Tightening the prop would, if anything, pull the crankshaft forwards. Crankshafts do not tend to move only bend if subjected to an “inappropriate” sudden force being applied. Indeed I have had, and witnessed, a number of nose in crashes with no subsequent crankshaft damage. As Martin says, if the crankshaft had moved, it would almost certainly create float. It hasn’t and the engine feels fine.

I could cobble something together, given the right materials, to get the job done and have received several suggestions. Whilst that might save money it probably wouldn’t save time but would, in fact, mean more work which I would prefer to avoid.

And if I ever have to get the prop driver off my new Saito, I note that not only is there a similar minimal gap between prop driver and bearing housing but also a much narrower and shallower groove in the prop driver! So, there HAS to be a proper tool for the job, I would think!

bert baker11/08/2019 16:02:34
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1524 forum posts
317 photos

Have you got any wart Freezing spray, could give it cold then hot shock

if you don’t fancy putting it in the freezer as previously suggested

Denis Watkins11/08/2019 16:14:33
4197 forum posts
85 photos

Yep Bert, Freeze the motor, warm the prop driver, PING, job done

bert baker11/08/2019 16:17:49
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1524 forum posts
317 photos

Off to bed 🛏 now then

Jonathan W11/08/2019 16:30:59
111 forum posts
11 photos
Posted by Denis Watkins on 11/08/2019 16:14:33:

Yep Bert, Freeze the motor, warm the prop driver, PING, job done

When you are heating the prop driver, what is stopping the heat conducting instantly also into the crankshaft, which is in direct metal-to-metal contact with the prop driver?

According to my understanding of the laws of physics, the crank will not remain at freeing temperature as soon as you apply significant heat to the prop driver.

Certainly, a few heat cycles - heating followed by quenching - might shock it loose by rapid differential expansion/contraction, but I don;t see how it is possible to maintain the crankshaft at a significantly different temperature to prop driver.

Denis Watkins11/08/2019 16:47:52
4197 forum posts
85 photos

Ha haa Bert !

It just works Jonathan

The cast iron crank will remain cold, as there is more mass and the metal is denser and heavier

The Aluminium prop driver will conduct the heat rapidly, and it is On the outside of the assembly

This works every time it the fit is a taper with no other obstruction

Just do it and remove the prop driver, even boiling water will do

 

Edited By Denis Watkins on 11/08/2019 16:50:40

Don Fry11/08/2019 16:59:17
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4557 forum posts
54 photos

Does not conduct instantly though. The aluminium alloy need few joules to heat, and is a good conductor of heat. The steel is relatively speaking a poor conductor of heat, and has a higher density. So a no messing about gas troch can for a few seconds get a big temperature gradient across the metal to metal surface.

Martin Harris11/08/2019 17:25:59
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9171 forum posts
242 photos

The co-efficient of expansion of typical aluminium alloys is over twice that of carbon steel. Heating should loosen a taper fit but Keith has tried heating with no success so far. Other than more heat and force (with an extractor that can transmit a shock effectively) I don't think there's much alternative to cutting it off.

I'd prefer to try a decent extractor on it - I'm sure a good car mechanic (or gearbox specialist) could do something for you Keith at a nominal cost.

P.S. My bearing separator has had no problem gripping the Saito drivers I've used it on.

P.P.S. On the subject of the crankshaft having moved, I suppose it is possible that the bearings could have moved if the prop was changed while the engine was hot. Your attempts at extracting the driver would not have moved this relationship and once cooled the bearings would be pinched in the cases again.  Check this by removing the backplate and use a hammer and brass or aluminium drift on the crankshaft web.  If you heat the engine in the wife's oven to 150 degrees C it will help - and shouldn't affect any rubber parts left assembled.

Edited By Martin Harris on 11/08/2019 17:52:27

Keith Miles 211/08/2019 18:47:03
301 forum posts
6 photos

514b33cb-e8c7-44eb-a7bc-afbb16756a11.jpeg

Finally, what you’ve all been waiting for! Thanks to my brother in law (fellow contributor and IT genie) a telephone tutorial walked me through the photo upload process. That said, he usually uses his PC and the I-pad process is a little different which had him foxed for a while!

So, again thanks for all further contributions and here is an update!

I have just ordered a bearing separator. £14 and free postage from E-bay. Supplier is Cromwell Tools In Wigston, Leicester. Ironically, I had earlier been discussing my dilemma with a club member, a car mechanic whose business is in Wigston! Indeed, a number of our members live in that area! Should have it by Thursday.

My plan is to use the separator with the above puller and, this time, up the anti with my recently rediscovered 1500w paint stripping heat gun!

Watch this space!

Denis, are you sure that crankshafts are made of cast iron?

Martin, luckily I don’t have a wife. Unluckily, my oven packed up recently so, currently, I don’t have one of those either!

Keith Miles 211/08/2019 18:52:26
301 forum posts
6 photos

2935f74a-4f31-4b4f-b7c1-f384ab30fa9c.jpeg

And this is what the prop driver/bearing gap should look like, for those who don’t know! Zoom into the pictures to see the difference!

Keith Miles 211/08/2019 19:05:18
301 forum posts
6 photos

Oh, and by another coincidence, I’ve just received an e-mail from Just Engines informing me about their new web site which, actually, I discovered yesterday!

I hope they have the spares I need!

Keith Miles 211/08/2019 19:30:26
301 forum posts
6 photos

Seems that JE may, indeed, have the spares I need ‘cos I just ordered them! There’s even a 5% discount for a few days!

smiley

Don Fry11/08/2019 19:53:03
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4557 forum posts
54 photos

A small puzzle, if the driver has split, that would show as a line, revealed under a glass, or a ridge under a finger nail.

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