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help - crank thrust face problems continue
https://www.ausmini.com/forums/viewtopic.php?f=2&t=63553		 Page 1 of 1
Author:  mickmini [ Mon Jun 07, 2010 1:13 am ]
Post subject:  help - crank thrust face problems continue
After vowing not to get certain things done in the Netherlands because they cannot do anything right, I ignored my own advice and was convinced that a particular machine shop was able to assess if they could salvage my crank after the thrust bearings damaged it.

I was particularly worried about a deep hole that looked as if it would not be able to be ground out, see pic below.

Image

I was assured it was no problem, and in fact had already cleaned up perfectly. I gave them the specs of the thrust clearance to aim for and they said that they could do it.

I needed a new crank damper and had them change the ring gear on the flywheel. This meant re-balancing the rotating assembly.

All this costs a shipload of dough over here.

Received the engine back last week with the crank, pistons and rods all assembled and torqued up plus the flywheel and damper attached. Of course I dissasembled to make sure everything was good as well as to give it all a final clean and make sure all the little bits of metal are gone.

This is what I found on the crank thrust face.

Image

The damn hole is still there. I can feel a sharp edge with my finger. I think this will tear the thrust washer to shreds taking me back to step one.

Should I stick it in and take the chance? Anyone had a thrust face in not perfect condition last for a reasonable timeframe?

Can I linish this to be smooth but still a divet and have it survive?

cheers
michael
Author:  Convertible Mini [ Mon Jun 07, 2010 6:52 am ]
Post subject:  Crank with hole
I Believe that crank is usable but you will need to clean the edges around the hole with a very small tool like something used in Dentistry. If you had a bit of a hole there it does not matter as long as there is no edges to scrape the thrust washer. A hole will fill up with oil. If the edges are not there it will be ok. They just need to be opened up to form a small ramp. Otherwise it will be get another crank or get it built up / re ground / Hardened and re balanced. Surely it would not be hard to get another 12G1505 crank sent form the UK. Try Ring Minitechnique in Pilling Lancashire he will have one and post it to you. It would probably be a better option.
Author:  mickmini [ Mon Jun 07, 2010 7:03 am ]
Post subject: 
I was kind of hoping that would be the answer, but I wanted to see if anyone has actually done it by smoothing out the edges etc.

Anyone else?

This is a stroker crank and the pistons are machined to suit. If I get another crank, i will have to get new pistons, more money that I don't have. I would rather be able to save this one, hence the question.

I have a contact here who can do the metal spraying to build up the crank who normally does it for air compressors, but I am worried about the ability to re-harden if they are not familiar with the EN16 steel and other problems from the hardening process. You can see how hard it was just to get the thrust face ground back properly.

cheers

michael
Author:  850man [ Mon Jun 07, 2010 10:01 am ]
Post subject: 
I would have the thrust surface machined again untill it is smooth. then use oversize thrusts. .030 are available, I had them remade here in Australia a while ago.
Author:  mickmini [ Mon Jun 07, 2010 4:17 pm ]
Post subject: 
850man wrote:
I would have the thrust surface machined again untill it is smooth. then use oversize thrusts. .030 are available, I had them remade here in Australia a while ago.


already done that, hence my questions. If it is ground back again I will need a +0.040 thrust washer - you got any of those?
Author:  GT mowog [ Mon Jun 07, 2010 4:58 pm ]
Post subject:  Re: Crank with hole
Convertible Mini wrote:
I Believe that crank is usable but you will need to clean the edges around the hole with a very small tool like something used in Dentistry. If you had a bit of a hole there it does not matter as long as there is no edges to scrape the thrust washer. A hole will fill up with oil. If the edges are not there it will be ok. They just need to be opened up to form a small ramp. Otherwise it will be get another crank or get it built up / re ground / Hardened and re balanced. Surely it would not be hard to get another 12G1505 crank sent form the UK. Try Ring Minitechnique in Pilling Lancashire he will have one and post it to you. It would probably be a better option.


+1 and a crack test.
Author:  drmini in aust [ Mon Jun 07, 2010 7:24 pm ]
Post subject: 
mickmini wrote:
850man wrote:
I would have the thrust surface machined again untill it is smooth. then use oversize thrusts. .030 are available, I had them remade here in Australia a while ago.


already done that, hence my questions. If it is ground back again I will need a +0.040 thrust washer - you got any of those?

When .030" thrusts were not available some racers we both know used to silver solder some steel shim stock on the back, to make them thicker.

Another way is to get a thicker pair turned out of solid bronze. I have a pair here that were in a 1310 I bought, very nice job it is, kudos to the maker.
If you do this, personally I would put them on the front (crank pulley) side, so they don't have to cope with the end load of your clutch. However this pair were on the rear, and they are fine. They will go back in if/when I sell the motor.

As a fitter & machinist I agree with the posts above though, just deburr that hole and it will be fine.
Author:  mickmini [ Mon Jun 07, 2010 8:54 pm ]
Post subject: 
Thanks guys,

Nice to know that I am not so crazy.

Will pick up something to clean it up this afternoon.

cheers
michael
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