42 replies to this topic

[MiniMadRacer]

You could have the crank and flywheel checked and balanced as an assembly, but yes, you wouldnt know for sure until full assembled and warmed up  to allow for any expansion caused by heat, and yes the dolalrs / pounds / euros start to mount up then

[sonscar]

I do not think anyone has welded anything.As moke said the flywheel has been moving and bits of it have mechanically welded to the crank.In fairness the seller would probably not been aware of this,indeed some of our engines may look like this.
I am not an engineer but I would dress the high spots and lap with grinding paste then reassess.Steve..

[Ethel]

It's essentially friction welding. If you're going to get it dressed, I'd have the fly & crank done together and make sure whoever does it is aware there's a limit on how far the flywheel can up the taper.

[Spider]

I gotta say, I didn't like the taper in the flywheel. I'd look to replace that.

[dodge44]

 

That damage looks more like fretting than welding to me so the next question is what is the condition of the taper on the flywheel as that will need either work or replacing as well?
 
Roger

I agree, but it's really difficult to take pictures that shows that it bulges upwards like a weld and not down into the material.
I've tried giving it a shot.
20210425_110930.jpg

 

I would be minded to say the crank can be saved but the flywheel is probably toast. The machine shop will leave the good area of the taper largly untouched and only turn the raised area off. It won't look very pretty but will work OK. I ran one like that for 50,000 odd miles In the era before the internet when a replacement couldn't be found so had to dress the original.

Edited by dodge44, 25 April 2021 - 10:10 AM.

[nicklouse]

 

That damage looks more like fretting than welding to me so the next question is what is the condition of the taper on the flywheel as that will need either work or replacing as well?
 
Roger

I agree, but it's really difficult to take pictures that shows that it bulges upwards like a weld and not down into the material.
I've tried giving it a shot.
20210425_110930.jpg

 

The bulge will be material that has come off the fly wheel insides. File the crank so you can get the primary gear off and then get it checked out/machined. Replace flywheel.

[SirBallD]

I do not think anyone has welded anything.As moke said the flywheel has been moving and bits of it have mechanically welded to the crank.In fairness the seller would probably not been aware of this,indeed some of our engines may look like this.
I am not an engineer but I would dress the high spots and lap with grinding paste then reassess.Steve..

My initial thought was that it was a weld. After looking at the flywheel it's pretty obvious that it's a "mechanical weld". I've never seen this before, but I guess that I'm still learning.

As dodge44 and Nicklouse mentions, "fretting" and "the bulge will be material that has come off the fly wheel" gets really obvious when looking at the inside of the flywheel. It's very clear that the material on the crank is coming from the inside. It's almost 1:1. It's annoying but quite fascinating. 

I'll give the machineshop a ring tomorrow and ask. Let us see if they can save the flywheel too, although I'll probably just replace it.

 

By the way, how is balancing of the crank usually performed? Is it done with the flywheel and conrods connected?

[SirBallD]

Just a thought. Isn't it possible to just replace the center hub of the pressure plate on the verto clutch? The center hub is the part that is worn. If replacing the center hub, is a balancing inevitable or is it just a "plug'n'play"?

 20210425_171941 (Small).jpg   177.11K   1 downloads

 

I inspected the remaining components and I found that the locking plate key had Loctite on the surface facing the crank. There was also a big blob in the slot on the end of the crank, which indicates that the bolt, locking plate key and thus the rest of the clutch assembly was not correctly assembled. I guess that the locking plate key should be flush with the crank end, so the flywheel assembly is perpendicular to prevent it from going all wobbly and shaking.

 Loctite crank (Small).jpg   72.98K   0 downloads

 

I guess everything was tightened to the correct torque, but the key was not set correctly and then everything went south from there.

[Shooter63]

You can save it but you will have to weigh up the costs, if you take it to a machine shop they will probably charge you at least an hrs labour, its a simple job for a machinist to do in a lathe, I personally wouldn't file it as I think its a bit animal but then I have a lathe. You only need to take the lumps off then lap as others have said. I've checked the cost of shipping from the UK to Denmark for the weight and size I think £25.00 will cover postage but then you have to buy the crank as well. Put a wanted Ad on the forum some kind soul may have one.
If you do decide to get it machined and the machine shop does take a fine cut on the taper you have to remember that it will move the flywheel towards the primary gear so will need to machine the rear of the flywheel, normally .5mm off will do the job.

Shooter

[Ethel]

No, if the key bottomed in the crank that's what the would bolt be clamping instead of squeezing the clutch down the taper. Suppose it's possible it was already a bit of a mess & whoever last put it together was hoping  gluing it would help 

[SirBallD]

You can save it but you will have to weigh up the costs, if you take it to a machine shop they will probably charge you at least an hrs labour, its a simple job for a machinist to do in a lathe, I personally wouldn't file it as I think its a bit animal but then I have a lathe. You only need to take the lumps off then lap as others have said. I've checked the cost of shipping from the UK to Denmark for the weight and size I think £25.00 will cover postage but then you have to buy the crank as well. Put a wanted Ad on the forum some kind soul may have one.
If you do decide to get it machined and the machine shop does take a fine cut on the taper you have to remember that it will move the flywheel towards the primary gear so will need to machine the rear of the flywheel, normally .5mm off will do the job.

Shooter

So what you're saying is that if machining the crank and removing a minimal amount of material from the taper, will cause the taper to be slightly smaller in diameter which would cause the flywheel to move closer to the primary gear.

What area of the flywheel needs to be machined? The entire side facing the clutch plate or the opposite side facing the block? I'm sorry for asking somewhat obvious questions, but I'm not really sure how it works.

Is it the surface highlighted here, that needs machining?

 Flywheel surface 1.jpg   47.95K   2 downloads

 

What about the flywheel center hub? If I replace that to remove the uneven surface, does that need any machining too? I would believe that a machined surface on the crank and a new flywheel center hub, would create the maximum mating surface.

[nicklouse]

Just buy a new center
​http://www.minispare...22.aspx|Back to

[Spider]

So what you're saying is that if machining the crank and removing a minimal amount of material from the taper, will cause the taper to be slightly smaller in diameter which would cause the flywheel to move closer to the primary gear.

 

I usually take my time and dress them back with a small file, but leave it slightly proud, then finish it with a Diamond Lap, which will take immeasurable material, it'll only knock off the high spots.By doing them this way, you don't loose the original taper.

Then lap the (new) flywheel or new hub, to it.
 

[Shooter63]

You can save it but you will have to weigh up the costs, if you take it to a machine shop they will probably charge you at least an hrs labour, its a simple job for a machinist to do in a lathe, I personally wouldn't file it as I think its a bit animal but then I have a lathe. You only need to take the lumps off then lap as others have said. I've checked the cost of shipping from the UK to Denmark for the weight and size I think £25.00 will cover postage but then you have to buy the crank as well. Put a wanted Ad on the forum some kind soul may have one.
If you do decide to get it machined and the machine shop does take a fine cut on the taper you have to remember that it will move the flywheel towards the primary gear so will need to machine the rear of the flywheel, normally .5mm off will do the job.

Shooter

So what you're saying is that if machining the crank and removing a minimal amount of material from the taper, will cause the taper to be slightly smaller in diameter which would cause the flywheel to move closer to the primary gear.
What area of the flywheel needs to be machined? The entire side facing the clutch plate or the opposite side facing the block? I'm sorry for asking somewhat obvious questions, but I'm not really sure how it works.
Is it the surface highlighted here, that needs machining?
Flywheel surface 1.jpg
 
What about the flywheel center hub? If I replace that to remove the uneven surface, does that need any machining too? I would believe that a machined surface on the crank and a new flywheel center hub, would create the maximum mating surface.

No its the centre of the rear of the flywheel,adjacent the C clip if you get my drift

Shooter

[Cooper Mac]

As said before, the damage is from fretting, but why?? It would suggest to me that the tapers were not engauged properly ie, there was a discrepancy between the two tapers, or the flywheel wasn't tight enough allowing movement between the two parts, and therefore fretting.

 

Yes the taper can be ground back, but even taking the minimum amount of material off would change the axial position of the flywheel, which may cause other problems.... This would assume that the taper is concentric to the main axis of the crank.

 

I'd recommend binning the crank and getting another one, it will be less hassle in the long run. What condition are the bearing journals in? If they are suspect, or need a regrind, it's time to bin the crank!