Crankshaft wear question.

[dougal9887]

I've just removed this crankshaft and found quite a groove worn by the rear oil seal.
How much of a groove is acceptable? It looks about 15 thou deep. If unacceptable is there any solution?
I've not used this block so can't say if there was any leak here. Pics attached.

Crankshaft rear oil seal wear.

Crankshaft rear oil seal wear.

Dougal.

[oldchieft]

Metal spraying and re-machineing.

Jon the Chief

[types26/36]

I had the same problem and fitted a speedi sleeve to a crank, still have not used it so dont know if it was successful but all the details can be found in this thread.
lotus-twincam-f39/crankshaft-repair-t20092.html

[dougal9887]

Thanks for the link. Should have searched before panicking! Speedi Sleeve looks like a solution.
Dougal.

[512BB]

The rear crankshaft oil seal is very forgiving , so when you get the crank reground, as it appears it needs, have the crankseal area ground down as much as is required to make the whole area flat, and it will seal fine if you fit a new seal.

I estimate you could have that part of the crank reduced by about 50 thou overall before you experience any problems with oil escaping there.

Do not forget to GREASE the new oil seal before fitting the housing over the crank end.

Leslie

[AHM]

Don't forget that the flywheel locates on the end of the crankshaft - Before you add or remove stuff.

[types26/36]

Don't forget that the flywheel locates on the end of the crankshaft - Before you add or remove stuff.

Exactly as I noted at the end of the thread I linked.

[512BB]

I had not forgotten that the flywheel locates on the end of the crank Simon.

I have used cranks that have been reduced by up to 50 thou at the sealing face without issue. There is plenty of meat in that area that can be turned off, without any danger that the bolt threads will become weakened.

However, on a standard size crank, in the area of the seal, the flywheel is somewhat of an interference fit, which obviously helps in locating the flywheel, and securing the bolts. Turning down the diameter of the crank in the area in question, will therefore destroy that interference fit, but as I say, I have used more than one crank that has been turned on that oil seal face, without problems.

And thinking about it, I am sure I have a crank in stock that has been reduced in size so much, it has fractionally eaten into the bolt threads. However, I have no knowledge of whether the bolts possibly loosened in service, as that is how the crank came to me. I shall take a pic and post if I can find it easily.

Now Brian, get yourself up out of your pit and down to the boatyard to retrieve your twin cam head. I am eager to see how a twin cam engine goes fitted to the back of a speed boat All aboard

Leslie

[Craven]

Hi,
My solution to the location problem was add two dowel pins, do this before you loose location by grinding.
Ron.

[rgh0]

I would be very concerned about using a flywheel which is not a light press fit onto the crank due to grinding down the rear crank hub or due wear in the joint . If its at all loose in its fit, it can fret on the bolts and eventually cause a failure. A couple of substantial dowels would help but they are not as good as maintaining the fit on the crank hub.

cheers
Rohan

[AHM]

Leslie,

Another factor worth considering:

With 6 bolts, both the bolts and the holes in the flywheel would need to be made to a tight tolerance for it to ensure good balance. Which would make it expensive and very difficult to assemble. They aren't which means you are compromising balance.

[512BB]

Simon, Rohan, All,

All I can tell you is that I rebuilt an engine in an Elan of mine about 10k miles and 10 years ago, where the crank rear face was turned to eliminate a groove similar to what Dougal shows. The engine had covered 93k miles.

I do not remember by how much it was reduced, I take measurements of everything now, both before and after machining, just out of interest, but it was double dowelled, and if you are using the correct flywheel bolts Simon, they are shouldered and a good fit in the flywheel hole, and to date, have experienced no problems. The engine was balanced at the same time.

I shall report back in another 10 years, or sooner if there are any mishaps, but I do not expect there to be.

Leslie

[AHM]

Leslie,

I fear trying to explain would be futile.

Good that you have it double doweled - why not 4 or 6?

I wish you at least another 10 years of blissful...... Motoring.

[512BB]

How I have gotten through 35 years of Elan ownership without your knowledge and guidance Simon, is a mystery to me. Still learning though, still learning.

Leslie

[Craven]

The suggestion here seems to be, six correctly torqued up bolts will not provide adequate clamping force to stop lateral movement of the flywheel. If this were the case surely it would also follow the flywheel could rotate back and forth under acceleration de-acceleration, causing continual fretting between the mating faces.
When torque from a performance engine overcomes the friction between the crank and flywheel, dowels are added to share the load.
Workshop manual gives :- Flywheel run-out ( Lateral ) 0.004 in Starter Ring gear run-out ( Lateral ) 0.016 in
Ron.