42 replies to this topic

[Cooperman]

Unless it is a Cooper S EN40B crank, then it will be best to scrap it.
The cost of machining would not be cheap and even then the flywheel position is quite critical.
Put a crank and flywheel in the 'wanted' section on here and see what's on offer.

[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
 
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

 

I get it    In my case it would be the flywheel boss that needs .5mm machined off.

So the reason for this is to prevent the flywheel (boss) squeezing the primary gear, so it's unable to rotate freely. 

[SirBallD]

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!  

My guess is as good as anyone. 

I agree that a new crank would be easy and maybe less of a hassle, but it just seems so cumbersome. One thing is to import it from UK with all the taxes and VAT (sigh), the other is what will I get? Will it be a dud? I know that I could go for a brand new shiny crank, but £1000 is way off my budget.

 

By the way I also checked the primary gear end float and I measure 0.126", which obviously is way off. The thrust washer is measured with a venier caliper ~0.115"), and the backing ring (0.157") and c-clip (0.120" measured in worn area, 0.124" in the not so worn area  ) I don't know the specs for these.

 

I'll get my hands on a micrometer and measure the bearing journals. They look smooth and the bearings coming off of it was 10 oversize. The crank seem to be tight and no wobbling, and turning smoothly, with only the friction of the pistons. My main issue seems to be the taper end...for now. I learn new stuff to look for every minute in this project. 

[Spider]

 

By the way I also checked the primary gear end float and I measure 0.126", which obviously is way off. The thrust washer is measured with a venier caliper ~0.115"), and the backing ring (0.157") and c-clip (0.120" measured in worn area, 0.124" in the not so worn area  ) I don't know the specs for these.

 

There's something quite a miss here. If you have all the parts on the crank tail, then even in a very worn state I'd expect to see on a very badly worn set, no more than about 0.012". The adjustment is done with different thickness Thrust Washers, but these only cover a range of 0.022" from memory. Unless you had one made, you won't find one that will shim it around 0.120".

 

The Endfloat needs to be set in the range of 0.003" to 0.006". It's checked using feeler gauges is the easiest.

With the Endfloat you are seeing, I suspect the Top Hat of the Rear Bush has been broken off. Can you post up some photos of your Primary Gear and all the other parts that keep it in place ?
 

[SirBallD]

 

 

By the way I also checked the primary gear end float and I measure 0.126", which obviously is way off. The thrust washer is measured with a venier caliper ~0.115"), and the backing ring (0.157") and c-clip (0.120" measured in worn area, 0.124" in the not so worn area  ) I don't know the specs for these.

 

There's something quite a miss here. If you have all the parts on the crank tail, then even in a very worn state I'd expect to see on a very badly worn set, no more than about 0.012". The adjustment is done with different thickness Thrust Washers, but these only cover a range of 0.022" from memory. Unless you had one made, you won't find one that will shim it around 0.120".

 

The Endfloat needs to be set in the range of 0.003" to 0.006". It's checked using feeler gauges is the easiest.

With the Endfloat you are seeing, I suspect the Top Hat of the Rear Bush has been broken off. Can you post up some photos of your Primary Gear and all the other parts that keep it in place ?
 

 

My bad! I did the measurement again and its 0.0126" (I dropped a zero on my walk from the workshop to my computer 

 

Obviously there is a longitudinal movement, but also a slight transverse movement can be felt. I guess new bushings is the way to go.

 20210426_214108 primary gear accessories (Small).jpg   21.88K   0 downloads  20210426_214438 backing lock c clip (Small).jpg   31.42K   0 downloads  primary gear (Small).jpg   106.18K   1 downloads  Bushing primary gear (Small).jpg   70.27K   0 downloads

[Cooperman]

A good used 998 crankshaft should cost you around £50 to £75. Sure, it may need a re-grind to the next size down, but that's not a big or expensive job.

A Verto flywheel in good condition should cost around £50.

Add shipping at around £50. Is there VAT to pay on second hand imports? I know not, but it won't be a lot.

[SirBallD]

A good used 998 crankshaft should cost you around £50 to £75. Sure, it may need a re-grind to the next size down, but that's not a big or expensive job.

A Verto flywheel in good condition should cost around £50.

Add shipping at around £50. Is there VAT to pay on second hand imports? I know not, but it won't be a lot.

I went on the danish version of ebay and found an engine for sale. In the picture I could see some other parts on shelves so I contacted the seller to see if he by any chance had a 12A1451 crank lying around...and he did. He had actually just pulled and engine apart and had no plans with the crank.

He told me that all the journals are standard size and there is no damage to see anywhere. The tail of the crank was looking good and no fretting.

I asked if he could add the primary gear to the lot and he agreed. 60 quid and I'm on with the project. He even offered to deliver it at the doorstep for free, if I could wait a couple of weeks when he drove past my town.

 

When importing to Denmark you have to pay the danish VAT which is 25% and 3% tax on shipments containing goods for more than £134. I guess that if it's second hand goods, they will estimate the value and then add 25% + 3% tax (>£134). On top of that they put a fee of around £30 for handling. So I agree that it's not that bad...but it's just a little cumbersome.

 

Let see how the crank looks when he comes by with it. Hopefully it's not shaped like a banana 

[SirBallD]

Finally I received the new used crankshaft (12A1451).

In some areas it looks better, but I'm in doubt regarding the surface in the clutch end.

It's pitted on one side. I've tried to polish it but I can still feel the pitting using my nail.

 Crankshaft spots.jpg   46.34K   1 downloads

Would this be an issue?

 

I've planned to have the crankshaft grinded to next undersize, so the next issue might not be as big an issue as I initially thought.

I measured the size of each main bearing journals and it is standard size (1.750").

On the main bearing journal nearest the clutch end, has some marks, which points towards lack of oil supply or dirt?!?

 Crankshaft lines.jpg   37.73K   0 downloads

 Crankshaft spots other side.jpg   64K   0 downloads

I have no idea how to measure the depth of these lines/marks/grooves, so I guess a grind will show.

Should I go on with this crankshaft or should I send it back?

[GraemeC]

The journals should clean up with a grind - at a push they may need to go two sizes under.

 

For a weekend toy, I think the tail of the crank would be ok as long as all the marks are pits and not high spots. Also depends exactly where the pitting is - there is a chance it has missed the primary gear running surfaces.

[SirBallD]

The journals should clean up with a grind - at a push they may need to go two sizes under.

For a weekend toy, I think the tail of the crank would be ok as long as all the marks are pits and not high spots. Also depends exactly where the pitting is - there is a chance it has missed the primary gear running surfaces.

It's pits, no high spots.
The pits are mostly located on one side of the tail, but the pits are on the entire length of the tail.

[stoneface]

If someone sold me a crank like your photos with a statement like "no damage to see anywhere", I'd send it back.

 

[SirBallD]

If someone sold me a crank like your photos with a statement like "no damage to see anywhere", I'd send it back.

I contacted the seller and he agreed to take it back, no questions asked.

He took it well and he even admitted when seeing the pits, when he picked it up, that it was worse than he remembered.

 

Then my "Schutzengel" came to the rescue. A big shout out to MaximMini who offered to send a 12A1451 to me. It was shipped to me and it arrived today. It's in very good condition and now I can continue with the project.

Thank you so much MaximMini, you're amazing. 

 

I guess this thread is solved as "Yup, the crankshaft was scrap!"    I'll transform it to a paper weight or a bottle opener. 

Thank you to all who took time to give their answers and suggestions. I appreciate it very much.

[stoneface]

Marvellous, I'm pleased it all worked out good in the end.