Self Steering 'Grunting'

[MagicalArmchair]

Next step, I have that chamber off now, and I note the screws in yellow are very loose, leading to the seam in yellow kind of waggling around.



To get these gears off do I need to use a puller to get the cap (bearing?) in red off?

[Yngmar]

I didn't need a puller for these nor the chain sprocket. Everything just lifted off by hand.

Found my pix from 2017:





Looks like your grub screw got lost - did you look if it's still rolling around under the drive unit somewhere? Also looks like the chain sprocket has been wobbling a fair bit, which possibly was the source of your grunt. Or perhaps it was just fore and aft movement. Also some wear on the shaft? A sprocket fitted with a key shouldn't be wobbling this much.

Did you ever look at the other sprocket up in the binnacle? On our boat you can observe it with the compass lifted out.

The drive unit looks good so far. The interesting bit will be the clutch. You can test it by simply putting 12V on the thinner set of wires. Keep your fingers out from in between 

[MagicalArmchair]

Thank you, those photographs were very helpful. A bit of persuasion with a plastic pry tool and a mallet saw the bearing off.

I have ordered some stainless grub screws to replace the missing grub screw. I haven't had a look at the sprocket on the wheel hub, although I'll likely need to on Wednesday as I'm going for a sail, so I'll need to take the chain off (and live with no autopilot for the trip!).

What should I be looking for when I put 12V through those wires? Whether it engages?

Did you threadlock all the screws when you put yours back together? I've ordered some more bearings also as some that I have removed sound a bit grindy.

[MagicalArmchair]

So half of the hex head machine screws are missing, and note there is a kind of cardboard "gasket" between the clutch body.

The grinding noise that is apparent aloft, is when plate here turns:



Did your plate just drop out Yngmar? This is yet another part that is solid... not sure how I will pull this guy off to get behind it to where the grinding is coming from.

https://youtu.be/IzIMnV9IUAU

[geoff]

That is the clutch plate , sounds like my problem. This is pulled off using the two threaded holes to mount the puller ,mine was quite tight. Underneath the rear of the plate is binding on the body. You may find that just shifting it a few thou will do the trick, I removed mine and found it a bit of a sod to replace. Keep the faith nearly there!! Geoff

[MagicalArmchair]

Thanks Geoff, to remove the material from behind the plate, did you just remove the plate, sand the housing behind the plate, and then replace the plate? I'll go and try and get that sucker off now.

[Yngmar]

The clutch plate probably moves forward when engaged and may not rub on the housing when engaged? Which side are we looking at, the motor side or the output side?

[MagicalArmchair]

That's the output side Yngmar. I fashioned a puller by drilling some holes in a brake caliper tool



Now I am left with the clutch:



And the plate:



Geoff, is the below where you abraded?

https://youtu.be/TraDXKbyXm8

Edit: Or Geoff, was it the below?



Yngmar any thoughts of how to proceed?

[geoff]

Sadly I cant remember which of the two places was rubbing , but in my case I could see evidence of abrasion /heat . It was certainly the plate that you have removed. Geoff

[Yngmar]

Ouch. That's certainly been rubbing! I didn't take my clutch apart this far as mine didn't have any problems in that area.

I wonder if it was always like that or if some wear has caused it to rub - is the shaft having any sideways play due to worn bearings perhaps?

Being on the output side of the clutch, the part with the wear marks will move even when the wheel is turned manually. So it should've made grunting noises with the autopilot off while hand-steering. Perhaps different movements though

Still think you might be looking in the entirely wrong area for the source of the grunt, but you certainly found some issues worth sorting in the process 

[MagicalArmchair]

Thanks Yngmar. So, the bit that is showing friction is on the DRIVEN side of the unit, the side on the right in the below photograph, which is driven by the pancake motor:



Hence it will only show that friction when the drives engaged. That electromagnet should never, ever touch the wear plate, correct? As all its job is to do, is draw the wear plate on the LEFT towards it to engage the clutch. Wear in the bearings (and the fact none of it is screwed together properly!!) could account for how it's now rubbing, causing that friction, making that grinding noise and drawing more current, as its having to drag itself around the electro compass that does not rotate?! Hence Geoff's solution of freeing it, but rubbing it down where it looked like it was making contact should work...?

Electro Magnet:


Back of the DRIVEN wear plate:


And indeed, should the base of the electromagnet, be greased? It is dry at present.

[MagicalArmchair]

Final thought for the day, after the kids were in bed, I thought sod it, did as Geoff suggested and abraded the reverse of the friction plate. Cleaned it all, greased it all, it all felt a lot more free, put it all back together, and when I put the side back on the unit with the electric motor on it, the clutch appears to be "pushed" on and the sprocket that goes to the wheel is no longer free. Now, I can't remember if that sprocket was free when I got it off the boat, but I figure if the electromagnet is off, that sprocket should jolly well be free?

Is there perhaps a spring missing that should disengage the clutch when the electromagnet is not engaged?

https://youtu.be/09ChnCyTjyE

Apart from sanding the crud off the friction plate, its gone back together in exactly the same way as I found it - apart from the fact I have screwed the bolts up a bit more snugly. 

[geoff]

Slacken off the ring of small screws and put 5 or 10 thou spacers between the two sections ,youshould find that frees it . If it does experiment with thickness till just free ,then wake a gasket of that thickness. It sounds as if you have pushed the two clutch bits a bit too close together. Geoff

[MagicalArmchair]

Thanks Geoff - so that explains it; why there is this mad bit of cardboard here, in the below. It's the previous owners rather grubby attempt at a spacer gasket. It also explains why these screws were finger tight - any tighter and they would compress the cardboard. And when I have put it back together, with proper torquing, its locked the whole thing up.



Well, so much for getting it all back together for my sail today. I'll have to drop the chain off the other sprocket and sail with no autopilot.

[Yngmar]

There should definitely be some kind of spring that pushes or pulls the clutch plates apart when not engaged. And one of the plates must be able to move freely along the shaft (or with the shaft).

It could be a flat spring or a coiled one. I don't see anything like that in your pictures. I can't imagine a cardboard piece doing this job very well?

[symphony2]

The manual shows a "shimmed clutch kit" as a spare. Might be worth giving Lewmar a call - I have always found them very helpful.

[geoff]

No spring in mine just a gasket/ shim Geoff

[MagicalArmchair]

Thanks all. I spoke to Lewmar for advice and they said to send it to them for servicing and bench testing 😂. I will find out what their turn around time is, I may still try and get it working for this year and then send it to them over winter. I'm now pretty certain I know what the problem is, my concern is I don't know why the problem exists (why do I need that spacer to replace the cardboard? What happened to make the air gap between the clutch plates disappear and require bodging by the last owner?)

[sy_Anniina]

No first hand experience on this type of drive unit, but my thought of what may have gone wrong in the first place:

- Wear and vibration has caused the small screws holding the clutch together loosening
-> clutch top has some play
-> play = movement on original gasket
-> original gasket worn / ground to dust
-> botched by p.o or the piece of cardboard is the only remaining piece of the gasket

Solution: once working, mount each screw with strong enough thread-lock

my 2c,

Tommi
s/y Anniina

[MagicalArmchair]

I emailed Lewmar with my breakdown of the problem and they said just send it to us and we'll sort it out . I can confirm it is on its way to them now...

I am 95% certain that introducing that spacer would have fixed the 'problem' - my worry was I wasn't sure why that original 'problem' existed that forced the previous owner to hack at the unit with a grinder, use that ridiculous cardboard spacer and not do any of the screws up properly.

With the amount of family sailing (effectively single handing a lot of the time) I do, I need this unit to be bulletproof, so I've opted to send to the experts. Lets hope Lewmar don't just condemn it... 

[Yngmar]

Keep us updated. Especially if you decide to strip down the repaired unit to see how it's supposed to go together! 

[MagicalArmchair]

Ee gads! They've condemned it!

"So the drive has been inspected by our drive team. I'm sorry to say that the conclusion is that the drive is beyond economic repair. They are advising a replacement drive of part number 89300016. You will be able to order this through your local Lewmar retailer."

A cool £2,500 from Lewmar, or this from eBay from a Mamba drive (not a Constellatio Drive, so no shaft), note the different number part number: https://www.ebay.co.uk/itm/174447220005?hash=item289ddd5525:g:2JcAAOSwdJlfah85

I could cobble something together from both, and be left with a spare clutch, pancake drive and gears... or two busted drive units    .

Do I just spend the flipping money? I have responded to Lewmar with shock, awe and horror at their prognosis...

I could get it back and effect my original repair suggestion of introducing the shim to the clutch?

[geoff]

My repair/rebuild seems to have been a success , it is now about 2 years since I did it. As I said your fault sounded much the same as mine , and having freed off the friction in the clutch housing I found the need of a gasket/shim to retain the clearance between the plates . I would just finish off your old unit . Nothing to lose really, and you can buy a lot of goodies for £2500 . Geoff

[Markus]

Ee gads! They've condemned it!

I would seriously consider switching to (Jefa) linear drive in your case: https://www.jefa.com/steering/products/drives/drive.htm

The added value would be that it connects directly to the rudderstock so if all else (cabling, etc) fails it can be still used.

[Mirror45184]

I would go with continuing the repair, the grinding is likely to be due to the loose front plate which would allow the clutch to potentially be off center or eccentric when engaged. Hence it will slide across the driven plate and cause the munching sound.

In this style of electro magnetic clutch there is no spring pack as the driven plate is designed to act as a diaphragm spring. When disengaged there is only a small clearance required. On method to get the right shim thickness for the front plate is to assemble the clutch with a piece of cardboard (cut up a manila folder) and measure the gap between the front plate and housing with a feeler gauge. Cut the right shims, assemble, test and get a nice red wine to celebrate!