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Mike Adams

J2 how much crankshaft float?

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3 hours ago, Mike Adams said:

Mine has a hydraulic drive so it is somehow fixed in forward or reverse and I never use the gearbox! 

Hydraulic drive on a Kelvin - not heard of that configuration before, but you still have the gearbox fitted? my assumption would be that if you fitted a hydraulic gearbox (velvet drive) or an hydraulic drive system pump, then the kelvin gearbox would be removed and the new drive fitted direct to the engine. Do you know why the gearbox was left in place? was it maybe an easier solution to engineer/fit the pump? Like to know a bit more about your system - is the prop shaft in place or do you have a hydraulic motor fitted direct to the stern stub? (like the ARS fitted systems), do you run the kelvin at one speed and use the hydraulics to control your speed or is hydraulic pressure dependent on engine speed. It would be an expensive retrofit so not an option for me but just interested in your experience of using this system.

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4 hours ago, Mike Adams said:

Mine has a hydraulic drive so it is somehow fixed in forward or reverse and I never use the gearbox! 

 

 

In which case this endfloat you have is all the more perplexing. If it is locked in gear the gearbox thrust bearing race should be stopping the crankshaft moving longitudinally. 

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yup it is the Frodsham and it has the original gearbox. I am undertaking a major restoration of the Frodsham but as the engine is going that is a job for next winter. Logic makes me think there is some preload set up from the hydraulic pump but I have not checked.  Not a good week for me as somebody hit the gates on the Basingstoke and I couldn't get to the dry dock and now in France only to find the lock on the river lys is shut for ten days. Such are the joys of boating!

ARS system with two bent axis pumps/motors so just like a solid drive unless you go over pressure.

Edited by Mike Adams
Answer a further point

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Hi Mike, notes from our Frodsham log 1987. A stay bar was put on the engine to stop it rocking at low speeds. We had a muff coupling made to link up the engine shaft and the hydraulic shaft - this proved to be accurately  machined at the engine end but was 18 thou out at the other. This caused a big brass toothed bearing to overheat, grip the shaft and stop the engine.Another problem was the slipping in and out of gear, the flexible coupling kept pulling apart - hydraulic pump too heavy for mounting, a tie bar was put onto the engine cover and that seems to have cured the problem. Hope this is of interest, Pat.

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Thanks Pat. When going over the engine a few months ago I noticed that the stay bar had broken out of the cylinder and someone had tapped a second hole in the cylinder and attached the tie bar to that. Although the engine runs OK when it is warm, it is difficult to start and smokes very badly for a few minutes. I have installed a new engine in the forepeak in front of the engine room driving another hydraulic pump which worked well on a first outing on New Year's day except for having a hydraulic leak which I hope is now fixed. I am now deciding what to do with the Kelvin and I have cut a doorway though from the cabin to the engine room so I don't have to run along the deck and down the engine'ole all the time.

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Installed new head on April 8, 1988, engine only fired on one pot, cracked across valve seals /seats? letting  water into the venturi. £200? direct from Kelvins, last one on shelf !  Pat.

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They found some more after that!  I had two new heads from Kyle Street in about 1991.  £142.37 each Inc VAT.

Still have them?,but they ain't eating owt.

N

 

 

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22 hours ago, BEngo said:

They found some more after that!  I had two new heads from Kyle Street in about 1991.  £142.37 each Inc VAT.

Still have them?,but they ain't eating owt.

N

 

 

I picked up a couple of new “very old stock” K heads, and a water cooled 2cyl exhaust manifold last year from a retired marine engineer on the south coast. All he wanted was a donation to the RNLI, I made a big one. Unfortunately though he didn’t have a barrel, I really need a decent barrel.. If someone has one going spare please let me know! 

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Hi Pat. No, but I have both stripped out all the internals and motored the boat on the shallow Basingstoke and I can say that it steers perfectly and I haven't noted any significant assymetry on the stern. It is quite a fast boat and I suspect the author was going to fast but we have lost a couple of cylinders since then! If you go out of the channel it does pull more to the side more than some others I have steered but I can't see any obvious reason for this - maybe it's to do with the steering position as you have a differnt viewpoint compared to a tiller and the rudder arrangement is slightly different with the fixed forward section.

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Hi Mike, I wonder where the 'missing' cylinders got to, they must have been up to no good in the engine room to produce a J4. Possible reasons for pulling to one side  - prop walk, and the longer than average swim combined with the length of the rear deck overhang. The hydraulic hoses are Volvo and designed for the Volvo tipper trucks, they were provided by Uncle Paul who owned Reliance Tankers of Runcorn at the time and ran a fleet of trucks - the truck racing at Donington was great! Cheers, Pat. p.s. what is your new engine?

Edited by Frodsham
Forgot to ask about engine.

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Pat

I have fitted a Isuzu 4 cylinder engine in the forward compartment coupled to a new smaller voac pump. It doesn't sound as nice as the Kelvin but there is much less general noise and vibration and you can't hear anything from the steering position. Unfortunately I will now be able to hear cursing fishermen as we pass! When I remove the Kelvin we will have space for a permanent berth and now we can walk through the entire boat without needing to go on deck. Removing the roof of the engine room is  a possibility but there are now welded hand rails across the roof access and my engine crane/gantry doesn't have enough hieght to get it out in one piece. If I dismantle the engine in situ I can slide the block though the boat and lift it through the side door.Well that's the plan. I will sent some pictures when the J2 is out. Mike

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Some interesting material here.............couple of points ...a deep grove ball bearing will have some endfloat in the common C3 spec.........next.... clonking in a Velvet Drive may well be the flex plate ,which is often just like a motor car/truck clutch plate without linings........the springs in the cushion centre get worn and loose.....To replace ,you obviously have to separate the box from the motor ,or whatever.........third......about 15 years ago we did some interesting hydraulic drives for a contractor barge set........normal Linde pump,but with a small Linde bent axis motor mounted on a stalk.........a hyd outboard ,as it were...........the beauty of this setup is obvious .....no stern gland ,no rudder ,steering at deck level......and if an obstacle is struck,the whole thing folds back,just like an outboard......but Linde stuff aint cheap,but Chinese knock off hydraulics is..

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