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lh150 gearbox, damsel in distress!!!


shazzer

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Hi all im new here ive just replaced the flywheel on my sr3 and reinstalled the gearbox but there is no neutral well very little it mainly goes in forward and straight back into reverse with very little selection for neutral it will go into neutral but i have to really play with the selector to get it in and when it stops the prop the selector is nowhere near the neutral position its almost in reverse please help me driving me crazy. Have i installed properly do i have to align anything? do i have to adjust the clutch? im really struggling, ive never even seen these engines until i bought this boat, help!!!

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6 hours ago, shazzer said:

Hi all im new here ive just replaced the flywheel on my sr3 and reinstalled the gearbox but there is no neutral well very little it mainly goes in forward and straight back into reverse with very little selection for neutral it will go into neutral but i have to really play with the selector to get it in and when it stops the prop the selector is nowhere near the neutral position its almost in reverse please help me driving me crazy. Have i installed properly do i have to align anything? do i have to adjust the clutch? im really struggling, ive never even seen these engines until i bought this boat, help!!!

I'm very curious. Why did you replace the flywheel? Very little to go wrong with a flywheel other than the ring gear wearing out. 

Is the oil level in the gearbox correct? 

No adjustment to the clutch necessary, given there isn't one!

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15 minutes ago, nicknorman said:

Good point and I stand corrected. I allowed myself to be misdirected by mention of changing the flywheel followed by a question about whether this necessitates adjusting the clutch. Sometimes people refer to the drive plate (which will have been swapped over to the new flywheel) as the clutch, but it does not function as a clutch. 

It seems unlikely that unbolting the gearbox then bolting it back on would lead to the internal gearbox clutch needing adjusting though. 

But obviously something is wrong. I'm more inclined to suspect the morse control cable connection as this was probably disturbed. 

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30 minutes ago, Mike the Boilerman said:

Good point and I stand corrected. I allowed myself to be misdirected by mention of changing the flywheel followed by a question about whether this necessitates adjusting the clutch. Sometimes people refer to the drive plate (which will have been swapped over to the new flywheel) as the clutch, but it does not function as a clutch. 

It seems unlikely that unbolting the gearbox then bolting it back on would lead to the internal gearbox clutch needing adjusting though. 

But obviously something is wrong. I'm more inclined to suspect the morse control cable connection as this was probably disturbed. 

Don't know much about this gearbox except that forward is engaged as the default state, and oil pressure is required to get neutral. So whilst I agree with your Occam's razor analysis in general, I suppose another possibility is that removing the gearbox and thus possibly giving it a good shaking and turning it over etc, could have resulted in some sediment being disturbed which now clogs the oil system.

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10 minutes ago, nicknorman said:

Don't know much about this gearbox except that forward is engaged as the default state, and oil pressure is required to get neutral. So whilst I agree with your Occam's razor analysis in general, I suppose another possibility is that removing the gearbox and thus possibly giving it a good shaking and turning it over etc, could have resulted in some sediment being disturbed which now clogs the oil system.

Using that razor thing again, an inch of oil spilt from the gearbox whilst off and possibly lying on its side could also lead to the same symptoms as I was getting at in my first reply, asking if the op had checked the oil level. :)

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As the friction linings wear with these boxes the forward cone clutch will lose its free play and need adjusting. As the astern brake band wears the free play will increase and need adjusting. If the free play is lost on the forward clutch it will begin to slip under load and wear the lining more rapidly. Like riding the clutch on a car. And likewise, too much play free play due to wear on the friction lining of the astern brake band.  Both adjustable once the boxes top plate is removed.

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I replaced the flywheel because whoever had the boat before us had come up with the brilliant idea of cutting away the cooling fins so the engine overheated so i had to replace the flywheel with one that had the fins on, but now the engine runs fine the gearbox decides it doesnt like neutral , but the gearbox was running fine before it was taken apart 

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9 hours ago, bizzard said:

They have a simple dipstick, as does the reduction gear on the back if its got one.

Don't mix them up. The short one goes in the front, the long one in the back

Richard

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Remember these boxes will run in ahead for a few seconds after starting, then as the oil pressure in the box builds up they go into neutral.  This concerns some but is normal, however the symptoms as described do not accord with this being the cause.

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All sorted now.

Oil levels were fine and the oil had been changed using the correct oil to answer Mikes question.

An exchange of pictures revealed the problem.

The gearbox had been removed complete with the adapter when the flywheel was changed.

When put back they didn't realise there was a small peg on the drive shaft from the flywheel which had to be aligned with a corresponding slot in the driving gear in the gearbox. Without this being correctly seated the gearbox didn't get properly driven. they've found this problem, got the gearbox aligned with this peg properly seated and it's working now.

Life is so much easier when you can send pictures, rather than just describing what you see over a phone call!

Sue

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14 minutes ago, Mrs Tawny Owl said:

All sorted now.

Oil levels were fine and the oil had been changed using the correct oil to answer Mikes question.

An exchange of pictures revealed the problem.

The gearbox had been removed complete with the adapter when the flywheel was changed.

When put back they didn't realise there was a small peg on the drive shaft from the flywheel which had to be aligned with a corresponding slot in the driving gear in the gearbox. Without this being correctly seated the gearbox didn't get properly driven. they've found this problem, got the gearbox aligned with this peg properly seated and it's working now.

Life is so much easier when you can send pictures, rather than just describing what you see over a phone call!

Sue

Excellent news and what a good service you provide, well done.

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They got the more confusing result that was possible. In this case, the pump drive gear was still engaging with the pump driven gear, so they got some pressure. Enough to get the gearbox out of forward, but only just. As the drive gear was only driven by friction from an O ring, it was slipping

There is another problem possible, where the pump gears don't mesh and you get no pressure at all. Then the box sticks in forwards.

Devious little beasts, these LH150s

Richard

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5 minutes ago, RLWP said:

They got the more confusing result that was possible. In this case, the pump drive gear was still engaging with the pump driven gear, so they got some pressure. Enough to get the gearbox out of forward, but only just. As the drive gear was only driven by friction from an O ring, it was slipping

There is another problem possible, where the pump gears don't mesh and you get no pressure at all. Then the box sticks in forwards.

Devious little beasts, these LH150s

Richard

 

Remind me, what sort of gearbox are we having on Jennifer Gleniffer?

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1 minute ago, Mike the Boilerman said:

Oh I thought we had, but I'd forgotten. 

I have a Velvetdrive 1:1 here in my living room if you think that would be suitable. Shall I bring it to Braunston?

I have a big Parsons box that looks ideal

Richard

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11 minutes ago, RLWP said:

They got the more confusing result that was possible. In this case, the pump drive gear was still engaging with the pump driven gear, so they got some pressure. Enough to get the gearbox out of forward, but only just. As the drive gear was only driven by friction from an O ring, it was slipping

There is another problem possible, where the pump gears don't mesh and you get no pressure at all. Then the box sticks in forwards.

Devious little beasts, these LH150s

Richard

I had forgotten those details. The last time I worked on a Lister box was at least 15 years ago, and it was just changing cone clutches as I remember it.

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3 minutes ago, RLWP said:

I have a big Parsons box that looks ideal

Richard

 

That doesn't sound very hydraulic.

The mechanical box under the back cabin floor in Reg turns out to be no better than the Gleniffer box at engaging astern. Are all mechanical boxes like this?

Prolly best to discuss at Braunston...

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