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Lister SR2 gearbox swap


gregich
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Hi, i have an SR2 engine with an LM100 gearbox, i want to swap this for a hydraulic gearbox as the mechanism is very stiff and heavy and the only way to improve this would be to take the lever through the decking. I have a very dry bilge and would lose this if i do that so looking at hydraulic options. Is this possible and what would it entail.

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Yes it is possible.  AFAIR it is a straight swap with the Lister LH 150 hydraulic box but check with MES ( Midlands) who will probably be able to sell you any parts needed. You have to be very careful with the gearbox pump drive when offering up the LH 150.

 

You could otherwise fit a suitable PRM or other box but that will involve new drive plates, mounting , bell housing and fan intake etc.  Not too difficult if you have a machine shop or if you can find someone who has done it and can remember where the bits came from.

 

N

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It may be easier and in the end cheaper to replace the engine and the gearbox though you would need skin tank/s for cooling a water cooled engine.

 

Sell the boat and buy something more modern, quieter, more reliable, more comfortable?

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7 hours ago, gregich said:

Hi, i have an SR2 engine with an LM100 gearbox, i want to swap this for a hydraulic gearbox as the mechanism is very stiff and heavy and the only way to improve this would be to take the lever through the decking. I have a very dry bilge and would lose this if i do that so looking at hydraulic options. Is this possible and what would it entail.

If the existing gearbox is that stiff, is it perhaps in need of servicing and maybe repair/refurbishment, rather than replacement? 

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13 hours ago, gregich said:

Hi, i have an SR2 engine with an LM100 gearbox, i want to swap this for a hydraulic gearbox as the mechanism is very stiff and heavy and the only way to improve this would be to take the lever through the decking. I have a very dry bilge and would lose this if i do that so looking at hydraulic options. Is this possible and what would it entail.

The levers on these gearboxes are quite stiff and that is how they should be when adjusted correctly. If they move in and out of gear easily the chances are the gearbox would slip. If you were to fit a Lister LH150 (hydraulic) gearbox it would also involve changing the adaptor plate, drive gear and adding the pump drive to the drive gear. The other option would be to fit something like a PRM gearbox but that would involve sorting out an adaptor and drive plate arrangements. You would be looking at one of the larger cast iron PRM boxes as I am guessing your engine is clockwise rotation and with these boxes you can turn the oil pump for either rotation of input. The other thing to consider when going away from the Lister gearbox is the drop of the reduction box, which is quite big. Most newer boxes will have a smaller drop therefore you would have to lower your engine to get it to line up.

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On 05/05/2022 at 03:12, Steve56 said:

The levers on these gearboxes are quite stiff and that is how they should be when adjusted correctly. If they move in and out of gear easily the chances are the gearbox would slip. If you were to fit a Lister LH150 (hydraulic) gearbox it would also involve changing the adaptor plate, drive gear and adding the pump drive to the drive gear. The other option would be to fit something like a PRM gearbox but that would involve sorting out an adaptor and drive plate arrangements. You would be looking at one of the larger cast iron PRM boxes as I am guessing your engine is clockwise rotation and with these boxes you can turn the oil pump for either rotation of input. The other thing to consider when going away from the Lister gearbox is the drop of the reduction box, which is quite big. Most newer boxes will have a smaller drop therefore you would have to lower your engine to get it to line up.

Sounds complicated although not beyond me and possibly quite expensive. It might be easier to redesign the leverage operating the gearbox. It's made from very heavy thick steel. I'm fairly sure it doesn't need to be that built to that spec to function properly. 

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On 04/05/2022 at 20:14, David Mack said:

If the existing gearbox is that stiff, is it perhaps in need of servicing and maybe repair/refurbishment, rather than replacement? 

It's always been the same and has very little use really. 

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On 04/05/2022 at 17:01, Tracy D'arth said:

 

 

Sell the boat and buy something more modern, quieter, more reliable, more comfortable?

Genius 🙄

On 04/05/2022 at 13:22, BEngo said:

Yes it is possible.  AFAIR it is a straight swap with the Lister LH 150 hydraulic box but check with MES ( Midlands) who will probably be able to sell you any parts needed. You have to be very careful with the gearbox pump drive when offering up the LH 150.

 

You could otherwise fit a suitable PRM or other box but that will involve new drive plates, mounting , bell housing and fan intake etc.  Not too difficult if you have a machine shop or if you can find someone who has done it and can remember where the bits came from.

 

N

No machine shop here unfortunately, I will look into the LH150.

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40 minutes ago, gregich said:

Sounds complicated although not beyond me and possibly quite expensive. It might be easier to redesign the leverage operating the gearbox. It's made from very heavy thick steel. I'm fairly sure it doesn't need to be that built to that spec to function properly. 

 

I'm afraid it absolutely does need to be robust, and the force to change gear on those LM100 boxes is always quite high. That's why it has a long lever

 

Richard

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On 10/05/2022 at 08:13, RLWP said:

 

I'm afraid it absolutely does need to be robust, and the force to change gear on those LM100 boxes is always quite high. That's why it has a long lever

 

Richard

The main lever coming off the gearbox shaft is a 30mm diameter solid steel bar stretching about 700mm, I'm pretty sure it doesn't need to be that robust :). You could chuck a hand grenade in there and it would still be intact. I'll try and take some pictures and see if some clever bod can't give me some pointers to improve the set up.

 

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On 13/05/2022 at 14:17, gregich said:

The main lever coming off the gearbox shaft is a 30mm diameter solid steel bar stretching about 700mm, I'm pretty sure it doesn't need to be that robust :). You could chuck a hand grenade in there and it would still be intact. I'll try and take some pictures and see if some clever bod can't give me some pointers to improve the set up.

 

 

That sounds exactly how the lever should be. We rebuild these gearboxes for a living

 

Richard

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Richard is right.  The lever I had had a nasty habit of breaking at the top of the taper that fits into the gearbox operating spindle.   The most spectacular occurrence was when selecting reverse whilst stonking into Stoke Prior lock on a Saturday at about 3 p.m. watched by an assortment of waiting  would-be Black Prince hirers.  The subsequent stop at the top cill was abrupt!

 

I modified it  by making a collar for the spindle, with a hefty  bolt right  through the collar with a tapered middle portion to fit into the spindle then a parallelogram linkage off the collar to an operating lever about 36 in long.  It was still a hard shove to get it in gear.

 

N

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On 14/05/2022 at 20:48, BEngo said:

Richard is right.  The lever I had had a nasty habit of breaking at the top of the taper that fits into the gearbox operating spindle.   The most spectacular occurrence was when selecting reverse whilst stonking into Stoke Prior lock on a Saturday at about 3 p.m. watched by an assortment of waiting  would-be Black Prince hirers.  The subsequent stop at the top cill was abrupt!

 

I modified it  by making a collar for the spindle, with a hefty  bolt right  through the collar with a tapered middle portion to fit into the spindle then a parallelogram linkage off the collar to an operating lever about 36 in long.  It was still a hard shove to get it in gear.

 

N

Sounds similar to my set up.

 

On 14/05/2022 at 18:28, RLWP said:

 

That sounds exactly how the lever should be. We rebuild these gearboxes for a living

 

Richard

Could i replace the bar with some 25mm box section maybe 2 or 3mil thick?

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My parallelogram linkage was mainly 25 mm square by x 3 mm  RHS.  You do need do get the bit that goes into the gearbox spindle the right shaped taper, or you will damage the gearbox spindle.

N

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Surely a remote change mechanism can be devised using a servo motor,or even a handwheel up on deck ,as some of the bigger boxes had.......changing a gearbox seems an extreme expense to cure a minor problem.

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