reverse gear not engaging - cable or bearing?

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superboots

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I have a VP/hurth mechanical gearbox series 250 which has done about 1250 hours. Reverse gear does not engage smoothly - it slips - when the control is activated although if the lever on the gearbox is rotated further by hand it fully engages. There is no problem in forward. Is this a cable problem - stretched perhaps or is it - as has been suggested to me - a bearing problem. What's the remedy?
 
Sounds like cable to me. If you can engage the gear by moving the lever on the gearbox, you should be able to adjust the cable to make it do it for you :)

(I could be wrong, but it's what I would try first.
 
Richard10002 said:
Sounds like cable to me. If you can engage the gear by moving the lever on the gearbox, you should be able to adjust the cable to make it do it for you :)

(I could be wrong, but it's what I would try first.
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+1

Try adjusting the cable before anything else but if that fails to sort it, disconnect the cable and try engaging both ways by hand. If it then works OK, you may have a problem with the morse control.
 
A cable problem is the easier to cure. I remember that the gear selector jammed and it took some force to free it up. I wonder if that could have stretched the cable. Unfortunately there is no adjustment possible on the cable - without changing the bracket.
 
superboots;5715560I wonder if that could have stretched the cable. Unfortunately there is no adjustment possible on the cable - without changing the bracket.[/QUOTE said:
Doubt you stretched the cable, but part of the mechanism may have distorted. Unusual to have no adjustment. Sometimes the gear actuator lever on the box has more than one position: if so, that may offer you the range of movement you need. For many boxes the minimum amount of lever movement is specified. Less than this can lead to long-term problems.
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Normal method of adjustment is the threaded end on the inner cable
Check that the clip securing the outer is engaged in the groove
 
Dont know how relevant this is, but I had a similar issue with a Yanmar mechanical box with a cone clutch. The clutch wears over time, particularly once it starts slipping. The first stage cure is to re centralise the action of the cluthc lever ie ensure that there isnt excess pressure when in forward and insufficient in reverse. Eventually I had to get an engineer to re-shim the action after which I used oil with less lubricity. Yanmar had changed their recommendations from engine oil to a lighter oil anyway.

In your case if you jammed it in reverse and had to use force to get it out, then it could be that you have bent the selector mechanism rather than just wear. But its all pretty simple so best take the box out and take it to bits to see whats happening.
 
superboots said:
A cable problem is the easier to cure. I remember that the gear selector jammed and it took some force to free it up. I wonder if that could have stretched the cable. Unfortunately there is no adjustment possible on the cable - without changing the bracket.
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Normally the cable adjustment is on the back of the remote control lever. check you haven't bent or damaged something on the lever mechanism.
 
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FulmarJeddo said:
Normally the cable adjustment is on the back of the remote control lever. check you haven't bent or damaged something on the lever mechanism.
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Is it? On all the installations I've seen, the adjustment is at the other end of the cable, where it fits on the gearbox.
 
Yes. No adjustment at the control end. Adjustment is usually at the gearbox end of the cable plus on some boxes a choice of holes on the lever itself.
 
Richard10002 said:
Easy for you to say :) The thought of it frightens me to death!!
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Well dont be. Its simple common sense. When I had the same problem in Spain, I took the box out of the boat and took it back to the UK in hand luggage ( possible at that time) where an outfit called Cellar Marine shimmed it for me. And I'm no mechanical genius.

A boat gearbox is a simple mechanism with just one forward and one reverse. I once stripped an automatic gearbox , a BW35, to see how it worked and that took me some time to get back into the car in working order. A month if I remember right.:o
 
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What oil is in the gearbox.
When I had a problem like this with reverse gear being very slow to engage, and consequently slipping, I changed from the very slippery ATF Dexron III oil that Volvo had recommended, to good old fashioned mineral diesel engine sump oil, that previous users had specified and the problem was gone, never to return.
CJ
 
Dont know how relevant this is, but I had a similar issue with a Yanmar mechanical box with a cone clutch. The clutch wears over time, particularly once it starts slipping. The first stage cure is to re centralise the action of the cluthc lever ie ensure that there isnt excess pressure when in forward and insufficient in reverse. Eventually I had to get an engineer to re-shim the action after which I used oil with less lubricity. Yanmar had changed their recommendations from engine oil to a lighter oil anyway.

Had the same problem with mine recently. Caused the engine to shudder so took a while to identify it.
 
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