Merc 1000 L/U Reverse Slipping

[bh357]

Reverse is not functioning correctly on my 1963 Merc 1000; feels like it is slipping. When I try to rev it up in reverse, I can hear a faint "ratcheting" sound. I can move backwards slowly if I stay at idle. When in reverse with the motor not running, I am able to force turn the prop by hand, past the clutch dogs. When I try turning the prop with the l/u in reverse, I can feel where it hits the clutch dogs (both directions), but with some effort, I am able to turn the prop further. I have ruled out the linkage as being a problem (the problem is there with the l/u off of the motor). When I had the l/u apart last year, there was slight wear to the clutch dogs (radius of less than 1/8", both fwd and rev).<br />Does anyone have any suggestions, i.e. shift cam and follower, shimming, acceptable wear to clutch dogs, etc.? Forward works great with no slippage. Clutch dog wear is about the same for forward and reverse gears.<br />Thanks.

 

[bh357]

Re: Merc 1000 L/U Reverse Slipping

I opened up the lower unit this evening and took a couple of photos of the clutch.<br />Can you please provide feedback on the amount of wear? Thanks.<br /><br /><br />

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[Laddies]

Re: Merc 1000 L/U Reverse Slipping

That clutch dog is in bad shape, you should be able to find a machine shop that can repair the dog and gear for you we have it done all the time

 

[bh357]

Re: Merc 1000 L/U Reverse Slipping

Thanks Laddies. Do the forward dogs appear to be in ok shape? Also, would this be something any machine shop would be able to do, or do I need to hunt someone down who has experience with marine parts? I'm assuming that they would take a little off of the side of the dogs, to get rid of the radius. Is this correct? How sensitive would this part be to balance? Lastly, would this wear be enough to cause the slipping out of reverse, or is the wear a symptom of another problem causing poor engagement of reverse?

 

[Laddies]

Re: Merc 1000 L/U Reverse Slipping

Yes it looks lile fwd will live, rev is pushed it to gear in fwd is sping loaded, thats why rev wears quicker, when repaired remember never to shift that engine it to rev when it's not running as it can twist the shift shaft

 

[bh357]

Re: Merc 1000 L/U Reverse Slipping

Thanks for the advice on shifting into reverse, Laddies. In the past, whenever I shifted into reverse without the engine running, I made sure I was turning either the driveshaft or the propshaft by hand.<br />Where abouts in northern Michigan are you from? I live in SE Michigan. Do you have any suggestions for a shop in my area to have the dogs reground? Is this something that any machine shop can handle, or do I need to look for a specialist (experienced with marine parts, etc...)? Also, what is the typical cost of this repair?<br />Thanks.

 

[Laddies]

Re: Merc 1000 L/U Reverse Slipping

You mght ck with some local marinas (not the office but the shop) they should be having it done some where it the area

 

[Chinewalker]

Re: Merc 1000 L/U Reverse Slipping

I think you can get away with that clutch dog as is. Your bigger issue is likely a shift cable adjustment needed to engage reverse more completely. The slightly crowned over lugs on your clutch dog will not prevent it from entering reverse. They MAY make it want to jump out of reverse if you put a large load on it, which isn't likely in reverse gear. The crowned over lugs also suggest that the motor has been eased into gear for much of its life. These motors need to be firmly shifted into gear with minimal grinding. Adjust the cables at the motor end to make this easier.<br /><br />- Scott<br /><br />- Scott

 

[bh357]

Re: Merc 1000 L/U Reverse Slipping

Thanks for the advice so far. I called a few local shops, and nobody is able to remachine the dogs, or recommend someone to do so. One of the shops I spoke to is even willing to work on the old Mercs, just not remachine the dogs.<br />Is this something that any good machine shop could handle?<br /><br />Chinewalker, I shifted the l/u into reverse, both with the cables disconnected (shifted from the motor), and also with the l/u removed (shifted by turning the shift shaft manually). When turning the prop by hand, I was able to feel reverse slipping. The amount of force required to make reverse slip was the same weather or not the l/u was on the motor, or the cables were connected.

 

[Chinewalker]

Re: Merc 1000 L/U Reverse Slipping

Hi BH,<br /> How does the shift cam look? The reverse lobe is the one furthest from the pivot point on the cam, so if it's worn, reverse would be the first thing lost... Also could be the shift pin in the propshaft is worn.<br /> Your clutch dog should still engage the reverse gear regardless of the crowned over lugs. The rounded lugs are a problem but not THE problem...<br /><br />- Scott

 

[bh357]

Re: Merc 1000 L/U Reverse Slipping

Chinewalker, here are some photos of the shift cam and follower.<br /><br />

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[Chinewalker]

Re: Merc 1000 L/U Reverse Slipping

Looks to be a fair amount of wear on there. That could be the source of the problem. Probably a good chance that both of those parts were used in later models. Find a good dealer who will let you compare a new one with an old one and you'll know for sure...<br /><br />- Scott

 

[bh357]

Re: Merc 1000 L/U Reverse Slipping

I'll try to get a better photo of the shift cam posted tonight. Do you know how deep of a groove is supposed to be in the shift cam?

 

[Laddies]

Re: Merc 1000 L/U Reverse Slipping

If you look at the wear on the dog and add it to the wear on the gear, I think you will see there is very little engagement surface left to keep the unit in gear. I have seen many without that much wear jumping gear, save alot of time and fix them while the thing is apart. I don't disagree with Scott about the cam and pin possibly being worn I have even shimed between pin and cross shaft in the dog to reach reverse. Also before complete assembly, but with the shaft and cam in place slide the unit up into position and ck the position of the detents on the cam to see if the upper shift shaft is twisted--Bob

 

[bh357]

Re: Merc 1000 L/U Reverse Slipping

Thanks for all the advice so far. As promised, here are some photos of the cam and follower.<br /><br />

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<br /><br />Is the clutch dog repair something that any good machinist can handle?<br /><br />Thanks.

 

[Laddies]

Re: Merc 1000 L/U Reverse Slipping

I think any good machinist could handle it our guy only charges 40 to 50 dollars for the gear and dog, that pin does look like it should be replaced

 

[bh357]

Re: Merc 1000 L/U Reverse Slipping

Thanks Laddies. Are there any major pitfalls to having the dogs machined? I'm assuming that I will have him take about 1mm or so off of the side, and ensure that the cut is radial.<br />You mentioned that the follower pin looks like it should be replaced. Should I replace the cam also?

 

[Laddies]

Re: Merc 1000 L/U Reverse Slipping

It proably wouldn,t hurt to replace them both and the recutting is a simple matter of taking them same amount off each surface to keep them all loaded the same

 

[Clams Canino]

Re: Merc 1000 L/U Reverse Slipping

If need be - send them to Laddies machinist and be done with it. <br /><br />-W