Ours is slipping in forward - reverse is fine and we have not tried the various adjustment techniques. My guess is we need a new cone clutch. Waterway Marine seems to have ordered one in the last year or so. Our local boatyard is not happy to be working on internal transmission parts. I was going to send it out to a shop in Maine, but they want to know the exact make of the transmission. Learned from Tony (rcouach@aol.com) the UK parts guy (who just sent me gaskets and seals) that he can't get cones but they rebuild the transmissions in Italy for 1745 Euros. I did get my hands on the service manual in a two part e-mail. Erik
What brand of transmission on Renault RC8D
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Many Thanks
Thanks - this was all a little mysterious. We are seeing some oil in the bilge (clear not black) so I bet the rear seal is shot on mine as well. I am also calling Mack Boring in NJ who was last reported to work on these. There is a report of a shimming procedure if the forward cone is worn- does that look possible? Also detailed instructions were given on adjusting the shift linkage via the external plate the linkage attaches to. I think I neeed to replace the cone clutch - $500 was the last reported price for the part. The little engine runs great- I hate to replace it -a new Ynamar is $9000 installed we think. There is another H27 next to ours at the yard with a Yanmar for $5600 - we could buy that one and pull the engine out.
Thanks - this was all a little mysterious. We are seeing some oil in the bilge (clear not black) so I bet the rear seal is shot on mine as well. I am also calling Mack Boring in NJ who was last reported to work on these. There is a report of a shimming procedure if the forward cone is worn- does that look possible? Also detailed instructions were given on adjusting the shift linkage via the external plate the linkage attaches to. I think I neeed to replace the cone clutch - $500 was the last reported price for the part. The little engine runs great- I hate to replace it -a new Ynamar is $9000 installed we think. There is another H27 next to ours at the yard with a Yanmar for $5600 - we could buy that one and pull the engine out.
$500!!!!!
$500 for the cone!!! I bet a good machine shop could turn one on a lathe for a heck of a lot less... Definitely try the adjustment first, just loosen the three bolts on the unit that the linkage attaches to. You rotate whole unit in one direction or the other and retighten. As far as shimming I never heard about it (would like more info though). Maybe some material could be added to the cone or the gears? Also make sure your linkage isn't flexing or anything, and the prop isn't fouled by growth or some line. Don't order a rear seal from Overseas if you need it, it's pretty generic 52mm x 38mm x 7(i think) mm. I now have a spare (I had to order two- minimum). Manny
$500 for the cone!!! I bet a good machine shop could turn one on a lathe for a heck of a lot less... Definitely try the adjustment first, just loosen the three bolts on the unit that the linkage attaches to. You rotate whole unit in one direction or the other and retighten. As far as shimming I never heard about it (would like more info though). Maybe some material could be added to the cone or the gears? Also make sure your linkage isn't flexing or anything, and the prop isn't fouled by growth or some line. Don't order a rear seal from Overseas if you need it, it's pretty generic 52mm x 38mm x 7(i think) mm. I now have a spare (I had to order two- minimum). Manny
Non-Reversable
My recollection is that the double-male cone is threaded at its core so it slides fore and aft on the secondary shaft that is similarly threaded. I don't think it would be possible to reverse it as the threads would go the wrong way. I have a hard time seeing how the cone could actually wear down that much. Seems like the forward thrust of the cone is just being restricted in some way. The adjustments to the linkage seem like the first order of business. If that fails, I would just have a shop take the cone and build it up a bit with a weld rod and then turn it down. $500 seems pretty steep. Good luck, Dan
My recollection is that the double-male cone is threaded at its core so it slides fore and aft on the secondary shaft that is similarly threaded. I don't think it would be possible to reverse it as the threads would go the wrong way. I have a hard time seeing how the cone could actually wear down that much. Seems like the forward thrust of the cone is just being restricted in some way. The adjustments to the linkage seem like the first order of business. If that fails, I would just have a shop take the cone and build it up a bit with a weld rod and then turn it down. $500 seems pretty steep. Good luck, Dan
Got it apart- it's the cone
After much begging our yard took it apart today and the forward part of the cone clutch is worn as is the gear it nests into. Now if Waterway can get the parts.... Or send the works to Italy ($$$) or the weld-rod idea indeed. Thanks for the help everybody we are part way there. They did check the linkage-alignment directions as suggested. There is this "shimming" procedure which might be worth looking into. Erik
After much begging our yard took it apart today and the forward part of the cone clutch is worn as is the gear it nests into. Now if Waterway can get the parts.... Or send the works to Italy ($$$) or the weld-rod idea indeed. Thanks for the help everybody we are part way there. They did check the linkage-alignment directions as suggested. There is this "shimming" procedure which might be worth looking into. Erik
A possibly dumb suggestion
Erik, If you could indulge my interest in all things mechanical, what exactly is it that is worn down? Is the top of the cone bottoming out onto the flat face of the forward gear before the cone faces engage? If the torque is delivered from the cone faces (rather than the truncated top of the cone), does it make sense just to turn a couple millimeters off the top so that it can now snug in a bit further into the forward gear? Just a suggestion, but its a heck of a lot easier to take metal off than add it on. You would have to adjust the shift so that it throws the cone assembly a bit further forward, but that's easy. Best of luck, Dan
Erik, If you could indulge my interest in all things mechanical, what exactly is it that is worn down? Is the top of the cone bottoming out onto the flat face of the forward gear before the cone faces engage? If the torque is delivered from the cone faces (rather than the truncated top of the cone), does it make sense just to turn a couple millimeters off the top so that it can now snug in a bit further into the forward gear? Just a suggestion, but its a heck of a lot easier to take metal off than add it on. You would have to adjust the shift so that it throws the cone assembly a bit further forward, but that's easy. Best of luck, Dan
RC8D Transmission Parts *are* available 
Found out today Waterway Marine - Annapolis -can get the transmission parts. They seem happiest dealing with my boatyard - wholesale. Not cheap, but compared to the alternatives, no worries at all. 017 Renard CT Annapolis, MD 21401 (410) 266-0590 Mack Boring said no they don't work on these. Marine Parts Express said the same thing.
Found out today Waterway Marine - Annapolis -can get the transmission parts. They seem happiest dealing with my boatyard - wholesale. Not cheap, but compared to the alternatives, no worries at all.
017 Renard CT Annapolis, MD 21401 (410) 266-0590 Mack Boring said no they don't work on these. Marine Parts Express said the same thing.- Status