BaysideMarine
Seaman Apprentice
- Joined
- Feb 17, 2005
- Messages
- 35
Right guys,<br /><br />Trying to resolve a shift issue with a 470 Mercruiser. Here is a copy of an email I just sent to Merc's tech department:<br /><br />Thanks for your speedy reply Steve (and thanks also to Jim),<br /><br />Merc's service is unquestionably exceptional. Keep it up guys (and girls)!!<br /><br />Originally, the port engine (when pulling directly on the lower unit shift cable) could engage forward gear correctly but not reverse. Manual manipulation of the linkage junction (intermed. shift shaft and upper shift shaft) would then engage reverse gear correctly. The starboard engine was correctly selecting forward and reverse around 50% of the time.<br /><br />I swapped the drive unit from the starboard engine to the port engine and noted that the reverse gear problem was still evident.<br /><br />I took measurements from the bell housing face to the outer edge of the aluminium casting on the end of the shift cable. The casting on the port shift cable protruded 2mm further out than that on the starboard housing with the cables in the reverse gear position. It would appear that at some time when the cable has been replaced in the port leg it has not been screwed down hard enough.<br /><br />However, would that 2mm I measured not be a problem if the spool inside the gearcase was not worn (assuming it may be)? I note that the starboard engine can engage both forward and reverse when pulling on the shift cable manually although reverse gear is at the absolute extremity of the cable, whereas forward gear is engaged before the end of the cable travel.<br /><br />I have had a good look at the upper shift shaft in both bell housings and also compared it to the shaft in the 485 I have in pieces on the workshop floor. I found no difference in terms of shaft diameter or flare on the bottom piece, although I am puzzled that you say the tolerance was increased in the bottom bush in later years as this is an 85 model and the 470's in the Bertram are 82 model and the tolerance is a lot tighter in the 85 model 485 (with no sign of corrosion evident). <br /><br />I guess all this is pointing towards a worn spool and a worn intermediate shift shaft perhaps in both lower units? I'd just like to get a good feel for the precise location of the problem before I start heating up and pulling apart lower units (and maybe breaking bearing carriers etc) as obviously this seriously impacts the final costing for the customer (who happens to be a friend). <br /><br />What are your thoughts in relation to the shift issues? <br /><br />Kind Regards,<br /><br />Nicholas Hubbard<br /><br /><br />What do you guys think?<br /><br />Cheers,<br /><br />Nicholas
