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1977 pre alpha mr upgrade to alpha 1 ?

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doc_2048

Member
Have a 77 mercruiser with mr outdrive ser # 4535567. My mechanic informed me that the clutch assembly in the lower unit is worn causing hard shifting problems.
can i use a alpha 1 lower unit in place of my old pre alpha? Or would i be better of replacing the upper and lower units to alpha 1 if possible
thanks
 
Yes, the lower will bolt right up.A worn gearset or clutch dog will cause it to pop out of gear, not be hard to get out of gear.
Is the shift interupter working correctly
 
The shift interrupt was giving me trouble and the mechanic changed the Intermediate cable. I was out of adjustment on the intermediate cable and was almost not able to mount it on the shifting plate. He could not adjust it and unhooked the shift interrupt and left saying my clutch dog was sloppy and that i needed a new lower unit.
so i guess i better go back to trying to work on this guy myself, i am about ready to upgrade to a later model boat. Got to fix this old girl first. The drive never would pop out. The shift interrupt checked out ok, just was out of position when shifting and killing motor.
 
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That guy dosent know what hes talking about.If a new shift cable is not properly installed and routed it wont work correctly and will activate the interupter. post some pics of how it is routed.
pull the drive and move the brass shift shoe on the drive. It must move freely with no resistance Y,N
remove the lower cable and move the black sleeve , must move freely Y,N
Test the control box by shifting , it must move freely Y,N
 
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Thank you BT For help. I just brought the boat home from the moorage.
On the alpha 1, if you don't mind another question , Would a complete alpha 1 outdrive be a problem installing ,to replace the old M/R drive?
 
NO direct fit

I 100 agree with BT

Your "mechanic is full of it.

I consider myself a somewhat expert on Alpha 1 shifting.

So,

if it is difficult to go into gear then rpms are too high or possible bad cable adjustment.

If once in gear it pops out then as said clutch dog and/or gear engagement teeth are worn and a new gear set is needed.

If it wont come out of gear, then no interrupter switch or nonfunctional/disconnected switch. Or bad cable adjustment. Switch MUST be working for drive to be shifted OUT of gear (forward or reverse) NOT INTO gear........................

If only stalls while going into reverse then either bad short cable or bad cable adjustment 99% of the time.

Many reasons for a drive not to shift INTO gear,
bad cable (s), Bad cable adjustments on either or both the primary shift cable or the short shift cable. Worn cables with too much slack.
Also any one of the shift linkages in the gimbal housing and the drive it self could be worn, or bent or possibly a missing piece. (small wheel on bell crank) seen it!!


So to simply replace a cable and disconnect the interrupter switch, That "mechanic" should find a different line of work...............Maybe Midas Muffler!!
 
Thanks Jack I agree the mechanic was not qualified to work on marine engines, well not the late models anyway. I was pissed off for sure.
My original problem was not going into reverse without a lot of effort and sometimes the interrupt would lag and kill the engine. If i throttled up quickly, in reverse, once it engaged it would stall but not die, not safe way to get reverse. I called a different marina father from my home and he thought from what i mentioned that the after market shift controller may be the problem. This was the owner not the certified merc mechanic he has working for him. I had good luck with them before, they are father out and hoping to find a good mech close to home.
 
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