Alpha 1 Fitting - Leg removal etc...

[dmanmtl]

Due to some damage that occurred to my lower unit recently I am getting ready to make a decision on the best way to repair my drive more permanently than the JB Weld patch that is currently holding everything together.

Pretty simple question here - will any Alpha 1 Generation 2 lower unit fit on my upper ? I assume the ratio is set in the upper portion of the leg. Is there anything I need to be aware of before I make the plunge on a used part (obviously the over condition, seals etc is important).

Secondly, I would like to remove my whole lower unit before winter. I have researched this a bit, watched a couple of videos etc. It seems pretty simple - about 6 bolts and the pin attached to the rams. There never seems to be any mention of things such as the oil line that comes from the reservoir, the speedo cable, shifter cable...from what I can see these do not have to be disconnected or addressed separately and simply reconnect themselves some way when the unit is remounted.

I successfully managed to change my water impeller last spring and was surprised how easy it was - from what I read, removing the whole leg might even be easier than removing the lower unit.

Any advice/constructive comment you can provide would be greatly appreciated.

D

 

[thumpar]

As long as what you have is a Gen 2 you can just fit a new lower on it. Since you asked about speedo tube and lube monitor I would assume you do have a Gen 2. You do need to disconnect the speedo tube. It connects on the front side of the drive in a pocket. If you raise the drive up it is pretty easy to see. The lube fitting is between the drive and the bellhousing and you don't need to do anything to disconnect it. I would recommend pulling the lube monitor hose off and plugging it because it will slowly drain when the drive is off. Make sure you are in forward gear when you take it off.

 

[Watermann]

Easy job, I just pulled my A1 and put it back on after inspection and a recheck of alignment. While the OD is off be sure to grease the U joints, inspect the gimbal bearing and bellows for any water or oil. Get the genuine quicksilver gasket kit for around 8 bucks. A couple of things I've learned doing that job is to put a light coating of bearing grease on both sides of the paper gasket so it will come apart easily the next time. On the water O ring I use a bit of bellows adhesive to hold it in place during reassembly.

 

[achris]

STOP... Right there!

No, not all lowers are the same ratio. There are in fact 3 different ratios used in the Gen II lower unit. GENERALLY, the overall drive ratio is set in the top, but for the 2.4 and 2.0 to 1 boxes, the lower is 14/28 tooth count gears. The other ratios used are 13/21 for 1.81, 1.94, 1.47 and 1.62.... And 17/28 for 1.84, 1.50, 1.32, 1.98 and 1.65...

So, when you go and find a Lower unit, check the ratio, they are NOT all the same....

Chris.......

 

[dmanmtl]

STOP... Right there!

No, not all lowers are the same ratio. There are in fact 3 different ratios used in the Gen II lower unit. GENERALLY, the overall drive ratio is set in the top, but for the 2.4 and 2.0 to 1 boxes, the lower is 14/28 tooth count gears. The other ratios used are 13/21 for 1.81, 1.94, 1.47 and 1.62.... And 17/28 for 1.84, 1.50, 1.32, 1.98 and 1.65...

So, when you go and find a Lower unit, check the ratio, they are NOT all the same....

Chris.......

Woah - Thanks for that Alert! - I have a 2.0 ratio - is the Tooth count marked on the lower anywhere?

Thanks for all your replies - as always fantastic info on this site.

D

 

[achris]

No markings on a lower as to what's inside. There is only 2 ways to determine what the tooth count is.

1. Disassemble and count them. Not always practical, and most owners don't really want to see what's inside their lower, particularly if they are trying to sell it.....
2. Put marks on the drive shaft and prop shaft, put the drive into gear and start turning and counting. This method gives more accurate results as the turns count gets higher.

As far as the results of #2 method go, give the drive shaft enough turns to get the prop shaft to make exactly 3 turns. If the box is a 14/28, that will require exactly 6 turns of the drive shaft... If the box is a 13/21 it will require 4.86 turns of the drive shaft.... If it's a 17/28 it will require 4.95 turns (close enough to 5) of the drive shaft....

As far as the drive is concerned, the 13/21 and 17/28 are completely interchangable. Not even a prop change needed. The history behind the 13/21 is that some owners of the 17/28 complained of lower box gear noise, so Merc introduced the 13/21 to try and reduce that noise... You can see from the overall ratios that there is not a great deal of difference between them.... Hence is you have an overall of, say 1.65 (with the earlier lower), the new lower would only change that to 1.62....

As for that 'gear noise', some one's got some blo...dy good ears. I had a 1.84:1 drive (older 17/28 lower) with my previous 4.3. I now have a 1.62:1 drive (newer 13/21 lower) with my current 4.3MPI. The only sounds I heard on either was the burble of the exhaust...

HTH,

Chris......