Stern Drive alignment issue

moneyhole · #1 04-17-2011, 06:32 PM

I had a fellow that brought over a nice clean Alpha l unit I was going to buy today and run on my boat. Before he got here, I proceeded to remove to upper portion of the stern drive and after taking off the 6 bolts, I had to use a rubber mallet 6-8 times on the upper most top portion (eye hook) to get my old unit out. All looked well in there as the in-line 6 was installed in late '08. When the guy got here and we tried to fit his complete outdrive, we could not get the splines to line up. Actually never got his lower unit to "seat" into position - the bolts only went maybe 1/4" through the sterndrive holes. As I read into the manual some, I'm thinking my engine may be slightly to high mounted in the rear.
Shouldn't the unit slide in & out with relative ease. Am I doing something wrong. We fought slidinging it back & forth for 2 hours, then I had to take a break....man my back just gave out. Tried sliding my old unit back in and it did the same thing...it's hitting or binding slightly on the top housing of the driveshaft.
I can't see how in the world you can get wrenches in there to adjust the aft ( front) motor mount.
I give ????? I don't know what to do. Nothing has gone smooth since I got this boat- it has a cheap price tag on it right now!!!!

p.s.- it ran with the old unit on - would shift fine, that's when I found out the water pump was bad and then discovered the JB Weld...... That's when I knew I was a sucker.......

chumbucket · #2 04-17-2011, 06:58 PM

Sounds like you need to get your hands on a spline alignment tool. You'll wrestle with that thing for days without the correct alignment.

spareparts · #3 04-17-2011, 08:39 PM

First thing you need to know is any time you pull the drive off or install a drive is to have hte gear shifter in the full fwd position, this aligns the shift cable end with teh shift arm that turns the shift shaft in the bell, that turns the shift shaft in the lower unit(lots of shafts). the point where the shift shaft in the bell and the shift shaft in the lower, connect, the coupler must be pointed fwd, this will happen when hte shift cabel adn the lower unit are both in fwd position.
Second thing, check your engine alignment, most shops will rent you the tool to check it. Worse comes to worse, after you read the next step, you will have a spare input shaft that you can use to check aligment. It should slide in, engaging all the splines. Look at teh grease left on the splines to gauge which way the engine will have to change. Check it in more than one engine rotation position.
Third, the drive shaft on your Alpha is too long to replace the straigt 6 drive. Compare the input shaft lengths, you'll see the Alpha one is longer( they standardized them when they designed the Alpha). You just need to remove the end yoke(the splined end) by dissasembling the u-joint, be carefull and you can resue the u-joint if the rollers and trunions are in good shape. Just remove the c clips, tap the yoke o one side so the u-joint cup comes out, repeat the process for the other side. This is where you end having a spare yoke

moneyhole · #4 04-18-2011, 09:14 PM

thanks for the pointers, I did have her in drive. I think when these fellows put the engine in before I got it, simply got lucky enough to get the splines together, I think its off 1/8" +_
I'm going to use your advise & see if I can get an alignment tool. Then find someone small, without arthritis and get them to adjust those motor mount bolts. LOL

spareparts · #5 04-19-2011, 06:24 AM

make sure you check the length of the input shaft, it should be differnt between the Alpha upper and your old upper.

moneyhole · #6 04-19-2011, 03:52 PM

your 100% correct on that one too, spareparts...the 6 cyl 165hpmerc engine with a MR or M1 outdrive as some refer to it has a 8" shaft while the Alpha's have a 9 1/4" shaft. I measured and have over 10" until I reach the motor. Will there be any problem running an Alpha with the longer shaft? Or is it just best stick to the OEM specs and be safe. What's your though on the shaft issue?
Thanks again for everyone's advise!!!

spareparts · #7 04-19-2011, 06:04 PM

swap the shafts out

cfelton · #8 04-19-2011, 06:42 PM

Hey Moneyhole, If you have a machine shop close by I've got the measurements for an alignment shaft if ya need them! I'll try and find them. I had one made at the shop at my last job for free. Works great!

moneyhole · #9 04-20-2011, 09:42 PM

all help is appreciated...I have a shaft here I could weld given correct measurments and design, so yes, I'd appreciate your help.