Mercury blueband 850, shift shaft came out of lower unit

crazymac680 · 10 June 2010, 19:11

Hi guys
I'm hoping you can help me. I've spent all afternoon reading and not managed to find anyone with the same problem as me. While changing my waterpump everthing went smootly. However I realised it was stuck in forward. I have now realised that my shift shaft should not have come out of the lower unit and now with the lower unit off I cant get the gears to change. The shift shaft just seems to spin.
When I push the shift shaft as deep as it goes. It spins by hand easily but not changing gear. When I pull it out about a cm, it turns with resistance but it's not coming out of forward.
I've tried spinning the prop while turning the shift shaft without feeling any difference
Does anyone have any ideas? I really dont want to have to strip the gearbox as I dont have the tools for that job.
Thanks in advance for any help

Nos4r2 · 10 June 2010, 19:23

Do you mean the splined shaft came out leaving a hole into the gearbox?

crazymac680 · 10 June 2010, 19:37

Yeah afraid so Nos.

Nos4r2 · 10 June 2010, 19:38

Gearbox strip to fix I'm afraid.

crazymac680 · 10 June 2010, 19:47

lol I really hope your wrong mate. Just got a pretty awesome step by step guide. I'll paste it here for anyone else who has the same problem

There is constant pressure on the shift cam, via the shift plunger and spring-loaded shift clutch.

When the shift shaft pulled out of the gearcase, the plunger pushed the shift cam out-of-position. So when you stick the shaft back in the hole, it's just hitting the top of the cam (or bottoming out on the structure inside), instead of going back in the splines.

To fix this without disassembling the gearcase, you'll first need to drain out all the gear oil.

Then remove the shift shaft bushing/seal assembly so you can easily see down the hole where the shift shaft goes. The bushing has right-hand threads and just unscrews. You'll need the special tool to fit the slots in the bushing, or grind an old socket to fit.

Spray some carb cleaner down there to wash away any residual gear oil, be sure you keep the drain plug open to let the excess out.

Grab hold of the prop and turn it in the direction that it ratchets - clockwise.

Note that right before the next 'click', you'll feel a bit of resistance, then the 'click'. What's happening is, the beveled edges of the shift clutch are riding on the corresponding edges of Fwd gear. As you turn the prop, spring pressure forces the clutch against Fwd gear.

The click you hear is the shift dog suddenly moving from the top of one edge or 'ramp' on the fwd gear, to the bottom of the next.

As the clutch 'climbs' the ramps, it moves back slightly in the gearcase. This takes pressure off the shift plunger and will allow the shift cam to be 'jostled' back into position.

So, once you've got a feel for how the clicking works, turn the prop and stop just before the next click. When you feel that slight resistance.

Then, peer into the shift shaft hole with a strong lite. You may see the shift cam and the center splined hole looking at you.

If you don't see anything, give the gearcase a 'bump' to and fro, side-to-side, and you should see it come into view.

The goal is to get the splined hole in the shift cam centered so you can reinsert the shift shaft.

Soon as you get that hole lined up, get that shaft back in there!

You'll probably have to do this a few times 'til you get it just right. And the prop might come off the 'ramp'.

No Worries, Mate, just set it up and try again. The shift cam is pretty much captured in its little space. It can't do much more than move around a bit.

Note that you'll see a groove towards the top of the shift shaft; there's supposed to be a clip installed there. When the shaft pulled out, the clip was left behind. If you see the clip, use a magnet to get it out. If you can't see it, it's probably fallen inside the lower unit. In that case I'd definitely use a magnetic drain plug and likely that'll catch the clip.

You can go to an auto parts store and get a "C" clip which will hold much better than the factory spring clip. Just take the shift shaft with you to get the right fit.

Well, that's about it, HTH & G'luck.......ed

9D280 · 11 June 2010, 07:50

Just before you go dismantling evetrything (and I should add I'm asking this off the top of my head based on my investigations as to what I could get an old PT unit off for mine) but I think there are great similarities beween the 850 & the 650 / 600, in which case does your shift shaft push / pull or rotate?

If it rotates, those splines are meant to come out. On reassembly you engage Fwd up top and reassemble. The gearbox defaults to forward in the absense of the shift shaft to hold it anywhere else.

If it's a push / pull design, ignore this!

crazymac680 · 13 June 2010, 22:49

Quote:

Originally Posted by 9D280

Just before you go dismantling evetrything (and I should add I'm asking this off the top of my head based on my investigations as to what I could get an old PT unit off for mine) but I think there are great similarities beween the 850 & the 650 / 600, in which case does your shift shaft push / pull or rotate?

If it rotates, those splines are meant to come out. On reassembly you engage Fwd up top and reassemble. The gearbox defaults to forward in the absense of the shift shaft to hold it anywhere else.

If it's a push / pull design, ignore this!

The shift shaft is a rotating type. The shaft should have stayed in the gearbox and it should have split at the coupling. I disasembled in forward and reasembled and now the gears dont change.
Thanks anyway

9D280 · 14 June 2010, 10:50

Ah, now it makes sense.

crazymac680 · 15 June 2010, 04:56

Managed to make my tool yesterday before I came on night shift. I went round all the local garages and they all recomended that I just make one out of a socket. So I forked out for a grinder, vice and 4 x 23mm sockets. My first attempt came out pretty good after about 10min of grinding. I just need to get an attachment for my impact driver on the way home from work and I'll give it a try. Hopefully all goes sweetly
Dan

Nos4r2 · 15 June 2010, 14:29

It'll be nice if it does. However, isn't there supposed to be a circlip inside the box that holds the shift shaft in? How are you going to refit it if there is?

crazymac680 · 15 June 2010, 21:27

It's all back together and running again. Really chuffed all thanks to Emckelvy(iboats).
Thanks a lot
I searched high and low for the shift shaft bushing removal tool and needed the boat ready for the weekend so couldnt wait for it to come via postage. So I forked out for a grinder a vice and 4 x 23mm sockets. Thinking that there is no way I would manage to make this first time. However within 15min I had a good tight fitting socket that fitted my impact driver. Gave it a couple of firm taps and it loosened up. With the gearbox oil already out and bottom plug out. I poured in some clutch fluid so I could see what I was doing. I turned the prop in the clicking direction(clockwise) until just before the click to take the pressure off. I still wsnt exactly sure what I was looking for, so picked up the gearbox and had front of the gearbox pointing to the sky with the driveshaft horizontal. Gave it a shake and the cam slid into view. I held it there while a friend replaced the shaft. I then placed the bushing over the shaft and tighten it up with a couple of screwdrivers and a a few taps with the hammer. On my own now I set at putting the gearbox back on. For some reason I decided to put it back on in neutral but couldned get the driveshaft to line up. Lowered the driveshaft and the damm shift shaft came out again. This time I had it back in the gearbox in about 5 min on my own. Tried again with the gearbox and controls back in forward. This helps a lot since you can move the driveshaft to match the engine.
Little by little I'm getting braver. I think I might try a gearbox rebuild in the winter. Even with the gearbox off I cannot engage reverse. Not a big deal since I've been without reverse for 4 years
Thanks again
Dan

crazymac680 · 15 June 2010, 21:30

Hi Nos4r2
Yeah it's not ideal without the circlip. Thats why It came out on me again but once you know what your doing its not to much of an inconvenience. I'll refit it if I ever try to get a reverse gear
Thanks
Dan

stuee · 05 September 2013, 10:11

I know its an old thread but im pulling my hair out, i really dont want to try pull the box to pieces as i think it might open a can or worms.

I have attached a photo of what i see down the hole of the shaft, i removed the circlips from in there and its all clear, the pink bit i see move about 1mm when i turn the prop in the gear stiffness then turn the other way slightly, but the pink bit just doesn't seem to move anywhere even when i put the prop in the air and tap the casing with a rubber hammer.

Any suggestions also its a merc 1000 1964 v6

thanks

9D280 · 05 September 2013, 15:14

Stuee, Welcome to ribnet!

Not so sure about what you have there (it's been forever ago since I took mine apart, and yours is (I suspect) the next size up, even if it is the same basic idea...)

Have a clicky on this & see if the pics shed any light?
Mercury Outboard Parts by HP / Serial Range

Hopefully someone welse will come along soon & add something a bit more useful than that.....

Nos4r2 · 05 September 2013, 16:02

yep, or hop over to iboats.com's forum and have a chat to a guy called Clams Canino. He's very very good with antique mercs.