War with lower unit

[Yesterday]

Re: War with lower unit

Thanks mate.
Both the original and my replacement are metallic. 210 ft pounds if I recall?

 

[Bosunsmate]

Re: War with lower unit

Thats a whole lot of torque, are you sure about that?
The flywheel to crank is only at 85 foot pounds itself
Dont want you cracking it
My Mercury Master Service manual doesnt provide a torque value, it says to check gear lash-
"Check gear lash by pulling out on driveshaft and pushing in on prop shaft.
Rotate drive shaft very lightly in both directions to feel gear lash. No more than .006" to 0.008"play Add or remove shims to obtain proper mesh."
I just tightened mine tight. It slipped in reverse so i straight away tightened it again. And then again after i had being out and its being fine ever since

 

[Yesterday]

Re: War with lower unit

Hmmm I'm quite sure I had read that in another thread somewhere and I assumed (I believe it was Moody Blue's post) he actually meant the pinion nut, but then I came across the torque in a manual for my motor specific and it was the spanner nut. My heart sank! To me that's a ridiculous amount of torque for most anything but... I will double and triple check myself before I torque it. I haven't done it yet because for me that's going to be one of the last steps.

I didn't check the lash, I basically just reassembled everything as-was. Reading what you've included concerns me. Which shimms are we referring to? There weren't any I was able to access during this rebuild which made me wonder from get-go. pulling "out" on the drive shaft? as in towards the power head?! We're not looking for up/down play here but rather within the gear mesh itself right?

 

[Yesterday]

Re: War with lower unit

OK I'm going to explain my concerns and perhaps you can tell me if I have some new issues to content with. When I pull up on my drive shaft, I think the upper drive case bearing is tapered because it feels as though the bearing separates a little. there is no play when the drive shaft is pushed down, but when it's pulled up (about 1/8th of an inch!) the shaft develops a fair bit of play to it which would make measuring the lash (Ive checked how to do this) a bit difficult or imprecise. Do I have an upper bearing issue?

 

[Bosunsmate]

Re: War with lower unit

The shims would i think refer to the ones between the bearing carrier and the cover nut you made that tool for. I had three on mine, some have none, i dont think its a major but perhaps it might be, the 210ft pounds just sounds a very big amount to me
The top of the drive shaft has (well on mine) a pin and a spring which acts against the bottom of the crankshaft which keeps the drive shaft pressing down.

 

[Moody Blue]

Re: War with lower unit

Here you go, from the manual.

 

[Moody Blue]

Re: War with lower unit

Hmmm I'm quite sure I had read that in another thread somewhere and I assumed (I believe it was Moody Blue's post) he actually meant the pinion nut,

Nope, pinion nut torque value is 70-80 Ib-ft.

 

[Yesterday]

Re: War with lower unit

Nope, pinion nut torque value is 70-80 Ib-ft.

Ahh It was your thread too wasn't it?
Well there I can consider myself tripple checked. I was quite sure I had read (after the fact) that it was indeed the spanner. Thanks for the confirmation. Now I'll dig into that upper drive bearing and hope it's actually OK.

 

[Moody Blue]

Re: War with lower unit

I went thru the lower unit rebuild a few years ago when I had to replace a badly corroded driveshaft. I ended up replacing bearings, shift cam, clutch dog and reverse gear as well. I'm going by memory and that's not my strong point but I'll put this out there for discussion sake.

Since your driveshaft has the spring loaded "preload" pin, you can assume that the upper bearing in the lower unit is a tappered roller bearing. As such, without any preload on the driveshaft (from the preload pin), there will be axial play in the driveshaft. Once the lower unit is installed onto the motor, the preload pin pushes down on the driveshaft forcing the tappered bearing to seat properly. The method for measuring backlash differs depending on the type of upper bearing and driveshaft used.

There were a number of different combinations of bearing types and gear "cuts" used in the early lower units. There were left-handed bevel, right-handed bevel, and straight cut gears. Tappered roller bearings were replaced with ball bearing type upper bearings. When the ball type bearing was used, there would NOT be a preload pin on the driveshaft. Preloading would then be determined by shims under the lower waterpump housing.

 

[Yesterday]

Re: War with lower unit

Mine's definitely a preload pin type and also behaves very much as a tapered upper bearing. I read your old thread (yes I found it!) here:
http://forums.iboats.com/mercury-ma...embly-1971-merc-800-update-photos-401704.html
And now I'm half convinced before I can do this I'm going to have to replace the shift cam because it behaves oddly when I try these lash tests.

 

[Streffpilot]

Re: War with lower unit

How well did your tool work???? I need to make one for my lower unit. I may copy your setup if yours was successful for you.

 

[jimg984]

Re: War with lower unit

streffpilot try advance auto parts,,,, look at their water pump tools $16.95 take a carrier bearing housing nut with you to size with

 

[Yesterday]

Re: War with lower unit

OK so the power head is back together in one piece with the crank seal sleeve in place and new lower crank seals. All I am awaiting is a shifter cam to finish re-assembly of the lower unit with a complete seal replacement. Thanks to all who've helped me out, and here's to hoping this thread will be a resource for others on the same path.

 

[Yesterday]

Re: War with lower unit

@Streffpilot :
Works like a top! If JimG's suggestion fails you - you cant find one or whatever. If you want/need higher resolution pics let me know. Note: I will get to use it again to take it apart once more! grrr! LOL

 

[Yesterday]

Re: War with lower unit

Thought I would post come pics of the crank with the seal sleeve (saver) installed.

Note the nasty corrosion on the bottom of the lower end cap. Thankfully it had not effected anything inside or beyond the seals, nor around the seal seats. I debated getting that built up with weld some, but that's for another time.

 

[Yesterday]

Re: War with lower unit

Now I have a couple of general questions Ive been pondering and any input available is more than welcome!
I will soon be reassembling all of this motor and I've been wondering what to do about the drive shaft corrosion. I've gone ahead even before seeking advice with this first bit but would be interested in hearing what others think. I decided to get a can of galvanizing spray paint (high zinc solids) and paint the shaft. I had thought about encapsulating it in a long heat shrink tube, but thought that could cause issues removing the LU again, as well as possibly trapping salt water in and making things worse. Any thoughts on the paint choice? Can you see this causing any issues? Should I (carefully) do the shifter shafts as well?

I will also similarly be re-assembling the motor swivel/tilt mount which was also, a bloody mess. Everything stainless/aluminum was frozen solid together and had to be cut & drilled out. I've also wondered about coating the steel pipes which come in contact with aluminum on this assembly, with the galvanizing paint. After removing the corroded materials, theres plenty of clearance for a decent layer.

Any thoughts/input/speculation is greatly appreciated.

 

[Yesterday]

Re: War with lower unit

To answer my own question such that others might find it of some value, I checked into this a little. Zinc and Aluminum have a very low threshold of reactivity when it comes to galvanic corrosion, so they two basically won't 'react' with each other. Since clearances are not an issue here for me I've reached the conclusion that it can only help my situation. It does however mean I can not use any oil based top coats over that paint. The shift shaft (see earlier pics) is getting the same treatment as well!

Anyone who's curious about it can check out Rustoleum cold galvanizing compound. I paid less than $10.00 for a rattle can of this. It's an expoxy based carrier and claims to be %93 zinc solids.

 

[Yesterday]

Re: War with lower unit

Long awaited update:
Shifter cam finally got here and is installed. The spanner nut tool performed like a gem though getting 210 ft lbs of torque on this was an effort. Next up: Water pump (have an entire replacement on hand) and then some work on the hydraulics. Never an end to these projects it seems.

 

[Bosunsmate]

Re: War with lower unit

Whyd it take so long to get a little cam?

 

[Yesterday]

Re: War with lower unit

Whyd it take so long to get a little cam?

I'm not sure why it took 6+ weeks. I suspect it was back ordered but they were certain it'd still come. I didnt mind as long as that was for certain. Cam's in and L/U fully assembled now. Water pump installed. Power head's all ready. All I need to do is sort the hydralics and I should be good to go. The 40HP is also off of the boat, so it's sitting patiently.