Prop shaft questions

[Laker]

Before I pull my A4 for winter detailing , a couple of questions regarding my prop shaft :

When watching my engine run at idle & neutral , I notice that the shaft rotates slowly. Is it normal for the clutch system , about which I know nothing , has a little bit of contact while the tranny is in neutral?

While watching this slow rotation , I see a very slight wobble in the shaft. It is not enough to cause vibration under load. I disassemled and rebuilt the shaft log and cutlass bearing last spring and all seemed normal. Is a very slight "out of round" common and/or tolerable? I suppose that with the engine out I should have the shaft inspected to see if it is ever so slightly bent. Bottom line , since all is functioning well , should I let this sleeping dog lie?

And , finally , when in forward gear , if I advance the power from a low to high setting the clutch sometimes slips. To avoid this I must keep a forward pressure on the shift lever. Is this likely the result of a bad linkage adjustment , or might it be something internal ?

Considering the fact that I own a sailboat , it sure seems that I put a lot of time and energy into the powerplant...

Laker

[sastanley]

There are some gears spinning around inside the reversing gear that cause that 'wobble'. Try moving the shifter just a little closer toward 'reverse' and see if it stops....I find that I just start to hear the 'reverse whine' when my shaft is not actually spinning..the 'quiet spot' in neutral allows the shaft to spin a little....I try to avoid this to keep from wearing out the cones and other fancy parts I know nothing about inside the reversing gear system.

If the assembly is slipping in forward (are you in the detent?) you may need a one notch adjustment. Do you have the book? I also hear the DVD's from Moyer are great, but I do not own them myself.

[Mark S]

To avoid this I must keep a forward pressure on the shift lever.

Somewhere in the forum is a thread in which Don says not to keep pressure on the shift lever to prevent slippage while in reverse as doing so can damage a bearing which is difficult to replace. I assume one shouldn't do it in forward as well. Adjust the collar one notch and see if that makes a difference. It made all the difference for me when I had similar symptoms.

[Kelly]

Mark S-

Your comment about not applying pressure on the shifting lever in reverse really took me by surprise. I was under the distinct impression that this was necessary to keep the reverse gears engaged, to the point that some skippers lean into the lever with their knee to accomplish this.

Can others help clear this question up?

[Laker]

"Adjust the collar one notch "

The collar...?


"Do you have the book?"

No , but I clearly need it.

[ArtJ]

Before I pull my A4 for winter detailing , a couple of questions regarding my prop shaft :

When watching my engine run at idle & neutral , I notice that the shaft rotates slowly. Is it normal for the clutch system , about which I know nothing , has a little bit of contact while the tranny is in neutral?

While watching this slow rotation , I see a very slight wobble in the shaft. It is not enough to cause vibration under load. I disassemled and rebuilt the shaft log and cutlass bearing last spring and all seemed normal. Is a very slight "out of round" common and/or tolerable? I suppose that with the engine out I should have the shaft inspected to see if it is ever so slightly bent. Bottom line , since all is functioning well , should I let this sleeping dog lie?

And , finally , when in forward gear , if I advance the power from a low to high setting the clutch sometimes slips. To avoid this I must keep a forward pressure on the shift lever. Is this likely the result of a bad linkage adjustment , or might it be something internal ?

Considering the fact that I own a sailboat , it sure seems that I put a lot of time and energy into the powerplant...

Laker

There shouldn't be any shaft wobble provided engine is aligned properly
to shaft. Usually can set this by shimming motor mounts. Otherwise could
be issue in cutlass alignment or problems in output shaft area.


Regards

[sastanley]

Art, you are of course correct...maybe we are interpreting 'wobble' differently. When the reversing gear is quiet, I notice a slight forward spinning on my prop shaft..not usually enough to make the boat move but it is a revolution every second or two...there is distinct vibrating of the shaft as it spins...it doesn't really spin 'smoothly' but the reversing gear continually catches and lets go as it slowly spins the prop around....maybe I have a messed up reversing gear or one of my gears is odd shaped?

I will comment that I have not observed it closely since I did all the prop shaft work and re-aligned my engine..it is possible I was observing the misaligned shaft spinning due to its slow speed.

I've gotten used to the motor enough now that I push the lever back just a bit & barely begin to hear the whine in 'neutral', where I am pretty confident by the sound that the prop is not inadvertently spinning when I am docking.

Laker...the Moyer Manual is worth its weight in gold. If you think you need other parts from Moyer, put together a list and add that to it...Call Ken and get it right away. The 'adjusting collar' Mark refers to is a big washer with notches cut in it..in fairness, I haven't needed to adjust mine so you are asking the wrong guy to explain it.

From what I understand, adjusting the collar would change the tightness with which clutches in the reversing gear engage to eliminate the slipping in forward, which is important..in forward (as the shift lever goes into the detent) there should be a positive 1:1 engagement of the gear set & prop shaft all spinning as one unit...hence, 'direct drive' - if there is slippage, there are loads on various bearings and gears where there shouldn't be since they are not moving as one entity. I would not dig into this type of work without the manual in front of me...I personally think the reversing gear is more complex than the engine itself.

Get the book.

[thatch]

"a4 101"

Laker,
"Buy the book" and then go "by the book".
Tom

[lat 64]

Laker,
I concur with Art.


This thread is about three different things:
1 Shaft alignment,
2 Bent shaft or log,
3 clutch adjustment,

Poor shaft alignment is when the prop shaft is not exactly inline with the centerline of the gearbox output shaft. This will cause vibration.
You need to unbolt the flanges and measure the gap all the way around the flanges. Do this with a feeler gage. This is a matter of a few thousandths of an inch. You can not "see" it. If you can see something wobble, I'm quite sure it's way out of alignment.


If you can see a bent shaft, I'm sure it needs to be fixed. Make sure it is not just a rough casting on the flange that you are interpreting as out of round. I say this because you said you don't have unnecessary vibrations.

The clutch adjustment has been covered many times here. it sounds like yours is a bit off. The only "cone" I know of in the transmission is a bell-shaped ring that the three fingers ride on. The clutch is like a motorcycle clutch pack. It is a stack of discs that run close to each other. Even in neutral, the oil can sort of stick and turn the driven set of discs when the prop is free to turn. This happens when the the lever is not centered between forward and reverse.

Don Moyer has put a sample video up to show the workings of the clutch.
Go to the video section in the catalog and look for the reversing gear video.
The complete vid is only $35.00. "Cheep" as Alfred E. Nueman used to say.

Russ

[Mark S]

Your comment about not applying pressure on the shifting lever in reverse really took me by surprise. I was under the distinct impression that this was necessary to keep the reverse gears engaged, to the point that some skippers lean into the lever with their knee to accomplish this.

Kelly,

See these threads:

http://www.moyermarine.com/forums/showthread.php?t=377&highlight=shift+lever+reverse+bearing

http://www.moyermarine.com/forums/showthread.php?t=3499

In rereading Don's comments, maybe what he's talking about applies only to leaning on the lever in forward. I don't think the throw-out bearing is implicated in shifting into reverse. I had it in my head that he was discouraging leaning on the lever to keep either direction engaged.

I've found that accelerating gradually in reverse, rather than briskly, prevents slippage and it's way easier than adjusting the band.

Mark

[sastanley]

I've found that accelerating gradually in reverse, rather than briskly, prevents slippage and it's way easier than adjusting the band.

Mark

I agree with this 100%...it takes a second or two when you lean on the lever to get reverse fully 'engaged'..revving up early only wears out parts and exacerbates the waiting for a good reverse engagement. - (about 10 months too late on the word game!! )

I engage at idle if I can and when it is 'all hooked up' I increase the throttle.

[Kelly]

Speak of the devil, this quote comes from Shawn:

"you lean on the shift lever a little to keep the reversing gear engaged"

This has been my experience too and as I understand it, the reversing gears do not hold their position once engaged as the forward ones do (detent?). Hence the "leaning"...

[rigspelt]

In http://www.moyermarine.com/forums/showthread.php?t=377
Don wrote, "using a bungee cord (or anything else) to hold the forward clutch assembly engaged puts a continual side load on the "throw-out" bearing of the operating cone. These bearings were not designed for
continuous duty and if they are used in this fashion they will not last very long before failing." He was talking about holding the shift lever in forward, as I read it. I understand him to be saying that the forward detente alone should be enough to keep the transmission properly engaged in forward.

I hold the shift lever in reverse, which I understand is normal procedure. I follow the same procedure as the others of engaging in reverse at idle and then increasing the throttle as needed for increased reverse thrust, while firmly holding the shift lever in reverse.

[Laker]

Good , good. I am sure now that there is a clutch adjustment in my future. Obviously , holding pressure on the shift lever in fwd is BAD. By interesting coincidence , I operate an older model greensmower which has a simple version of the same system - once past the detent , if there is slippage , time to adjust the clutch.

As to the slight wobble , the jury is still out. The east way to start is to inspect the shaft after boat/engine is pulled. The gearbox output shaft also sounds figure-outable. As far as shimming the engine is concerned , I cannot see a practical way to engage in trial and error in that process as it would require lifting the engine and re-setting it multiple times.

Laker

[sastanley]

Laker...in my opinion, it is actually going to be easier to check the shaft in the water...you can't go spinning the shaft around on dry land..it wears out the rubber in the cutless bearing..If you are on the hard, the only practical way I see is to remove the shaft and put it on a machine with a dial indicator. I happen to have a buddy with one, but I don't think your average weekend warrior mechanics like us normally stock one in the garage.

Are the motor mounts 'hard' or 'soft' on your boat? Many of us have the style that Moyer sells in the store which have a stud in the & adjustment nuts on them to raise/lower each corner of the engine which are mounted into hard rubber rubber mounts (vibration reduction)..the mounts themselves have one bolt hole slotted, so you can slide them on the 'rails' for athwartships (side to side) alignment. I had to move all of mine to re-align my engine after the prop shaft wore a hole in my shaft tube. - This would be standard procedure upon re-installation anyway if you pulled the engine or shaft.

Anyway, it sounds like you may have multiple symptoms...let's tackle them one at a time - I'd tackle the clutch adjustment first to alleviate the wear on the throw-out bearing, the slipping and the necessity to hold the lever in forward, then mess with the other stuff.

Here is Ken's number in the parts dept for the book! - 610-410-4436