How much play is reasonable?

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ExcaliburII

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My Bayliner 2255 (Mercruiser 5.0LX, Alpha 1 drive) has always wandered quite a bit at slow speed - in common with most sterndrive planing mobos, I suspect, so I've never thought too much about it. However, I noticed a short while ago that the steering wheel is now turned about 60 deg to starboard when going straight ahead at planing speed, and it never used to be. It doesn't pull to one side and I don't remember any particular incident which caused this, but now it's on the trailer at home I've been having a bit of a poke about to see what's wrong.

There's nothing loose that I can see at the engine end, so I'm wondering if the rack and pinion behind the steering wheel has somehow jumped a tooth. The casing is not loose or anything, but there's about 15-20mm of play at the rim of the steering wheel before any movement at the aft end of the cable is visible. The steering wheel is not loose on the shaft, I've checked that.

So, two questions:

How much play in the rack and pinion would be considered excessive?

and

Does anyone know if it is actually possible for the rack and pinion to slip a tooth without failing catastrophically?
 
I would not of thought a rack could slip a tooth without failing entirely.

Are you sure its a rack and pinion? I would have expected power assisted hydraulic?
 
Best wait for confirmation from the experts who should be along soon but

Isn't there a trim skeg you adjust on the leg just above the prop.

use it as a mini rudder so you steer straight again while on the plane.

The trim skeg also acts as a sacrificial anode and you would expect your trim to change as the anode wears away.

Dont know what the real name is click here to see skeg
 
Thanks for the replies so far, chaps.

Deffo not hydraulic, there's a big cable thingy that goes from the back of the dash down to the transom and connects to the steering arm (sorry, tiller, if any raggies are watching). /forums/images/graemlins/grin.gif It is power assisted, but that's all at the engine end. It works by sensing the reaction at the cable mounting point and pushes or pulls to help. Behind the dash is a big square casing at right angles to the steering shaft, with the cable coming out of the end of it. It is slightly offset from the steering shaft so I can't think of anything it could be other than a rack and pinion.

I must say it seemed a bit far-fetched to me that it could have jumped a tooth without breaking anything, but I can't think of any other explanation for the wheel being out of line, given that nothing seems to have come loose or shifted at the engine end.

I don't think it's the trim tab for two reasons. Firstly, the tab hasn't moved since I fitted it at the start of the season and it hasn't dissolved much either so we can assume it's still working the same. Secondly, when it is incorrectly adjusted you have to hold the wheel quite firmly in the straight ahead position and if you let it go, the boat immediately starts to turn one way or t'other. It's not doing that now; it goes straight OK hands off (more or less /forums/images/graemlins/tongue.gif) but the wheel is not on straight. And, no I haven't taken it off and put it back on wrong. /forums/images/graemlins/grin.gif

Oh, and 10 hours play is nowhere near enough - I'm retired now, so nothing short of 24/7 is acceptable, much to SWMBO's disgust /forums/images/graemlins/laugh.gif

So, thanks again for the suggestions, one and all. Anyone got a Mercruiser with a similar setup that can tell me how much slack there is at their wheel? If they're all like this, maybe I'm worrying about nothing. But if it's going to go twang and leave me with a load of excitement but no steering at some inconvenient point, having some bright spark saying "Oh yeah, mine did that, it was the . . ." when I post about the experience on here would be less than enthralling.
 
You sure your not looking for the problem at the wrong end, sounds like wear in the gimble ring to me. Have someone hold the steering wheel, then move the drive from side to side, if there's excessive movement, then it'll probably be an engine out job. You could try tightening the clamp bolts up, bit if it's badly worn then it's gone past that stage!

New gimble ring is loads of dosh!
 
I had an alpha 1 gen 2 that seemed to have a bit of play in it,more noticable when trying to steer in a straight line due to single prop,is there anybody at your marina that has same set up that you can compare with?

ash
 
I would assume that your rack and pinion steering is made by Teleflex. Do you know if you also have a tilt helm unit. If you have, it is likely that the play is caused ba a combination of a small amount of slack in the rack and pinion together with some play in the universal joint which links the steering wheel to thesteering shaft.
regards
Dave
 
PB thanks for the suggestion but it's not the gimbal ring. When I bought the boat in 2001 the steering arm was all loose and badly worn so I had to fit a new arm and top swivel shaft. There's no slack there now, I can watch the cable at the transom end as I rock the steering from side to side and can see it start to move when the slack is taken up. With someone holding the drive unit I have forced the wheel both ways in an attempt to make it slip or jump, without success.

Kendal - the helm unit does not tilt, it is a solid unit. Apart from the free play at the wheel, the only slackness I can detect is the merest hint of movement where the cable outer is attached to the end of the casing, but it's only a fraction of a millimetre, not the 3 or 4 that I estimate would be needed to account for the amount of slack at the wheel rim. Hence my assumption that it might be the rack and pinion and my quest to find someone with a similar setup for comparison, either on here or, as Ash suggests, at the marina.
 
[ QUOTE ]
Behind the dash is a big square casing at right angles to the steering shaft, with the cable coming out of the end of it. It is slightly offset from the steering shaft so I can't think of anything it could be other than a rack and pinion.

.

[/ QUOTE ]

That sounds like a rotary system. A rack and pinion is a rectangular casing about a foot long, and about 1 1/2'' square.

You sometimes get wear in the gears of a rotary system, What colour is the cable, and it should have a part number and length stamped about a foot from the end of it. A rotary helm is cheap and very easy to replace.
 
[quote A rack and pinion is a rectangular casing about a foot long, and about 1 1/2'' square.

[/ QUOTE ]

Yep, that's what mine is like. Sorry if my earlier description was a bit clumsy /forums/images/graemlins/blush.gif

I'm currently trying to get the steering wheel hub off the shaft so I can investigate further, but it's a bit tight and getting my puller to grip it cleanly without damaging it is proving a bit tricky. There's also an interesting warning on the underside of the rack casing that says words to the effect of "Don't take this to bits as it might not work properly again" /forums/images/graemlins/shocked.gif. So, once the hub is off I can move the instrument panel out of the way and take the casing to bits and have a look. /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif
 
Hmm, yes. That was actually Plan B if I couldn't find anything wrong. But unfortunately, the steering wheel boss is fixed to the shaft with a key, not splines, so it's not possible to replace it other than as it is now. Similarly, the wheel itself will only fit on the boss one way.

So, my only option is to separate the bit holding the shaft from the long square casing containing the rack to find out what, if anything, is loose. I don't know how the inner cable is attached to the body of the rack and my main fear is that if that is where the slack is, it might come apart completely and leave me with no steering. If it all looks OK and/or I am able to fix the problem, I will be able to set the wheel straight when I put it all back together, I hope.
 
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