280 SS pulls to the left

[qflyer]

I have a new to me 2001 SR 280 Sun Sport with twin 350 MPIs & Bravo I drives. Once under way, the wheel noticably pulls left, and requires constant pressure to keep the boat going straight. The props are counter rotating, trim tabs are fully retracted, drives both appear to trim evenly and there's no "wiggle" to either one. Also, the anode on each drive is just a flat plate, so there's no "tab" that's misaligned on either drive. The left turning tendency is way more powerful than steering torque you might experience on a single bravo 1 or alpha drive.


Any ideas what could be causing the hard pull to the left?

 

[magstang1]

Ding in one of the props? How are you syncing rpms? By ear or with the sync gauge?

 

[BillK2632]

You can adjust the tie bar for the steering, the STB engine is the one that "Steers" the Port is simply tied to it. I had a similar issue with my old 290DA, twin BIIIs. We adjusted the Port drive to "toe in" a little to correct the steering pull.

 

[johnsross3]

Hopefully someone can chime in with the correct name for the part, but is there a small skeg looking attachment to the bottom plate of your outdrive? If so, it can be loosened and re-positioned to correct for pulling issues.

 

[Chris Nowell]

Hopefully someone can chime in with the correct name for the part, but is there a small skeg looking attachment to the bottom plate of your outdrive? If so, it can be loosened and re-positioned to correct for pulling issues.

I believe he mentioned that his were flat. I read somewhere that those aren't needed if power steering is installed. :huh:

 

[qflyer]

From what I've found, on twins the anode tab (no idea what it's actually called) is not needed because counter rotating props should negate any torque steering. I can't find much info on the exact problem I'm having, but there's a lot of discussion out there about toe in vs toe out vs parallel. My props rotate outward, so I believe I'm supposed to have toe out (front of drive angled outward, props pointed inward.) I measured today, and my drives are toe in, with the measurement between the prop shaft being about half an inch wider than the measurement at the leading edge of the drives. I've searched forums, part diagrams, youtube, etc and can't find a "tie rod adjustment for dummies" so can someone point me in the right direction or give some instructions on where to start? Thanks!

 

[qflyer]

Well, still can't sort out this left turning tendency while underway...adjusted tie rod and tried setting drives parallel, 1" toe in, and 1" toe out and there was no change. Steering is still very smooth in both directions, stays straight at idle power/speeds, but once I start to accellerate it pulls left. There's nothing creating drag, trim tabs are fully retracted and symmetrical. I can't find anything that would cause the left turn. I'm down to replacing the power steering actuator, but the part number (89645a36) is no longer in production. Local Sea Ray dealership said there's no OEM replacement available, so I'll have to go aftermarket. Before I spend the time and money on trying to find an aftermarket replacement for the actuator, any other possible solutions to this problem that I haven't covered?

 

[Lazy Daze]

Does this still happen up on plane, with the drives trimmed about a quarter of the way up?

You're positive the RPM's are matched between the engines?

Did this problem exist during the sea trial or earlier runs?

Is the bottom of the boat clean?

 

[magstang1]

How much experience do you have driving a boat with twins?

 

[qflyer]

Does this still happen up on plane, with the drives trimmed about a quarter of the way up?

You're positive the RPM's are matched between the engines?

Did this problem exist during the sea trial or earlier runs?

Is the bottom of the boat clean?

Yes, it happens at all speeds above 1300-1400 RPM, but there's a big increase in left turning tendency once it gets on plane. It's strongest around 25-40 mph, and only lessens slightly between 40 and WOT 57 MPH. No left or right turning tendency at idle speeds.

RPMs are spot on according to the tachs, syncro, my ears, and a laser tach.

It did exist on the sea trial, but I mistakenly believed the props rotated in the same direction and it was just strong torque steering. This is my first twin engine boat - lesson learned, never assume.

Bottom is spotless, no damage/repairs/growth/bottom paint.

How much experience do you have driving a boat with twins?

As mentioned above, this is my first twin engine boat. I've been boating since I was a kid so 25+ years. I can't imagine what my experience level with twins has to do with a boat pulling hard left while on plane. Now, my lack of knowledge is certainly contributing to not being able to figure this out on my own, but that's why I'm here.

We've even gone so far as to laser tach the RPM at the props to rule out something crazy like a previous owner damaging a drive and replacing it with one that's geared differently...that's not it either.

The steering is smooth as silk, no roughness, tightness, etc. Fingertip steering in both directions, but you have to keep a hold on the wheel at all times in cruise, otherwise it's gonna go left quick.

I certainly don't have a full understanding of exactly how the internals of the power assisted steering work. However, looking at the very basic parts manuals, it looks like moving the wheel left or right of center, opens a valve and allows high pressure hydraulic fluid to enter one side of the steering actuator to assist in turning. Only thing I can think of is that once power is applied, the increase in power steering pressure could be causing some fluid to slip by a weak/faulty valve and put continuous pressure on one side of the piston which would make it steer, in my case, left. It makes perfect sense to me, but again I don't fully understand how the system works. I'm also doubting myself because it seems, according to many different forums, that the power steering actuator virtually NEVER fails and when it does, it's typically due to a leak. There's no indication of any leaks in my PS system.

Plausible, or am I just grasping at straws?

 

[Lazy Daze]

How about trim levels? Does trimming up help?

 

[CliffA]

just a basic question but are you sure the right props are on the Bravo drives?.....if one of the drives has the wrong pitch props that could cause this issue....or maybe one of the props was repaired and it was repaired with the wrong pitch....

cliff

 

[scoflaw]

Hooked hull.

 

[magstang1]

Yes, it happens at all speeds above 1300-1400 RPM, but there's a big increase in left turning tendency once it gets on plane. It's strongest around 25-40 mph, and only lessens slightly between 40 and WOT 57 MPH. No left or right turning tendency at idle speeds.

RPMs are spot on according to the tachs, syncro, my ears, and a laser tach.

It did exist on the sea trial, but I mistakenly believed the props rotated in the same direction and it was just strong torque steering. This is my first twin engine boat - lesson learned, never assume.

Bottom is spotless, no damage/repairs/growth/bottom paint.


As mentioned above, this is my first twin engine boat. I've been boating since I was a kid so 25+ years. I can't imagine what my experience level with twins has to do with a boat pulling hard left while on plane. Now, my lack of knowledge is certainly contributing to not being able to figure this out on my own, but that's why I'm here.

We've even gone so far as to laser tach the RPM at the props to rule out something crazy like a previous owner damaging a drive and replacing it with one that's geared differently...that's not it either.

The steering is smooth as silk, no roughness, tightness, etc. Fingertip steering in both directions, but you have to keep a hold on the wheel at all times in cruise, otherwise it's gonna go left quick.

I certainly don't have a full understanding of exactly how the internals of the power assisted steering work. However, looking at the very basic parts manuals, it looks like moving the wheel left or right of center, opens a valve and allows high pressure hydraulic fluid to enter one side of the steering actuator to assist in turning. Only thing I can think of is that once power is applied, the increase in power steering pressure could be causing some fluid to slip by a weak/faulty valve and put continuous pressure on one side of the piston which would make it steer, in my case, left. It makes perfect sense to me, but again I don't fully understand how the system works. I'm also doubting myself because it seems, according to many different forums, that the power steering actuator virtually NEVER fails and when it does, it's typically due to a leak. There's no indication of any leaks in my PS system.

Plausible, or am I just grasping at straws?

The reason I ask is because I previously asked how you were syncing but you didn't respond. Tachs lie and so do sync gauges. Bring the boat onto plane and leave one throttle set. Play with the other one a bit in either direction and see if your problem goes away. My 290 is synced and the handles are not right next to one another. One of the cables is adjusted slightly differently.

Not meant to be a knock against your experience or knowledge. Just trying to help you out.

 

[Molson]

Check the gear ratio in both drives. One may have been replaced at some time?

 

[cfd95]

Spun Prop Hub?
I had Twin Alphas one had a spun prop hub boat would pull.
I'm not familiar with Bravo drives but its something to check

 

[NorCal Boater]

I agree with Magstang. Get out on the water and on plane where the pull is most noticeable. I believe the boat is not "pulling" left but rather it is being "pushed" left by the starboard motor. So I would get the boat where the situation is occurring and begin backing off the starboard throttle in very small increments until the "pull/push" goes away. I don't care what your tachs or lasers are telling you, I think one engine is turning less than the other.

Let us know how that works out.

 

[qflyer]

How about trim levels? Does trimming up help?

Split trim isn't enough to offset the left turn.

just a basic question but are you sure the right props are on the Bravo drives?.....if one of the drives has the wrong pitch props that could cause this issue....or maybe one of the props was repaired and it was repaired with the wrong pitch....

cliff

Props are same brand/pitch/condition.

Hooked hull.

Just eyeing it, not a hooked hull. I'll put a straight edge on it, but I can't imagine that being the cause.

The reason I ask is because I previously asked how you were syncing but you didn't respond. Tachs lie and so do sync gauges. Bring the boat onto plane and leave one throttle set. Play with the other one a bit in either direction and see if your problem goes away. My 290 is synced and the handles are not right next to one another. One of the cables is adjusted slightly differently.

Not meant to be a knock against your experience or knowledge. Just trying to help you out.

I don't belive my tachs are off. I verified with a laser tach. However, I have done what you suggested, and it took almost a 1000 RPM split to keep her straight. Port motor at 4000 RPM and starboard at 3000 RPM. Probably a two inch split on the throttle levers.

Check the gear ratio in both drives. One may have been replaced at some time?

Gear ratios are the same, as verfied with a laser tach on the prop. I put muffs on both drives, put both in gear and had identical RPMs at the prop.

Spun Prop Hub?
I had Twin Alphas one had a spun prop hub boat would pull.
I'm not familiar with Bravo drives but its something to check

Not sure. I've never experienced this, so what are the symptoms?

I agree with Magstang. Get out on the water and on plane where the pull is most noticeable. I believe the boat is not "pulling" left but rather it is being "pushed" left by the starboard motor. So I would get the boat where the situation is occurring and begin backing off the starboard throttle in very small increments until the "pull/push" goes away. I don't care what your tachs or lasers are telling you, I think one engine is turning less than the other.

Let us know how that works out.

Nearly a 1000 RPM split is needed to eliminate the left turn. At WOT both engines are showing 4900 RPM. Since I've ruled out a bad/inaccurate tach, I'm interested in the slipping prop theory. I'm guessing there would be more symptoms though, but I'll wait to hear y'alls' thoughts. I'll be back on the boat Friday, so I could put a mark on the prop and drive and check to see if they remain lined up after a quick ride.

 

[Lazy Daze]

"Split trim" - I'm not sure what you mean there. I don't mean to have the drives at different trim levels - I'm talking about raising the drives to a normal run position - say 1/4 to 1/3. Too much "down" trim will cause the exact problem you're seeing. It's at least one explanation that hasn't been ruled out, yet.

Along those lines, are both drives trimming at exactly the same rate? Is one low on fluid or leaking fluid?

Unless someone put on an old, crappy prop, you won't have a typical "rubber hub". If the hub in that prop was bad, you'd know it - that engine would over rev when a load is put on it. However, you can easily check by using just one engine at a time. In fact, doing that (and noting performance) can help in many ways to compare one engine to the other.

You mentioned you've been boating for a long time, so I was hesitant to mention this, but, how is the onboard gear/loads distributed? Is there more weight on the port side?

 

[cfd95]

"Split trim" - I'm not sure what you mean there. I don't mean to have the drives at different trim levels - I'm talking about raising the drives to a normal run position - say 1/4 to 1/3. Too much "down" trim will cause the exact problem you're seeing. It's at least one explanation that hasn't been ruled out, yet.

Along those lines, are both drives trimming at exactly the same rate? Is one low on fluid or leaking fluid?

Unless someone put on an old, crappy prop, you won't have a typical "rubber hub". If the hub in that prop was bad, you'd know it - that engine would over rev when a load is put on it. However, you can easily check by using just one engine at a time. In fact, doing that (and noting performance) can help in many ways to compare one engine to the other.

You mentioned you've been boating for a long time, so I was hesitant to mention this, but, how is the onboard gear/loads distributed? Is there more weight on the port side?

Thanks for the info.
I am unfamiliar with the Bravo 3 dual prop.
I thought all mercruiser drives use the rubber hub in the props to prevent damage to drive if prop strikes an object