Hydraulic steering failure

**AlliStan** · 09-18-2024, 06:37 AM

Originally Posted by PaulR

I had that bolt snap off in the mid 1990's on a dual Ride Guide system, the bolt was still fully threaded into the tiller arm with the nut still on it, that was the bolt Merc used back then. Luckly I was only running about 50-60mph, but the hard right turn still chucked me out of the boat. After that we all switched are boats to dual opposed cable steering, that way three bolts have to fail all at the same time to lose steering completely.

Were the bolts, Merc was using at that time, grade 8 bolts? I wish I knew for sure.

The difference between shear strengths in Grades 2, 5 and 8 are eye opening. For a 3/8 bolt (as I recall that's the size of the bolt in question) the single shank shears are 4904 lbs, 7952 lbs. and 9940 lbs, respectively. Someone's going to have to show me in person how side torque from an OB motor can generate 9940 lbs. of shear. I have friends that replace them every year too, and that's fine. But, having been a row crop farmer all my life I have lots of experience with shear bolts on farm machinery, and understand the forces necessary to break them. For me it's just a matter of physics. And right now, I'm unconvinced that an unworn, undamaged 3/8" grade 8 bolt can be sheared by the torque of a 2.5L OB. Not arguing with you, Paul. Just can't get my head around it.

**KIRCHNER** · 09-18-2024, 07:17 AM

Originally Posted by AlliStan

Were the bolts, Merc was using at that time, grade 8 bolts? I wish I knew for sure.

The difference between shear strengths in Grades 2, 5 and 8 are eye opening. For a 3/8 bolt (as I recall that's the size of the bolt in question) the single shank shears are 4904 lbs, 7952 lbs. and 9940 lbs, respectively. Someone's going to have to show me in person how side torque from an OB motor can generate 9940 lbs. of shear. I have friends that replace them every year too, and that's fine. But, having been a row crop farmer all my life I have lots of experience with shear bolts on farm machinery, and understand the forces necessary to break them. For me it's just a matter of physics. And right now, I'm unconvinced that an unworn, undamaged 3/8" grade 8 bolt can be sheared by the torque of a 2.5L OB. Not arguing with you, Paul. Just can't get my head around it.

it wasnt a grade 8

**blt2rok** · 09-18-2024, 10:03 AM

I had a line pop in my viking. Long sweeping right turn at about 55mph. Heard a loud pop like a gunshot and instantly lost any resistance in the wheel. Boat spun and broke my seat and I flew into my wife knocking her out. We were lucky and stayed in the boat.

**rjdubiel** · 09-18-2024, 10:08 AM

check your rigs, check the hoses to make sure there are no rub marks on them. If there is replace. They are not expensive and make sure you got the 1500 lb pro hoses. Dangerous situations are all around us when we all go out and run. Just like BLT just said, he was not hauling just a cool 55 mph and still went back very quick and was not a good situation.

**LakeFever** · 09-18-2024, 11:39 AM

I check my fasteners like an OCD person after every single run out in my rig I check all transom, jack, steering, and lower unit hardware. The ARP steering tiller bolt will be getting replaced on a service schedule. I'm thinking every 50 hours of use. Thoughts?

**rjdubiel** · 09-18-2024, 02:14 PM

Too much for the tiller bolt I think but to each their own, its only $.60 per hour to do that, nothing as far as expense! I am on the every time I pull the power I use a new one. I am probably going to do it this winter when I pull it all apart for bushings.

**LakeFever** · 09-18-2024, 02:43 PM

So 20 hours? I think a general rule of how frequent that bolt should be replaced is a solid topic we should all try to figure out

**rjdubiel** · 09-18-2024, 03:20 PM

I know people that have them in for years, reuse again and again. It shouldn't fail and with MFG quality checks less and less maybe the old ones are better than new! haha.

**skialot2** · 09-18-2024, 04:34 PM

I am with Allistan on the tiller bolt. If you use the proper grade tiller bolt and keep it properly tight, it will never shear from the steering torque of a 2.5. Mine is probably over 20 years old. The only problem I have ever heard of is the threads stripping out of the tiller. And you must use the nylock nut. That same bolt has been used for decades. I believe it is still in use today. If there was a problem, it would have been redesigned a long time ago. Instead of 3/8" Make it 7/16". There is really not all that much torque on that bolt. If there was, you would not be able to get a tiller on every mercury outboard up to 300 horsepower.