Stinking Tohatsu Shear Pin!

Jeff Reardon

Jeff Reardon

Well-known member
I've ranted about this here before, but am hoping someone new may see it and can provide a solution.

I have a short shaft 2 stroke Tohatsu 3.5 hp kicker for my sculling boat. It's the perfect size, starts within 3 pulls almost every time, and I got for little money, so it's been a great little motor. It doubles as a highly portable motor that at a high idle will just push a 14 foot Aluminum along at the perfect pace for trolling streamer flies for landlocked salmon. (My 15HP Yamaha is a just a hair too fast, and I need to drag a bucket to slow down.)

Anyway, my only complaint on the motor is the stinking brass shear pins, which appear to have about the same resistance to breakage as a stick of string cheese. Last year, as I was getting used to this motor, I think I broke 3 sheer pins. I never hit anything, mind you. The sheer pins would break just from shifting into gear out of neutral. This year I've done better, by always ensuring that I have the motor at the lowest idle before I put it in gear.

Well, today I got impatient. The motor was cold and kept stalling when I shifted from neutral into gear, so I kicked up the idle just a hair to avoid that. Problem Solved! The motor didn't stall at all, but the sheer pin sure did break. I had an extra with me (the last of package of five, so I must have broken 4 of them last year . . . .) but the damn things round over on the ends when they break, and it takes a hammer and a nail punch to knock them out.

So I got a nice row back to the mooring against both tide and wind. (I will say that my old sculler was really built for oars, not a motor. It moves right along even with my crappy technique and oars that are a little too short, holds a straight course, and carries its momentum beautifully between oar strokes.)

Anyway, my understanding is that somebody makes a steel sheer pin with a higher breaking point for this motor. Anyone got any good ideas where I could get one? It's 5/32" by 1". When ordered the set I just used up, I couldn't find the steel ones anywhere.
 
I've ranted about this here before, but am hoping someone new may see it and can provide a solution.

I have a short shaft 2 stroke Tohatsu 3.5 hp kicker for my sculling boat. It's the perfect size, starts within 3 pulls almost every time, and I got for little money, so it's been a great little motor. It doubles as a highly portable motor that at a high idle will just push a 14 foot Aluminum along at the perfect pace for trolling streamer flies for landlocked salmon. (My 15HP Yamaha is a just a hair too fast, and I need to drag a bucket to slow down.)

Anyway, my only complaint on the motor is the stinking brass shear pins, which appear to have about the same resistance to breakage as a stick of string cheese. Last year, as I was getting used to this motor, I think I broke 3 sheer pins. I never hit anything, mind you. The sheer pins would break just from shifting into gear out of neutral. This year I've done better, by always ensuring that I have the motor at the lowest idle before I put it in gear.

Well, today I got impatient. The motor was cold and kept stalling when I shifted from neutral into gear, so I kicked up the idle just a hair to avoid that. Problem Solved! The motor didn't stall at all, but the sheer pin sure did break. I had an extra with me (the last of package of five, so I must have broken 4 of them last year . . . .) but the damn things round over on the ends when they break, and it takes a hammer and a nail punch to knock them out.

So I got a nice row back to the mooring against both tide and wind. (I will say that my old sculler was really built for oars, not a motor. It moves right along even with my crappy technique and oars that are a little too short, holds a straight course, and carries its momentum beautifully between oar strokes.)

Anyway, my understanding is that somebody makes a steel sheer pin with a higher breaking point for this motor. Anyone got any good ideas where I could get one? It's 5/32" by 1". When ordered the set I just used up, I couldn't find the steel ones anywhere.
Click to expand...


Last time I bought pins I was told they only come in stainless now. I ordered from Defender.
 
Jeff,
I have a 3.3 hp Mercury and had that problem with it the first 2 years I owned it. I was ready to sell it because it was pointless. I was still poling AND dragging around a useless motor! Luckily I able to get stainless shear pins from a local dealer. He warned me that they probably wouldn't break. After talking to him about it, he thinks the plastic prop would become the "weakest link" For me, that was a no-brainer since I was having it shear if it touched ANYTHING such as a clump of grass in the water. Since changing it, I've gone through some pretty heavy stuff with no problems. I don't use it in areas where there's anything hard like rocks, only vegetation/mud.

Scott
 
Jeff,

Years ago I had a 3 hp Evinrude for a square end canoe. One night coming back from our hunting spot I sheared 3 pins!! Went to town and nobody had any left. Finally stopped at a garage and the mechanic said "just buy a length of brass brazing rod and carry it and a pair of side cutters with you. I never bought another shear pin again. The brazing rod seemed to withstand impact a bit better also. Personally, I don't know if I'd go so far as using stainless because you might break something else before that pin breaks.
 
Jeff,

Years ago I had a 3 hp Evinrude for a square end canoe. One night coming back from our hunting spot I sheared 3 pins!! Went to town and nobody had any left. Finally stopped at a garage and the mechanic said "just buy a length of brass brazing rod and carry it and a pair of side cutters with you. I never bought another shear pin again. The brazing rod seemed to withstand impact a bit better also. Personally, I don't know if I'd go so far as using stainless because you might break something else before that pin breaks.
Click to expand...


Stainless is OEM.
 
That's a good point. OEM should be good, then again it might be too good for a rough environment. I was also thinking about the expense of a lot of SS pins if they still broke but considering they are stainless they probably wouldn't break very often so that's a moot point. In any event the brazing rod worked for years for me and the motor I used it in. I never did use up all that rod.
 
When I bought the motor, it had a small bit of cut sheet metal screw for a sheer pin! At the time, the Tohatsu site recommended brass or stainless, and I couldn't find steel anywhere in stock. As I recall, Jamestown Distributors and West Marine both listed it, but neither had it in stock.

The Tohatsu site now reccommends steel, with brass as an option.

[font=Verdana,Arial,Helvetica] "I don't use it in areas where there's anything hard like rocks, only vegetation/mud."[/font]

That's not possible up here. We've got rocks on our rocks, sitting on bedrock.

In any case, the prop is plastic, so i suspect it will break or bend if I hit anything hard.
 
Actually, I must have misread that website. Glad I checked. Here's what they really say--clear as mud. "You should use brass, but we are giving you steel."

[font=Verdana,Arial,Helvetica] .

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[/url]I have a Tohatsu 2.5hp (or 3.5hp) outboard. What size shear pin do I need to use?
For the 2-stroke models and 4-stroke 2, 2.5 and 3.5, any 5/32" x 1" (4mm x 24mm) shear pin will work just fine. There are two types of shear pins available; brass and stainless steel. Brass shear pins are available through aftermarket companies and will "give" if you strike an underwater object. However, brass shear pins may also break more easily if shifting or accelerating too quickly. Stainless steel shear pins are much harder than brass shear pins and won't "give" if striking an object which could cause damage to the prop. However, stainless steel shear pins won't break as easily as brass shear pins when accelerating quickly or when shifting gears. Stainless steel shear pins are standard with new motors, along with the resin prop.
 
That's interesting Jeff, I haven't seen a shear pin in years to begin with but all the old time motors that I have used (not that many) had brass shear pins. Maybe Mr. Retiredoletimemotormechanic, Tom, will see this thread and offer a comment.
 
I've had my Nisan 3.5 hp for some 12+ years now. When I bought it it had a plastic prop and brass shear pin. The shear pins were hell, frequently deforming when shearing making them a PIA to remove. I upgraded to the aluminum prop which Nissan recommended with the SS pin. The fragile shear pin issue is cured, at 3.5 hp the aluminum prop has held up well.

Scott
 
I am with Pete on this one , I just carry a piece of brazing rod and side cutters. I would not bet on it but I think stainless is not exceptionally strong, just corrosion resistant. With the small horsepower motors I wouldn't worry about tearing up the gearbox.
 
Tom,

SS pins are much stronger in this application. Darn brass would shear if you put it in gear at too high an rpm. No problem w/ the SS pins.

Scott
 
Scott, I didn't mean softer than brass but softer than common steel like a steel welding rod. Steel welding rod is what I use on my larger OMCs. This whole thread is about finding the weakest link and then improving it. Sometimes it seems to me that the manufacturers never get out and use their motors!!
 
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I agree with the brass welding rod. Made the switch on my small mud motor and haven't broken a pin since. Used to break a few every year. I don't carry a shear with me i the boat. I just cut up a bunch of them and put thme in an old aspirin bottle. Figures after cutting all those shear pins and carrying them with me the past year, I never broke another one.

Mark W
 
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