brass rod for shear pins?

[nwcove]

has anyone found a good material for making shear pins from for small motors? is brass to soft?

 

[oldboat1]

Re: brass rod for shear pins?

interesting question. I know the cotter pins/drive pins in my '50s stuff are brass, up to and incl the 35s. I guess they could be made of an alloy that I'm just assuming is brass(?) Aluminum would seemingly be too flexible, and steel too strong.

 

[gm280]

Re: brass rod for shear pins?

Actually the shear pin I purchased for my 1976 40HP Johnson was steel. And the one I removed was steel as well, but bend to the point that I almost couldn't remove in anymore... Just some info...

 

[F_R]

Re: brass rod for shear pins?

Depends on the motor. Some use soft "shear" pins, others use stainless steel "drive" pins. The 40hp would be an example of a drive pin. Drive pins are not supposed to shear. A rubber cushion inside the prop absorbs the shock of striking underwater objects. Motors without some kind of an impact protection will generally have a shear pin.

Bottom line: You need to know what is correct for your particular motor, and stick with it.

 

[nwcove]

Re: brass rod for shear pins?

Actually the shear pin I purchased for my 1976 40HP Johnson was steel. And the one I removed was steel as well, but bend to the point that I almost couldn't remove in anymore... Just some info...

thats why i asked the question, shear pins should shear, and not bend. just spent a good hour getting what was a nail, bent and rusted out of a prop shaft. they must be made of an alloy that is strong, but breaks clean under a shock load?

 

[oldboat1]

Re: brass rod for shear pins?

F_R -- don't think my note is accurate about cotter pins (misspoke), but I've always taken the brass "drive pins" identified in the parts manual to be shear pins. Lower hps in my '57s have the pin in the back of the prop, and the 35 has it in front. Are these shear pins?

 

[HighTrim]

Re: brass rod for shear pins?

Those are drive pins oldboat1. Made of SS, if you use a soft metal like brass you will be changing them often possibly! Unless you are easy on it and don't have many underwater obstructions. What model 35 do you have from '57 with the drive pin in the front side of the prop?

Then of course you have the third system of protection in the small 5.5s and 7.5s for example, the shock absorber.

EDIT: ...to note as well, only use SS cotter pins! Don't want to be fishing for your prop

 

[HighTrim]

Re: brass rod for shear pins?

Tim what motor do you need pins for? I could have thrown some in your care package.

 

[nwcove]

Re: brass rod for shear pins?

Tim what motor do you need pins for? I could have thrown some in your care package.

still messing with the little jw 10. plan to use it fishing in the rock strewn lake i fished as a kid, knew where all the rocks were 30 years ago, but im sure i will find em all again. lol

 

[oldboat1]

Re: brass rod for shear pins?

Well, shoot HighTrim. I only have the parts manual in front of me here in the house, but I'm looking at part no. 304575 drive pin in front of the prop for the mod. 25028 Big Twin ('57). That prop has a hub that extends out in front and has the pin situated there. I didn't think these props had the type of hub that could be spun, but in looking more closely at the prop pictured in the diagram (35hp), it looks like there is more to it than I thought. It would make sense then that the drive pin would be stainless, as you say.

The Fleetwin (a.t. the diagram, again) has a drive pin in front of the prop. (as does the 5 hp fisherman). I need to get out there and take a look at these now. In the diagram, I can't see the shock absorber you describe, so confused. There is the gearcase head and bearing assembly (part 376776 for the fisherman), but that has to be a different animal(?) I need to pull off a couple of props and look at them.

Thanks.

 

[boobie]

Re: brass rod for shear pins?

Geez, years ago when you went to a marina all you could get was brass shear pins. What happened ??

 

[oldboat1]

Re: brass rod for shear pins?

yeah, I ain't sayin' nothin. The pins I'm using are all the original ones as far as I know -- get pumped up enough, I'll put my coat and boots on and go check to see if I can figure out what they are. Nah. maybe tomorrow.

 

[boobie]

Re: brass rod for shear pins?

Down here all I do is put my shorts and boat shoes an go.:laugh:

 

[oldboat1]

Re: brass rod for shear pins?

H.T. -- by "front", I mean out toward the end of the prop shaft -- that side of the prop. Maybe my language is wrong. But the pins are in "front" of the props, apparently, for at least the 5, 7 1/2 and 35. Checked the Lightwin, since that's similar to what nwcove mentioned in the later post, and that has a shear pin (so identified) behind the prop -- gearcase side of the prop, behind the clutch assembly for the 3 (weedless gearcase, anyway). Thanks.

 

[oldboat1]

Re: brass rod for shear pins?

Down here all I do is put my shorts and boat shoes an go.:laugh:

getting to that point way up here too. But took a look at the lake today, and they are still ice fishing. Went grouse hunting three days ago, and almost got stranded in a dang snow storm. Meanwhile, you guys are sipping cool ones on the beach.

 

[kfa4303]

Re: brass rod for shear pins?

HI nw. I had the same problem and was able to find a 6' length of brass rod at my local ACE hardware. I think the rod was less than $5-$10 total.I cut probably a dozen spare pins and I still have 5' left. I've had a few bumps and dings using them and they've held up just fine on my '66 20hp.


I think this is it. Note, price is for a 4 pack, ut I was able to buy a single rod out of a bin for < $10.

K & S? Brass Rods - Hobby & Craft Metals - Ace Hardware

 

[HighTrim]

Re: brass rod for shear pins?

Ok understand the language now.

The shock absorber is inline of the drive shaft, not prop shaft. It sits beneath the water pump assembly. They are getting harder to find. They can be welded closed if they break, but that is difficult to do and get it straight. Just for future knowledge, they should measure 6 3/4" long. Any more and they are shot. If shot, the will cause it to die at idle, or not even start at all. Sometimes a "seized" motor is just a broken shock absorber.

 

[racerone]

Re: brass rod for shear pins?

There was a day when folks did not mind changing a shearpin.---As motors got bigger the job got harder to do, if not impossible out on the river or lake.------------The MARTIN outboards had a feature that allowed the motor to be pivoted so that prop was above the boat and no lost parts / tools.----------People love the idea of " shearproof drive " with splines and drive pins.-------------This concept in many cases means you will get home / to shore with a damaged prop.---Then you get out the wallet to make lower unit repairs / replace the prop.------If you don't mind a bit of effort a brass or bronze pins will save you money.

 

[oldboat1]

Re: brass rod for shear pins?

yup. think I've either been lucky, or too careful to have fun -- never sheared a pin. But always carried them in the tackle box (maybe another reason I never needed one). I won't mention what they were as that's apparently open to question (but they sure looked a lot like brass....) Used my uncle's Martin whenever he would let me when i was growing up -- didn't know it had that pivot feature, but just as well. I probably would have tinkered around with it and busted it somehow -- had a very patient uncle.

 

[kfa4303]

Re: brass rod for shear pins?

Here's an even better source.......

Rods - Round & Threaded