PSS stern seal grub screw

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rogerthebodger

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Any one know the size of the grub screw that clamps the stainless rotor on to the prop shaft.

Mine is a 40 mm shaft and need to adjust the rotor as the compression is less than then 25mm it should be.

I know I can get a set of grub screws from PSS but I can get them local from a local bolt supplier.

I have looked on the PSS web site but not found the info.
 
The one I have off my 1" PSS is 1/4" x 20 tpi which makes it either BSW or UNC. I'd guess the latter as the PSS is of US provenance I believe.
The 40mm seal screws might be larger of course
 
Rogershaw said:
Any one know the size of the grub screw that clamps the stainless rotor on to the prop shaft.

Mine is a 40 mm shaft and need to adjust the rotor as the compression is less than then 25mm it should be.

I know I can get a set of grub screws from PSS but I can get them local from a local bolt supplier.

I have looked on the PSS web site but not found the info.
Click to expand...

WARNING

They are not standard grub screws but cupped pointed set screws.

This is from the instructions.

Do not re-use the supplied cupped pointed set screws. If multiple tightening has flattened the cupped-point set screw, replace the affected screw with a new one.
 
Get new from PSS - they are one use, cup-point. UNC thread.
It's very disconcenting to notice a cold current of water over your feet, whilst at rest.

It happened to me in 1995 in Weymouth - attempting to re-use the old grub-screws.
 
Flica said:
Get new from PSS - they are one use, cup-point. UNC thread.
It's very disconcenting to notice a cold current of water over your feet, whilst at rest.

It happened to me in 1995 in Weymouth
Click to expand...

It happened also to a friend and myself a couple of years ago, in Falmouth Harbour..... and a fair few others in between times.

It didn't just dribble - it poured in.
 
zoidberg said:
It happened also to a friend and myself a couple of years ago, in Falmouth Harbour..... and a fair few others in between times.

It didn't just dribble - it poured in.
Click to expand...

I was alerted by the gurgling sound; of course the speed of ingress is dependent on how deep below the waterline the shaft might be. Unfortunately this increases dramatically as the boat goes down by the stern.
It starts very slowly. but increases geometrically - not amusing.
 
Isn't it common practice to tighten a couple of hose clips on the shaft to prevent the collar from moving when the grub screws lose their grip?
 
Thks Guys

It look like 3/8 UNC which has a 3/16 in allen key 4.76 mm that why none of my metric allen keys will fit and of cause my imperial allen keys are at home.

I do know about the refitting of the existing screws but plan to fit a clamp boss between the rotor and a thrust bearing retaining the shaft so the rotor is more secure and does not rely only on the grub screws.

Split%20Clamping%20Collar%20Stainless%20Steel.jpg
 
Last edited by a moderator:
I might have a couple of spare unused PSS grub screws in my bits box. I was going to suggest a jubilee clip next to the rotor as belt and braces, but the hefty clamp Rogershaw shows would certainly be superior in that regard.

PM me if these might be of use for you.
 
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