Refitting Cutlass Bearing But Grub Screws Just Turn

[sailingjupiter]

Refitted the cutlass at the weekend on my Spring 25. 20x35x80mm so it's a small one. Getting the old one out was hard but managed it. The grub screws came out far too easily but thought nothing of it as I was worrying about how to get the new bearing in. I had read that the done thing is either Araldite or grub screws. As I already had grub screws I was going to use that method to hold it in place so didn't Araldidte it. If I had used Araldite I am sure it would have all been pushed out on re fitting the bearing anyway.

Fitting was straight forward initially tapping it in with a hammer but got harder and harder so obviously didn't want to bang it harder in fear of dislodging the P bracket so made up a simple puller (or pusher in this case) that got it in position nice and slowly but it was a very tight fit. On refitting the grub screws I found that the thread on the carrier itself has gone so the screws just turned then fell out.

So the question is - As it was such a tight fit can I assume that the bearing will be held securley in place or do I need to re drill some new grub screws holes in a different place? If I do have to drill do they have to be opposite each other and how can this be done? Hopefully the bearing and shaft can be kept in place.

Hopefully you will say stop worrying, it will be fine as it is.

Any advise appreciated....

 

[macd]

Is it possible to put in thread inserts? They're often known generically as Helicoils, a brand name, although I much prefer Recoil inserts. The Recoil system is very simple and easy to use -- certainly easy enough, I'd have thought, for someone who's just changed a cutless bearing. Since they're stainless, they also have the secondary advantage of largely confining any dissimilar metal corrosion to between the insert and the parent metal, rather than between fastener and thread. Google 'recoil thread inserts' in domain uk and you'll find plenty of hits. Alternatively, hail a passing Snap-On van.
Note: Recoils come in a variety of lengths but can easily be cut down to the correct size with side-cutters.

 

[GrahamM376]

Drill and tap new holes - you don't need to remove the cutless to do it, just drill through.

 

[Tranona]

But remember to use a flat bottomed tap. Drill with the correct size tapping bit, slowly - bronze is relatively easy - untl you feel the casing then tap. Fiddly but not too difficult.

 

[macd]

Quite agree that drilling new holes and tapping would be the simplest solution for anyone who doesn't have inserts to hand. You'll probably need a set including a bottom tap (the flat bottomed tap Tranona mentions). But if you don't want redundant holes (which I'm sure will do no harm) then inserts is the way to go.

 

[Norman_E]

Don't worry too much, the grub screws are a backup to the usually tight fit between bearing shell and P bracket. Stripped threads in the bronze bracket are common. You can use thread inserts, as stated above, and need too buy a kit with the special tap as well as the inserts. The easiest cure is to tap the holes the next size up, and fit larger diameter grub screws, which should have a shallow point to fit into a dimple drilled into the cutless bearing shell. To do either job you need to get the cutless bearing out again, and you should not use a hammer in case you damage it or the P bracket fixings. I do not recommend using araldite to fit a cutless bearing as you will need to apply heat to get the thing out again.

If the shaft is out a very simple extractor cum fitting tool can be made from a length of studding, a piece of tube and some big washers. With the shaft in you need something more complex. The photo shows the parts, (except the two lengths of studding and some washers) of the one I made. Their are two split tubes, either of which can be placed round the shaft to push the bearing out.

EDIT: THe stripped threads are often caused when people are careless using a drill to dimple the cutless bearing, and to avoid causing problems you need to centre punch the cutless bearing so that the drill does not wander, and use an undersized drill, for example if the grub screws are 6mm, the core hole size is 5mm, so a 4mm drill will make an adequate dimple without scraping away at the theads.

 

[Norman_E]

Drill and tap new holes - you don't need to remove the cutless to do it, just drill through.

You can do that, but must ensure that the grub screws only just enter the bearing and cannot touch the shaft. If you are going to do that then drill the bearing tapping size (assuming it has a brass shell and not plastic) and tap it. Then use headed screws cut to a length that will enter the brass shell but not go further. I still recommend that you remove the bearing and tap the existing holes oversize, as I explained above.

 

[Neil_Y]

Any advise appreciated....

The use of epoxy as a bedding/fixing for a shaft bearing is used by us on clearance fit bearings, these are slid into place by hand and to remove you simply heat the carrier. With an interference fit the epxoy will do very little so you do need a grub screw. We can get away with no grub screw on a clearance fit as the epoxy will hold the bearing in place unless the sea temperature gets to 60C !

If you are using epoxy make sure you use low temperature such as Araldite 2011.

 

[Skysail]

Putting the new bearing in the frig or ice gives you a little more clearance, but too late now!

Agree with all the grubscrew advice.

 

[KREW2]

Yup! deep freeze the night before, then transported wrapped in a cloth inside a thermos flask if possible, or in a small eski box with ice pack.