Aluminium and corrosion (prevention) questions.

[ProDave]

Current job is replacing the tiller top bearing on a Leisure 17.

We have the tiller head off and a new top bearing, so the job is well in hand.

To get the tiller stock off, we had to drill out the old grub screw.

Question 1: Will be re tapping for a larger grub screw to go back. Should that be mild steel or stainless steel into an aluminium tiller stock?

Question 2: what if anything to apply to the threads to hopefully enable the new grub screw to undo at some future date if needed?

Question 3: what if anything to apply to the stainless steel tiller shaft before putting the aluminium tiller stock back on, again to ensure at some future date it will come off again?

 

[rogerthebodger]

Duralac

 

[lw395]

1) I'd use s/s
2) and 3) your choices are some sort of grease, some sort of adhesive or Duralac.
Loctiting screws into aluminium can be quite effective
Grease, inc copper grease can be quite effective.
Duralac will work so long as there is no movement in the joint.

 

[john_q]

Tufgel maybe be better for this application as it is more flexible

 

[vyv_cox]

Tufgel maybe be better for this application as it is more flexible

Tefgel only isolates component parts. Duralac additionally provides some chemical protection.

 

[Lon nan Gruagach]

1) I'd use s/s
2) and 3) your choices are some sort of grease, some sort of adhesive or Duralac.
Loctiting screws into aluminium can be quite effective
Grease, inc copper grease can be quite effective.
Duralac will work so long as there is no movement in the joint.

The skipper of the aluminium boat that I work on occasionally goes a strange colour when ever I mention copper. She is of the opinion that it will eat through aluminium like molten lead though butter.
I would have thought that in copper grease there will be virtually zero contact with any copper but it is banned on her boat.

 

[rogerthebodger]

The skipper of the aluminium boat that I work on occasionally goes a strange colour when ever I mention copper. She is of the opinion that it will eat through aluminium like molten lead though butter.
I would have thought that in copper grease there will be virtually zero contact with any copper but it is banned on her boat.

I was told a story about the owner of an boat with aluminium tanks who dripped a UK penny which landed on the top of the aluminium tank and found a nice round hole the size of a penny in the top of the said tank 12 months later

 

[john_q]

Tefgel only isolates component parts. Duralac additionally provides some chemical protection.

Thanks for the clarification, I have both on board and did not know the difference

 

[Dave100456]

I was told a story about the owner of an boat with aluminium tanks who dripped a UK penny which landed on the top of the aluminium tank and found a nice round hole the size of a penny in the top of the said tank 12 months later

I too, was told a story about a man who comes down the chimney and leaves presents, turns out that was not true, also?

 

[lw395]

The skipper of the aluminium boat that I work on occasionally goes a strange colour when ever I mention copper. She is of the opinion that it will eat through aluminium like molten lead though butter.
I would have thought that in copper grease there will be virtually zero contact with any copper but it is banned on her boat.

I've been putting copper grease on s/s bolts into ali parts on motorbikes for about 45 years now.
It's standard practice. Stainless in the kind of alloys used on bikes is disastrous without grease and copper grease is the most common choice. There are silvery-coloured metal loaded greases which must be better because they cost more.
The chemistry of copper grease sounds wrong, but real life experience over-rides A-level theory.
My mech-eng mate would probably suggest re-making the ali part in s/s or boring it out and putting a plastic liner in to isolate the s/s fom the ali.
Tefgel is a good teflon grase, but it is only good for very tight fitting parts.

 

[ProDave]

Thanks guys. So Stainless grub screw and Duralac everything.

Not that I am expecting it to need to come apart again any time soon.

 

[Lon nan Gruagach]

I've been putting copper grease on s/s bolts into ali parts on motorbikes for about 45 years now.
It's standard practice. Stainless in the kind of alloys used on bikes is disastrous without grease and copper grease is the most common choice. There are silvery-coloured metal loaded greases which must be better because they cost more.
The chemistry of copper grease sounds wrong, but real life experience over-rides A-level theory.
My mech-eng mate would probably suggest re-making the ali part in s/s or boring it out and putting a plastic liner in to isolate the s/s fom the ali.
Tefgel is a good teflon grase, but it is only good for very tight fitting parts.

I too have no qualms about copper grease on vehicles... But there is the significant issue of salt water. My post was intended to be presented as a question. Thanks.

 

[rogerthebodger]

I too, was told a story about a man who comes down the chimney and leaves presents, turns out that was not true, also?

Now to tell me farther christmas is not true, I am devastated. In fact where I live not many houses have chimneys more like air conditioners.

 

[Poignard]

I was going to replace the leaking, manky old tube of leaking Duralac Yellow that I have had on board for more than 20 years and I notice that Duralac Green is now available.

Here's a data sheet:

http://www.llewellyn-ryland.co.uk/downloads/DuralacGreen.pdf

The green does well in the tests and doesn't contain chromate.

I think I'll buy a tube of that.