Saving Old Seagulls

I am trying fit a new (ie rechromed) drive shaft casing into the water pump housing, and finding it a very tight fit

I don't think it's the chroming - all my other similar bits have the same problem. Obviously I am missing something here - perhaps at the factory they were heated to give a tight fit on the chrome?

Anyway, as an amateur without access to professional facilities, am I better to sand away at the female housing, until it goes in freely, or am I better to drive a wedge down between the gap in the housing by the bolt - or something else? I've tried the wedge method (with a small cold chisel) but it does not widen the female enough

It also occurred to me to torch the aluminium, so that it expands - but I've been caught by this before - aluminium has a low melting point, so suddenly it melts.......

There has got to be a better way?!!

Donald

Did you remove it originally(before rechromeing ) if so then you will remember how tight it was I'd chap it downwards with a block of wood at power head end we all like pics they tend to help...

Have you tried reversing the pinch bolt so it first goes through the threaded side and then put a coin or similar to stop going through the other side which in affect opens the gap as you screw it open? It is good to have tight fit. Stops the box dropping off!

Donald.

To help answer your question it might help us if you could show some pictures.

Tam's right in that a careful measurement before and after the re-chroming process might have eliminated such a tight fit, although a fairly tight fit is what was intended in the first place with these.
Heating the aluminium casting will help a bit, but you'd have to heat it an awful lot with a typical plumbers type blowtorch to reach those sorts of temperatures before it melts. Give it a go and see what happens. Persuade it along with a hammer and a block of wood.

If it still feels as if it's too tight, try removing the last inch or so of the chrome that will be hidden once the tube is fully home inside the pump housing. Worth a try, but i'd still err on a tighter fit rather than a looser fit.

Jon

Normally the polishing before chroming makes the drive shaft a loose fit, the amount of copper, nickel & chrome deposited when chroming is very, very little, the usual instructions are don't polish the bottom 25 mm! to avoid water pump housings that fall off.

I can't work out why yours is a tight fit, Hugo's method is the one I always use, just don't over do it, you could snap a lugg off!

How do I post a photo - I don't see a hot spot for an attachment?

Thank you for all your helpful replies - I like the reversed pinch bolt idea, but take Charles's point about breaking the lug - aluminium shears suddenly....
I think the problem is of my own making - I got some casings off eBay, and did not specify the last bit to be narrower, so I am putting a casing from another engine onto it, after chroming

Donald

Donald A wrote:How do I post a photo - I don't see a hot spot for an attachment?

Thank you for all your helpful replies - I like the reversed pinch bolt idea, but take Charles's point about breaking the lug - aluminium shears suddenly....
I think the problem is of my own making - I got some casings off eBay, and did not specify the last bit to be narrower, so I am putting a casing from another engine onto it, after chroming

Donald

Once you write a message scroll to bottom of page below submit to the left click attachment find tour pic wait for the wee green tick then upload and submit china

Where the drive shaft tube fits into the water pump housing the drive tube should be 1.125" diameter, the powder coated tubes tend to be a little bigger than this, but will still fit in the housing.

Using the reversed pinch bolt method carefully will open them more than enough, & not cause any damage.

What's the diameter in the problem area?

Photo attached. Engine is EGF 506FF2
Measurements
EGF tube still attached 1.123
EGF housing ditto 1.119 - 1.124

spare chromed tube 1 1.124
ditto 2 1.123

spare housing 1 1.123
ditto 2 1.132


Armed with the idea of the reversed bolt, and Charles's standard of 1.125, I think the penny might be beginning to drop as to how this was intended to work - correct me if I am wrong. If the tube and the housing are roughly the same diameter, and you then have a way of easily widening the housing (reversed bolt) then the assembler widens the housing enough to allow the tube to be fitted, then relaxes the bolt, which tightens the housing onto the tube, with no bolt present - the metals are then doing some of the work for you, by elasticity. Reversing the bolt to its rightful position and tightening then completes the job by adding more tightness.

Armed with the idea of the reversed bolt, and Charles's standard of 1.125, I think the penny might be beginning to drop as to how this was intended to work - correct me if I am wrong. If the tube and the housing are roughly the same diameter, and you then have a way of easily widening the housing (reversed bolt) then the assembler widens the housing enough to allow the tube to be fitted, then relaxes the bolt, which tightens the housing onto the tube, with no bolt present - the metals are then doing some of the work for you, by elasticity. Reversing the bolt to its rightful position and tightening then completes the job by adding more tightness.

You got the idea 100%

Nice tidy looking motor!

Thank you for that – it is nice to know that one's tentative logic is along the right lines!

What a beautiful prop – what engine is it from?

Regards Donald

What a beautiful prop – what engine is it from?

My one!!

It is off an LLS. I use it on a silver century. It only took me an hour or two to clean and polish it up!
I could have got it shinier but I was finding it hard to see!