HGF - so depressed

[alan_thomas]

Seeing your pics of your water pump reminded me of a pump failure I had. There were a batch of replacement water pumps where the shaft was not hardened at all. the teeth were worn out in no time. Too late to doing anything about it but you can check.

If you try running the corner of a swiss file across the area marked by the arrow it will either skate across (hardened shaft) or start to cut into the shaft (unhardened shaft)
I would check any pump I was about to install in this way to ensure the shaft was hardened. The good news is that it is very likely the jackshaft is still good as I don't remember any reports of unhardened jackshafts and because the jackshaft is hard and the pump is not all the wear is on the pump. - Alan
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[Motorsport Micky]

I'm afraid there were jackshafts that were not hardened also, I got the pair !

Buy a good used one, easy to pick. it will have shiny marks on the teeth from use but effectively unworn, already tested for you.

Micky

[TR5convalescent]

Micky, this lack of hardening seems to be a recurrent theme with engine spares which are in contact with each other. I have a vague recollection of a school lesson in which hardening steel (in the context of sword making I think) was done by heating and quenching. I was wondering if this method might be adopted with our parts since they seem to be made with no regard for their use.

I realise that this is probably naive, but I thought that a good machine shop might do this at cost if it's doable. And I'm assuming it must be doable because forty five years ago it was being done!

[Motorsport Micky]

Yes higher carbon steels can be hardened by heating up (to straw colour if I remember correctly) and then quenched, there is more information here in this recent post and threads http://socforum.com/forum/showthread...ight=hardening

All in all the Stag has not been served well with the jackshaft and single timing chain design, complicated further by indifferent quality from component manufacturers and then even worse incompetent quality checking by the component retailing base, a shrug of the shoulders and a claim of "they are all like that" or "other customers haven't complained " have been used too long to fob off the customers, ultimately it came back to bite Triumph and BL but when you see the design and car which is the Stag and it's problems and then consider what the Stag could have been and at a cost of 3/5ths of bugger all (it often doesn't cost more to do the job correctly as wrongly, you just have to be bothered), as the song goes "salt water stings my eyes".

Micky

[Guest]

higher carbon steels are hardened by putting in a high temperature salt bath.
(Used to do that all the time at good old GRM heat treatment in Park Royal, long since gone...)

The salt bath increases the surface carbon (called carburizing) so it's called case hardening and goes down up to 0.5mm.
Completion of the process is done by finish grinding, so that's why gearbox parts are done this way.

I don't think the jackshaft is a case hardening steel.
I threw my last dead one away so I can't check.

Cast iron is hardened by chilling with jets in the places you want hard.
It's quite similar in some places to a cast iron weld, which chills itself as it's cooled rapidly by the other cooler iron.

Again I don't think the jackshaft is cast iron, it looks typically like EN19T which is really a tough nitriding steel used like for later Jaguar crankshafts and austin camshafts. (often they are forgings).

Maybe they were done this way and (RF?) induction hardened locally, which saves on distortion.

[StagManiac]

I agree strongly with your post #37, Micky, especially this part:

...it often doesn't cost more to do the job correctly as wrongly, you just have to be bothered...

Cast iron is hardened by chilling with jets in the places you want hard.
It's quite similar in some places to a cast iron weld, which chills itself as it's cooled rapidly by the other cooler iron.

Is that the same principle as induction hardening?

Paul

[Guest]

Is that the same principle as induction hardening?

Paul

In the respect it's LOCAL, I suppose it is.
There's various ways to get local hardening rather than overall through-hardening or skin hardening, depending on what people are trying to achieve and the material used.

[StagManiac]

Cheers, Gareth.

Paul

[Bandit1200]

See my thread fitting an external electric water pump