[edit 2] Disclaimer:
The following info refers to Australian manufactured hydrolastic displacers, as used in Mini Deluxe, Mini K, Mini Matic and 1098 Clubby.
I am unsure if there are construction differences at the fluid entry on UK made or Cooper S bags. When I get to repair these I will advise further.

Tomorrow I am going to drill/tap a 1/8NPT thread into an old (rusting away) hydro bag, objective being to sort an easy & reliable hose repair method for these things by just screwing an adaptor fitting in and attaching a new hydraulic hose.
I might then put the bandsaw through this bag so we can all see how much metal is in there to work with.

I need to sort 4 bags for the van I'm building, and I'd rather have new hoses than 45 year old ones.

So, stay tuned... pics to come.

[edit] I decided to cut the thread 1/8 BSP, not NPT, as my NPT tap has a long lead in and the drilled depth into the bag plate is only 12mm. And BSP fittings here are easier to obtain.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Progress today- excuse the poorly focussed pics.

Hose and crimp removed with die grinder:



barb cut off at shoulder:



Drilled and tapped 1/8 BSP:



A 1/8BSP nipple screwed in-
Not the right one, I need to make or find some with 5/8-18 UNF thread on:




Hose will be Pirtek MPH-06, if I can get the right thread fittings.
[edit 1] 3/8 BSP crimped fittings sourced for the bag end. But they cannot supply fittings for the 5/8-18 UNF connection to the pipes.
So, unless I find some elsewhere I will strip the fittings from the old hoses and zinc plate them, then Pirtek can re-crimp them onto the new hoses.
[edit 2] I found can get 3/8 brass tails from Pirtek, and 5/8 UNF brass nuts (used on oxy hoses) elsewhere, this would save me stripping and replating the old steel ones. I'll get one crimped up and see how strong it is.

Next step is to finish building my hydro bag test rig...

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Any special tricks in keeping swarf out when cutting the thread? Or does it not matter?

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1967 Cooper S - new front bearings to do.
1965 Cooper S shell - Slow progress. No time or money!
1966 Deluxe- next rustoration!
Mk 2 & XJ6 Jags. Less said the better.

Good stuff.
I'd say this would need a very very decent flush once the machining work has been carried out.

Check the metal depth before you start (I drilled 12mm deep, not quite right through). I did this in the mill which has digital Z axis readout.
Grease the drill flutes, drill it in a bench drill on slow speed. Set the depth stop.

Same with the tap, I greased the flutes and started it square in the mill (turned spindle by hand) then finished it in the vice with a tap wrench.

After tap was withdrawn there were a couple of tiny chips left sitting in the thread, I picked these out with a cotton bud.

There is a rubber thingamy that's right behind the hole, so swarf won't fall right inside the bag, you will see it.

[edit] typo

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Impressive! There's quite a bit of 'meat' left when you cut down the spigot, looks enough for the thread to be very secure.

I guess the only downside for us 'anoraks' is the new hose doesn't look the same...

BUT! your mention of getting someone to re crimp the hose could be the answer! Do you think you could take some spare fittings off an old hose and have the same fittings on both ends of the old hose, thus re-using the original hose for appearance? The length would be ok, even allow for trimming back the old hose as fitting would make it longer.

The fittings on the displacer end are hidden away down in the guts of the thing, so no visible way of knowing?

Keep it up Kev!

Cheers

Graham

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Sir Alec! we are not worthy!

awesome

and nothing to stop you putting a right-angle fitting on there and feeding the hose through the subframe instead of using that chopped up subframe Les gave you

Graham, the fitting down inside the bag is 3/8 BSP, and looking in there you really won't see it.
The new textile braided MPH-06 hose is pretty much the same construction as the old 40+ year old stuff, but without that external pattern.
I think it's got neoprene outer, so would outlast you and me both.

The 5/8 UNF hose end fittings onto the pipes are not in Pirtek's 12MB catalog that I can see. So I will probably re-use old (replated) ones, with new Pirtek hydraulic crimps as said.
A 3/8 BSP flare nut will screw onto the 5/8 thread, but it's ~1.3mm looser and the thread pitch is 1 TPI different. Some people have done this I bet, but I won't risk it...

Simon, the stock hydro hoses fitted fine in Les's subby, and also the one I did for Mike Byron. An elbow won't help at all.


If this all goes to plan, I might offer a re-hosing service for all the hydrolastic lovers.

pics today with new Pirtek hose-
Note the end fitting onto the pipe/bleeder block is wrong (this hose is prototype) it will have a 3/8 BSP-5/8 UNF adaptor for bag testing.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

yeah, I figured an elbow on the end of the hose might mean the hose could go through the box section of the inside, instead of through the back.... doesn't matter

It does go through the side, right next to where the new cross channel is welded in.
It doesn't go out the back of the subby.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Sensational. I have a few needing some professional attention.

Now I can tell my wife - See, I made the right call keeping all those old hydro bags.
(And BTW, how much Tupperware do you really need to keep in your kitchen?)

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1967 Cooper S - new front bearings to do.
1965 Cooper S shell - Slow progress. No time or money!
1966 Deluxe- next rustoration!
Mk 2 & XJ6 Jags. Less said the better.

I finished welding the `ex-rusted out Cooper S's subby' hydro bag test rig today, tested one old bag OK then hooked up the re-hosed one.

It's holding steady @ 300psi, I'll check it in the morning but I see no problems.
[edit] It's still holding 300psi pressure this morning, no problems.

More pics-

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Hi Kev, I'll have to get down there and see you (I know I keep saying it!) So now I've got to bring Hydro bags and steering racks!

With your test rig, did you evacuate the bag before pumping it up? I've considered this set up, but was not sure how to deal with air in the system?

Maybe you prefilled the bag with fluid?

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Sir Alec! we are not worthy!

Graham,
Yeah I prefilled it with a horse syringe, took a while. I'm going to add some medical technology- a long bit of thin plastic tube, so I can get the fluid down inside easier without it blowing bubbles.
No need for a vac pump.
Most BMC dealers never used the vacuum side for normal pump ups, only if fitting new bags in the system.
If you pump it high then blow it down hard at the bleed nipple it blows the air out anyway.
This old `Mini clutch MC + scrap bits' pump has done me fine for 20 years now.

If I needed a vac pump, these days I'd grab a pneumatic vacuum generator. Much easier to add.

re your previous idea of using the old hoses, maaate.... the ends just crumble when the crimp comes off, rubber is rotted, so is the textile braid.
They are FUBAR, you would want new hoses, safer!

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Is there any reason why you can't crimp a new hose on to the existing post rather than cutting it off? The old hoses lasted 30 years new ones should last as long? I fear I don't have the background knowledge to fully understand why you need to cut and tap a new thread.