Renovating brake cylinders

[Orkney]

In the process of replacing all of the brake cylinders on the trav, and being the skinflint i am thought i'd have a go at restoring the old cylinders for the time inevitably when I acquire another mogg.
They are all original cylinders not pattern so thought it would be good to try restoring them all using the repair kits.
So question is easiest way to get the old cylinders out.
Thoughts so far are to rig up a connection using an old copper brake pipe bodged onto a grease gun and use that to drive it out - assuming that 2 of the 6 are seized don't suppose air would be any good to try after soaking them in penetrating oil ?
Anyone tried this ?

[rayofleamington]

Air is not a good choice - if the seals leak then you don't get pressure (it's too leaky). If you compensate by cranking up the pressure, things can get very dangerous.
Oil can be used - or even grease (eg from a 500psi grease gun). The advantage with oil is that the pressure godrops off if the piston starts to move, so you won't fire it out like a bullet.

However - back to the root of the issue... If the cylinders have corroded then new seals may not fix them, and even if they are fixed, they may not last long. A cylinder is about twice the price of a seal kit, so most folks would just replace the cylinder.

If you are really sure you want to try - then one technique that rarely fails is to get serious wth them! Find a short length of hex bar that's a bit smaller than the piston. Put cylinder in a vice. Remove the sheet metal piston cap. Mig weld the hex bar onto the piston! Rotate the hex bar to make the piston turn (usually goes with a crack). Once it is turning, use plenty of release fluid and keep turning whilst pulling it out.
Once it's out, grind off the welds to remove the hex bar. clean up the piston and carefully tack weld the cap back on.

This is a lot of effort for Minor cylinders! However on irreplaceable cylinders it's a good method - especially if the bores are then relined in stainless.

[bmcecosse]

If they are that stuck - they will be beyond renovation. Only worth fitting new seals where the old seals have been leaking - and the cylinders not 'seized'. Yes - a grease gun is the way to shift them if you want to give it a try!

[paulhumphries]

One trick I've tried on calipers in the past, that worked, is boil them in a large saucepan of water for 10 minutes or so !
Try it - you have nothing to loose if it doesn't work.

Paul Humphries

[bmcecosse]

Unless your wife/mother catches you doing that with her saucepan!

[Orkney]

Unless your wife/mother catches you doing that with her saucepan!

Dont let the Dragon in the kitchen very often - too much of a foody

OK so grease gun it shall be, like the idea of boiling it up in some water as that will help clean them up considerably - if they wern't so filthy could have put them in the deep fat fryer

Will be interesting to get them apart at any rate just to see what was wrong where, even if half of them can be salvaged its better than none.

[paulhumphries]

like the idea of boiling it up in some water as that will help clean them up considerably

I've an old saucepan I rescued from the tip that I use for such purposes.
As long as I clean up afterwards my wife isn't the slightest bit bothered if I use the cooker but I suppose a camping stove would do just as well for those with less understanding wives.
Try adding a spoonful of dishwasher powder to the water if boiling to clean - works great.

Paul Humphries.

[Orkney]

Have a spare Jam making stainless 2 gallon thing, think that can be solely for parts from now on
Have the luxury of an always on year round aga type range so simmering things and never ending hot water never a problem.

Think i've heard it said that Biological washing machine powder works best - my dishwasher doesnt use powder - it has 2 legs and moans a lot

[paulhumphries]

Have a spare Jam making stainless 2 gallon thing, think that can be solely for parts from now on
Have the luxury of an always on year round aga type range so simmering things and never ending hot water never a problem.

Think i've heard it said that Biological washing machine powder works best - my dishwasher doesnt use powder - it has 2 legs and moans a lot

I think a jam making pot is what mine might be. A neighbour asked me to take it to the tip but seeing I could find a use they were happy for me to have instead.
I used to use bio powder until I read somewhere how good dishwasher powder was. A cheap container full (99p) has lasted over a year and certainly better than bio powder for dirty car parts.
Unfortunatley I tend to do mostly of the household dishes so am desperate for a dishwasher in our kitchen but we don't have the room.
I've suggested my wife washes clothes by hand and I can then have a dishwasher in the place taken by washing machine at present but that didn't go down very well

Paul Humphries

[kennatt]

as mbc says if they are stuck to the point of needing force to move the piston then the unit is us and should be regarded as scrap. .Not worth the risk,if you renovate the brakes with new linings and the old pistons leak you will need to buy new linings again just piling up on the cost and compromising road safety.I'm all for cutting costs on rebuilds and maintenance and will use secondhand items wherever I can, but never on brakes and steering components.The old addage buy cheap pay dearly comes to mind

[Judge]

Unless your wife/mother catches you doing that with her saucepan!

Well naturally, everyone knows that a saucepan is for gently warming up the grease to immerse old motorcycle chains in

[Orkney]

Sorry judge have to disagree -
Fish kettle is the way to go for bike chains - its the right shape

[Judge]