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Unseizeing brake unions ..

Posted: Fri Mar 10, 2006 11:08 am
by JustinMinor1000
All of the (two year old) brake unions seem totally siezed ... all soaked in WD40 to no obvious effect ..

Any tips ?

Posted: Fri Mar 10, 2006 12:32 pm
by Alec
Hello Justin,

I don't know if it is steel or brass unions, but for steel, Plus gas is a much better fluid to use.
Get the best fitting spanner you can, ideally a proper flare spanner is best. (An open ended ring spanner is my best description)

Alec

Posted: Fri Mar 10, 2006 2:35 pm
by simmitc
Not much help when already seized, but on re-assembly use copperease or similar on the threads and tube, but keep the end and innards of the pipe clean. Since adopting that practice I've never had a problem.
Once seized then sometimes a sharp tap on the well fitting spanner works better than constant pressure. It's still best to have a spare pipe ready just incase the old one twists - once it does then it's weakened and shouldn't be used.

Posted: Fri Mar 10, 2006 3:34 pm
by rayofleamington
If you grerase them, make sure you don't overtighten!
with lubricated threads it will be extra easy to flare the end of the flare nut, making it impossible to use twice.

Posted: Fri Mar 10, 2006 4:09 pm
by bmcecosse
Best to burst the pipe - and then you can get a good ring spanner on it. Spot of heat from a gas torch may be needed too.

Posted: Fri Mar 10, 2006 7:35 pm
by JustinMinor1000
ARRGH .. Well .. I ignored all the advice .. fortuantly it is only one outboard union that didn't respond to the ring spanner treatment.

With one side in a vice and the second (sacrificial joint) in a pair of overstressed mole grips. I felt it give and thought all was well ..

No .. it had of course sheared ..

Hi ho hi ho it's off to the parts car we go ..

Posted: Fri Mar 10, 2006 7:38 pm
by bmcecosse
Told you to use some heat!

Posted: Fri Mar 10, 2006 7:42 pm
by JustinMinor1000
bmcecosse wrote:Told you to use some heat!
I know :( just shoot me and be done with it .. :D

Posted: Fri Mar 10, 2006 7:47 pm
by bmcecosse
Never mind - maybe would not have come out anyway - was it front or rear ?

Posted: Fri Mar 10, 2006 8:11 pm
by JustinMinor1000
bmcecosse wrote:Never mind - maybe would not have come out anyway - was it front or rear ?
It was rear .. I made a rather silly mistake .. the nearside cylinder was siezed and (in my opinion) very badly fitted and knowing they had both been done at the same time I assumed that the other side would be the same, and that the best course would be to change them both.

As the nearside one had a new rubber boot and the unions were all free(ish) I bought the parts on that basis .. New cylinders/pipes/copper washers.

What i didn't do was to dismantle the other side .. assuming they would be the same ..

They wern't .. 30 year old rubber boot almost perished seised in union etc etc .. My guess is that the other side the boot fell to bits when they dismantled it so it had to be replaced this one stayed together ..

So it's more new bits tommorow ..

It could have been worse! The three way union could have been siezed ..

Posted: Fri Mar 10, 2006 8:45 pm
by bmcecosse
And it's the one with the unusual threads. New cylinders are best bet - they will then last for many years. I keep a bit of slack in the handbrake cables so the cylinders get some movement when the brakes are used. MOT lad always grumbles - I explain why it's like that - he's happy.