Master Brake cylinder plunger

[Chris H]

Any one know where I could source a plunger for a Vitesse Mk2 master brake cylinder, part number is 511137 (~17mm diameter).

The one I have has hole in it, I think it's where I drilled it years ago to get the seized plunger out of the cylinder, I guess it seemed a good idea at the time !

I don't really want to buy a complete replacement cylinder if I can avoid it.

Chris  

[Rabbit]

HANG ON! This is your brake master cylinder, not a refill for your Thermos flask. By bodging up a master BRAKE cylinder you put not only your life in danger but MINE and Other road users. Bite the bullet, buy a new one or lay the car up until you can afford to be safe. 

[Pete Lewis]

you will not find any supplier for a piston

if costs apply then  get a landrover upright reservoir new unit for less then £15  on ebay 

[Chris H]

Thanks for the replies, perhaps I should have been more explicit.

This is for a car that's been off the road for about 30 years and the brake/clutch parts were removed maybe 10 - 20 years ago. It's a long ongoing, body off, restoration project and I'm at the point now, having earlier this year got the engine running again, of sorting the hydraulics (new pipes/seals etc ). I've already, some years ago, replaced the clutch master cylinder as the casting was cracked around the pipe union thread.

I could of course replace the brake MS  but as it's in very good condition, apart from the holed plunger (which fundamentally stops it working ... the fluid would leak out :-) there's no reason not to keep it, unless I can't source a placement plunger, which it may turn out I can't . If new ones aren't around then a used, unfixable MS (e.g damaged casing) would solve the problem as a source of the plunger. 

There's no hurry for this, the cars not going anywhere near a road for some time.  

 

Chris

[dougbgt6]

Chris,

When you say plunger, are you are speaking my dysfunctional language? Do you mean the rubber bit? MS cylinder repair kits are available from the usual suspects, Rimmer Bros, Canleys, Paddocks.

Doug

[NonMember]

I suspect he means the metal piston that the rubber bit fits onto.

[dougbgt6]

Yes, he says the piston has a hole, but I'd like to see that.  How does the piston have a hole?

Doug

[Pete Lewis]

doug  youre slipping he says he drilled it some years back to de seize it ........not the best result 

Pete

[Chris H]

Hi all,

 Yes I mean the metal piston that fits inside the MS cylinder. I call it a plunger as that's what the parts manual calls it , personally I'd have gone with piston, but I think it best to defer to the Standard-Triumph company''s definitive knowledge on these matters. 

Non of the repair kits include that, I guess because it rarely gets damaged, unless of course you drill a hole in it as a last pitch attempt to get the bugger out with a self tapping (probably metric) screw, thinking you'd just order another one when the time came.

Live and learn eh?

Chris

[dougbgt6]

Ah, If you had to do that to get it out then I would venture that both plunger AND cylinder bore are buggered. New master cylinder time I’m afraid.

Doug

[Badwolf]

I have a complete master cylinder and piston assembly which looks perfect but the bore is badly scored so, no messing, a new one was fitted along with one for the clutch. I concur with everyone else. If you want to stop, get a new one otherwise, please, don't put it on the road for the safety of all.

[daverclasper]

I agree. Though if it was clutch M/C, maybe some liquid metal, or even 2 part Araldite type stuff (used pound shop one, a lot and has been good), to seal the drill hole?.

Dave  

[Pete Lewis]

no dave nice idea  . thats a bodge too far  

Pete

 

[Colin Lindsay]

They're so cheap - relatively speaking - that you may as well buy a good replacement (and I'll emphasise good) rather than risk a bodge, even on the clutch. In the past I've seen them 'lightly honed' to death! I've tidied some up with 1200 grade sandpaper on my fingertip and even then was wary, but I've seen them 'restored' with a wire brush on an electric drill and to be honest I wouldn't get in that car afterwards!

[Pete Lewis]

a quick search on the bay shows many 0.7  0.75"  with upright reservoirs ( not overly important) at £28   

[daverclasper]

3 hours ago, Pete Lewis said:

no dave nice idea  . thats a bodge too far  

Must stop being such a cheap skate 

[Chris H]

Thanks all for your suggestions. I think pragmatically a replacement is the only viable option.

However out of interest I inspected the bore of the cylinder  (with an inspection microscope) and it's smooth as the proverbial babys bum.

As I recall (from many years ago) although the plunger was stuck it was purely gummed up with dried fluid around the rubber and so was impossible to "suck out",

I guess maybe  high pressure air could have done it. 

I'd have no real compunction re-using it if plungers where available but as they're not ... 

Cheers,

Chris

[Colin Lindsay]

1 hour ago, Chris H said:

As I recall (from many years ago) although the plunger was stuck it was purely gummed up with dried fluid around the rubber and so was impossible to "suck out",

I guess maybe  high pressure air could have done it. 

I'd have no real compunction re-using it if plungers where available but as they're not ... 

You just beat me to it! I've refurbished three or four over lockdown including a GT6 0.7 version, and in each the plunger / piston was solid. The way I did it was heat - immerse in boiling water for a while - then spray with liquid spray grease whilst upright in a vice to keep the grease in the 'reservoir' on the end of the piston. The grease or penetrating oil may drain in and get round the sides, but if not try boiling water again and gentle pressure with the end of a thick wooden spoon; the plunger may shift and move inwards, but not fully out again. Gentle gradual pressure from a two-legged puller will also work. Each fraction of an inch of bore that's uncovered should be cleaned gently - polished with a soft cloth - and greased with spray grease. Eventually you'll reach a point where the piston will start to move both up and down, so gentle taps with a rubber mallet may free it, but if you push it down, then quickly let it spring up again, it may fly completely out. Compressed air works but can blow the piston out at some speed.

As you say, it was just dried gunge and stuck or decayed rubber causing the problems. Most of them required nothing more than a soft polishing buffer on a Dremel, one that completely fills the bore, and light polishing - light enough to clean but too light to remove metal. Clean with brake cleaner and regrease with the proper red grease. A good repair kit should have the spring too, so no matter if the old one was terminally rusty.

 

[daverclasper]

So. if all good?, except for drill hole, could this be welded (or too much distortion of cylinder maybe) instead of liquid metal, if that's dodgy.

Seems a shame to chuck parts.

I don't want to give up yet, on safe bodging/repairing, unless necessary, though also don't wan't to give out dodgy ideas either. 

 

Edited July 26, 2020 by daverclasper

[Chris H]

Colin, Thanks for the reply, pity I didn't ask you 10 (?) years ago when I when I removed and dismantled the MS,  but at that time the object was to

dismantle whatever I could on the car to preserve it for a later day when I had time !

Photo shows what it looked like at that time.

Ah well , maybe on the next restoration project ... in another life.

[Colin Lindsay]

Chris, we all do it; I remember a disbelieving Spitfire owner standing looking at a rare part, and asking me in astonishment: "so you cut it into two pieces to remove it?"

[Peter Truman]

Over the years I've successfully had master cylinders sleeved, either a thicker brass or thin stainless sleeve, they have an interesting gizmo for deburring the hole drilled from the reservoir without damaging the sleeve. cost wise generally probably not cheaper than replacement BUT they last forever.

Ref the piston if it was very rare and couldn't be replaced with new, as a temp outback type repair could you tap the hole and thread a small bolt/grub screw in suitably lock threaded, mech strong and sealed.

Ref clutch masters we in the club here have used similar dia trailer master cylinders picked up new from trailer suppliers for around 20 to 25 dollars, a lot cheaper than originals and haven't heard of one failing yet, but clutch's are not a life threatening issue. 

[Chris H]

Thanks again for the replies, I had similar thoughts to Peters suggestions about repairing the hole but wouldn't want to do that as a permanent fix for on the road,

however at the moment all I want is to be able to get the car (rolling chassis) out of  the garage and up on ramps under its own steam and be able then to stop,  also to fill the

system and check for leaks in the slave cylinders and pipe unions.

So yesterday I filled the hole with a tight fitting ball of metal (oval nail head as I had no suitable grub screw) and brazed it in, then ground down the  excess  metal to a rough cup shape for the push rod to fit into. It looks good but I've yet to fit and test it for leaks. I wouldn't be happy leaving it long term as I can imagine the brazed metal eventually cracking with fatigue.

However as an interim fix it's OK until I get nearer to OTR* day.

Cheers,

Chris     

*(On The Road - 2021 maybe)