giz a break, broke brakes

[norsa]

Having put the MG brakes back together. (Single circuit splitting 4 ways, no proportioning no servo drum disc) no leaks, new flexis, fluid getting to bleed nipples. I can pump the pedal up but let it relax for a second and it hits the floor. Working fine when I took it off the road October. Master seals??
Nick

 

[Robotstar5]

Master cylinder seals gone would be my guess, don't know whether you can still get overhaul kits?.

 

[norsa]

available but I wonder how the cylinder bore would be after probably 40 years service??

 

[Robotstar5]

Anything other than perfect and I would replace the cylinder as it's a single circuit system so I wouldn't take chances.

 

[The_Yellow_Ardvark]

Master cylinder seals. They may of dried out and when wetted inverted.

Strip it down and if the have remove clean, a bit of red rubber grease and you are away.

But any wear or rust in the Master cylinder junk it..
Had it on a Moggy a few years ago.

 

[MCKDAVID]

donkeys years ago, had the same problem with old mini master cylinder, I was bleeding it again and gain, just couldn't keep the pedal. ended up I bought one of those cheap pressure bleeders, (gunsons eezibleed) and that fixed it. I put it down to not getting all the air out manually, whereas the pressure pushed it through.

might be worth trying before condemming the master cylinder.

 

[norsa]

Thanks all. I always bleed with vacuum so the air will have been pulled out, then finish with a manual pump. Interestingly as we were pondering, I just had another look and dark brown matter was seeping back into the clean dot 4. Suspect this is one of the seals disintegrating

 

[The_Yellow_Ardvark]

Or rust.

 

[norlander]

donkeys years ago, had the same problem with old mini master cylinder, I was bleeding it again and gain, just couldn't keep the pedal. ended up I bought one of those cheap pressure bleeders, (gunsons eezibleed) and that fixed it. I put it down to not getting all the air out manually, whereas the pressure pushed it through.

might be worth trying before condemming the master cylinder.

I've had that sometimes when I change calipers/refurb brakes on mocycles, rear caliper often a pig, had to take it off and hold it to get the fluid to go.
Use something like this now

http://www.frost.co.uk/automotive-c...mp-test-kit-one-person-brake-bleeder-kit.html

Just seen your last post as I was about to send this but left it in as other folks look at threads.

Anything other than perfect and I would replace the cylinder as it's a single circuit system so I wouldn't take chances.

I usually replace everything as a complete overhaul - even though I think brakes are for cissies (I made that up)

 

[rtbcomp]

If your cylinder is obsolete I think there are firms that can reline them with a stainless liner.

 

[johnik]

Is that on a midget, master cylinder does clutch as well ?.
If so, had endless problems with mine,2 repair kits failed to cure it,eventually i found another master ,resealed that and no more probs tho i couldnt see anything wrong with the original.

 

[Keith 66]

When i rebuilt my Moggy pick up i put a complete new braking system in it. Master cylinder, pipes, slave cylinders etc.
I put Dot 5 Silicone fluid in it. There were lots of articles in the classic car press about how it made the pedals feel different etc.
I noticed no difference at all apart from one thing. The yearly ritual of seized up cylinders at one corner or another necessitating replacement of the affected cylinder with the bleeding of brakes that went with all that became a thing of the past, The silicone fluid does not absorb moisture and so 17 years on it was still running on the same cylinders.
Its been laid up now of road for 7 years & they are still not seized up.
I think that to use anything else is false economy.

 

[MCKDAVID]

@norlander

aye had many fun sessions bleeding "bleeding" bike brakes....
looks like a decent kit, still have my old kit, I picked up a old garden sprayer with knackered hoses / lance, was planning to make a little pressure bleeding set up with that, but looking at the frost one, it hardly seems worth the bother. might just get one of them.

 

[norsa]

Well. Drained the system though. Happy to report the brown seeping matter is non metal. Seal kit ordered. £5.50
Thanks all for inputs.
Nick

 

[norlander]

@norlander

aye had many fun sessions bleeding "bleeding" bike brakes....
looks like a decent kit, still have my old kit, I picked up a old garden sprayer with knackered hoses / lance, was planning to make a little pressure bleeding set up with that, but looking at the frost one, it hardly seems worth the bother. might just get one of them.

The one I have pumps the fluid through the bleed nipple up the line and into the M/C. Best not forget to take the top off the M/C first though

 

[norlander]

Well. Drained the system though. Happy to report the brown seeping matter is non metal. Seal kit ordered. £5.50
Thanks all for inputs.
Nick

hope thats it sorted now.

 

[norsa]

Just to let you know. The seals had not inverted or broken up. Looked fine. Fitted the new seals, bled up straight away. Huge pedal now.