Brake master cylinder won’t dismantle

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ChipChipChipper
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#1 Brake master cylinder won’t dismantle

Post by ChipChipChipper » Sun Aug 04, 2019 12:47 pm

So I’m rebuilding the brake system on a 1970 S2 2+2 4.2

I’ve removed the master cylinder and started dismantling but I can’t get out the main piston, bearing or plastic cover.

I’ve removed the circlip and the books I have (Autobooks, Haynes & Bob Bate) say the piston should just pull out but I’ve tried everything and can’t get it to move.

So far I’ve put the piston end circlip back on so I can tap a spanner to try to pull it out. I’ve blocked the other outlets and pressured the cylinder and tapped it again. I’ve put a thick plastic pipe on the bearing and tapped it to see if will dislodge but nothing seems to have moved it at all.

I thought about leaving it but looking in the outlet hole looks like the spring might be broken so I want to check that.

I’ve read the bearing and plastic cover are no longer available so am trying not to crack either and the piston needs to be sealed so not scratching it.

Am I doing something wrong or do you know any tricks or is it just a case of strong arming it off?

Here’s a photo of the stubborn bugger (the bearing not me)

Image

Thanks
Ian
1970 S2 2+2 4.2l

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Mich7920
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#2 Re: Brake master cylinder won’t dismantle

Post by Mich7920 » Sun Aug 04, 2019 1:07 pm

Hi Ian,

Do you fit out the "stop pin" locate at the botton of the hole of the inlet connection ?
Look the knowledge base / serie 2 / brake

Mich
Michel
1963 E Type OTS - Angus Restoration
1965 E Type FHC - On the road at last !

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ChipChipChipper
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#3 Re: Brake master cylinder won’t dismantle

Post by ChipChipChipper » Sun Aug 04, 2019 1:56 pm

Thanks Michel. Can’t find any sign of a stop pin.

In the KB for S2 brakes there’s this diagram which I presume is originally from Jaguar as it’s in all my manuals:

Image

I can’t see a stop pin here either and it seems to conform to what I have. Is there something missing from it?

Thanks
Ian
1970 S2 2+2 4.2l

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ChipChipChipper
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#4 Re: Brake master cylinder won’t dismantle

Post by ChipChipChipper » Sun Aug 04, 2019 2:00 pm

I should add I got it from the Dropbox pdf from S2 brakes link on this KB page (in case I’m on a different page to you)

http://forum.etypeuk.com/viewtopic.php?f=16&t=700

Thanks
Ian
1970 S2 2+2 4.2l

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Mich7920
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#5 Re: Brake master cylinder won’t dismantle

Post by Mich7920 » Sun Aug 04, 2019 2:29 pm

With the bulge of the body I thought it was the servo.
Sorry I did this but didn't remember any problem.
Do you try with pressure air ? Beware your eyes.
Michel
1963 E Type OTS - Angus Restoration
1965 E Type FHC - On the road at last !

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#6 Re: Brake master cylinder won’t dismantle

Post by ChipChipChipper » Sun Aug 04, 2019 2:47 pm

Yes tried with pressure and tapping a spanner on the piston at tHe same time. I had the compressor up to 10bar with a tube held into the cylinder by hand internal cylinder pressure wouldn’t have been 10.

Think I’ll fashion a tapped attachment to directly pressure the cylinder and try that. Will get everything clear of the piston including eyes!
Ian
1970 S2 2+2 4.2l

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Mich7920
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#7 Re: Brake master cylinder won’t dismantle

Post by Mich7920 » Sun Aug 04, 2019 3:26 pm

I just advise you to have a drink and a good night before doing the job... :drinkingcheers:
You'll find the solution more quietly
Mich
Michel
1963 E Type OTS - Angus Restoration
1965 E Type FHC - On the road at last !

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mgcjag
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#8 Re: Brake master cylinder won’t dismantle

Post by mgcjag » Sun Aug 04, 2019 3:27 pm

Hi Ian...think i remember mine was stuck.....dont do anything drastic....use combination of tap it in a touch then air to push out....just keep on....in/out.....Steve
Steve
1969 S2 2+2 & Building a C type replica

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ChipChipChipper
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#9 Re: Brake master cylinder won’t dismantle

Post by ChipChipChipper » Sun Aug 04, 2019 3:36 pm

I’ve had two nights sleep on it. This is the third day of trying.

Just tried a ring spanner on the piston then cabletie and circlip and tapped that. Didn’t work and has marked the piston a bit so won’t try that again.

So the only thing left is to try the drink.

Cheers chaps
Ian
1970 S2 2+2 4.2l

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angelw
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#10 Re: Brake master cylinder won’t dismantle

Post by angelw » Sun Aug 04, 2019 3:59 pm

Ian Wrote:
Just tried a ring spanner on the piston then cabletie and circlip and tapped that. Didn’t work and has marked the piston a bit so won’t try that again.
Hello Ian,
Arrange threaded nipples to allow a high pressure grease gun; 10,000psi is what I use on stuck Brake Caliper, Master and Slave Cylinder pistons, to be connected to the port downstream of the piston and blank off all other orifices. Its way more controllable than compressed air and will shift the most difficult to move pistons without damage.

Regards,

Bill

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Mich7920
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#11 Re: Brake master cylinder won’t dismantle

Post by Mich7920 » Sun Aug 04, 2019 4:00 pm

Sure a drink ( or more ) work fine...
Perhaps gently with a inertia hammer fixed on the circlips ?
It's very annoying when we don't understand the WHY of the problem. :banghead:
Michel
1963 E Type OTS - Angus Restoration
1965 E Type FHC - On the road at last !

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abowie
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#12 Re: Brake master cylinder won’t dismantle

Post by abowie » Sun Aug 04, 2019 9:25 pm

The blue/green plastic valve housing has an o ring around the outside of it to make it seal in the bore.

In an old master cylinder these go hard and make it very hard to get this piece out, especially if there is any corrosion of the bore above it. Problem is if you break the bearing you can't get them as a spare part.

You should be able to get it to move with some lubricant and either pulling on the piston or pressurising the cylinder or a combination of both.

In the past we used to get the masters resleeved and rebuilt for restorations but these days it's cheaper and easier to just buy a new master.
Andrew.
881824, 1E21538. 889457..oops
http://www.projectetype.com/index.php/the-blog.html
Adelaide, Australia

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Mich7920
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#13 Re: Brake master cylinder won’t dismantle

Post by Mich7920 » Tue Aug 06, 2019 12:34 pm

What are the news ?
Michel
1963 E Type OTS - Angus Restoration
1965 E Type FHC - On the road at last !

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ChipChipChipper
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#14 Re: Brake master cylinder won’t dismantle

Post by ChipChipChipper » Sun Aug 11, 2019 8:16 pm

I had a drink and realised the gauge on my compressor goes to 20bar and I have a heavier hammer in my toolbox.

The result :

Image

In truth it was a case of lubricate, tap, lubricate tap and repeat. The comments on this forum confirmed that was the way to do it and thankfully my father persisted and persisted until it came out.

Thanks all
Ian
1970 S2 2+2 4.2l

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Mich7920
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#15 Re: Brake master cylinder won’t dismantle

Post by Mich7920 » Mon Aug 12, 2019 2:05 pm

Great !
:drinkingcheers: Only with your father...
Michel
1963 E Type OTS - Angus Restoration
1965 E Type FHC - On the road at last !

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#16 Re: Brake master cylinder won’t dismantle

Post by abowie » Mon Aug 12, 2019 11:51 pm

Good outcome. They can be very tricky to disassemble.
Andrew.
881824, 1E21538. 889457..oops
http://www.projectetype.com/index.php/the-blog.html
Adelaide, Australia

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