Master cylinder.

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The Black Baron
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Master cylinder.

Postby The Black Baron » Mon Jun 12, 2017 9:01 pm

Hi all,

Just filling up fluids tonight. Went to fill up the brakes, and fluid pouring out the chassis from around the master cylinder.

Took the cylinder out, Andy the fluid is pouring out of this little hole (upper left). Anybody seen this before, as we don't know why its there. Maybe missing a blank or something? It's thrown us.



Cheers,

David.
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les
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Re: Master cylinder.

Postby les » Mon Jun 12, 2017 9:18 pm

Never seen a hole like that in a cylinder before, I presume it's a replacement. Where did you get it from?


BLOWNMM
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Re: Master cylinder.

Postby BLOWNMM » Tue Jun 13, 2017 1:02 am

Definately should not be there !!??
Bob
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Trickydicky
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Re: Master cylinder.

Postby Trickydicky » Tue Jun 13, 2017 6:55 am

Is there a hole in the chassis leg in the same position? It looks like someone has drilled a hole in the chassis leg and and gone straight through to me.
Richard

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BLOWNMM
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Re: Master cylinder.

Postby BLOWNMM » Tue Jun 13, 2017 7:04 am

The hole is in a curved section towards the top. I thought a drill bit would have tended to run off a bit and not produce such a clean neat hole without ragged edges as the pic shows.
Bob
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RobThomas
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Re: Master cylinder.

Postby RobThomas » Tue Jun 13, 2017 7:44 am

Is the hose at the back a clue? Looks like a remote reservoir.

The hole would be the right height for an overflow but you'd need a reservoir to be at the same height. Is there another filler somewhere?
Cardiff, UK

BLOWNMM
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Re: Master cylinder.

Postby BLOWNMM » Tue Jun 13, 2017 8:12 am

It certainly looks like a remote filler hose at the rear however why would you need an overflow? I have a remote reservoir installed on my MM and it does not have an overflow nor does it need one. Seems something of a mystery.
Bob
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oliver90owner
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Re: Master cylinder.

Postby oliver90owner » Tue Jun 13, 2017 8:45 am

I thought a drill bit would have tended to run off a bit and not produce such a clean neat hole without ragged edges as the pic shows.

Easy to do - just use a rigid cutter, like an end mill. OP needs to seal up the hole and carry on. Having ascertained that clearly it is not a standard attribute, remove it or replace the whole M/C.

Declan_Burns
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Re: Master cylinder.

Postby Declan_Burns » Tue Jun 13, 2017 9:07 am

There could be still some swarf inside the M/C. I would remove it and flush it out just to be on the safe side or replace it for peace of mind.
Regards
Declan


Regards
Declan

BLOWNMM
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Re: Master cylinder.

Postby BLOWNMM » Tue Jun 13, 2017 9:17 am

Oliver - see my post at 4:04 pm.
Bob
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les
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Re: Master cylinder.

Postby les » Tue Jun 13, 2017 9:42 am

Yes there would be a run off if a drill hit the cylinder, rather than a clean hole.


The Black Baron
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Re: Master cylinder.

Postby The Black Baron » Tue Jun 13, 2017 3:36 pm

Yeah, its a perfectly smooth hole. There are no holes in the chassis and definitely not a drill hole for sure. It's too good.

Remote reservoir pipe at rear indeed, goes underneath and into engine bay.

Don't know where we got this one from- we did start the project over 20 years ago, so much has been forgotten.

New cylinder or weld up then!

David.

philthehill
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Re: Master cylinder.

Postby philthehill » Tue Jun 13, 2017 7:06 pm

'New cylinder or weld up' - I would do neither.

Blind tap (not all the way through using a second or No: 2 tap) the hole and fit a short grub screw using Loctite Loc & Seal so as to ensure a complete seal.
Greasing the tap will catch most if not all of the tapping swarf - but as advised above clean out the inside of the cylinder.


firedrake1942
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Re: Master cylinder.

Postby firedrake1942 » Tue Jun 13, 2017 7:14 pm

Were the brakes working before you did your fill up ? I can't really see how if there is a leak for the MC.

philthehill
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Re: Master cylinder.

Postby philthehill » Tue Jun 13, 2017 11:40 pm

There would be no reason for the master cylinder not to work as it should as the hole duplicates the vented cap normally fitted; and as the hole is at the top of the cylinder there would still be fluid contained within the cylinder body as normal so that when the pedal was depressed the brakes would operate as normal.
If the hole was at the bottom of the master cylinder it would be different as the brake fluid would drain out and there would be no brake.
I would suggest that who ever fitted the master cylinder and what appears to be a remote reservoir has read the fitting instructions wrongly, fitted non vented caps to the remote reservoir and master cylinder and to overcome the lack of brake fluid entering the body of the master cylinder drilled the hole to vent the master cylinder.
There is no sane reason that the hole should be drilled so the above may be so fanciful to be true - but who knows.


The Black Baron
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Re: Master cylinder.

Postby The Black Baron » Thu Aug 22, 2019 9:03 pm

philthehill, I can answer that having had it all apart and been underneath it for far too long!

It was a drill bit through the chassis for a securing clip that went a ‘little too far’!

The remote reservoir is vented and works fine. I will post a quick update in restorations. :)

simmitc
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Re: Master cylinder.

Postby simmitc » Fri Aug 23, 2019 11:05 am

13th June 14:36 "Yeah, its a perfectly smooth hole. There are no holes in the chassis and definitely not a drill hole for sure. It's too good."

22nd August 20:03 "It was a drill bit through the chassis for a securing clip that went a ‘little too far’!"

I'm glad that's cleared up :roll:


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