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Brake master cylinder orientation

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Hi All.

I'm in need of some guidance from those that know some stuff about brakes.

My original single circuit master cylinder had its mounting lugs at the 6 and 12 o'clock positions. My proposed replacement is a dual circuit unit that in its natural habitat is mounted with its mounting lugs at the 3 and 9 o'clock positions which means that I will effectively be mounting the unit on it's side. I'm wondering if this change will have any adverse effect on the operation of the unit. Maybe more difficult to bleed or some such thing. Or am I just highlighting my ignorance ?

Pic one is of the units side by side and pic two shows the new unit temporarily clamped in place.

Any guidance would be greatly appreciated.

Thanks in advance.

 

20200914_103227.jpg

20200914_121907.jpg

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On 14/09/2020 at 14:44, tortron said:

as long as the res is above it.

might want to bench bleed it first

you should bench bleed any master cylinder before fitment anyway. 

 

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Sorry - I'm a little late to this thread 

I'd be wary of not having the compensation port at the highest point of the master-cylinder. In the years I spent in the industry I can only remember one OEM setup where this did not not apply - the very early vertically mounted 'tin type' mini  was a dog in more ways than one, it was quickly replaced with a conventional setup.

Yes if you bench bleed before installation (as you always should) there's every chance you'll get away with it but don't forget the compensation port is open to the atmosphere when the pedal is at rest effectively leaving leaving the system not only partially exposed to the atmosphere but  also at atmospheric pressure. Relying on fluid being held in an 'inverted' syphon is OK in theory but if in practice  it's not something I'd be comfortable with. If with a little extra fabrication you could mount conventionally I'd recommend it. 

I'd be interested in knowing what brakes you're running and if you've considered a booster?

 

 

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Simon, thanks heaps for taking the time to review the proposed orientation of my master cylinder and for generously sharing your knowledge on the subject. 

The front brakes are standard mid 80s Mitsubishi L300 discs and calipers. The rears are mid 80s Toyota HiAce drums. I'm planning to run a remote VH44J booster for the front circuit with the rear drums plumbed directly into the rear circuit on the master cylinder. For certification purposes I am forced to run a load proportioning valve on the rear circuit and plan to use the standard HiAce unit that I have pulled from the same donor vehicle. The remote fluid reservoir for the master cylinder will sit around 450 mm above the master cylinder.

 

 

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