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Brake fluid reservoir location - low or high ?
Andrzejsr - 28/12/19 at 08:25 PM

I am propably going to change brake master cylinders (front and rear). Currently in my car (Westfield) there are master cylinders integrated with fluid reservoir, so located low - below calipers (floor pedals) .

Would it be good idea to change to master cylinders with remote - located highier brake fluid reservoirs ? I have read that when low, there could be first braking longer pedal travel. After few trackdays in this configuration, I think I did not noticed such pedal behaviour. But then, I am new to brakes without servo, everything new so I maybe did not noticed.

What are the pros and cons for both reservoir locations ?
(highier - easier to maitenance, easier to check and fill up fluid, easier with bleeding).


Slimy38 - 29/12/19 at 10:25 AM

quote:
Originally posted by Andrzejsr
I have read that when low, there could be first braking longer pedal travel.


I'm afraid I can't really help with your question, but I was interested in this bit. How does a reservoir location change the pedal travel? I was under the impression that once a system is filled with fluid, the reservoir plays very little part in the system. It's only there to keep things 'topped up'.

I'm still learning myself so I'm always looking for holes in my own knowledge.


Andrzejsr - 29/12/19 at 11:38 AM

So am I (learning) that is why I am asking questions .

Here is one of the sources of this statement :
https://books.google.pl/books?id=sjdDXMWhGIsC&printsec=frontcover&hl=pl&source=gbs_ge_summary_r&cad=0#v=onepage&q&f=false />
(page 166)

In road driving it might not play a big role, but in racing maybe it is worth to relocate brake fluid reservoir ? I wonder if someone experienced the difference after relocating .

[Edited on 29/12/19 by Andrzejsr]


theconrodkid - 29/12/19 at 01:10 PM

dzien dobry,location really makes no difference unless the fluid is below the level of the master or brake calipers, up high is easier from a maintance point of view as you say


Andrzejsr - 29/12/19 at 05:28 PM

Dzien dobry


What they say in this book - some quote :


https://ibb.co/fdSGnD1

makes sense, assuming that when pedal is not pressed there are no valves active , so the pads can retract a little in calipers (air pressure, dust etc beetweeen disc and pads) with fluid going down to master cylinder wiuth reservoir on the same lever as master cylinder. When reservoir is highier than caliper level, then it is not possible.
The same process as when installing new - thicker pads- pushing cylinders in the csalipers - fluid in reservoir is going up.
So with next braking we have a little more distance for pads to cover.

I wonder if this is something that amateur driver can feel.

Anway, assuming only maitenance / easier bleeding factor now I think it is worth to relocate the reservoirs.

[Edited on 29/12/19 by Andrzejsr]


theconrodkid - 29/12/19 at 07:50 PM

the pressure created by mounting the res higher (called head) is just about zero but as i said, it must be the highest part of the system.
where in Poland are you, i spent many happy times with my Polish girlfriend there


Andrzejsr - 29/12/19 at 09:38 PM

Now "only" need to find good location for the containers... just up above master cylinders is tidy , cables, water hoses...
Best will be in front but then the lines will go above mainfold (hot) . So it should be metal (copper) lines rather than rubber...

(Im in south-east : Rzeszow. Yes, a lot of pretty girls in our country not a lot of tracks, but girls... we can not complain )


Mr Whippy - 30/12/19 at 09:18 AM

Well given that a whole 1m of head of water = 1.5 Psi (as brake fluid floats on water it will be even less) and a typical person can blow about 1.3 Psi then we're not talking very significant forces here against the friction of the piston seals. Personally I have never managed to move any brake component by just blowing down the pipe...


atomic - 3/1/20 at 11:31 AM

If your Master Cylinder is below or equal to the level of your calipers install a residual pressure valve (ensure you use the appropriate pressure valve as they are different for disc or drum) and place you reservoir somewhere above the level of your MC.


Andrzejsr - 4/1/20 at 06:23 PM

Yes, I have read about those valves, have to consider.