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Floor mount pedal box
goaty - 1/1/09 at 04:54 PM

hey,
Just wanted to ask someone in the know about floor mounted pedal boxes.
I am currently looking at fitting one with bias bar set up. using .750 and .625 master cylinders for my Wilwood midilites 31.8 pistons(m16 replacement) and using sierra rear calipers, fist off are these a good size to use??

And the main question is, will i be ok to use integral fluid pots or will i get fluid passing back too much??
or are remote fluid pots a must??

any thanks

Echidna - 1/1/09 at 05:38 PM

Joe,

To make an analysis as to whether your brake MC's are up to the job for your brake system you should use this spreadsheet. It's really helpful.

goaty - 1/1/09 at 08:11 PM

thank you once again

goaty - 1/1/09 at 08:58 PM

anyone able to help out? not to sure if i am using the tale correctly.

what size M/C's are you all running?
thanks

Echidna - 2/1/09 at 05:53 PM

quote:
Originally posted by goaty

And the main question is, will i be ok to use integral fluid pots or will i get fluid passing back too much??
or are remote fluid pots a must??

any thanks


If you use the integral MCs you will certainly need to do something that will neutralize the bad effect caused by the MC being lower than the calipers. And pressure residual valves are a solution. There are many people having used these valve. I don't want to tell that they are obsolete or useless. What i tell is. Why to do something to neutralize a bad effect and not choose the solution which don't cause any bad effect right from the start?
Problem is that anytime the MC is mounted below the hydraulic components at the wheels ends (be it calipers or drum wheel cylinders), thanks to gravity, brake fluid will flow from the wheel end components back to the MC reservoir when it's not pressurized. Then, as soon as you hit the brake pedal, you will have reduced available pressure and you will get excessive brake pedal travel. A residual pressure valve is nothing more than a one-way flow restrictor at low pressures. It will hold a constant amount of pressure at the wheel ends preventing fluid from draining back to the MC when the brakes are not applied. Please note that you will need to use 2 pressure valves one for each brake hydraulic circuit.

And i made a sup of all the parts you will need in each case with their costs:

Integral MC
MCs = 28.5x2 + IVA = 65.5 GBP
Residuals valves = 19.5x2 + IVA = 44.8 GBP
Total = 110 GBP

Non-integral MC-remote reservoirs
MCs = 26.5x2 + IVA = 61 GBP
Drop line kits = 16.5x2 + IVA = 38 GBP
Remote reservoirs = 11.5x2 + IVA = 26 GBP
Aluminium bracket for 2 reservoirs = 3.9 + IVA = 4.5 GBP
Total = 129.5 GBP

So you will have to pay about 20GBP more for the remote reservoir option.

goaty - 2/1/09 at 07:14 PM

the reason i said integral is that is what i have to hand, or waiting to be given anyway.
I will forget them and go for remote cause as you say. its Brakes.

Any idea what size M/C's? i should use, i cant work that spreadsheet out properly....

Echidna - 2/1/09 at 07:26 PM

I will work it out for you, Joe, and let you know as soon as possible. I will need some info from your car though:

1) vehicle weight
2) front weight split
3) wheelbase
4) CoG height-approximately (it can be calculated but it's a bit difficult to do)
5) brake pad friction coefficient
6) tyre dimension
7) disc diameter (front and rear)
8) caliper piston diameter (front and rear)
9) number of pistons per caliper (front and rear)

For the spreadsheet to be useful, it assumes that you use disc brakes all round.

Regards,
Theo

goaty - 2/1/09 at 07:42 PM

will get the info all sorted out 2mo when i am at the workshop, and i am running discs all round .
thanks again.
very kind of you