Mix
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| posted on 29/5/03 at 12:50 PM |
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Brake master cylinder types
I've decided to construct a floor mounted pedal box and use two master cylinders and a bias bar in the braking system, there are several helpful
photos on archive but I can't find a reference to the origin of suitable master cylinders. Thanks in advance
Mick
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ChrisW
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| posted on 29/5/03 at 01:11 PM |
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Luego sell the two cylinders and the remote reservoir for £100 or so for the set. Looking around at Stoneleigh that seemed to be a fair price.
I'll be ordering them on pay day!
Chris
My gaff my rules
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Mark H
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| posted on 29/5/03 at 01:53 PM |
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Or Stuart Taylor if they're closer. Either way, I think we've agreed that they are all the same design!
Mark Harrison and
Q986 KCP back from the dead...
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Glenn
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| posted on 29/5/03 at 02:48 PM |
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try rally design :
http://www.raldes.co.uk/2003/page023.htm
£24.50 for non-intergral 0.75 master cylinders, this is what you will need.
Ive got to order 3 for myself, brakes and clutch.
BTW its £11.50 for the reservoir's, but im nicking some off some old bikes
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Mix
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| posted on 29/5/03 at 04:11 PM |
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Many thanks for the quick response, Rally Design looks particularly good value. Any comments ?
Mick
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alister667
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| posted on 2/9/03 at 10:32 PM |
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I looking to fit a brake bias bar myself. Any further reports how you got on? Did anyone fit the rallydes cylinders? Did the ST and Luego versions
work OK and were they easy to fit?
Thanks in advance.
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eddymcclements
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| posted on 3/9/03 at 09:12 AM |
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I am using an ST pedal box, and I ordered Girling master cylinders directly from Rally Design as they were the cheapest source. In the end I was sent
Wilwood m/cylinders as a substitute, and very nice they are, too.
Pics of pedalbox here and master cylinders
here.
Cheers,
Eddy
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Browser
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| posted on 3/9/03 at 11:35 AM |
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Is there any point having a bias bar unless you are planning to take to the tracks on a regular basis? As far as I can understand, bias adjustable
brakes are there to compensate for lightening fuel loads and changing tyre dynamics in racing cars, neither of which will be anywhere near as extreme
in a road-oriented 7. I can see the point in a pressure limiter and I intend to use one when I build mine but once set I hope I can leave it alone.
Your thoughts/arguments please?
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eddymcclements
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| posted on 3/9/03 at 01:20 PM |
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Surely a pressure adjuster to the rear brakes is just another way of setting front/rear bias? I am not planning on having a remote adjustment for the
bias bar - it's just a way of getting the car set up correctly, then I'll lock it in position. The dual master cylinders in the pedal box
also comply with the requirement for dual-circuit brakes.
I realise it's possible to utilise a single master cylinder with two circuits from a donor vehicle, but a. they are virtually all designed for
use with a servo and b. I didn't have a donor vehicle!
Cheers,
Eddy
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alister667
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| posted on 3/9/03 at 04:45 PM |
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Well it's my hope to take the car to track days a few times a year, and it would be nice to be able to adjust the brakes. I just see the bias
bar or valve solutions as different ways to do a similar job. I know the SVA won't let you through if it can be adjust by hand, that got me
thinking about using a bias bar and either split pins to hold it or nylock nuts.
Once I get it set it's not something I'm going to fiddle with much, but I imagine as brakes/tyres wear or get changed (say over a course
of 3 months between track days) it's ideal position could change a bit, possibly causing 'brown moments' under braking I'd
rather avoid ;-)
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alister667
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| posted on 3/9/03 at 09:15 PM |
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....mind you, you have got me thinking about this! I suppose if I just used a standard Sierra master cylinder (1 cylinder -> 2 break lines), and
mounted a Rally Des adjustable valve (44 quid) that was tucked in out of the way near the diff at the back, it would be as easily adjustable (while
not moving), cheaper, SVA compliant and do a similar job......
Hmmmmmm.
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Dick Axtell
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| posted on 4/9/03 at 02:29 PM |
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quote:
Originally posted by eddymcclements
Surely a pressure adjuster to the rear brakes is just another way of setting front/rear bias?
Eddie & the Rest,
Any brake pressure control valve is used merely to regulate line pressure to the rear brakes. The aim is to ensure that the front brakes will lock up
first. This is required by Govt. legislation (EEC Directive 71/320).
Front vs Rear brake balance is governed by the size of the brake assemblies, (i.e. frictional swept area & piston area of hydraulic actuator),
and is usually pre-determined at the vehicle design stage.
The binocular mcyl + balance bar is a simple and convenient method for varying the proportion of effort from a single input (brake pedal) between 2
outputs to the 2 mcyls. A combination of the shared effort applied to a mcyl, and its bore area, will determine the associated line pressure.
So all you're balancing is the proportion pedal effort applied to each mcyl.
Now to wait for the arguments.
[Edited on 4/9/03 by Dick Axtell]
Work-in-Progress: Changed to Zetec + T9. Still trying!!
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alister667
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| posted on 4/9/03 at 09:47 PM |
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quote:
Any brake pressure control valve is used merely to regulate line pressure to the rear brakes
Does that include an adjustable proportioning valve? Surely it can be used to proportion the rear brakes? Same as the one in the Rallydes catalogue
http://www.raldes.co.uk/2003/page023.htm
(down near the bottom, "Knob Style Proportioning valve".
As I understand it a valve like that could never be used to increase the rear brake balance, but if your original design was set up so rear brakes
were slightly stronger with the valve open, using a valve to reduce the effectivness of the back brakes would allow you to balance the front and rear
effectively?
...mind you I haven't even started my build yet, and I've only just started thinking about brakes in the last couple of days :-) I could
be talking rubbish!
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Rorty
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| posted on 5/9/03 at 02:31 AM |
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alister667:
quote:
As I understand it a valve like that could never be used to increase the rear brake balance, but if your original design was set up so rear brakes
were slightly stronger with the valve open, using a valve to reduce the effectivness of the back brakes would allow you to balance the front and rear
effectively?
You'll probably find the brakes seem more powerful in the Locost than in the donor, simply because of the lesser weight of the Locost.
Therefore, the rear brakes can quite easilly over-power the fronts.
The balance adjuster, whether hydraulic or mechanical will allow the rear pressure to be backed off, so the front brakes definitely lock first.
Incidently, if, for some weird reason you did want more line pressure to the rear than the front, the mechanical adjuster would obviously cater for
this. The hydraulic bias valve could be installed in the front brake circuit for the same result.
Cheers, Rorty.
"Faster than a speeding Pullet".
PLEASE DON'T U2U ME IF YOU WANT A QUICK RESPONSE. TRY EMAILING ME INSTEAD!
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Mix
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| posted on 5/9/03 at 07:31 AM |
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Dick
I have been looking for the formula to work out braking effect and have asked the question here before. The best response I received, (it may have
been from you) was very complex so if I were to rephrase the question and ask for a formula which would give me a good approximation, (disregarding
the effects of suspension), could you enlighten me, or would this be meaningless??
(All goes back to trying to work out what size master cylinders to use).
Mick
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Dick Axtell
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| posted on 5/9/03 at 01:37 PM |
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Hi Mick,
I'll try and blag some info from (former) work, 'cos that'll be the kosher version.
LoL
Dick
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eddymcclements
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| posted on 5/9/03 at 03:34 PM |
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quote:
Originally posted by Dick Axtell
Any brake pressure control valve is used merely to regulate line pressure to the rear brakes. The aim is to ensure that the front brakes will lock up
first. This is required by Govt. legislation (EEC Directive 71/320).
OK so far.
quote:
Originally posted by Dick Axtell
Front vs Rear brake balance is governed by the size of the brake assemblies, (i.e. frictional swept area & piston area of hydraulic actuator),
and is usually pre-determined at the vehicle design stage.
So far so good.
quote:
Originally posted by Dick AxtellThe binocular mcyl + balance bar is a simple and convenient method for varying the proportion of effort
from a single input (brake pedal) between 2 outputs to the 2 mcyls. A combination of the shared effort applied to a mcyl, and its bore area, will
determine the associated line pressure.
Absolutely agree with you. I need more pressure in the front brake lines, so I have a .625" front master cylinder and a .75" rear master
cylinder. Together with the bias bar I think I'll be able to find a point at which front/rear bias is correct (erring on the side of caution)
and will lock the adjuster at that stage.
All I was pointing out was that a rear brake line limiter achieves the same end result - ie. removes the possibility of rear brakes locking before the
fronts - of course the way in which this is achieved with the two setups is different.
quote:
Originally posted by Dick Axtell
Now to wait for the arguments.
Not from me!
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Stu16v
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| posted on 5/9/03 at 06:07 PM |
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Yup, if you have means of altering the front/rear bias, whether it be mechancial or hydraulic, what is there to argue about?
quote:
Any brake pressure control valve is used merely to regulate line pressure to the rear brakes. The aim is to ensure that the front brakes will lock up
first. This is required by Govt. legislation (EEC Directive 71/320).
Can I assume that you also include inertia valves and load sensing valves in this statement Dick?
[Edited on 5/9/03 by Stu16v]
Dont just build it.....make it!
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mad4x4
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| posted on 6/9/03 at 04:03 PM |
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quote:
Originally posted by alister667
I looking to fit a brake bias bar myself. Any further reports how you got on? Did anyone fit the rallydes cylinders? Did the ST and Luego versions
work OK and were they easy to fit?
Thanks in advance.
To throw another option in I used Landrover IIA masters they are girling 1" needing 7/16" nipples. If one can stop a 3.5 ton Landrover
2 with bias bar will stop a kit car.
Cylinders from Paddock's @ £16.00 each <
Balance bar from Raceparts UK @ 34.52
7/16" Nipples from Think Automotive Ltd 27p Each
Scot's do it better in Kilts.
MK INDY's Don't Self Centre Regardless of MK Setting !
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Stu16v
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| posted on 6/9/03 at 08:23 PM |
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IMHO I reckon two 1" cylinders would be too 'overgeared' for most Locost applications, requiring a lot of pedal effort to stop the
car.
My car has two 0.625 cyls fitted, and I have little pedal travel and a 'firm' pedal.
The one Landy cylinder was running the complete brake system on it's orignal donor IIRC....
Dont just build it.....make it!
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Rorty
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| posted on 9/9/03 at 05:58 AM |
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Stu16v:
quote:
IMHO I reckon two 1" cylinders would be too 'overgeared' for most Locost applications....
Not if he has longer pedals.
Basically, if you're pedal is too firm; fit smaller diameter master cyl or longer pedal. Vica versa for the opposite.
If altering the length of the pedal, don't forget to raise/lower the pedal's pivot point to keep the pedal pad the correct height off the
floor.
Cheers, Rorty.
"Faster than a speeding Pullet".
PLEASE DON'T U2U ME IF YOU WANT A QUICK RESPONSE. TRY EMAILING ME INSTEAD!
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Dick Axtell
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| posted on 9/9/03 at 07:57 PM |
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quote:
Originally posted by Stu16v
Can I assume that you also include inertia valves and load sensing valves in this statement Dick?
Yes. But beware inertia, or so-called 'G' valves. Their performance can be too variable.
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Stu16v
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| posted on 9/9/03 at 10:09 PM |
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quote:
If altering the length of the pedal, don't forget to raise/lower the pedal's pivot point to keep the pedal pad the correct height off the
floor.
Accepted mate, but hence my comment.....most folk building locosts have floor mounted pedals when using dual M/Cs', and it just so happens that
more often than not, the pedal pivot is already on the floor....
There may be scope to lessen the distance between the pedal pivot and the bias bar mount, but I personally dont think there will be enough to get a
nice feel with 1" cyls IMHO.
Of course, with top mounted pedals there isnt an issue......
Dont just build it.....make it!
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