bodger
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| posted on 14/3/07 at 01:54 PM |
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Balance bar setup
It seems that not many people are using balance bar setups for braking but are using a proportioning valve instead. Just wondering what people's
thoughts are on this. Is there much difference between the two setups, obviously plumbing in a valve is a lot quicker but cost-wise there
doesn't seem to be much in it. ProComp what's your opinion ?
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Mr Whippy
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| posted on 14/3/07 at 02:01 PM |
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I have a balance bar, don't like it much and wish I'd fitted an valve instead. Alot easier to fit and adjust a simple valve.
on the other 7 I am going to fit a valve on the tunnel just behind the gearlever since the brake pipes are fed down there
[Edited on 14/3/07 by Mr Whippy]
Fame is when your old car is plastered all over the internet
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will121
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| posted on 14/3/07 at 03:12 PM |
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ive got mine set up with a balance bar, but once set its left alone! in board adjustment may be better for track day use for varing conditions but a
bit ott for every day driving on the road, also believe there is problems with passing SVA test with accessable adjustability. there info on Rally
design web for adjusting and setting balance bars
http://www.rallydesign.co.uk/catalog/balancebar.php
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JAG
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| posted on 14/3/07 at 03:23 PM |
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No real need for a balance bar or bias valve. If you select your brakes carefully you can get away without and still have superb braking under all
conditions.
I have a standard tandem m'cyl' 20.64mm diameter with M16 (54mm piston) front calipers and 8" diameter rear drumbrakes fitted with
22.2mm diameter wheel cylinders. No valve and no balance bar.
Justin
Who is this super hero? Sarge? ...No.
Rosemary, the telephone operator? ...No.
Penry, the mild-mannered janitor? ...Could be!
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AdamR
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| posted on 14/3/07 at 04:53 PM |
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Didn't know there was an easy alternative to a balance bar.... Where can I get an adjustable proportioning valve from?
Cheers,
A
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bodger
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| posted on 14/3/07 at 08:26 PM |
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Try here.
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rally design
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| posted on 15/3/07 at 05:29 PM |
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Balance Bar v Prop valve
You cannot use a prop valve in place of a balance bar setup.The prop valve can only be used to degrade the brakes in either the front or rear brake
line to reduce the power in either line.Whereas the balance bar system can change the bias between front and rear...once correct master cylinder
selection gets it about right.In practice most race cars have both balance bar and prop valves,where the balance bar is used to fine tune the balance
and the prop valve used where a drastic reduction is required(on the rear of a rally car to change from tarmac to forest stages)...hope this
helps...rally design.
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rally design
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| posted on 15/3/07 at 05:33 PM |
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Sorry,bit late in the day...my last post should have read....'where a drastic reduction is required,on the rear of a rally car when changing
from forest to tarmac stage.'...rally design
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britishtrident
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| posted on 15/3/07 at 06:56 PM |
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To put it another way balance bars only work really well if the pivot is roughly centralised to start with. To do this you have to either juggle the
master cylinder or wheel cylinder sizes.
In club circuit racing the difference in balance bar setting between the wet and dry setting is usually little as a single turn, two at most.
Proportioning or pressure cut off valves can only be used in the rear circuit, the implication is that to make use of a valve you must start out at
least slightly over braked on the rear axle.
[Edited on 15/3/07 by britishtrident]
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JB
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| posted on 16/3/07 at 04:25 PM |
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Do a Search For brake balance.......
Brake Balance
The advantage of the balance bar is you can fine tune the balance very easily. Once mine is set I never adjust. But.......
However ideally you need a balance bar AND a brake proportioning valve.
Brake balance will be only at the optimum in one set of grip conditions. In the dry when you can brake very hard you need LESS rear brake as you have
more weight transfer. In the wet or on ice you can run nearly 50 : 50 balance. So an adjustable balance bar will let you easily adjust the balance for
different conditions.
But (again) if the surface is wet and then dry you will not be able to adjust the balance bar fast enough. This is where you need a proportioning
valve (AP sell them). This limits pressure depending on the pressure applied. So at low pedal pressures (ice) it does not limit pressure to the rear,
but at high pressures (heavy braking ) it will restrict pressure to the rear.
With one of these valves you calculate your sizes to give 50: 50 balance.
John
http://www.locostbuilders.co.uk/viewthread.php?tid=59113
http://www.locostbuilders.co.uk/viewthread.php?tid=43744
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designer
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| posted on 16/3/07 at 07:11 PM |
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Balance bars are overkill on anything other than a race car.
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britishtrident
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| posted on 17/3/07 at 10:55 PM |
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A proportioning valve is different from a limmiting valve.
A limmiting valve shuts off any increase in line pressure to the rear brakes over a given pressure -- as used on early single circuit BMC Minis.
A proportioning valve passes a fixed proportion of the line pressure to the rear brakes. Many proportioning valves are dual rate.
[Edited on 18/3/07 by britishtrident]
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