John Bonnett
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| posted on 25/1/07 at 06:24 PM |
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Setting Up Brake balance Bar
Evening All
I would appreciate any help and advice on the above. I have read the instructions in the rally design catalogue and I am still in the dark. There are
three adjustments; screwing in an out each push rod and screwing the cross shaft in and out. Without actually being able to drive the car is there any
way of knowing when it is about right?
Second question; what do you have to roll pin to satisfy the SVA man and if you have roll pinned it and got the balance wrong it means drilling
another hole.
I'd be really interested to know how others have tackled this problem.
I look forward to hearing from you.
thank you
John
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BenB
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| posted on 25/1/07 at 07:06 PM |
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You won't know the exact required position for the brake bias bar unless you can take the car onto private road and set it up. Most people set
it up well on the side of caution e.g. front locking up well before rears and put it through the test.
AFAIR as long the the push rods are screwed in fairly equally and bearing in mind the RalDes instructions the exact length isn't super
critical.
On SVA you may be able to pass with the brake bias bar covered with a box (I passed with this though some SVA meanies say if it is possible to remove
the box (even if this means drilling out rivets) the bar must be locked). In which case you're looking at drilling and pinning it (new hole for
new position). If you have a dashboard bias bar adjustor some SVA centers let you drill and pin the dash adjuster.... but still, new position new
drill....
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RazMan
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| posted on 25/1/07 at 09:08 PM |
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I have been setting my bias bar up this week so I am now an expert on the subject !! 
Firstly, set up both m/c pushrods so they are equal length in the clevises when the pedal is at rest and the bias adjustment is central. In theory
this will give you equal brake pressure to each m/c. Then screw the adjuster to bring the central bearing closer to the front m/c and give the brakes
a test - the fronts should lock before the rears. Screw the adjuster the opposite way and the rears should lock first. Ideally you want to find the
sweet spot where everything locks up together under heavy braking but you will find that it varies due to the inherent design limitations of the bias
bar so I would keep the bias toward the fronts to be safe.
You can tweak the bias a little more by varying the lengths of the pushrods into the bias bar clevises but be careful not to go too far or they could
fall out 
Obviously the bias bar has no effect on the braking efficiency of your setup and as I discovered, if you get the wrong caliper & m/c combination
the results can be scary. My particular setup required a 0.625" front & 0.7" rear m/c and I have just spent the best part of today
replacing said m/c and bias bar - testing tomorrow after bleeding the system.
Regarding SVA, I passed with an unlocked bias bar and just demonstrated that it could be adjusted (not even a locknut)so I gues it is all down to
interpretation of the rules by the testers.
Hope that helped 
[Edited on 25-1-07 by RazMan]
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
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John Bonnett
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| posted on 26/1/07 at 08:56 AM |
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Many thanks to BenB and Raz for their prompt replies and advice which I will follow.
I've decided to hire the Haynes test track for half a day to set everything up properly in 3 to 4 weeks time.
Anyone care to join me?
John
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