macnab
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 posted on 4/2/07 at 11:34 PM |
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Is this normal!!?????
Been fighting the pedal assembly or what’s left of it all night and am totally stumped, how on earth is this brake bias thing is suppose to work?? It
rocks back and forward and wiggles around basically looking well dodgy, especially when the pedals pressed!!
Is there something missing? I'm virtually at the point off just welding the whole thing solid as confidence in this setup is pretty much
zip...
 
Rescued attachment brake.jpg
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Avoneer
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| posted on 4/2/07 at 11:48 PM |
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Should be a bush in the tube on the back of the pedal that doesn't move that holds the bar solid and at right angles to the mc's.
Pat...
No trees were killed in the sending of this message.
However a large number of electrons were terribly inconvenienced.
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RazMan
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| posted on 4/2/07 at 11:51 PM |
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You need to tighten up everything leaving a small amount of play so the bar can pivot easily. You should also have 2 large washers between the tube
and clevis assemblies.
I was stumped by this little gizmo only last month - Rally Design's pic shows how it should look
[Edited on 5-2-07 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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RazMan
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| posted on 5/2/07 at 12:00 AM |
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Here's a detailed setup procedure ..
Link
Extra tweaking can be achieved by adjusting the lengths of the m/c rods. It's quite basic but works within certain limits although I think the
dash mounted ones are easier.
[Edited on 5-2-07 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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macnab
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| posted on 5/2/07 at 12:14 AM |
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great thanks guys
That explains a lot...
cheers
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Avoneer
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| posted on 5/2/07 at 12:15 AM |
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Ooops, got all that wrong!
Good pics raz.
Pat...
No trees were killed in the sending of this message.
However a large number of electrons were terribly inconvenienced.
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NS Dev
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| posted on 5/2/07 at 08:36 AM |
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follow the rally design instructions carefully though, don't tighten the clevises up too much or you will find that the bar doesn't
actually do any biasing!
They do flop about a bit bit they work just fine!
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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britishtrident
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| posted on 5/2/07 at 12:56 PM |
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quote:
Originally posted by NS Dev
follow the rally design instructions carefully though, don't tighten the clevises up too much or you will find that the bar doesn't
actually do any biasing!
They do flop about a bit bit they work just fine!
Equally well give it too much and it won't fail safe if one circuit fails.
Compromise like everything else in the build.
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Liam
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| posted on 5/2/07 at 06:03 PM |
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Aye - clearance between the bush tube/washer and the clevises is crucial. The clevises have to be close enough that in the event of one circuit
failing, the whole assembly locks up and applies effort to the functioning circuit before the pedal runs out of travel.
This brings me onto something i've always wondered... With the above in place, how do you bleed/fill the brakes with a bias bar setup? Do you
have to be doing both mcs at the same time? If you just bleed one, surely the bias bar will (should) lock up not allowing you to pump the mc
you're bleeding? Or will you get enough travel for bleeding before the bias bar locks up? Hmmmmm...
Cheers,
Liam
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flak monkey
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| posted on 5/2/07 at 06:08 PM |
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quote:
Originally posted by Liam
This brings me onto something i've always wondered... With the above in place, how do you bleed/fill the brakes with a bias bar setup? Do you
have to be doing both mcs at the same time? If you just bleed one, surely the bias bar will (should) lock up not allowing you to pump the mc
you're bleeding? Or will you get enough travel for bleeding before the bias bar locks up? Hmmmmm...
Cheers,
Liam
Easibleed 
Sera
http://www.motosera.com
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RazMan
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| posted on 5/2/07 at 09:50 PM |
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If the bias bar did a PERFECT job it should technically be impossible to bleed both systems, however it isn't perfect and you won't
normally have a problem. You will just notice a shorter pedal movement on the second system's bleed - but still plenty enough to expell any air
bubbles.
Cheers,
Raz
When thinking outside the box doesn't work any more, it's time to build a new box
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Bob C
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| posted on 5/2/07 at 10:34 PM |
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To stop unwanted "floppiness" of the bar, it could be constrained to remain in the right 'plane' by a simple link (made of,
say, 25mm x 3mm steel) from the pedal pivot bar (or another pivot designed to give a longer link) to the threaded bias bar on one side outside of the
clevises.
Bob
PS - hope that makes sense - I'll maybe draw a picture tomorrow
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ady8077
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| posted on 5/2/07 at 10:42 PM |
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Hi
Rally design do special cone shaped washers that you can fit either side of the pivot, these stop the bar pivoting too much in the event of one
circuit failing
I think there
http://www.rallydesign.co.uk/catalog/product_info.php?cPath=562_580_581&products_id=4065
But theres no picture
Adrian
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John Bonnett
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| posted on 6/2/07 at 05:59 PM |
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Hi Liam
I wondered that too but in fact it couldn't be simpler to bleed the brakes. You do front and rear separately. Unscrew and move to one side the
pushrod of the cylinder serving the circuit not being bled. Bleed the one operational circuit in the normal way and then do the same with the other
one.
alb
John
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