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

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...

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]

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]

great thanks guys

That explains a lot...

cheers

Ooops, got all that wrong!

Good pics raz.

Pat...

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!

quote:

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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!

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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

quote:

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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

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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.

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

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

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