Good evening all,
After some advice on our balance bar arrangement (Rally Design balance bar)
Is it normal that with everything nipped up that we can get hold of the bar and move it side to side (with the spherical bearing moving inside the
tube)
I know obviously the adjustment in BIAS is gained my moving the bearing towards one of the master cylinders, but what is actually stopping it from
moving of its own accord whilst driving?
Thanks in advance for any help.
Dan
Just to add to the above, i have just gone out an measured between the clevis and the pedal tube and we do have too much clearance but in order to get
the master cylinder rods to be straight and true we are going to have to wind the clevises out more, making the clearance between the clevis and the
pedal tube even larger.
Im thinking we are going to have to pack the gap out with more washers, can anyone see any problem with this?
We are going to try it at the weekend and make sure that as a failsafe one of the systems will function with the other disconnected but would
appreciate any tips :-)
Thanks
Dan
You should be able to move it by 1mm or so. If more than that then it's not set up right. Without MC pushrods attached then it should be able to
fully articulate freely - worth checking. Also work checking that when the gap is set to minimum with the above conditions, the MC pushrods are in
line with the MC bodies, or thereabouts.
FYI - When you articulate the joint, the distance between the two clevices reduces (when measured parallel to the pedal tube). This reduction must be
permitted to allow the full articulation of the joint. This is a weakness of the bias bar design, but in reality doesn't make a significant
difference. Proper race cars use mechanisms with significantly improved position control, so that this float is all but eliminated.
Thanks for your reply, we definitely have more than 1mm!
It would appear that we have our master cylinders mounted too far apart, so that when the clearance is correct on the bias bar the master cylinder
push rods are as pissed as a cricket.
My thinking is that if we set them straight and true, and then pack the resultant massive gap with washers, and as long as we have full movement of
the bar with everything disconnected and no binding with the brakes fully applied then there shouldnt be a problem, should there?
Would almost be like installing fatter clevises or thats how it works in my head :-)
[Edited on 12/5/15 by brown_d9]
Have you looked at the article on Rally Design web site explaining how to set up a bias bar
Ive made my own pedal box, i used a willwood bar and they say there should be a total of 0.20-0.25" which is about 5mm, seems a lot to me so i think im going to make some thicker washers
You dont need any washers, the spherical floats inside the tube. it doesnt matter if the bearing moves inside the tube as the fulcrum stays in same
position relative to the two clevis on the balance bar.
You should set up the two cleviss (clevii? clevis's?) to be the same distance apart on the balance bar as the two MC's are apart on the
bulkhead.
If you put washers in you will stop the spherical rotating freely to give you the brake bias that the bias bar is designed to.
It may be counter intuitive but it is correct, the first time I set one up it seemed wrong but it always works.
Edit:
Information on the OBP pedal box here:
http://www.obpltd.com/index.php?route=information/downloads&downloads_id=63
They have thin washers in there but this should only be to stop the edge of the clevis catching on the tube and not to take up the free float, I have
never seen this done on a proper balance bar set-up, I assume they have added them in as a catch all to cover people having there MC's different
distances apart which could give more than the recomended 6.35mm float.
[Edited on 13/5/15 by Doctor Derek Doctors]
ah ok, yeah that makes perfect sense now you have explained it, cheers for clearing that up
quote:
Originally posted by Doctor Derek Doctors
You dont need any washers, the spherical floats inside the tube. it doesnt matter if the bearing moves inside the tube as the fulcrum stays in same position relative to the two clevis on the balance bar.
You should set up the two cleviss (clevii? clevis's?) to be the same distance apart on the balance bar as the two MC's are apart on the bulkhead.
If you put washers in you will stop the spherical rotating freely to give you the brake bias that the bias bar is designed to.
It may be counter intuitive but it is correct, the first time I set one up it seemed wrong but it always works.
Edit:
Information on the OBP pedal box here:
http://www.obpltd.com/index.php?route=information/downloads&downloads_id=63
They have thin washers in there but this should only be to stop the edge of the clevis catching on the tube and not to take up the free float, I have never seen this done on a proper balance bar set-up, I assume they have added them in as a catch all to cover people having there MC's different distances apart which could give more than the recomended 6.35mm float.
[Edited on 13/5/15 by Doctor Derek Doctors]
No problems.
My personal bugbear is the lack of clarity with kit cars.... you could purchase a set of plans for my single seater (when I complete them) which will
have assembly drawings, parts lists and clear instruction for everything.