Brake bias bar question

[dogwood]

Evening all

I just bought a pair of brake master cylinders from Coozer
Now all I need to know is how to fit them...:rolleyes:
I know I need to buy or make a brake bias bar, but not sure where to go from there.
Can anyone point me in the right direction.

Cheers David.

Edit.....I've just Googled it, now I'm even more confused.....

[Cobra289]

Evening all

I just bought a pair of brake master cylinders from Coozer
Now all I need to know is how to fit them...:rolleyes:
I know I need to buy or make a brake bias bar, but not sure where to go from there.
Can anyone point me in the right direction.

Cheers David.

Edit.....I've just Googled it, now I'm even more confused.....

The most frequent used cylinders for a balance bar are the Girling and Wilwood, both are the same.

The template to make the holes can be seen here bellow, but that is when you use a balance bar with 63,5 mm [that is equal to the distance between the cylinders.

http://www.cobratech.nl/FORUM/BOMBIN_FIJACION.JPG

What I am afraid is that you make a bad selection of the cylinders.
You mention that you all ready have those ones.
Now be careful because the selection is very important and depends from your car and the components used on the build.

To bring a balance in the brake system you start with a balanced selection of the cylinders, than the fine adjustment you do with the balance bar.

I did made a excel sheet for the calculation, but it is in Spanish.
It looks like this:

http://www.cobratech.nl/FORUM/BRAKE_CYLINDERS_02.JPG

All the calculations are related to the weight of the car, the weight trasfer, etc. etc.

Here is a picture where I explain the the Spanish guys how to do it.

http://www.cobratech.nl/FORUM/BRAKE_CYLINDERS_03.JPG

As you can see there is needed some calculation to get it right.

Regards,
Cobra289

[dogwood]

Thanks for the reply Cobra......I think.:D

Now I am definatly confused, I have enough trouble with English:rolleyes:
Anyway the masters I bought were as supplied by MNR. 0.625 and 0.75.
So I am reasonably happy they will be OK for my app.

Just not sure how to attach the balance bar to the brake pedal.
Once I figured that I can worry about how to balance them,

David

[Cobra289]

Thanks for the reply Cobra......I think.:D

Now I am definatly confused, I have enough trouble with English:rolleyes:
Anyway the masters I bought were as supplied by MNR. 0.625 and 0.75.
So I am reasonably happy they will be OK for my app.

Just not sure how to attach the balance bar to the brake pedal.
Once I figured that I can worry about how to balance them,

David

The balance bar has a tube with an outside diameter of 30 mm, now you can make a hole of 30 mm at the center of the hole of 6.5 mm of the Haynes pedal.
You will get a halve hole of gap that is located at the 31 mm as the book mention.

There you weld the tube of 30 mm of the balance bar and probably you will get a good setup.
You need to know that you will have more surface at the cylinders compared to the Sierra cylinder so that means that you will need to have a heavy force at the pedal, or you change the pedal ratio [make it longer]

Regards,
Cobra289

[dogwood]

Thanks for that one Cobra.
I didn't realise there was a weldable tube with the bar.
I thought it was some sort of bearing.
Not seen one up close, only on the web.
And longer pedals is my plan anyway, because I find the clutch a bit sharp when in traffic. (Big Feet Like Bonzo:D )

David

[Cobra289]

Thanks for that one Cobra.
I didn't realise there was a weldable tube with the bar.
I thought it was some sort of bearing.
Not seen one up close, only on the web.
And longer pedals is my plan anyway, because I find the clutch a bit sharp when in traffic. (Big Feet Like Bonzo:D )

David

Yes! you get a weldable tube of 30 mm dia, with a balance bar, the balance bar itself has indeed a spherical bearing like the ones of the rod-ends.

Once you have weld [not to much penetration] you need to clean-out the inside of the tube, because the balance bar need to slide inside the tube.
Use a hand hone machine like the ones used for honing of the master cylinders.

Regards,
Cobra289

[davidimurray]

You don't have to weld the tube in - it can also be pressed in which is what I used to do on Alu pedals

[Cobra289]

You don't have to weld the tube in - it can also be pressed in which is what I used to do on Alu pedals

To do that you need to use two plates instead of the single plate of 5 mm pedal.

[davidimurray]

Or just press a tube into another tube. I actually thought you were not supposed to weld the tube as they were case hardened.

[Coozer]

Check this pic out, balance bar has a bearing in the middle that slides along the brake pedal letting the force be moved across from front to back.

http://www.demon-tweeks.co.uk/products/ProductDetail.asp?cls=MSPORT&pcode=OBP0040

This one from Rally Design looks like it comes with the tube needed to be welded to the pedal.

http://www.rallydesign.co.uk/product_info.php?cPath=562_580_581&products_id=4062

Hope that helps.

Steve

[dogwood]

Cheers Steve.

I couldn't find them on Rallydesign when I looked
No I've seen a pic close up I understand how it works.
http://i129.photobucket.com/albums/p212/muddypaws4x4/RD3613product.jpg


David

[flyerncle]

RD3613 is the part number you need David

[Cobra289]

Hi,

I made a drawing to show the relations.
It is all about leverage.

The foot force will spread equally to both cylinders, but when we move the bar we have a different leverage [arm].
Because we change the distance [arm] between the clevis to the brake pedal the force at the pedal [for that cylinder] will be heavier or lighter, if we shorten or enlarge the distance.
Shorter = Heavier
Large = Light

We know that the [line pressure] is = [Force] divided [surface]

So we can conclude that there will be a different in line pressure due to the change in leverage.

http://www.cobratech.nl/FORUM/PEDALS_11.JPG

Regards,
Cobra289

[dogwood]

Thank's for that drawing Cobra.
Now everything is making sence..


Nice computa work by the way, Makes my feeble attempt look stooooopid:rolleyes:

David

[Coozer]

MNR are selling some bits on the bay, theres two floor mount pedal boxes going very cheap..

Heres the link to one of them...

http://cgi.ebay.co.uk/locost-floor-mount-pedal-box_W0QQitemZ220507944383QQcmdZViewItemQQptZUK_Car sParts_Vehicles_CarParts_SM?hash=item33574c35bf