AU1 Master cylinder upgrade

[terryk]

HI All

I have fitted BA XR8 front brakes on the front and territory rear brake assembly they are great with the exception of the brake pedal feel due to the piston size increase in the calipers therefore requiring additional fluid from the master cylinder to move the piston the same amount. When I checked the PBR book the AU master cylinder is smaller than the BA, AU-PBR part# is B224-067 22.22mm/28.57mm verses BA PBR part# is B227-109 23.83mm/31.75mm. But the BA unit is slightly different.

After all that my question is what is the best way to go, can the AU unit be resized or can the BA unit do the job with a T for the pressure sw or something else??

Cheers
Terry

[GS608]

Is the AU Series 2/3 booster the same as the BA? you can fit that just have to drill new holes in the fire wall as the bolt pattern is different.

[terryk]

From what I can see the AU and BA/BF master cylinder will fit but there is a pressure sw in the front and underneath of the AU unit where the BA/BF unit has no prevision for the pressure sw's

[terryk]

Hi All

Has anyone had the factory AU master cylinder modified??

Terry

[Noddy]

I am also interested in a modified or upgraded master cylinder. Will going to a larger bore mc reduce the amount of pressure required to apply to the brake pedal?

[XR Lita]

The BA b/m/cyl will bolt straight up, but you will lose cruise control for the AU. Going to a larger b/m/cyl will reduce the amount of pressure as it will be displacing more fluid with each application. It is not really required though. I am running Brembo calipers front and rear on mine, and have no dramas at all in regards to pedal effort.

[Noddy]

Thanks for the reply. My circumstance is a little different to most, i drive with hand controls so the brake pressure is applied through my hands hence why i am trying to reduce pedal pressure/effort/travel.

Why do you lose cruise control by going to the ba cylinder?

EDIT: i had a think about my last question, i guessing because you lose the pressure switch on the ba b/m/c the cruise has nothing to trigger its release when the brake is applied.

[mik]

thats a good question Noddy, i`m putting b series stuff on my au also, the master cylander swap cruise control thing has me my interest too, if its the loss of pressure switch surely the cruise could be deactiveated by a brake light switch, if they don`t have them it would `nt be hard to fit one to the brake pedal i reckon.

[terryk]

But can the pressure switch be still fitted with a T fitting?

[terryk]

Here are some photos of the different master cylinders. What would it take to use the BF Master Cylinder?

Any assistance will be appreciated

Cheers
Terry






Brake failure switch fitted under M/C & the cruise control pressure switch towards the front of the M/C


I think that is a fluid level sensor

[AMB]

Originally Posted by Noddy

........ i guessing because you lose the pressure switch on the ba b/m/c the cruise has nothing to trigger its release when the brake is applied.

Interesting thread here guys. Just thought I'd point out, cruise off is triggered from the brake light switch, the pressure switch trigger is a back up in the case when your brake switch fails, which it often does.

[terryk]

Originally Posted by AMB

Interesting thread here guys. Just thought I'd point out, cruise off is triggered from the brake light switch, the pressure switch trigger is a back up in the case when your brake switch fails, which it often does.

Thanks AMB, so a 'T' junction will sort that out.

Does the BF have the brake failure sensor in the ABS unit or is that the sensor in the bottom of the fluid reservoir?

[terryk]

Anyone have any idea with respect to the use of a BF unit on an AU?

[mracoval]

slightly off topic but might help. I've upgraded my series 1 au to series 3 ront and rear and found no significant difference effort wise but one thing I did notice was how much the plastic booster flexed while standing on the brake pedal. I experimented using cable ties around the master cylinder down to the upper control arm bolts to stop it flexing and increased pedal feel dramatically. Now to fabricate a bracket.

[Daniel B]

Ok, time to bump an old thread.

To the OP, did you ever work this out, get it sorted?

Also, why did you use the territory rear brakes, were they a direct bolt on? Did you use the discs and calipers? and what model Territory?