Brake Booster Delete

[zossy1]

Why not just relocate the booster?

More room for trumpets etc, and you still get to have decent brakes.

As tricky as it is, I would take dual masters with no booster any day over a remote booster install. A remote booster install wouldn't be much easier than dual masters and would be no cheaper in terms of parts. And not only do I have awesome brakes, but I have in-cockpit bias adjustment and an inbuilt safety feature that has already saved my backside once (when I had a front brake circuit failure).

[Magpie]

zossy1 thank you very much for the posts, it is helping me with my future plans!

[taminga16]

Visit your local Hot Rodder, know how, databases, tools and skills.
Greg.

[Magpie]

Finally the booster has been deleted, now comes the test period.

Initial reaction after doing this was very negative as it was not what I expected. Simply the amount of force now required to stop was in my mind excessive!

HOWEVER, now after a few more road test stops I can honestly say WOW this is fantastic. It is no longer a case of judging how far the brake pedal travels as with a booster BUT how much pressure you put on the pedal when you brake. A little like motorcycle brakes, heaps of control of the brakes. Plus there is no 'knee' point in the brake system, the ratio between F/R is consistent.

It is not as simple as disconnecting you booster to see what it would be like, a proper system needs to be used.

Also 'tricked' the PS1000 to using a temp channel for brake pressure, still needs a bit of refinement but it should work!

This stop washed off 38.3kmh in 2.604 seconds and the brake balance was 71%
Brake_01 by Eipeip, on Flickr

There were a few more runs and the bias tweaked up to 73%, this time 34.1kmh washed off in 1.958 seconds.
Brake_02 by Eipeip, on Flickr

[zossy1]

How was the install? I have to say, mounting that pedal box is one of the least fun jobs I ever had to do on the race car

[Magpie]

Biggest issue was the hoses, hence why I replaced them with braided

Also I still had the OEM fuse box so space was an issue. Still have to install the clutch master.

Would have been easier if I did not forget to put the bias adjuster on... Had to remove the dash again

Getting used to the setup, a lot more leg pressure required, but so much more control.

[a222133]

If you don't want to go with a full B/B delete perhaps what I did will of interest .[ NA-- 1.6 ] Techno Toy inlet , silver top ITB,s , 75mm stacks with a clear 22mm flow over the rims using a KN rectangular pleated mesh filter , this will not clear the standard B/B so a 150 mm unit with the same pitch mounting holes is used giving around 7mm clearance between the filter and B/B , an engine steady is also fitted to take out the engine rock . So you can still have ITB,s with a reasonable length stack and B/B , but needs a bit more grunt on the brake pedal , just like old times !

[Magpie]

So you can still have ITB,s with a reasonable length stack and B/B

Prior to the booster delete I already had sufficient clearance for an air box with 111mm trumpets. The reasons for the booster delete was

1. better control of brakes
2. bias adjustability by balance bar and not a valve
3. safety, as the front and rear now have seperate fluid sources
4. peer pressure

Inital feedback is positive, will comment further when dríven at QR.

The other issue with the brake booster and OEM prop valve is when you use aggressive (track) pads the overall system pressure is reduced. In the NA6 the F/R pressure is 1:1 then above 427psi it is 3.34:1 and the max pressure is 975 for the front. A rough calc using F brake pressures from Sandown and Winmax 6.5's, if the OEM brake system was installed the bias would have been around 85%. At Sandown I maxed at 504 psi on the front, however with the bias the rear was the same as the front. This allowed better brake control as well as trail braking very late into the corner.

However, the brakes are only part of a system, to stop depends on tyre grip. The limit I have found with the AD08R's is about 1.3 in braking/cornering. Therefore to be optimal the G force should be around this (conditions dependant), it is no use having a powerful brake system if the tyres cannot grip.

The biggest change is instead of deciding how far to push the pedal it is now how much pressure do I use on the pedal. A bit like power steering delete, the change is move then turn as opossed to turn and move with power steering. Only negative at the moment is my knee is still sore

[bruce]

At Fan Fest there was an ITB car with a smaller booster fitted. He had a big rectangular filter fitted.

[a222133]

yer , that was mine

[bruce]

Cool. A subtle mod.