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Hi! I have a Wilwood reverse twin pedal box in my car. It's a build in making so nothing has been road tested yet.
It's a Nissan s13 drift car. Expected weight 1100kg, 4 piston Skyline front calipers, 2 piston 300zx rear calipers. 0.625 front brake cylinder size, 0.75 rear cylinder size.
Normally there could be some debate about cylinder sizes, balance calculations etc, but since it's a dedicated drift build, I want all the brake force in the front.
I managed to adjust the balance bar all the way towards the front cylinder, there's no binding. The thing that confuses me and what I am here for is setting the push rod length.
Do I need to adjust the push rods to a "cocked" position? If so, which way and by how much? The instructions for Wilwood didn't cover this. I tried instructions for Tilton, but my result doesn't match the description in the instructions.
Thank you for your help!
Both push rods should be adjusted so that the balance bar is perpendicular to the brake pedal when the brakes are producing about 10-20% of the target pressure. This keeps the partial brake (trail braking, etc) with the same bias ratio.
If you really want most of the bias to the front, I would do that with master cylinder sizes & caliper bore sizes. Leave the bias adjuster about mid-stroke for your "normal" case.
If you really want all the brake force in the front, why don't you only run one master cylinder, and no rear brakes?
I have considered only running front brakes. Would save me some money and headache. Can't remember why I never went that way though. It was probably to do with the rulebook.
Do you think the 10-20% rule could work with 10-20% pedal travel rather than pressure? The pedal box is on the workbench at the moment. Couldn't do any adjustment in the car, it's way too tight.
The problem is the distance to build 10% pressure depends on the master cylinder bore sizes, and the fluid volume in the lines, etc. I think you could do it on the bench if you connected at least one front and one rear caliper. (Simulate the rotor thickness with a wood block).
I would suggest you do whatever vehicle modifications are necessary now to allow this adjustment in the car. Perhaps an access panel from the wheel well. It will never be any easier to do than right now. Really great designs anticipate future maintenance and modifications (like adjusting the pushrod length, pedal stops and changing a master cylinder).
I found these two videos useful to allow for the visualisation of the process involved in setting up the balance bar in my car.
And this one as well.
Hi! I used all three of the videos before I came here to ask. Unfortunately they don't describe push rod adjustment with enough detail.
I will reroute all 6 of the lines, that should give me some more access from above. The design of the box housing isn't the most helpful there either. After hooking up and bleeding the lines I will try adjusting the push rod length to where they are parallel at 10-20% pressure like David said.
If it's OK, maybe leave this thread open a while longer while I source all the fittings and do the modifications.
Guys from Wilwood got back to me and one of their guys actually has a lot of experience with drift setups.
Front caliper piston 4x40mm per side (nissan r33)
Rear caliper piston 2x38mm per side (nissan z32)
Wilwood twin 6:1 hanging pedal box
For a drift specific, front biased setup and firm pedal they advise a 3/4 front master and a 7/8 rear master cylinder. Balance bar maxed to favor the front with about a quarter inch longer front cylinder push rod.
For me, that's resolved.
If that's with the balance bar centred, because any offset will introduce side loadings to the pistons and restrict the adjustment range in that direction, and the bar square to the pedal and cylinders under maximum load, go for it.
HOWEVER, the elephant in the room are the pads being used - or more specifically the co-efficient of frictions they have through their temperature working ranges! Depending on the pad materials used for the selected axle, there can easily be 25-30% difference between brands and/or compounds and that will have a directly proportional affect on the line pressures needed.