E30 Secondary Hydraulic Handbrake

Introduction:
Secondary handbrake systems have many advantages and only a few minor disadvantages to in-line hydraulic handbrakes. The main disadvantage of full secondary systems is added unsprung weight. With lightweight parts like wilwood calipers, this is mitigated fairly well.

In contrast, in-line hydraulic handbrakes tap into the existing braking system. This adds complexity and risk to the factory brakes by adding more points of possible failure. There is a chance of uneven brake pressures front to rear if the regular brakes and the in-line hydraulic brakes are used simultaneously.

No matter the debate, a full secondary system is preferable to in-line. This is a generic tutorial for the E30 but only minor changes are needed for any vehicle.

Parts:
Wilwood 120-9689 dual pistol calipers (buy two)
Wilwood GTO brake line kit wil-220-8756 (optional)
Wilwood grabby pads (only need to buy one)
Sikky handbrake with 5/8″ Master cylinder
2 psi residual pressure valve
A way to mount the calipers
Spare factory soft lines
Various metric hard lines, fittings, and one T fitting

How To:
hydro setup

To start, a handle and master cylinder should be chosen. ASD and Sikky both make basic handles that come with housings and your choice of master cylinder. Master cylinder sizing is of the utmost importance. The usual choice is between a 3/4″ or 5/8″ bore. The larger bore (3/4″) pushes more fluid but will take more effort. The positive side is that it will require less distance on depression to lock the wheels. The 5/8″ will be physically easier to actuate but may require a larger pull of the handle to lock the wheels. There is lots of math that goes into cylinder sizing but ASD has a nice Master cylinder sizing chart. These rely on the type of caliper being used in order to size the master properly.

The next part is really personal preference. The guys at Sikky sent me a banjo bolt for the wilwood master with a -3 AN soft stainless steel line. This saved me from having to manually bend hard lines, makes maintenance 100x easier, and made the install look much cleaner. With it, they gave me a little adapter that works to my hard lines. I purposefully did my entire install with metric hard lines that can be found at any auto parts store. The wilwood caliper came with a double flare fitting but everything in my install is a bubble flare.

Soon after my master there is a 2 psi residual pressure valve. This is standard in most disc braking systems. This keeps just enough pressure in the line that pumping the lever isn’t necessary to use the brakes but not enough to drag the brakes.

Once the line exits the body of the vehicle, a T fitting is used to split the output to each wheel. Since E30 trailing arms have a significant amount of movement, soft lines are used. For this I used upgraded factory stainless steel hard lines that I had spare. This way, the hard lines aren’t fatigued when the vehicle goes over bumps. This soft line leads into a short hard line and back into an adapter for the final -3 AN line from the GTO stainless steel brake line package from wilwood. This was used because it came with a 90 degree NPT fitting for the wilwood calipers and was adapted for the metric hard lines.

Finally, the choice of calipers was the same kind from the Massive Lee E30 handbrake kit. For different cars, different rotor diameters and thicknesses should be taken into account. The wilwood pads chosen were due to biting hard while cold as drifting shouldn’t ever overheat the pads. The Massive Lee caliper mounting kit removes the factory drum handbrake so I opted to have custom brackets welded to the bottom of the factory trailing arms. The bottom of the trailing arms is the only place that has a good flat spot for mounting. The down side is that bleeding requires unbolting the calipers and moving them to prevent air pockets.

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7 Responses to E30 Secondary Hydraulic Handbrake

  1. Pingback: Drift Nirvana 9/13/15 lessons learned |

  2. Tye Varnes says:

    Do you have any photos of your setup? Whats did you use to mount all of the lines throughout the system? Also is the GTO line kit really needed? I have a set of 4 BMW braided brake likes and if at all possible, id prefer to use those. Im also using another set of OEM calipers.

    • Yoshi says:

      Uh here’s a video of me using it – https://www.youtube.com/watch?v=yO7ZO03g_RA

      The lines are just self tapping screws and some zip ties. The GTO line kit isn’t necessary but it came with the adapter from the wilwood calipers to the double flare I was using. If you use OEM calipers, you can just use all OEM lines. But then you’d need to bubble flare. IIRC OEM is bubble. Make sure to use the properly sized brake master with your setup.

  3. Tom says:

    Part number for master cylinder 3an banjo?

    • Yoshi says:

      I don’t have a part number but I’m pretty sure it’s just an m1x1.0 to 3 an adapter. At least I’m pretty sure it’s m1x1.0

      • Tom says:

        Can you check please

        • Yoshi says:

          The lines in this setup are 100% custom. You can use any thread size or anything you want. I used factory line fittings which are m1x1.0 bubble flare. But I did a double flare (different fittings). You can use any line setup you want. Just make sure it all matches up.

          Don’t go off this post as gospel. Research the size yourself and comment back how your setup goes.

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