double brake discs on a street bob

Discussion in 'Dyna Models' started by harleydocdavidson, Jun 11, 2009.

  1. Hi to every body, iI installed my heavy breather yesterday along with the TFI from Dobeck and the bike runs very nice with remarkable acceleracion compared with stock, which brings up a new question.

    The stock brakes for my 08 street bob are quite weak and coming from a sport bike it feels quite different.
    I was talking to one guys and they say that i could install a second front disc to the bob. Changing the inferior right bottle for the one from a Vrod and then trying with the stock front master cilinder would be enough:
    What do yo think guys? is there another solution?
  2. maine-e-axe

    maine-e-axe Junior Member

    I don't think the master cylinder will work, I tryed a single disk master on a dule disk system and it was mooshy, you could pull the brake lever to the grip. they have a different piston size for dule disks. the lower leg I'm not sure about. good luck
  3. glider

    glider Veteran Member

    It would require the right lower leg to match your left one and the necessary plumbing for the dual disc as well as a wheel change to take the second disc , and additional disc and a different master cylinder.
    It can be done but it would just require the right parts.

    Master Cylinder Bore Sizes - Harley Davidson Community
  4. wxflyer

    wxflyer Member

    Speaking of brakes...can anyone recommend brake pads that will perform better than stock HD units? That could be a much easier solution than adding a 2nd disc up front.
  5. I guess the solution goes that way, what about changing from two to four calipers; do I need to change the master cillinder
  6. glider

    glider Veteran Member

    LRB would fall into that category, or even replacing the stock caliper with a 6 pot caliper from one of the bigger manufacturers.

    Lyndall Racing Brakes
  7. DadzLowrider

    DadzLowrider Active Member

    I went with Hawg Halter 6 piston from caliper and rear and the brakes are great. Huge difference once the pads get seated. Took about 200 miles but a huge difference. Highly recommend them

    NEWHD74FAN Experienced Member Retired Moderators

    HarleydocDavidson, the soft braking may also be due to air in the lines or old fluid. You might try bleeding the brakes using Hobbit's overnight brake bleeding technique...once you have parked you bike for the night, 1) use a bungee cord and wrap it around the handle and grip firmly. 2) use a soft rubber mallet and gently tap from the brake caliper, up the hose to the crossover, and then up to the master cylinder, 3) hold the lever and unwrap the cord, and slowly release the lever, then actuate it two or three times moderately, the lever should be further from the grip than before (got rid of most of the air bubbles). 4) Press the lever to the grip and rewrap the bungee securely and leave overnight.

    In the morning, remove the m/c cover, check that the gasket "bellows" is flat and fluid is to full mark, repeat step 2) to with the rubber mallet from caliper up to the m/c, you may see bubbles rise in reservoir. Do step 2, holding the lever, but unwrapping the bungee, when you release and actuate 3 times you will see the final trapped air bubbles release and your lever should be nice and firm with good distance between it and the grip. You may do this over a couple days, but the biggest improvement will be the 1st day.

    The second method is not so cheap...adding a 2nd disk may not be an option using the stock 'Bob parts, so you may have to find the equivalent diameter forks assembly and correctly spaced triple tree compatible with the steerer tube. Which will require careful measurements of the stanchions, fork tubes and wheels. The Sportsters for example use 39mm stanchions and XL-R models came with dual disk brakes from 2004-2008... I saw a CVO Fatboy that had dual disk brakes with similar hardware, and I am sure that FatBob model as Hobbit elated to could be made to work (who needs mud guards anyway?)...some call my Sporty a "dirt bike" from the XR days, but thats another story. Gonna take a lot of research, but hey if you are going to spend your hard earned cash, honest to gosh research is "peanuts" and ensure it will be done right.
    Last edited: Jun 12, 2009
  9. wxflyer

    wxflyer Member


    Thanks for the link. Their pads/rotors are now on my wish list.
  10. Thank you guys, I have cleared my mind and started doing some research on six pistons calipers, though they are not bargain. I will keep you posted on the project
    Harleydoc davidson