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Thread: gp 320 calipers?

  1. #1
    i searched the forum and didnt found anyone using gp320 calipers from wilwood....so i am wondering are there any problems faced by teams on using these ?....because they just seems to fit our system and budget quiet nicely this year ....
    06, 07, 08 - Ashwa Racing (R.V. College of Engineering, Bangalore)
    09 - Rennstall (University of Applied Sciences, Esslingen)
    10,11 - Red Shirt / Scrutineer (FSG, Hockenheim)

  2. #2
    i searched the forum and didnt found anyone using gp320 calipers from wilwood....so i am wondering are there any problems faced by teams on using these ?....because they just seems to fit our system and budget quiet nicely this year ....
    06, 07, 08 - Ashwa Racing (R.V. College of Engineering, Bangalore)
    09 - Rennstall (University of Applied Sciences, Esslingen)
    10,11 - Red Shirt / Scrutineer (FSG, Hockenheim)

  3. #3
    We used the gp320 calipers last year. They came down in price significantly over the past year. We have a 600 lb car that they were on and the calipers were in my opinion overkill. They're fairly large and heavy and there isn't much choice for pad compound that we could find anywhere. Make sure that if you run them you also run large enough master cylinders to accommodate the large volume 4 piston design.

  4. #4
    hey derek

    we are planning to run tilton 75 series , with 5/8" in front and 7/10" in rear....the stroke is 1.1".....and i did not understand the volume thing?....how does it matter , once you fill and bleed the system, it's just the pressure created and pressure transmitted....kindly correct me...
    06, 07, 08 - Ashwa Racing (R.V. College of Engineering, Bangalore)
    09 - Rennstall (University of Applied Sciences, Esslingen)
    10,11 - Red Shirt / Scrutineer (FSG, Hockenheim)

  5. #5
    You need to take into account that your pads will be a couple thou off the discs, which means some displacement of the pistons.

    Matt Gignac
    McGill Racing Team

  6. #6
    Matt had a good point. We made some aluminum spacers to fit in there to take up the space. The pads last forever since they're made for a street motorcycle.

    What I was talking about with the volume thing is that if you displace a 5/8 cylinder 1 inch a two piston caliper with less surface area on the pistons will move the pistons farther than another caliper with more piston surface area.

    We ran a 3/4" bore mc in the front and a 5/8" bore mc in the rear with gp320s all the way around and the same rotors all the way around. With the proportioning valve we ended up being pretty close to the balance we needed, but I felt like there wasn't much pedal feel. It just seemed like there was alot of free play in the system. A foreward stop could have probably helped.

  7. #7
    Senior Member
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    1,061
    Assuming for 0.015" take up on each side of the rotor which is more realistic than a couple thousands due to runout, tolearnces,etc

    Assuming two calipers on the front axle and one on the rear.

    Assuming front 5/8 and rear 7/10

    (((1.25/2)^2)*pi)*8*.015=0.1472in^3 (front)
    (((1.25/2)^2)*pi)*4*.015=0.0736in^3 (rear)

    (.1472/((.625/2)^2)*pi))=0.479in (front mc)
    (.0736/((.7/2)^2)*pi))=0.191in (rear mc)

    If you can run two of the same sized master cylinders just to keep things simple like paperwork,ordering,etc. Remember that you will have to calculate the size of the remote res. that you will need to compensate for pad wear,ease of bleeding and other such factors. It is crucial to remember that brake fluid acts like an anvil in a crash so you will have to make sure you have a nice place to mount the remote res. if you use them. Hahah that was such drongo humor Make sure to mount them above your brake calipers height wise or you will need to add residual pressure valves to be sure you dont get back leak.

  8. #8
    Has anybody a CAD model of Wilwood GP 320 calipers??
    I need it to design front upright that must go in to the production next week, but the brakes won't come in few weeks at least...

    Best regards from Croatia!
    Riteh Racing Team

  9. #9
    We had used them in the past, but they were heavy and there are many alternatives that will be more than sufficient with a proper brake system design. We went down to a Dynalite and have had good results with them.

    If you are set on the GP320's I believe there is a rough drawing on 3dcontentcentral

    As for designing your upright, you have more than enough information on the Wilwood website (the drawing and dimensions of the GP320) to be able to make your upright tabs....You do not always need a CAD model.
    ------------------------------------------------
    Shields

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