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Thread: Modern-day Miura

  1. #151
    Senior Member C5GTO's Avatar
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    Post Disc Brakes

    In parallel with modeling the station buck, Iíve started working on the brake system. Iíve elected to go with an aftermarket brake system made by Wilwood. Itís a high-performance brake system utilizing 13Ē rotors on all 4 wheels, 6 piston calipers, and a pedal assembly with built-in balance bar for front to rear bias adjustment on the fly. I ordered up all the pieces a while ago and now am beginning the initial assembly process.

    While going aftermarket on a brake system gives a lot of flexibility, it also can make for some engineering challenges as this collection of parts didnít come off an assembly line in an auto plant. The first challenge I ran into is with mounting the calipers to the suspension uprights. The calipers were designed to be mounted with two 3/8Ē bolts and have only 9/16Ē between caliper mounting tabs and rotor for fastening. The suspension uprights are aluminum and given the limited space available, I canít use traditional fasteners like hex nuts behind the aluminum upright. The two milled off areas on the upright is the caliper to upright mating surface.



    I could have drilled and tapped threads into the aluminum upright but I donít like this especially for a critical safety item like brakes that will be constantly going through heat/cooling cycles. The 2 fastener options I came up with are heli-coil inserts or a tee-nut. While a heli-coil would give the bolt threads something other than aluminum to grip, the heli-coil itself would still be threading into the aluminum. So better from a standpoint of serviceability in tightening/removing caliper bolts a repeated number of times but still not so good related to grip strength of threads in the aluminum.

    A tee-nut gets its name because it looks like a ďTĒ in side profile. The most common use of tee-nuts is in wood where thread grip strength might be an issue and the associated fastener is typically a medium sized screw. I couldnít find a source to buy tee-nuts with a 3/8Ē bolt thread so Iíd need to machine them myself. While it would take quite a bit of time to machine tee-nuts, I felt it was worth it to end up with a superior end result for worry free brakes. A tee-nut would give me about ĹĒ length of thread in steel and a solid flange type head to sandwich the aluminum upright to the caliper.




    I started with partially threaded ĹĒ stainless steel bolts. I used a lathe to drill holes into the center of the bolt head and down the shaft. The drilled hole was then threaded for 3/8Ē-24 threads using a hand tap. I then used a vertical mill to machine the bolt heads down to 1/8Ē thick so they would clear the rotor. The bolt shaft was cut off with a hack-saw and remaining shaft ground to final length on a grinding wheel. The picture above shows at various stages of machining where rearmost one is completed tee-nut with a 3/8" bolt in it. Like I said lots of machining and time to make each one and 8 tee-nuts were needed.





    The rest of the assembly on the car was straight forward. I double checked the clearance and have about .030Ē between the tee-nut head and rotor surface. Not a lot but it should be enough. This brake system uses a separate cable operated caliper for parking brake. Thatís the smaller caliper in front.





    More to come on brake systemÖ
    Joel Heinke
    Be original; don't be afraid of being bold!

  2. #152
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    Sep 2003
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    your doing incredible work. I love seeing the progress.

  3. #153
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    May 2016
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    This is an amazing build!

  4. #154
    Senior Member C5GTO's Avatar
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    Quote Originally Posted by bodyman View Post
    your doing incredible work. I love seeing the progress.
    Quote Originally Posted by luke.jenner View Post
    This is an amazing build!
    Thanks guys!!

    This may sound funny, but I'm really having fun with the project as well. And I haven't even gotten to the part that prompted me to take the project on yet, metal shaping the bodywork.
    Joel Heinke
    Be original; don't be afraid of being bold!

  5. #155
    Senior Member C5GTO's Avatar
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    Post Radiator coolant tubes

    Iíve switched focus again from brake system to coolant lines. A great thing about a project at this early stage is that if you hit an issue with one area, thereís plenty of other areas where progress can be made. Iíve decided to connect the radiator openings to the main under chassis coolant tubes with 1 ĹĒ purpose routed, bent aluminum tubes. I am making these from mandrel bent Al 6061 tube and welding them together. I did some preliminary design and ordered up the mandrel bends and silicon hose adapters/couplers I thought were needed.

    I started fabrication with the bottom tube as I needed to establish its position so the upper tube could be routed around it. Both these tubes need to be routed to clear the spare tire.




    One each of 120 degree, 45 degree and 60 degree bends and 2 welds were needed to complete this tube. All in all, fairly straight forward. The upper tube is more complicated as it needs to be routed over the rack & pinion but still under the spare tire. A 180 degree bend cut in the middle and repositioned gives the needed jog for this. A hose clamp temporarily holds the joint for mockup purposes.




    I then started from the other end to determine what type of bend was needed for the middle. For the middle tube area, I need a bend thatís between 15 to 20 degrees. Of course, I donít have one of these and it took an Internet search to find a source. I found a source for an 18 degree bend and now have it on order.




    I need to have an air bleed valve at the topmost part above the radiator so I made a bung and welded it on at the top of the top tube.




    Iím now at a hold state to finish these coolant tubes until the last tube bend arrives.
    Joel Heinke
    Be original; don't be afraid of being bold!

  6. #156
    Senior Member C5GTO's Avatar
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    Post Radiator coolant tubes (cont.)

    I finished fabricating and welding up the front cooling tubes.



    A final check to ensure these will clear the spare tire. Thereís still an inch to spare

    Joel Heinke
    Be original; don't be afraid of being bold!

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