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John Coffey

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Everything posted by John Coffey

  1. John Coffey
    Projected tip plugs also slightly increase the CR. Most likely the change was a cost issue. The 280Z was getting pretty expensive in 1975.
  2. John Coffey
    Can't safely say that with me here... :classic:
  3. John Coffey
    The grooving is no different then a worn set of drums. Run a set of shoes down to the metal and you'll get grooves. The Toyota 4x4 conversion using the common 280ZX and 240SX rear disc and 15/16 MC setups are heavily front biased. I've worked on VARA cars that had that setup and we completely removed all rear brake proportioning and still couldn't get enough rear bias. One solution we found was to use Karmann Ghia front calipers in the back with the Brembo solid rotor. When Nissan built the FIA Group 4 brake system using the MK63 caliper they also increased the rear wheel cylinder size for the back brakes while retaining the front 7/8 MC. A balance bar solves the bias problem and that's why I developed the dual Tilton MC bracket I sell.
  4. John Coffey
    If you're going to have the head rebuilt, replacing the valve seats on a 40 year old head is a good idea regardless of the head casting. Given that, the N42 is probably the preferred choice just because of the performance potential down the road. But for anything under 225hp either head it fine.
  5. John Coffey
    The fix for the rear bite was the Ferrodo Green Stuff rear brake shoes. Unfortunately they are NLA. Porterfield R4S seemed to work the best and they work better if you machine about ten .020" deep grooves in the drum surface and then bed the shoes hard to match the groove pattern. More surface area.
  6. John Coffey
    1. No. 2. Hell no. 3. Don't make you head purchase choice dependent on a free header. Sell that round port header on eBay and save your money for the correct header for your cylinder head or install the stock exhaust manifold.
  7. John Coffey
    Well... I've done the CalClub 6 hour Enduro (E2 class) in an ITS 240Z using stock brakes (Hawk Blue pads, air ducting to the fronts, and Porterfield rear shoes) in which we had to do a pad change at the 3 hour mark. With lap times around 2 minutes and four hard braking zones from 100mph on each lap, that means (excluding a 10 minute fuel stop) we did 340 hard stops from over 100mph in three hours. That's one hard triple digit stop every 30 seconds - and doesn't count the 4 additional under 100mph braking zones needed in each lap. I beg to differ... :-)
  8. John Coffey
    IMHO, for a street driven S30, the stock brakes are fine. Even for track use the stock brakes are good enough for use for decades in SCCA ITS competition. I would focus first on your suspension and drive-line upgrades. Later you can revisit the S12W caliper and vented rotor upgrade. You will still increase front bias but the added heat capacity somewhat offsets that.
  9. John Coffey
    Based on a testing with the vintage racers, there is zero improvement in braking distance with the 4x4 caliper and a solid rotor. In fact, it generally makes braking distances worse because it makes the whole brake balance more front biased. It may feel better form the driver's seat but in objective comparisons with a well setup stock system it is a lower performance setup.
  10. John Coffey
    There's no benefit by going to the non-vented S12 calipers. Keep the stock front brake calipers if you're going to run a solid front rotors.
  11. John Coffey
    There shouldn't be a balance issue if you reassemble and don't have everything lined up as original. Wheel and tires are balanced as an assembly and tires are usually far more out of balance then a wheel. You should probably replace the fasteners and have the centers crack tested. Once they are reassembled seal the seam with Permatex Grey.
  12. John Coffey
    Part numbers 41000-E4621 RH and 41010-E4621 LH. Very rare here in the USA and worth a lot money to the folks in Europe who vintage race under the old FIA rule set. I have a customer with standing orders to buy a set if I find some for sale. I've found two sets so far that are not for sale.
  13. John Coffey
    Maybe I was a little harsh... Just remember, if skills and abilities are all you need, Senna wouldn't have died at Imola.
  14. John Coffey
    I teach people how to race cars for SCCA, Speedventures, and NASA. I know the value of driving skills, awareness, and experience. But there is always the unexpected and making sure the car is best prepared for an unexpected impact is a very smart thing to do. As a driver, if you're so full of yourself to think that you can avoid all accidents due to your superior skills, abilities, and situational awareness - you are a fool. You are exactly the kind of person that gets asked to leave race driver training because you're a danger to others on the track. Why do we bother to put roll cages and fire systems in race cars if superior skill makes them unnecessary? Why indeed...
  15. John Coffey
    Rick, What diff are you running? It looks like you get an initial push when you get on the gas in a corner.
  16. John Coffey
    36mm is the diameter of the shock piston with a larger diameter making the piston and shock more responsive to shaft movement and adjustment. The typical piston diameter for Koni 8610/11 and the Bilstein P30 is 30 to 32mm. For the Bilstein Motorsports 36mm shocks you'll have to cut off the strut tube, press in place, and weld a machined adapter to the spindle/hub casting. The shock body is threaded on to that adapter and becomes the strut itself. The shock body is threaded for the lower spring perch and its small enough in diameter that 2.25" ID spring can be used, saving a bit of weight and making room for wider wheels and tires.
  17. John Coffey
    Don't forget the diff. There is a lot of differential tuning in the BMW. Almost as much development effort went into the diff (including the mounting) as the shocks. When Toby won last year he was down on power compared to John's 240Z.
  18. John Coffey
    Four point roll bar, welded in subframe connectors, upgraded seat from any car made after 1995 or a FIA approved race seat, Schroth 4 point ASM harness, upgraded seat mounts, replace all the rubber lines running to the fuel tank including the vent lines, complete suspension and brake rebuild, replace all the fuel lines in the engine compartment, and a general refresh of the car.
  19. John Coffey
    Later this year I should have a setup using 36mm Bilstein Motorsports shocks. That would be worth waiting for.
  20. John Coffey
    There's a 4.5% difference in gearing between the two. I bet that if the tach was covered you wouldn't be able to tell which gear was installed.
  21. John Coffey
    .654 seconds. Henry pulled off a fast first run.
  22. John Coffey
    You guys are not going to be happy... Here's the 2012 FP National Champ.
  23. John Coffey
    91 Henry Bjoin - He's the one that purchased Toby's BMW. Loks like Tom's got a great chance at winning FP!
  24. John Coffey
    FYI... Toby sold the BMW and is now road racing an ex Toyota Long Beach GP Celebrity Celica. He's swapped in a JDM All-Trak 2L Turbo engine. Below is a pic of total joy when he got the engine to finally start after fighting crank position sensor problems:
  25. John Coffey
    He was not on the FP entry list when I checked a couple weeks before the event.
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