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74_5.0L_Z

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Everything posted by 74_5.0L_Z

  1. I have a 260Z with SubtleZ body kit and Ground Control coil-overs at all four corners. The SubtleZ kit provides an additional 1.5" of clearance between the fenders and tires compared to the stock fenders. The car currently has 15x10 wheels with a 5.25 inch backspace. On these wheels, I have run Hoosier 275/35-15 and Avon 23.0 x 10.5-15 race tires. I run no spacers on the rear and use 1/4" thick spacers on the front. I have previously ran 16x8 inch wheels with a 5 inch backspace on all four corners with no spacers and the stock body work. Clearance was perfect with 245/45/16 Hoosiers. The key is getting the backspace correct to clear the coil-overs. Then specify you width to fill the fender. For 15" wheels, the maximum backspace that you can run is 5". Any more than 5" backspace requires a spacer on the front wheels. The rear wheels can accept a little more backspace than the front generally. On my car the rear tire clears the strut by ~1/4" with 15" using a 5.25" backspace. The larger diameter wheels can run a little more back space, but then you get into making custom wheels. The pictures show the car with the Avons and the Hoosiers.
  2. Did you find one? I have one that I believe is from a 1972. You can have it for the price of shipping. Are there measurements that I can take to verify that this is the correct shaft?
  3. There are a few rare Long Nose R200 differentials with 3.36 gears (I have one in mine). I believe they were stock in the 1977 280Z 2+2 four speed cars. I would love to find an even higher gear 3.15 or 3.00.
  4. The hood won't lift if you give the air an escape route from under the hood. All the air that goes through my radiator exits through the duct in my hood. The air inlet is sealed to the front of the radiator and the outlet is seal the back of the radiator.
  5. There are several ways to gain some clearance. First, you can install adjustable bushing in the rear control arms and adjust them for maximum negative camber. This moves the strut outboard and gives you more clearance. The problem is that this may give you more negative camber than you want. If you have rear camber plates then you could move the top of the strut outboard as well to tweak the rear camber and gain more axle clearance. Second, you can lower the differential. The axles are shortest when they are in a straight line from the differential to the wheel. If the differential is low enough, then the stub axle at the wheel will always be above the shaft coming out of the differential. This works for low vehicles with limited strut travel, and is what I have done. I use bushings above the mustache bar to lower the rear, and adjust the angle at the R/T mount at the front of the differential. Third, in theory you could shift the differential forward or aft to gain clearance (same concept as lowering the differential). The axles would always be angled as seen from above, but the CV joints can handle that.
  6. It looks like you could get better angles on the steering shaft sections by rotating the pinion down toward the firewall and come in below the ear on your timing chain cover. Also, is the engine as far back and toward the passenger side as possible?
  7. I used an EZ 14 circuit harness mounted on the top of the driveshaft tunnel near the firewall. Mine is strictly a race car (no radio, no Heat/AC, no windshield wipers, etc...). I use a modified ford engine wiring harness between the ECM and engine while the EZ harness supplies all of the other body functions (ignition switch, brake lights, tail lights, gauge illumination, etc..) as well as power to the ECM and fuel pump. I like the compact fuse panel and the 175 amp circuit breaker that come with the kit. It definitely made it easy to clean up the wiring.
  8. Where are you getting contact? Tire to fender lip or tire to strut? With 17" wheels and coil-overs, you should be able to run more than -20mm offset. That equates to 4.46" backspace I run 8" springs, but my rear spring rate is 400 lb/in (probably not street friendly). With 15" wheels, I could run 5.5 inch backspace. With 17"wheels, you could get away with 5.75" backspace. Its always better to have more backspace than you can use because you can compensate with spacers. If you don't have enough backspace then there is no way to adjust besides getting different wheels. I use 5.25 backspace on all four corners, but only use spacers (1/4") on the front.
  9. What are you using the car for (street, drag strip, track days,...)? What size tire are you trying to fit? If you choose the right wheel diameter and backspace, contact of the strut tube is not the limiting factor. On the rear, if you have coil-overs, you can run at least 5" of back space with a 15" diameter wheel. I run 15 x 10 wheels with 5.25" back space. With Hoosier 275/35-15 tires I have about 1/2" clearance at the strut tube. As you increase the wheel diameter to 17 or 18", you can increase the backspace of the wheel. The inner wheel tub is the limiting factor for modern (17", 18") diameter wheels.
  10. Do you have the vacuum hose connected to the booster on the brakes? If so, disconnect it and plug it. You may have a big vacuum leak internal to the booster.
  11. When I designed my new cross-member, I added notches to positively locate it laterally relative to the frame. The bolts don't take any shear load.
  12. With the mount arranged horizontally like that, you are putting a bending moment into the side of the block. The lower bolts at the block are in tension, and the upper edge of the mounting plate is trying to push into the block. Typically, the mount is angled normal to the face of the block to assure that the mounts don't apply bending loads.
  13. I haven't had issues with it, but I do want to add a locking mechanism to support lateral loads trying to separate the rack tube from the rack pinion housing. Right now the engine is out of the car, so it might be a good time to revisit. An even better solution would be a nice Woodward rack. Do you have one I can borrow😀?
  14. You could try making your own cross-member like I did. The other thing that you can do is move the whole cross-member forward so that the engine drops in behind. This will also add caster and require custom T/C rods. crossmember.pdf
  15. https://www.classiczcars.com/forums/topic/48621-steering-rack-disassembly-and-refurb/?&page=4#comments
  16. It is offset toward the passenger side (I think the offset is about 3/4"). Duplicate that as much as possible to minimize driveshaft angle as seen from above.
  17. My posts in the thread above show the fitment.
  18. The dimensions for the bar above were for an S30. The original installation was in a 1974 260Z.
  19. I think you would be better off creating an SLA front suspension rather than the double ball joint set-up. Alternatively, have you considered putting narrower front wheels / tire on the car and using longer lower control arms to push them out to the width of your fenders. You would of course have to relocate the top of the strut outboard by a distance similar to the added length of the lower control arms. The factory LCA is ~11.3 long center to center. You currently have 15x14 wheels with essentially a 4" backspace. I would go to a 15 x 11 with a 5.5 inch backspace and make some LCAs about 16 inches center to center. Which ever avenue you pursue, I am watching eagerly and would be willing to provide any help I am able.
  20. I used the gorilla lugs for several years (black 7075 aluminum) and had no problem. I used P/N 44037B because I have replaced all of my wheel studs with M12 x 1.5 ARP. If you have stock wheel studs then you need M12 x 1.25 threads. However, when I started doing track days I bought a good set of steel lugs.
  21. Unfortunately, it is really hard to get more than about 5 degrees on an S30 without major modifications. I'm at about 6.5 degrees and I have moved my cross-member forward and the top of the struts backward. Yes you do get benefit from the effort. Just know that there is a lot involved in getting it right. This is what 6.5 degrees looks like in side view.
  22. For a street driven car, I would say dial in as much caster as possible without having clearance or binding problems. Unfortunately, adding caster is difficult to do correctly. If you add caster by lengthening the T/C rod then you have to have spherical bearings at the LCA to cross-member connection to avoid binding. You have to push the lower ball joint forward 1.25 " to get 6.4 degrees of caster. Because the LCA attachment to the cross-member is fixed, the LCA becomes angled forward pretty significantly as seen from above (See attached image). I used to set the car up with the control arms angled forward, but that causes other issues. The angled LCA causes loss of static camber. With camber plates you can compensate, but that is a band-aid. Another issue to deal with when you angle the arm forward is clearance between the tire and frame and tire and forward section of fender. Again, things that can be dealt with but have to be considered. In my current set-up, I moved the top of the strut back 3/4", lengthened the T/C rod to move the lower ball joint forward ~.5 inches, and made a cross-member that relocates the LCA attach point forward so that the LCA is perpendicular to the chassis center line at my desired caster.
  23. I think there are a lot of variables. The factory ALWAYS designs cars to understeer at the limit. That means that they always want the front suspension to reach its traction limit before the rear. Many newer sports cars have an SLA front suspension and a strut rear suspension, or they have struts at all four corners with tons of front caster. The SLA will almost always have more camber gain than a strut set-up, so the designers may be adding rear camber so that the rear will be optimized relative to the front at the lateral limit. Likewise, the newer front strut designs utilize a ton of caster compared to older designs. The added caster adds camber gain to the front wheels as steering angle is applied. So again, the rear needs added camber to match the front when both ends are near their limit of traction. The S30 is different than the newer designs (at least in stock form). The rear struts have more camber gain than the front (the fronts have about .5 degrees per inch of travel, and the rear have about 0.75 degrees per in of travel). You can see this on a lowered Z with stock suspension: The rear gains a lot of negative camber, but the front gains very little. Also, the stock front caster is really low compared to newer designs (<3 degrees), so there is no camber gain as the wheel is turned. If you add significant caster to the front of an S30 (>6 degrees), then you get the benefits of camber gain as the wheel is turned. You can then run less static camber, and you can run almost equal camber front and rear. I run 6.5 degrees caster and -1.8 degrees camber up front. I run -1.5 degrees camber in the rear.
  24. Thanks for the info. If I could time warp back to 1982, I could go buy one. It would be nice to find one someone has laying around.
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