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Everything posted by johnc
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Need help with Rims/Tires to buy
johnc replied to Jochen's topic in Brakes, Wheels, Suspension and Chassis
Remember, that once your flare the car its costs a lot of money to go back to the original style. Also, a larger wheel and tire combination is not always better on the S30. Without modifying the suspension pickup locations on the chassis you're limited to a about 610mm overall tire diameter if you want the car to handle well. IMHO, 225/50-15 on an 8" wide wheel is about perfect for a S30 making up to 225 horsepower. Here's a picture of my old 240Z with those size tires; And the same car with a lot more horsepower, ZG flares, and 275/45-16s: -
You'll also need to check the shock piston, seals, and shaft to make sure they are not damaged. And not just a look-see. You should send to parts out to be crack tested by a professional.
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Safest size for a slip-on spacer for a stock 280z?
johnc replied to lorenzo's topic in Brakes, Wheels, Suspension and Chassis
It all depends on the wheel. 5mm should be OK but you'll have to test fit and make sure the stub gets to the end of the nut or engage at least 5 full thread turns. -
From Mark Ortiz's latest newsletter: FOLLOWUP QUESTION TO FEBRUARY ISSUE ON A/R BARS I have a followup question to your comments on sway bars in your February newsletter. It seems to me that at full load, where all the car's weight has transferred to the outside wheel, springs and bars would have the same effect. But while in transition, while the outside is compressing, the way the bar resists that compression is by exerting upward force on the inside wheel. Would that not decrease grip on the inside tire, as long as it would otherwise still have corner weight (downward force) pressing the tire to the surface? Here's a scenario: - 1700 lbs of weight on the front end, 100 lbs/corner of unsprung weight - the springs are 500 lbs/in, and there is 1200 lbs of swaybar resistance (for every inch of chassis roll, or 2" of total swaybar flex) - the car should roll 1" when all 1700 lbs have transferred - at 1/2" of roll, approx 425 lbs will still be on the inside corner, and 1275 lbs on the outside - inside corner should be exerting 425 lbs of force on the inside tire against the ground, giving it grip - the spring is being compressed by 325 lbs of corner weight, and so it will be compressed .65" by that. The swaybar will be exerting 600 lbs of force in the other direction, and so will compress the spring another .83" Is the amount of force exerted on the tire reduced by the upward pressure of the swaybar, therefore reducing the traction on that inside tire? Is it correspondingly placing load on the outside tire then? The questioner is confused on a number of points. I will try to sort things out. First of all, springs, sway bars, and all other interconnective springing devices are purely displacement-sensitive. None of them have any different effect due to the suspension having a roll velocity. They are only sensitive to roll displacement. Dampers create forces that affect load transfer when the suspension has roll velocity, but sway bars do not, nor do springs. The scenario posited has a number of problems. Conventionally, the 100 lb/wheel of unsprung weight is not treated as transferring through the suspension, but as discussed in previous newsletters, if there is zero camber recovery in roll, the unsprung masses do create a roll moment that the suspension must resist. So for simplicity, let's suppose that the effective mass acting on the suspension in this half-car model really is 1700 lb. If that's so, the weight or load transferred due to cornering is not 1700 lb. It is, at most, the load on the inside wheel. If the half-car is assumed to be symmetrical, that's half of 1700 lb, or 850 lb transferred. At that point, the inside tire is at the point of impending lift. If the wheel rate in roll is 1700 lb/in, 500 from the spring and 1200 from the bar, the half-car has a displacement of only half an inch per wheel at 100% load transfer. Any further roll moment will lift the inside wheel. At half of that load transfer, 425 lb, roll displacement is ¼" per wheel. In either case, it would not matter if there were no bar and the spring rate at the wheel was 1700 lb/in instead. The half-car would act exactly the same. The tires do not know where the roll resistance comes from. They only respond to how much of it there is in total, at a particular instant. The roll resistance may be elastic (from bars and springs), frictional (from intentional and unintentional damping), or geometric (from linkage-induced support forces). But wherever it comes from, it can only hold the car upright by exerting force on the ground, through the tires. There is a simple, inexorable relationship between roll resisting moment, load transfer, and track width: • Load transfer through the suspension (i.e. less unsprung component) times track width equals roll resisting moment for the wheel pair. • Roll resisting moment for the wheel pair, divided by track, equals load transfer through the suspension. This is true regardless of what part or characteristic of the suspension generates what portion of the resistance. The total roll resisting moment from the front and rear wheel pairs together always equals the roll moment created by sprung mass inertia in response to acceleration (and gravity, which nowadays is sometimes considered an acceleration). The relative roll resistance of the front and rear suspensions controls the front/rear apportionment of the total, but not the overall magnitude of the total. Adding roll resistance only at the front increases front load transfer but not the total load transfer for the vehicle. It follows that rear load transfer must be less. So yes, the bar does unload the inside front wheel, and it does reduce front grip, and correspondingly increases rear grip, compared to the same setup without the bar. However, it does not do this any more or less than any other method of obtaining the same front roll resistance.
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How can the typical airline passenger be SO dumb?
johnc replied to Globerunner513's topic in Non Tech Board
Check in at Athens airport in Greece, probably 1998... Me: Hi, I'm on flight 123 to Frankfurt. Counter Person: Yes, I know. Me: How do you know? CP: You look like someone that would fly to Frankfurt. Ticket please. Me: How do Frankfurt bound passengers look? CP: Like arrogant pricks. Me: **** off *******. CP: Hah! You're OK. Here's a some vouchers for free drinks at the bar over there. Your flight is almost empty so I'll upgrade you to first class. Me: Huh? CP: Have a good flight. And it was probably my most enjoyable and relaxing flight ever. Olympic Air. -
Hah! Way back in my yoot I worked a Norris Wheels. UAW job and everyone started in Pallet Repair. Some of the employees had worked in Pallet Repair their whole career - they were the ones with the red eyes and slurred speech after lunch and spent their free time shooting at each other with nail guns. They had nicknames like Dawn of the Dead, Cockroach, and Scrotum. I was quickly promoted to Salvage Grinder where I met the Salvage Grinder lifers - Wife Beater and Whackoff. From there I was quickly promoted to Salvage Welder where I had a booth all to myself and didn't have to talk with the psychos. Anyone came into my booth and I pulled the mask done, pulled the trigger on the welder, and they left. My nickname became Jason.
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Just when you thought you saw brazen Smog Scams...
johnc replied to Tony D's topic in Non Tech Board
The odds are pretty good actually. BAR does a lot of undercover testing of smog check stations. When I had my 1977 Datsun 810 I had to go to three different shops until one agreed to do a smog check. I asked him why it was so hard to get it tested. He said that a clean cut white guy with a car like that screams BAR inspector. -
Exactly, although it takes me a bit longer to make the box. I generally screw something up and have to rebuild a part of it. Then there's the time I cut throw the power cord of the circular saw...
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Home Depot. 3/8" plywood base, 1/4" plywood sides and top. 1" x 2" wood for inner frame, skids, and engine mounts. Wood glue. Drywall screws. Lag bolts. Measure and cut the box bottom. Screw and glue 1 x 2s to the bottom so a forklift can get its forks under the box. Position the engine on the bottom and make mounts out of the 1 x 2 to hold the engine in place. Glue and screw the mounts to the bottom. use the lag bolts to attach the engine to the 1 x 2 mounts. Measure and cut the box sides and top. Glue and screw all the side together and to the bottom using the 1 x 2s. Make sure there's a frame at the top so the top can be screwed down. Measure and cut the box top and screw (no glue) it in place.
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240z frame damage advice needed
johnc replied to matt_w's topic in Brakes, Wheels, Suspension and Chassis
Measure the TC rod mount (where the bushing mount and where the rod passes through) to a couple places on the chassis itself. Maybe forward to where the crossmember bolts to the chassis, backwards to a trans mount, and then diagonally across those areas. A 1/16" of an inch difference is well within measurement error. Chassis strength should still be OK if everything is straight. -
FYI... those yellow signs that indicate a recommended speed for a turn are based on the passengers in a "typical" car feeling no more then .4Gs of lateral acceleration. Those signs are not a speed limit and you can drive through that corner at any speed up to the posted speed limit (white sign) for that road. Got pulled over by a LA County Sheriff who declared I was going too fast around a corner. I asked if I was speeding and he said no, but that I was driving recklessly. After showing him my SCCA National racing license, my NASA National racing license, and both my SCCA and NASA driving instructor credentials he told me to slow down and walked away.
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240z frame damage advice needed
johnc replied to matt_w's topic in Brakes, Wheels, Suspension and Chassis
Engine torque is not the issue most people make it out to be. Loads coming in from the suspension are much greater. I would measure to make sure the TC rod buckets are not moved out of position. Remove the TC rod and the bushings and them measure from the front and back faces of the mount to mounting holes on the chassis. Make sure both sides measure the same. -
I generally don't recommend spring rates above 350 lb. in. (2.5hz) unless the car is hugely stiffened and you know exactly why you want that rate. I have a customer that's transplanted a BMW E36 front suspension into his S30 and he's running 450 lb. in. front springs. He knows why and is very specific in what he wants the front to do.
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Correct. Or you can order the correct size gland nuts from me. Also, all my instructions are for shortening 240Z struts.
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question about fabricating a manifold and coatings
johnc replied to FJ 280z's topic in Fabrication / Welding
Tell the tuner thanks for his recommendations. Then ask him to do the work you asked him to. Make sure the coating you get is something like JetHot 2000 or Swain White Lightning. Ask for those coatings by name and don't accept anything that's "Just as good." Jet Hot Sterling or Extreme Sterling won't last. -
Strut Cartridge Removal Trick
johnc replied to philipl's topic in Brakes, Wheels, Suspension and Chassis
Drill a 3/8" hole in the bottom of the strut tube and pound the shock out with a punch or an air hammer. Buy a 3/8" rubber plug to seal up the hole when you're done. -
What are the stock 280+2 spring rates
johnc replied to Rumble Bumpkin's topic in Brakes, Wheels, Suspension and Chassis
Its in the FSM and its been posted on here. Maybe a little searching is in order. -
Coilover sleeve ??? for 280
johnc replied to CarolinaTZ's topic in Brakes, Wheels, Suspension and Chassis
On the ones I buy the OD is the same, they use the same adjustable lower perch. -
I probably pull a dozen spindle pins a year. Probably 98 total since I start playing with S30s. My best advice is really good penetrating oil (Kroil, Rost Off, Mopar), an air hammer, and hearing protection (to muffle the cussing).
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Coilover sleeve ??? for 280
johnc replied to CarolinaTZ's topic in Brakes, Wheels, Suspension and Chassis
There are 2.17" ID coil over sleeves available. I sell them or you can search Coleman or some of the circle track racing sites. -
Ding, ding, ding, ding, ding! Winner, winner, chicken dinner! There was nothing in this thread that I as an Admin here saw as offensive until people started complaining about offensive posts. Even those offended people didn't really post anything offensive, just a "feelings hurt" kind thing. Get over it. EDIT: And yes, we do give those members who contribute buttloads of technical information to this site a bit more slack in their "tone" because of the value of their contributions. That's kind of how life works.
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When shopping for seats, harnesses, and any other safety items, check for the proper safety certifications. For seats you should see an FIA 8855-1999 sticker which means the seats have been tested to 24G loading. For racing harnesses you should see a FIA date stamp (current is 2014 or 2015). If your focus is on safety make sure any aftermarket products you buy have those certifications. For a street driven car, I recommend the Schroth 4 point ASM harnesses (Rally 3, Rally 4, Rallycross, Autocontrol).
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Are wider tires really better?
johnc replied to logan1's topic in Brakes, Wheels, Suspension and Chassis
Assuming the following: 1. You're "better" means the highest lateral grip 2. The tires have the same tread compound, sidewall, etc. 3. The tires can get up to operating temp. 4. The car be be aligned to work best with the different tire widths. 5. The driver can get the most out of whatever tires are on the car. Then yes, a wider tire will be "better." -
No, that won't work either. An IRS car can very easily light up both tires with an open diff. There are no shortcuts and you shouldn't be taking any when spending hundreds of dollars on a diff.
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Nope. That doesn't work. A welded diff, a diff full of sawdust, and many other non-LSD items will cause the tires to spin in the same direction. You must take the rear cover off an look inside to see if the unit has a LSD. The seller should be willing to do that. if not, pass on the deal.