JMortensen

Since the control arm and the hub move independently, any change here might not be a toe change. You'd still need a front and rear marker to tell the difference in the movement of the front vs the rear of the hub. So now you would need 4 laser pointers and a reference point. That's why if you buy a bump steer gauge it comes with a flat plate that can be bolted to the hub. I've also heard of people strapping a metal plate to the wheel itself. The plate gives you a lot more room to jack the control arm up and down without the dial indicators falling off the surface. Yes to your other statement. The difference in the movement between the front and rear dial indicators indicates the toe change. I don't know how much I moved the pivot point. Enough to fix the problem. I get kinda frustrated reading about people arguing about 3/4 or 15/16 or whatever. What should be done is it should be moved until the problem is solved. Anything else is (bad) guesswork. If anyone is going to go through the trouble to fix it, it may as well be fixed right. You're right about the potential for the car to yaw I suppose, although my rear wheels were on the ground at the time. I should have taken the time to make a plate to attach to the hub so that I could raise the control arm, but I can tell you the difference was night and day on the track. I did the test in a spot where my jack would not roll, and I had repeatable results. I didn't just check it once when I got to where I thought it was fixed, I made absolutely sure before I locked the bolts down, then checked it again to make sure nothing had moved. Jon

The ZX is a totally different chassis. I don't think they are very close in length at all. It's been a while since I tore apart my last ZX parts car, but I would swear that they were a LOT longer. Sorry to give you a non-answer answer to your question, but I think you're barking up the wrong tree if you're trying to switch from one driveshaft to the other. Jon

Your laser pointer idea has merit but would be a big hassle in the end, I think. You'd have to have one on the front and back, and have a reference point to check against. The track width changes A LOT when you start changing the angle of the control arm, so your pointer would make a wide arc regardless of how you changed the control arm angle. So you would need a way to compare the arc vs the centerline of the tire, unless I'm missing something. Using dial indicators is easy, because you can zero them and as you compress the suspension you can see how the front and rear indicators move in relation to each other. So you jack the suspension up an inch, and watch the dial indicators. If the front goes around once and the rear goes around twice (just an example) then you've still got quite a bit of bumpsteer. Move the pivot until the dial indicators move very close to the same amount over a few inch range where the car will spend most of it's time (meaning measure the bumpsteer at the ride height you'll be driving at, not at full droop or full bump). You can buy 2 magnetic base dial indicators from Harbor Freight for like $40, then just stick them to a big piece of metal and start measuring. Jon

That'd be one hot floor... Jon

When I changed my bumpsteer I used two dial indicators, one on the front of the rotor, and one on the rear. I pulled the front springs, and put jackstands under the ends of the control arms. I jacked the car up and down very slowly while measuring the change on the dial indicators at the rotors. Prior to this I had tried strapping a long stick to the hub and using a plumb bob to measure on my garage floor, that just didn't work for me. I don't think the idea of jacking the body would work for most people either, because bushings will deflect and throw off your readings, but since I have rod ends on the control arms and TC rods, I think it worked pretty well for me. The "standard" way of checking is to bolt a flat plate to the hub and jack the control arm up and down while measuring with dial indicators. To get adjustability I drilled a new control arm hole directly above the original hole and connected the two making a slot, and removed the spot welded washers. I would do my test, then loosen the control arm bolt, tap the control arm up a bit, then test again, until I got it right. It took me a couple of hours to adjust both sides, and it was my first time and I stopped for a coffee break. Modding the crossmember was also easy. The only "hard part" if you could call it that was putting the crossmember in. I use washers on both sides of the control arm, but I never welded them back onto the crossmember. I have not had them move over 4 or 5 years of racing like this, and I check the torque every so often and they have stayed tight. Owen, if you extend your control arms 3/4" and don't change the length of the tie rods, you're going to have some pretty serious toe in! The tie rod length has to change with the control arm length. There is a decent amount of adjustment in the tie rods, but if you go too long on the control arms you'll be forced to make new tie rods. Jon

The reason people shoot for "nearly level" is because that is what is possible without moving the pivots, and using bump steer spacers. This has turned into the target for many people, but it is not what is ideal for best handling. John Coffey described the ideal situation in another post: The highly prepared 510's at the autox I used to go to every month in CA had the inner control arm pivots moved WAAAY up (like 3"), and I think they ran bump steer spacers in addition. They fixed the bumpsteer with spacers at the tie rods like Owen described. The more the control arm points down, the more neg camber is gained when the body rolls or the suspension compresses. Wheelman and Owen have it right on bumpsteer. The spacers are better at correcting the camber curve than fixing the bumpsteer. EDIT for Pop--the spacer deal that Owen is describing uses shims between the steer knuckle and the tie rod to move the outer end of the tie rod down until it is parallel with the control arm. Jon

I said don't bother because of the way he plans to use the car. The problem with using a rod end and bump steer spacer kit is the tie rods. You'll have to make them. The inner tie rods are metric thread IIRC, and any rod end you get is probably going to be SAE. I was planning on doing this myself, using 1" hex aluminum stock and drilling and tapping the inside end to match the rack and the outside end to match the SAE rod end. You'll also need to bore out the holes in the steer knuckles, and you would STILL benefit from raising the inner pivot and raising the roll center. My plan is to get the inner pivot as high as possible, and do all of the above, still haven't figured out if I want to continue running bump steer spacers or not. Might be overkill, but if I'm going to go for it, might as well go for it, right? This is a LOT of work compared to just raising the pivot, so you have to weigh the ROI of doing all of this. If it is an occasional autoxer, probably not worth it. Bumpsteer spacers or raising the pivots or both might be better if you're not building a racecar. Jon

Most classes are going to limit your engine choices, so you may want to consider that. Figure out what class you want to run in first. As to Johns assertion that L24's hold most class records, that's usually because a 240 with an L28 wouldn't be legal. Jon

Looks really good! That dashboard looks sharp though. Both types of sharp. Sharp pretty, and sharp "I just cut my thigh on the dashboard!" Jon

That totally reminds me of the Penn and Teller show "Bullsh!t" (sorry Nic - that's the name of the show). But that is WAY dumber than the episode where they were getting petition signers at the Earth day rally to sign something supporting a ban on dyhydrogen monoxide. The paralegal had time to look it over. I do like the "deadly if inhaled" bit. Clever. Maybe not quite as dumb as the other "Bullsh!t" bit which almost made my wife puke. They had a "mucus mask" treatment that they were getting people to subject themselves to in a shopping mall. People who wanted to try it had about 10 snails put on their faces for a couple minutes. Nothing like 10 snails creating a big foamy snail trail mess on your face and then showing that footage to millions of people. That show was the only good thing about Showtime... Jon

When tires are balanced on the inside only it is called a static balance. I am not an engineer, but from what I've been told static balance only works when the tire is rolling straight. As soon as you turn static balance goes out the window. I can tell you that balancing with weights on both sides (dynamic balance) is really the right way to do it. Static balance is a joke IMO. It is also possible that they were balanced dynamically, but one side did not need weights on the outside of the rim to be balanced. Jon

Were the wheels balanced with weights on the outside of the rim, or only on the inside? If inside only, have them do it again with weights on both sides. Jon

I say get the kid a STOCK 87 Volvo 240. You can't kill them, and he would have a tough time killing himself in one. It sounds like the kid needs to mature a little bit before you build something else for him. Jon

I assume that when you say you took it apart that means that you tore it all the way down. You can't really feel bad bushings with everything still together. Here are some teardown instructions for a ZX dizzy. I think all the L series distributors are similar inside, so it might help. http://www.jrdemers.com/280ZX/distributor/distributor.html If the bushings are good then I would guess that it is the gears causing the slop and swapping out dizzys should do nothing to help, but will let you know for sure what the problem is. Good luck, Jon

Super Mario Bros??? Jon

No. The ring gear bolts in the earlier diffs are 10mm. The ring gear bolts from the LSD diffs are 12mm. So you would need a sleeve to sit in the carrier to use the LSD with an earlier diff, or a shouldered ring gear bolt. Ross has said that he would make the spacers, but he needs a group to go in on it, or it wouldn't be worth it to him. The halfshafts do work. Jon

I wish we had this: http://www.popsci.com/popsci/auto/article/0,12543,358540,00.html I kinda like doing the driving all by myself, but that still seems pretty cool. Jon

Since you said it has a flanged output shaft it must also have a 2 piece driveshaft with a slip yoke in the middle. If that is the case then it has Porsche steel synchros and the same 5 speed bearings as the regular transmissions IIRC. Take it to a Porsche shop. They can rebuild it and get the synchros. They can either order bearings by number, or get a bearing kit from somewhere. Jon

Not trying to beat a dead horse, but you are describing a roll bar here, not a cage. I agree with almost everything you said though, particularly this: My main point is that if you don't wear a helmet you don't want metal next to your head - padded or not. I had an Autopower roll bar in my Z, and my old boss scolded me for not having padding on it in the middle between the seats. I asked "Why would I need padding there" and he got even more emphatic that your head will whip all over the place in the event of a serious accident. He's been roadracing for 30 something years, so I think he has some pretty good insight on what's going to happen if you crash. Since you are 5'7", if you wear a 4 point harness your likelihood of hitting your head on a good cage (which by the sound of it you have) is pretty minimal I would guess. I don't think that likelihood should be underestimated for people 6' and taller though. Especially with some of these cages I've seen where the bar above the door isn't even as high as the door frame itself. I don't have definitive proof, but I'm SURE that the reason that rooflines in cars keep getting higher and higher is to prevent head injury. I just don't want someone to spill gray matter in a botched attempt to make themselves "safer". Now I'm probably the preachy one... Jon

http://hybridz.org/nuke/index.php?name=PNphpBB2&file=viewtopic&t=31910 Look about 3/4 way down. Modifying just the vacuum advance is probably not what you're looking for. What you want is to "recurve" the distributor. You've got the right year distributor so that disabling the vacuum and running a lot of timing at idle should give pretty good results. Jon

I've always heard brown is good, black is best, white sucks. That's pure HEARSAY, so I really don't know, which is part of what ticked me off about the L6 valve stem seals. If you change the seals make sure you get the plastic little straw-looking tool (slides over the end of the valve) which allows you to slide the seals right over the retainer area so they don't tear when you put them on. It's hard to tell if either of the seals would function better, but its a fairly safe bet IMO, I've never had good luck with the stockers... Jon

That's a perfect example. I did a snap spin at an autox once. Turned into a full 360. When the car stopped spinning it grabbed really hard and I smacked my head (inside a helmet) so hard on the door frame that I saw stars. The last thing I would want on the street is another 3" (2" + padding) of room taken away so that I would be even more likely to hit something with my head, especially since I don't drive around town with a helmet on . Might make a good case for adding padding to the stock vehicle, but IMO this doesn't prove your point for putting a bar in that already limited space, padded or not. The SW bars I've seen have the bar over the door WAY too low as bluevx1 mentioned, I'm not sure about any of the others. I've seen "custom" cages with Petty bars 4" from the driver's head with no padding, and halo bars that were pretty close too. The worst was a friend's rock buggy that he built. Awesome machine, but sitting in the driver's seat you had about 2" between your head and the cage which directly above the driver was just a small rectangular hole. Not even a chance of putting a helmet on and getting in the thing unless you were 5'7" or less, I'm betting. If that thing were rolling it with me in it my head would be bouncing off of all 4 sides of that rectangle, no doubt. rc240z's cage is about the best I've seen. The bar over the door is very high and tight against the roof. http://www.classiczcars.com/photopost/showphoto.php?photo=6553&password=&sort=7&thecat=500 I wish I saw more that were like his, but most of the others that I've seen don't seem to take this stuff into consideration. I am going to put a cage in my Z, but I almost never drive it on the street anymore. Pretty soon it will be on the street only to bed in brake pads and stuff like that. Jon

Thanks to both of you guys for taking the time to take pics and all that. I think I underestimated the Nissan seals before I saw them, but the price on the Ford seals looks like a winner. Jon

Don't bother. Jon

I would try to get 18-20 degrees advance at idle and 34-36 degrees full advance, should be all in at 2500 rpm or so. You can cross reference your distributor and how many degrees advance it will have on the following site: http://home.att.net/~jason510/dizzy_specs.htm You can also modify the amount of advance and when it all comes in by changing the springs in the distributor to lighter or heavier springs, and by narrowing the slots so the mech advance doesn't travel so far. This mainly relates to the 240 dizzy. The ZX has a pretty good range already and lighter springs according to the chart. Here's another dizzy reference: http://www.jrdemers.com/280ZX/distributor/distributor.html Personally I disconnected the vacuum advance and JBWelded the mechanism on my ZX dizzy. They never work anyway (diaphragms always tear), and the last thing you want is the vacuum coming back up at the end of a straightaway and advancing the crap outta your ignition. If you are driving on the street, you'll get slightly better gas mileage/driveability with the vacuum advance, but IMO it is not worth it. If the jet blocks (long tubes with the jets in both ends) are OA, you'll probably never get rid of the midrange stumble. I just ran across something recently that said the 8 jet blocks don't have the big gap from the pilots to the mains, so they are better for street use. I think this was due to a change in the size of the aeration (sp?) holes in the blocks. Probably better for autox too, I'm going to try and track some down for my carbs. Jon