Pop N Wood

I see what you are saying. I kept thinking that as long as the two lines stayed the same distance apart, then the wheel hubs would be parallel. Not true if the tires get closer together. Maybe the way around that problem with the laser pointers is to attach one to the control arm and the other to the hub. Now the change in distance between the two dots is truly the change in toe. But don't know if beams will clear the wheel wells. You would need a good distance between the lasers and the wall to get much angular accuracy. I need to think about it some more. I have two of those laser chalk line things. Maybe I could work out something where the two lines (one on the control arm, one on the hub) stay parallel on the floor. But with dial indicators, I assume you had them sitting on the floor, hence the need for two? The whole wheel may move in and out as the car is raised and lowered, but the difference in the two readings indicates toe? And since the dial indicators are a fixed height off the floor, you need to move the car and not the wheel? If I am correct in my understanding, then my issue with the dial indicators is you first have to makes sure the car goes straight up and down without yawing, and second a 1/4 degree change in toe on a 12 inch rotor will only result in a about 50 thousands of an inch difference in dial indicator readings. I guess that should be measurable. But most importantly I already have a couple of laser pointers (zero is cheaper than $40) I need to go back though the old posts. I thought Pete did it with a single dial indicator somehow attached to the car. BTW, do you happen to know how much you moved the pivot point?

OK. The figure in Jeromio's link clearly shows it is the relationship of the control arm with the tie rod that causes the toe in and out. I was just thinking of the arc the control arm swings. So my believe that the control arm should be level may be close to the right answer, but based on an erroneous belief on my part. The ride height does vary, but the goal of having the toe change by as little as possible when the tire bounces up and down about an average height would be my goal. It would be interesting to do the laser pointer thing and see how much the toe changes over the entire range of strut motion, both before and after the JTR mod. It would be interesting to see if the toe could be held constant over the entire range, or if you can only minimize the change in toe about the average ride height only. Pete Paraska and a couple of others did the dial indicator method, but a laser pointer would take advantage of geometry to amplify even small angle differences. Plus I would think that moving just the strut would be prefferable to moving the entire car.

My understanding of the bumpsteer problem was gleaned from reading posts by John C and the like. After all the information that went in my brain, that was my take away on it. So admittedly I could have missed something. Sounds like there are multiple factors at play. The control arms swing in an arc, so if they are level they are at the average ride height, then they will be swinging through the top of the arc causing a minimum change in horizontal distance between the two pivot points (like a piston at TDC). I should probably go back and read some old posts to get my thoughts straight first, but the quote you posted from John is talking primarily about camber changes. Obviously changing the length of the lower control arm directly affects camber. And I have to admit, I can see how keeping your tire flat on the ground is a good thing but I get a little lost when those guys start talking camber gain. But I thought the bumpsteer mod primarily has to do with toe in and out as the wheels go up and down. (As the name implies, if compressing the strut causes the wheel to turn, then bumps will tend to steer you in a different direction.) And I am not sure how changing the length of the control arm influences that. To support my memory of the toe problem, one old post talked about measuring the change in toe by attaching a couple of laser pointers onto the wheel hubs. This will project two dots on the front of the garage wall. If you trace the dots on the wall as the front wheels are moved through their full range of motion (obviously need to remove the springs and have the crossmember on blocks for this), then measuring the distance between the dots will give you the change in toe. I couple of guys were doing something similar to this to try and dial in inner control arm point exactly for their car. Seemed like a better idea than the blanket statement of "3/4 inch up and 1/4 inch out", or what ever JTR recommends.

I feel a little awestruck answering a HybridZ Godfather, but here goes. The point of the crossmember mod is to relocate the pivot point so the lower control arm sits nearly level to the ground when the car is parked. Thus as the arm swings through an arc, the apparent length of the arm doesn’t change as much thereby limiting how much the wheels toe in and out. When you say heim joint, I think adjustable length control arm. I am not sure how this would affect bumpsteer since the arm will still be pivoting about the same point. BTW, even a stock height Z can benefit from the bumpsteer mod, since apparently Nissan put the pivot point where they did to compensate for all the rubber they used in mounting the front suspension. Urethane should take care of most of that.

I have read enough of Katman's posts to know that would address one of his bigger issues (with Z car cages at least). Door bars are pretty inconvenient though. So if if you are going to go Dukes of Hazard, might as well hollow out the door, weld the door skin back into place and make the door beams protrude out into the door cavity as much as possible. This would give you maximum cushion before the Olds Vista Crusier T boning you starts to tag your sholder. Katman was also big on getting a bar runing door jamb to door jamb right about where your feet sit.

You guys are getting a little too personal.

While we are on this subject, anybody know what firefighters think of cages? I often wonder if their "jaws of life" will work to cut through a cage. Or do they just pull out the gas powered cut off saw? Going to have to respectfully disagree with the shape issue. Like someone said, it is not the fall that hurts you it is the sudden stop at the end. Most brain deaths occur when the internal organ slams into the front of your quickly decelerating skull. This bruises the brain, causing it to swell and bleed, which in turn creates additional pressure and further cuts off blood flow. Not trying to be condescending, just thinking through the issue. What the cage does do is give your head less room to decelerate. Scrubbing off the same speed in less distance means higher G’s, thus more damage. One could argue that wearing a helmet further complicates the encroachment issue. Wearing a helmet gives up as much head room as a cage built tight to the sheet metal. Granted if I am going to bump my head I would rather be wearing helmet than not, but this could also mean the forces are just transferred to my neck making me a quadriplegic rather than an organ donor. And there is a huge difference between bumping your head when you get into a car and slamming into a structural member in a wreck. If the cage is such that you bump your head while seated, then that is another issue. I think there are a lot of valid points being made, but I don’t see this issue as a simple one with an obvious answer. But I will say that I am not a big fan of cages on street cars for a number of different reasons.

Hey, I posted that exact same idea some time ago! http://hybridz.org/nuke/index.php?name=PNphpBB2&file=viewtopic&t=24120&highlight=laser Great idea! Good to see someone actually implemented it! To simplify things slightly, you can go to a gun store and by laser pointers that are built into a pistol cartridge. They are used for boresighting gun optics. Nice thing about those is they have a flat base and should be already calibrated (i.e perpendicular). don't know what they cost, but my guess is your approach is cheaper.

I did nearly the same thing when I was 17. Swapped a 425 into my 65 Olds and on the initial run I fixed a leak near the oil filter by loosening it a 1/4 turn (the mount was bent from the engine laying on it's side). In the excitement of my first engine swap I didn't keep an eye on the oil level and turned the engine into a mosquito fogger within 2 weeks. You are doing the right thing by not giving up on the kid. Don't know where any of us would be if our parents had given up on us.

Might as well throw in my admittedly uneducated opinion as well. IMO, if you drive you car on the street in such a way that you think you need a cage to be safe, then the safety problem lies between your ears and not with your car. Most street cages are for looks and not performance (my opinion). And like the one guy's signature says, who needs to explain why you have a roll cage to the officer who has just pulled you over for a traffic violation? People go on about a "properly installed cage designed by a professional cage builder". Yeah, nice words but truth be known that anyone with an ebay account, a chop saw and a tubing bender can become a "professional cage designer". Even the established cage manufactures build "kits" that fit a class of cars. And unless you want a lot of returns, you are going to design that cage slightly undersized to ease installation on slightly out of dimension cars. Also the idea that by installing a cage you somehow have made your car too unsafe to drive without a helmet just doesn't make sense to me. Like ZR8ED says, steel tube or stock sheet metal the effect will be the same. So the issue comes down to one of encroachment. I have said this before, but I feel many people (not all) have a naive belief in the safety benefits of helmets. If you think wearing a helmet will overcome the impact of a poorly designed cage or reckless driving.... As for rectangular tubing, may not be sanctioned but if you only want to stiffen the chassis without calling unnecessary police attention to yourself, then I am thinking this might be a viable option. Auto manufactures build safe cars using only sheet metal stampings. I don't have enough tools for that, but I'll bet I can strengthen the stock sheet metal with some subframe connectors, strut bars and some yet to be designed bracing of the rear hatch area. One Austrailian HybridZ member posted he got rid of the body panel creaking and paint cracks on his 240 with a formed sheet metal brace.

I have a el-cheapo auto darkening helmet from Harbor Freight. http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=47277 A good budget helmet. My only complaint is the quality of the headband is such that I can see it breaking before too long. The electronics are fine. Having said that, a lot of the old timers don't like the autodarkening lenses. My brother preferrs flipping his head. Something about 30+ years of welding tank trucks. And I have to take exception to the notion that an auto darkening set is somehow safer to use. It is simply more convenient. You also need to be concerned about reflections causing sunburn on your backside. A welding hat or do rag is also helpful. Finally, people always seem to overlook a good oxy-acetelyne torch. If you can only afford a single welder, then the torch should be the first thing you buy. A torch will weld mild steel, sheet aluminum and chrome moly. It will braze stainless steel. You can do a lot of other things with a torch, like annealing aluminum, cutting off stuck bolts, and bending metal. It is also much quicker to use when you want to make one or two small welds without the trial an error of setting up the MIG. I also find it easier to balance the weld pool when trying to weld a thin piece of steel to a thicker piece. It also doesn't require a 30 amp 220 volt outlet (like all good welders do) and is completely portable. And the up side is if you get good at running a bead with a torch, then you will take to TIG welding like a duck to water. But everybody wants that Monster Garage/American Chopper and even HGTV look of striking an arc.

Do you feel better now?

I know there is a 35 mm difference between the early 240's and later 240's due to the differential mounting. I think it was in mid 72 that they remounted the diffs. Beyond that I think the shafts for the Z cars are the same. Don't know anything about ZX's.

From “I have been Demoted!â€

Sort of the point I was trying to make. Lots of different types of aluminum. The type you can weld doesn't have the same properties as the stuff you can't. The upshot is you had better know what you are doing.

Somebody brought up such a possiblity once before. The problem for a Z is you now have to bolt these adapter plates up to the JTR plates, and before you know it you have the motor mounts a long way behind the crossmember.

Corvettes use aluminum suspension parts, so if done right I have would have no worries. It is the "done right" part that is worrisome. I have to admit I don't have a good mental picture of what you are trying to do, but I can say it would scare me to no end. This isn't an area where you can afford a failure of an untested component. Chevy has buildings full of metallurgists, engineers and lawyers. Guys like you and I have a welder, a hammer and a pile of 30 year old car parts. I am not saying don’t do it, but I would seek out a competent machinist and run tests of some kind before I would drive on modified suspension components like that. You know I look at some of the adjustable control arms shown on this site and I think I could easily make that for less money. But there is something to be said for buying something that has stood the test of time. The parts don’t seem quite as expensive when viewed in that light.

Whatever damage you inflicted probably happend when it hit the floor (or will happen when you try to pick it up). Can't see how not moving it could hurt. I would, however, pull all the spark plugs before I would crank it over again. If one of the cylinders fills with some type of fluid, well let's just say I know first hand that the starter motor on a Chevy 396 has enough torque to bend a rod on a cylinder that is full of fuel from a stuck float and an electric fuel pump.

Mike Kelly just had someone test drive his for sale Mustang right through his patio doors. Said the guy was trying to find park (on a manual transmission) when it happened. Maybe a clutch switch had nothing to do with it, but the point is it might help someone who is unfamiliar with your car from doing something stupid. I say it can't hurt so why not put one on?

Sounds like if you just don't try and date the girl across the street you should be OK.

Cool. Thanks for the info. I copied that optispark upgrade article some time ago. The upgrade seems pretty bullet proof. So now you have just doubled the size of my "desired" engine base!

Good to know. But I assume the 94 still had the older PROM style ECM. But if I got a deal on a 94, any idea if I could swap out the later ECM (and vent the optispark) to essentialy have athe progamability of the 95?

Thanks for the advice. I bid on the 93 because it was looking extremely cheap up until an hour or so before the end of the auction. Kind of a pisser to be limited to a single year of engine. Maybe I should research all the different years some more so I will know what I can live with when a deal comes along. What is the advantage of a 94 over a 93? My Z is smog exempt, but I still want to do a 100% legal swap. I have read that 96 and greater is OBDII, which could result in cats, both O2 sensors and possibly the ABS wheel sensors (at least on the LS1's).

This week end I tried to buy an LT1 out of a 93 vette. Got outbid, but during the auction I started doing web searches on the engine. From what I read, the 93 is a speed density system with the old chip type computer. I would really like to have a flash programable ECM like the 95's did since the thought of paying $150 for a new chip everytime I change something is not appealing. Any body know what would be involved with a conversion like this? Or should I hold out for the correct year of engine?

Venting the engine bay is always a good idea, but you should not have to do so to stay cool. You most definitely have something else wrong. Make sure you have a spring in your lower radiator hose. At highway speeds the water pump can draw enough suction to collapse the hose cutting off coolant flow. I would also make sure there are no air paths around the radiator. Seal the gaps between the radiator and the body. Also calibrate both your thermostat and temp gage. Get a $5 thermometer at Pep Boys or a kitchen store, heat your thermostat in a pan of water and see what temp it opens. Make sure it fully opens. Then disconnect your temp sensor and use the pan of hot water to check it's accuracy. Finally, what brand of electric fan do you have? A lot of people have had major problems with aftermarket fans, so make sure yours is a good one.