jmortensen

The Jag didn't come out just as smog and safety regulations made cars crappier and crappier. Not too many mid 70's cars that are highly sought after. 1970 had quite a few great cars. The difference was in the government intervention in the car biz. Leave it to the govt to screw $^!# up.

Pretty simple job. Put car on 4 jackstands. Disconnect sway bars and brake lines and halfshafts in back then you can pull the three nuts from the top of the strut towers and the control arms will pull down. The struts will lean out from under the fenders and you can pull the struts right there. You can use a spring compressor right there then pull the springs. Put the top hat back on the strut and bolt it back in finger tight, then you can break the gland nut loose from the top of the strut housing. Then pull it back out and now you can unscrew the gland nut and pull the struts. Put the new struts in, compress the springs, put the top hat back on, reconnect brake lines and sway bars and that's pretty much it. Bleed the brakes and you're done. Another trick is get a 2x4 that is the right size so that it pushes the brake pedal 1/2 way down. Stick it in between the seat and the brake pedal before you crack the brake lines loose. This will prevent the system from sucking air and will make your brake bleeding job a lot easier.

It's not that difficult to cc chambers. I got good results using a graduated cylinder, but you can do better with a real burette. There was a BIG range in the chamber volumes in my head. I got mine within .5 cc. I checked the volume several times so that I could ensure that I got repeatable results. People assume that the stock head has exactly the same size chambers and that every port flows the same from the factory. FAR FROM IT. If you do like you describe and don't go crazy making the ports huge I think you can make a very good improvement over stock. A lot of the work on the L head is in the chamber unshrouding valves and taking out all of the sharp edges. A bunch more is in the bowls under the valve seats. The last part to worry about is the ports themselves. Common sense and some self control are all you need.

The driveshaft nuts are 12 or 14mm IIRC depending on the year, so 1/2" is not even close to the appropriate size wrench to use. If these are original driveshaft bolts the head is a D shape so you can't spin it, so you only need to worry about getting a wrench on the nut side. I use a long 12mm wrench on my 240 with a long screwdriver pushed thru the U joint to hold the driveshaft. This used to be a SERIOUS PITA when I had the MSA rear swaybar installed. Now I have the rear mounted ST rear bar which should open things up quite a bit and make it a lot easier. Don't think you can get a socket onto the driveshaft because it runs so straight the shaft itself is in the way. Much easier to get a socket onto the 1/2 shaft because it is angled so far down and you can turn it until the socket fits on.

Just in case anyone was going to do this, you might care to know that when the bottle of octane booster says it will raise your octane 5 points that means from 87 to 87.5. You can figure it out for yourself pretty easily. Octane booster is usually Tolulene (114 octane) or Xylene (118 octane). I was running ~95 octane by mixing 1 gallon Tolulene with 5 gallons 92, plus a little mineral oil and ATF as suggested by the home brew octane booster sites on the internet. Xylene and Tolulene are common solvents and you can buy them for about $9/gal at the hardware store, instead of $9 per 8 oz bottle at the gas station.

No problem. It'd be really cool if it worked out, and then he won at the Runoffs...

Uh, I MIGHT be able to help you out. 1st suggestion is Nissan Comp should have them or be able to get them for big $$$. If your friend is feeling adventurous, have him take the parts to a Porsche shop and compare those pieces to the equivalent older 911 Porsche "915" transmission pieces. Readily available and I am 99.99999% that the synchro rings work. Never really looked into the other pieces, but I'd figure if the rings are the same the rest are the same too. When you say synchro sleeve, I assume you mean the toothed ring that slides over the synchro, not the synchro itself. I know this sounds like a half-baked idea, but take it seriously. I'll lay out the whole Porsche transmission Datsun transmission history for you. This is cut and pasted from an email I sent to someone else not more than 2 weeks ago: This guy ended up sending his mechanic (who coincidentally is the same Larry Butler) to go and look at the synchros. Larry told me he thinks that they would work, but then they found out that the synchro through Nissan was only $55 so he bought the synchro direct from Nissan. I've seen both parts right next to each other. The synchro assembly and the gear selector ring looks pretty well identical to me. The fork I can't speak to because I wasn't focused on it, but if you're going to use a Porsche synchro and selector, seems kinda obvious that you'd use the Porsche fork as well.

You could have a shop weld them back in. It would be a very good idea to make sure this pocket area isn't weak. If it needs to be reinforced it should be reinforced now. I had a friend with a VERY rusty Z go around a turn kind of hard and hit a bump and the rusty TC area literally exploded, sending him into the curb and further damaging the rusted frame rail to the point where the car got totalled.

Should be an exact match.

I decided recently and too late to build the car I want to drive, and screw the rules. Just run exhibition classes or open classes. Wish I would have figured that out years ago, I would have had more fun. Some day I'll blow up the L6 and get a V8 too.

The Euro is smaller and lighter and has one pulley (no smog pumps in Europe)

240 with dealer option air had 3 pulleys IIRC. The last pulley bolted onto the front of the normal pulley I think. It's been at least a decade since I saw one, so I could be remembering wrong.

The 48/52 is a function of the engine chosen and the mounts used. Doesn't require any battery relocation or anything. As long as the JTR kit is used and the engine has aluminum heads and manifold, you're there. I think we're in agreement on the handling thing though. I took a guy for a ride in my L6 with triples and all that, it a pretty fun little ride, 4 wheel drifting over the crest of a hill, apexing everything just right, etc. When we get back he says "You ought to go for a ride with Jason. He put a V8 in his Z and he just steps on the gas and it goes completely sideways!!!" Different strokes...

Should also say that the problem with V8 swaps isn't the V8, it's mostly the guys who install them. I'd say 95% are just interested in drag racing and don't do ANYTHING to the suspension at all.

Not this again. A standard V8 with aluminum heads and manifold is only 40 lbs heavier than a L6, and has a lower cg and lower PMOI if installed in the JTR position. Should not be a hindrance to handling AT ALL. Makes weight distribution about 48/52, so should be easier on front tires and better in braking and a whole lot faster at the end of the straight.

Actually right after that I pulled a 1:29.742 with no juice. I then tried for a couple days to beat that by changing suspension settings etc but I could never do it.

They have more than just the GTOs: http://www.reactionresearch.com/940z.html http://www.reactionresearch.com/280yzgallery.html http://www.reactionresearch.com/subtlez.html And there is a convertible setup as well. I'm not much for the GTO thing either, but the 940Z and YZ are very nice.

Sounds like a good plan. I used the strap with an R200 on my '70 so it is possible, but the other options are far superior to jerry rigging the strap. As you already know when the strap breaks the diff tips up and the driveshaft beats the crap out of the transmission tunnel which is why you should get away from it if possible. To jerry rig the strap I took the two bolts off that hold the plate that the straps anchor to on each side, moved the plates back so that only one bolt was engaged, and screwed them back down. I think this required some very minor grinding as well. I ran my car that way for a LONG time while autoxing and doing track days, etc, and the plates never budged. The strap was looking done when I started my latest round of modifications, so I did one of those alternative ideas on my car to avoid trouble later on.

Found one: http://forums.hybridz.org/showthread.php?t=97816&highlight=strut+differences Looks to me like the strut tubes are the same height, but the spring perches are mounted differently, and the isolator hat is taller on the 280. The guy says he swapped in the complete 280 strut and the front end of his 240 sat too high, so he swapped out the isolators and then it was lower. He wanted it lower than that so he bought 240 springs and strut inserts and put them in the 240 strut housing and it was lower still. So it kind of helps with our argument but kind of doesn't. I think it is pretty clear though just from looking at the pictures that the struts are very close to the same length and the housings are very close to the same length. I would venture a guess to say that this guy didn't need to buy new struts, could have used the 280 struts in the 240 housings with no issues. The only thing left is the spring perches and spring rates. It's clear that switching to the Koni 240 springs lowered his car, but it's not clear to me why. In looking at the picture it appears that the 240 spring perch is welded higher on the strut tube, which makes me think softer springs and more sag is the reason the car was lowered. Agree?

That is a phenomenon known as Supply and Demand, and it is a key to the continued success of capitalist countries all over the world. It's not a new thing for cars to be subject to supply and demand either. Back when the original 240Z was released the same thing was going on. I remember one person saying they bought a 240Z off the lot and sold it USED a year later for more than the original purchase price.

OK let me change my wording. I believe the 240Z and 280Z have the same length shock and the same length strut housing in front. They also have the same length spring within .25" so I don't think the amount of travel is significantly different between the two in the front. I looked through the album archives and I could not find a side by side comparison of the two. I know the 280 has larger strut tubes (OD and ID) and that the rear struts are taller, but the front are the same IIRC. I don't get your point about "holding the shock beside its mounting location." The strut extends all the way when the suspension is out of the car, right? I mean the spring is still compressed a bit, but it can't extend any further because the strut insert is topped out. So it physically can't extend any further. And I know you can bottom the front struts from personal experience. So where is this shortcoming in the travel again? I'm sorry to perseverate on this, but I still just don't understand what you perceive the difference to be. People section struts because the Z has a limited amount of travel (about 5" at the strut itself) and when you lower a Z more than about 2" you lose enough of the available bump travel that it becomes a problem. The 280Z is identically affected by this problem in front since the inserts and the strut housings are the same length. Maybe you are saying that the 240Z sags more than a 280Z, meaning that the strut with the weight of the vehicle on it sits in a position that is further through the travel when just sitting at rest. I don't think this is correct though. If you have observed this personally, my guess is that what you really saw was a 240 with worn out springs.

I could be wrong, but I don't think so. The 240Z front strut is the same length as the 280Z front strut, of this I am 99% sure. I know the 240 and 280ZX front struts are the same length. The rear is a little tricky. If you buy an aftermarket 240Z strut like a Tokico Illumina for instance, you get a 240 front strut with a 2" spacer on the bottom. My understanding is that the 280 strut is a 240 front strut with a 3 inch spacer on the bottom. I don't have a 280, but I've read that quite a few times on threads where people are trying to figure out how much to section their strut housings. Your comment about the spring perch being mounted differently also doesn't make sense to me. I know Nissan raised the spring perch on the 280, but I assumed that they moved it up 1" to fit the new taller strut. Otherwise the spring would have to be shorter, or else it would just be that much more preloaded than a 240 spring. I thought they were the same length. Just did a little checking and I came up with spring lengths for 240s and 280s. Looks like the 240 had a free spring length of 15.19" and the 280 has a free spring length of 15.43". So there is a .24" difference in the length of the springs. The springs are not the same rate, but the 280 is heavier. So again, either the springs on the 280 are preloaded a whole bunch more, or else the spring is basically in the same position as the 240, just 1" higher on the strut. Again, all of this is contingent upon the struts have the same stroke, which I believe they do. If that is true, then the rest of it is pretty clearly going to be similar. The reason the 280 sits higher than the 240 is the bigger insulators on top of the struts, and because of the 1" taller strut in the back and the relate 1" raise of the spring perch. I tried to look up stock spring specs to see if I could find out how much preload they have on them, wasn't able to find it. If we had the spring rates, we could figure out the rate to weight ratio and see what kind of a difference there is there, I would venture a guess to say they're pretty similar in this respect as well.

But you did measure shafts from R180 and R200 equipped Z's yourself. And I've measured them from R160 equipped Datsuns as well. And they're all the same. Here's the other info you were looking for: http://www.classiczcars.com/forums/showthread.php?t=17417

What is the deal with "rolling resistance" being a selling point for narrow wheels??? Seen it on a few posts here lately. I understand not wanting unsprung weight and rotating weight, which is why I wouldn't put 18's on a Z (or a Solstice for that matter). But the difference in rolling resistance between a 245 and a 205 is more than made up for by the increased handling with the 245, by a HUGE margin IME. I speak from very repeated direct experience (drove to the autox on a 195, swapped my 250s on, did the autox, then put the 195s back on and drove home for years and had a set of R compound 205s that I competed on for 2 years that I could compare too as well). I suppose maybe if you were trying for a Bonneville record you might opt for a narrower rim, but then you'd want to go with maybe a 3 or a 4" wide rim, 7 would be overkill in that instance. They better put some big brakes on that Pontiac otherwise people are going to burn them off trying to slow the car down in canyons and on the track. I can only guess that the 18" wheel/tire combo is going to weigh somewhere in the 50-60 lb range, and it has a larger lever arm to work from than a 15 or 16" wheel. Takes some big brakes to slow all of that spinning mass down, more so to do it repeatedly...

I would like to know why the 280 has more suspension travel than the 240. I know that the rear strut housings are 1" taller on the 280 vs the 240, but I thought the fronts were exactly the same length. I was also under the impression that the stroke was the same on all of the Z struts, front or rear. Same stroke = same amount of travel unless there is something that I'm missing. Geometry is slightly different in that the 280 has a higher cg and higher rear roll center as far as I can tell. Above and beyond that I see no major difference in geometry, and I'd prefer the 240's geometry if it was to remain stock. Sway bars are easy to install on a 240 or a 280, FWIW.