JMortensen

I just remembered this thread. This might help to understand what's going on if you follow this one back to Juan's thread: http://forums.hybridz.org/showthread.php?t=101565

If you're going to that trouble you should section the strut housing too. If you just lower the spring perch to lower the car then the car will be sitting near the bumpstops just to get the right height. If you section then you can cut the strut tube to the height of a 240Z strut tube, or even to the height of a sectioned 240Z strut tube and get more travel. Then you can use coilovers or just relocate the stock spring perch.

Yeah, you remove the peened nut then drive out the stub axle. The peened nut is kind of a PITA, but we talked about that in this thread: http://forums.hybridz.org/showthread.php?t=101668. Then you need to push the stub axle out. I drove mine out with an air hammer, but if you don't have one you can use a big lead hammer or a slide hammer (slide hammer is going to be impossible without the strut mounted to the car I think).

You should have the stub, the spacer, maybe a copper washer, the wheel bearings (inner and outer) the seal, the companion flange, a washer, and a nut. The spacer is the big thing. You're not going to find it at the auto parts store. The strut has a letter stamped on it that I think corresponds with the spacer you need. The letter is on the front end of the strut right around the bearing area, on the inside about an inch inside of the backing plate. Every strut I've had has been stamped "B". The spacer will also be stamped "B" as well. Some of the struts used a copper spacer washer when the factory spacer wasn't big enough. What the spacer does is to hold the bearings apart. so that the outer races sit in the strut housing, and the inner races contact the spacer. If it is too short, then there is way too much pressure on the inner races, and I guess you'll know if you need the extra copper washer if you put it back together and the stub axle won't turn. The nut is the peened nut that is a PITA to get off. If you use the 280ZXT nuts you don't have to peen them, so it will be easier to get the nut off again if you ever have to.

I think I am in the same boat you were in. I could brake hard in my Z before, but the problem was always that the fluid would boil within a couple laps time. So I'd be waiting for the tires to warm up for a lap or two, then I'd get one or two laps of good braking, then the fluid would boil and I'd have to back way off. I know my car should be capable of a lot more braking than it had before with the old brakes. Can't wait to flat spot some tires while I'm figuring it out. Thanks for all the help Cary. If you wouldn't mind I'd love to know what size masters your 510 buddy is running. I would prefer a softer pedal effort, but I don't want the pedal hitting the floor, and Tom's spreadsheet doesn't really account for pedal throw, just the ratio between the two. Also, when you say you ran the numbers and came up with 57% and 43%, where are you getting that from? I tried to make all of the specs as close to correct as I could, and I got this for Brake Torque Distribution: Min Nominal Max Front 55% 68% 79% Rear 45% 32% 21% G force .23 .76 1.2 Are those the numbers that you're looking at?

All this talk about Phantom's setup got me thinking about my new brake setup again, and a problem I haven't resolved. I currently have a set of Wilwood Superlite calipers for the front with 1.75" pistons, and I have a set of smaller Dynalite 4 pistons for the back, also 1.75" pistons. Front and back will both be run on 12.2" rotors, 1.2" thick in front and .81" in back. I know that usually people buy 1.75" pistons for the front and 1.38" pistons for the back in Zs, but I already have these, so if they can be made to work that's what I'd prefer to do. I run on 10" slicks, and the suspension is not sorted to full F Prepared level, but it should be capable of some pretty serious braking. I think that stock Z's pull about .9g under braking (that's what I seem to remember from an OLD Car and Driver). I'm guessing maybe 1.4 or 1.5g's for my car. That's a SWAG, so I might be WAY off, I just don't know. I am not entirely sure how I would figure it out without being able to drive it. Any suggestions on how to get an accurate number for this variable? Anyway I'm trying to use Tom's spreadsheet. Here it is for anyone who doesn't have it already: http://sth2.com/Z-car/Brakemath.xls I think that I figured out that if I run .75" master in front and 1.125" in rear, that according to the spreadsheet that gives me 1.2 G's. Then I was planning on running a proportioning valve in the rear line as well because I already have it, and Cary said that he runs both the balance bar and the prop valve on his setup. Since as Tom pointed out they are not linear, I figure that Cary is running it to stay closer to the correct balance over a greater range of braking effort. So I guess the questions are: Do I need to replace the rear calipers? If I use these small and large masters, does that cause any problems since one will move so much further when I step on the brake? How much misalignment can dual masters take? Anyone think I hosed the spreadsheet and should be running other size master cylinders? Right now weight is 50/50, total of 2530 (will probably be significantly less when I'm done with all this crap I'm doing).

Then you wouldn't be able to use your snazzy toe adjuster. Keep the green bar if it makes you feel like it's braced better, I just think that with the rest of the structure being so massive it wouldn't matter.

1970 240Z, L28, 5 speed, R200, 14x6 6 spokes, sway bars, Toy calipers, early (heavy) 280ZX rear disc, full interior with carpet kit that covers all the vinyl, Autopower roll bar, 1/2 tank: 2350

I think what you've got there is way overkill, and I don't think it would hurt to remove the green link. Remember the initial structure was 2 4" wide pieces of 1/8" plate attached by 4 bolts and now you have these massive ribbed aluminum pieces that tie into the mustache bar bolts. The only downside I can see to this design is that it's going to take a lot of material and a lot of milling.

I think the mistake is in the piston size/pressure corellation, not the relief valve. The best analogy I've heard is to compare the master cylinder to the front sprocket on a bicycle and the caliper to the rear sprocket. The smaller the front sprocket the more pressure or torque you can exert, the larger the rear sprocket the more pressure or torque you exert. So if you're climbing a hill and you need lots of torque, you go to a small front sprocket (small master) and the large rear sprocket (caliper with large pistons). If you are going downhill you don't need as much torque so you switch to the larger front sprocket (large master) and smaller rear sprocket (caliper with small pistons).

Since visual is a big part of CA smog, I would say no way in hell is a SR going to pass in a Z.

Being the cheap *** that I am, that is exactly what I wanted to know. Any benefit to your setup over his, other than the fact that a leaky reservoir won't drip on your feet?

Oh, then you can install them as is with regular 240Z struts, but you won't be able to lower the car much beyond where you have it now without hitting the bumpstops. Or if you section you can run the same ride height or as much as about 2" lower than the current ride height and still not ride on the bumpstops.

Sounds right to me. I think that you still might have front bias after gutting the prop valve though, I know I did with my old setup. Then your next step IMO should be larger rear calipers.

So basically you're saying you want another 1.5" drop from where you are now. If that is so then the answer is sectioning the struts would be a good idea. If you don't you'll be pretty close to if not riding on the bumpstops all the time. Search the strut thing. I know the MR2 struts have a larger diameter threaded area at the top, and they don't have a flat section machined into them like the stock struts do. The hole in the stock strut top is too small and has a D shape to it, so I'm not sure if you need to do anything about that other than drill the hole out, but check it out before you buy the struts.

Any idea what the cost will be on those?

It boils down to how far you want to lower the car. If you want to run it really low, then get the shorter struts (88 MR2 rear struts for the front, and 240Z front struts for the rear), shorten the strut tubes and install the coilovers. If you just want it an inch below stock ride height then just get regular 240Z inserts and install them. The trick is like Richard says that once you have the capability to really lower the car a lot with the coilovers, you'll need to resist that temptation. You know yourself. If you're gonna want the car low, section. There are a bunch of other threads on sectioning the struts, I still think sectioning about 2" from the top of the tube is easier and safer.

I think Tim is wrong on the caliper thing. I had the same misconception a few years back about drums (smaller wheel cylinder = more throw = more rear bias = WRONG) and Dan Baldwin and some others I can't remember showed me the light. Same thing for calipers. Bigger pistons = more force. Smaller pistons = more travel. This is true. The problem is that once pads contact rotors or shoes contact drums, then it is the FORCE that matters, not the travel. So you might try a bigger pistoned caliper back there.

I wouldn't put a prop valve in the front brake system. I ALMOST did that on my car when I had Toy front calipers and 280ZX rear disc. I had the same problem of much too much front bias. Now I'm glad I didn't. Here's a quote from Tom Holt on the subject: What I'm getting out of this is the harder you hit the brakes with a prop valve in front, the more REAR brake you'll get, since the prop valve isn't linear. I'm considering going to dual masters as a result of this response. Duals might be the best way for you to go too.

Susp Tech springs are LOW. A friend of mine had them with the old dual exhaust setup. Dual exhaust was quickly crunched going over speed bumps. I'd say its lower than the Tokicos.

Hmmm.... sounds familiar... http://forums.hybridz.org/showthread.php?t=94933

A couple points: First off is the fact that even with AZC arms, you'll still have poly bushings on the inside. Cary wants no poly ANYWHERE, and with good reason. For a race car, it isn't a problem to have no bushings and the lack of stiction in the suspension means more accurate movement and less bind. For a street car, different story. Second, it should be fairly easy to convert a normal rear control arm to monoballs, but I've never seen it done. I know there are kits to replace the stock bushings in 911 semi-trailing arms with monoballs, so I know it is possible and I'm pretty sure I understand what is involved. Basically you just have to machine a monoball holder that fits the bushing cup and rides on an axle. The outer axle would be easily made with a 5/8" bolt, maybe even the stock spindle pin could be made to work. The inner pivot is larger, might be 3/4". I remember Terry had messed around with cutting the inner pivots off the stock control arm and then welding a big bolt into the stock control arm. I think that was a 3/4" bolt, but I'm not sure. He was already 1/2 way there though. Just weld in those bolts, make spacers, slide the monoballs in and bolt the spacers into the bushing cups. Viola. As to my setup, when I first bought my Z I had a close friend who worked at a Z shop do ALL the initial work on my car. At the time I hadn't been wrenching for a while, and he was the expert on Datsuns. When I just took all this stuff apart I found that I had GMachine inners and stock rubber outer bushings. So I haven't been running poly in the back on the outers, much to my surprise. Regardless, I am confident that the bushings won't be significantly bound at my 3/16" setting, because the toe change will be handled by both the front and the rear bushings. So 3/16 = 3/32 per side, and that = 3/64 deflection per end. I've seen poly bushings last a VERY long time under much worse conditions than that. I'm going to stick with poly because I don't have the means to manufacture the necessary spacers to run monoballs on the control arms. If someone made those spacers I'd run the monoballs, but it wouldn't be for fear of wearing out the bushings.

That's what I meant. I don't know if Cary was on the same wavelength. It still appears to me that you'll have an interference issue with the mustache bar and the uprights. Which got me to thinking about the mustache bar. You could eliminate the stock bar, and integrate a more modern design of a shorter bar into your framework. You'd need to beef the frame up on top I think, but the other advantage would be that you could move the diff forward, giving better weight distribution. As long as you're running CV's in back the halfshaft misalignment won't be a problem. Making the subframe instead of modifying an existing setup gives you so many possibilities. Talk about "outside the box"...

There's a good idea! Space it out about 2 inches and run a big X from the top to bottom. Then just forget the link at the bottom, you don't need it at that point.

I agree, and it still makes me think that your timing is the culprit. As to the wrap it seems to me that there was a thread about a WRX that burned to the ground as a result of fuel soaked wrap maybe a year or more back. I may be overly cautious on this one but I'd remove the wrap.