JMortensen

But if you halved the spring rate, wouldn't that mean you're way over-rebounded?

Oh, I get it now. You don't want to change the SHOCK settings. You want to change the springs/bars. Makes sense.

I thought the idea was that you just want to slow down the weight transfer to reduce sudden pressure changes at the tire. To put it differently, you can hit the magic number on the WTW with different springs, but the softer springs will be more predictable at the limit because weight transfer happens more slowly. Entirely possible I have that wrong. As to the workarounds, I'm not seeing how a rocker would work in the front with hood clearance, but I do recall you suggesting something like gutting the strut and using it just to take the side loads, then welding brackets to the strut housing and the top hat (or maybe the upper part of the strut shaft) and running a coilover shock right next to the strut.

Started down the shocks rabbit hole again after this exchange. Went and looked at the old info I had bookmarked years ago, and the 3kgt Bilsteins are still about $600 for a set, come with 36mm digressive pistons. Looks like DA strut shafts from Bilsteinrun $750 each, so could add 4 of those and already be at $3600, that's without valving or remote canisters and adjusters or figuring out how to mount in the strut housings, etc. Thinking about buying 1 shock and disassembling and screwing around with it. I do remember why I let it go last time though: I figured if it was going to be that much of a PITA I'd be better off going to SLA, then you can find DA quality shocks for a hell of a lot cheaper. Stopped there because changing to SLA requires new everything from stub axles and brakes to uprights and caliper mounts. Almost just as well to build another car. Could get a set of DA Konis and just replace them every couple years when the top bushing wears out. As much as I've resisted Konis that probably makes the most sense from a practical perspective.

That is it in a nutshell. At the time I bought mine, I thought that the Bilsteins were superior to the Konis which wear out the upper strut bushing and that there is a "correct" valving, but I think having the adjustability trumps having better bushings and a monotube shock. I do think that there is "correct" damping for a spring rate with a dry track, but if it rains that's out the window, and if you change springs, the shocks are no longer correct. For that reason I'm not going to buy anything else that isn't adjustable, and I'm really going to try to stick to double adjustable. The guy who did my shocks had a long career and could say that he set up shocks for so many race winners, etc, but I think that properly setting up shocks is very subjective and also feel that people can drive past the shocks too. I raced with an EXTREMELY fast 510 when I started autoxing in the 90s. Gian Bowles was the driver. Very very fast car. He had Rancho 9000 shocks from a Camaro IIRC in the back. Rancho. R A N C H O, FFS. And he was dominating everyone, taking FTD by a mile.

I could light up the inside rear on the Miata on the street at times, and did it often at autoxes. Never tracked that car. The tighter the turn the bigger the problem, but the Miata engine was stock, so not a torque monster by any stretch. Car was great, except for the incredible lack of go. Had my doors blown off by a Kia minivan on freeway onramp. Pathetic...

More V8 swaps??? LOL

Jacking down occurs due to too much rebound and I have way too little and super stiff springs, so no fears about that. By comparison, I had the stock Bilsteins in my 10th Anniversary MIata and it jacked down bad. Was VICIOUS on concrete freeway expansion slots. Would jack down to the bumpstops then the whole frickin car would bounce violently, kinda jackhammering your spine. Luckily the stretch of concrete freeway that runs through Seattle is only about 10 or 15 miles... LOL. I put much stiffer springs in it and it got better, was later told that if I had gone 1/2 again stiffer I could have eliminated it entirely and it would have been better in just about every respect. IIRC that would have been like 5 or 6 times as stiff as the original spring rates. I guess the idea was to valve the shocks for the Spec Miata spring rates, and screw all the idiots that bought Miatas with Bilsteins for street use... The theory the guy was using on my shocks was that it's better to ignore ride quality and focus on keeping the tire on the ground. Most valving schemes are centered around controlling the sprung weight with the rebound and the unsprung with the compression damping. If you have too much rebound and the car goes over a dip, the wheel will get light or possibly leave the ground altogether, see pics of cars pulling a front tire in a turn. This made sense to me at the time because I had a mountain bike with a really terribly valved fork with almost no rebound, and the thing tracked GREAT, but after a couple jumps your hands were beat to hell, so I let him talk me into it. I also found that BMW E30 racers back in the day were running 300/300 with a 3:1 motion ratio, so they were basically doing exactly what I was, and spring rates were pretty similar after compensating for motion ratio too. It still kinda sorta makes sense. The problem is that it's not just ride quality that you need to concern yourself with. Allowing the sprung mass to move too fast creates its own set of issues, like the porpoising that I'm getting. I do think these shocks might work pretty well on a smooth road course. The P30 pistons are linear, and my shock dyno plot shows that. They're not perfectly linear, but they are a lot closer to that than digressive. I have thought about revalving to 300/100, but I think that's wasted effort as you can't get a digressive piston nor are they able to be modded for adjustability. Was looking at 3000GT Bilstein inserts, people have modded them with canisters and made rebound and compression independently adjustable. Shocks are such a bummer for Zs, especially when you look at the options available for more modern cars. You can get Ohlins, Penske, FatCat, all these high end shocks for a Miata. For a Z it's Koni or some one off custom thing.

When I sold diff parts for Randy's Ring and Pinion we had a shelf full of GM 7.5" Torsens marked down to $150. Nobody bought one in the little more than a year I worked there, partly because the GM 7.5 is too small for the Camaro they put it in and people usually moved away from it and went to an 8.5 or 9" diff, but still. Practically couldn't give them away. Quaifes have this incredible reputation and honestly, the only thing I thought it had going for it was the lifetime warranty. Helicals tend to spin the inside tire way too easy. Huge improvement over an open diff, but I'd rather have a clutch LSD, and the OS Giken is the best of those for our cars, but I'd put the Nissan clutch LSD in front of the Torsen, and probably the KAAZ 1.5 way ahead of the Nissan, although I haven't actually used the KAAZ, the 1.5 way should be an advantage.

Quaife is no longer warrantying their units for life. Mark Haag had issues and they basically told him tough luck. I think the shop he was using was able to make it functional again.

Plan was to start doing HPDEs last year. Again, this year might or might not happen, but yeah otherwise primarily autoxing. I did do an Evolution 2 school a couple years ago and wasn't that impressed and didn't learn anything that I could point to. Look ahead, no further ahead, no further than that was about it. They wouldn't let me spray my R1Rs down between runs and they wore the shoulder off really bad due to overheating. I left kinda pissed off about the whole thing. Their Evo 3 school would probably suit me better. Basically you and a really good driver both drive your car, back to back, switching drivers. That seems like it would be much more helpful. I'm already a pretty decent driver, came in 2nd, 5th, and 14th overall at the 3 autoxes I went to in 2019 and that's on used slicks that were 2 years old already. 14th was the day after a demo derby and the track was slick and having gigantic tires just made it like driving on ice. I think a new set of Avons would put me right up at the front. When I jump online I find myself getting creamed though, so I know there's a trick or two I haven't learned yet. As to sims, I started with a TH300 wheel and pedals and a T3Pa shifter on the PS4 and I had AC, ACC, Dirt 4, and GTS. Found myself sticking with GTS and AC. AC was the more realistic, GTS is more of an arcade game. ACC just wasn't fun, Dirt 4 never really captured my interest. Then I started changing things around, bought Fanatec pedals which are much better, and I switched to PC. I was doing iRacing but found it expensive and the steering didn't feel realistic at all. Also bought RF2 and a crapload of cars and tracks, but it has the same dead wheel problem, so right now Assetto Corsa is my game of choice. I hear that if you use a direct drive wheel iRacing is much better, but I'd rather not spend all that money on a wheel when I can put it towards the real car. AC has H2H, but I've been racing against the AI and just turning laps. Recently I had a break through and picked up a lot of time on a particular car at a particular track, but the annoying thing is that I don't know why I got faster. That's the kind of thing that I think online coaching could teach me. I mean, you have the inputs there, so should be able to use the data just the same way you would out of the race car, in theory. I do need shocks. I had my Bilsteins revalved and the guy who convinced me to do it that way was... unorthodox. Stock valving was something like 250/75, Katman suggested 300/100, this guy valved them 100/100. Then he retired. LOL. Car porpoises a bit. The 30mm Bilsteins have linear pistons, would really like to move up to 36mm, digressive and have some adjustability. But if I'm not going racing, I think FG would at least be a creative outlet, and I already bought a vacuum pump.

I need some DA, both for the car and to analyze my driving. My intention was to get some app for the phone and then get some data from 2020, but I ended up not racing at all last year. Problem is that DA isn't all I need. Right now I have a little cash together, and it's still looking like my racing schedule is going to be sketchy at best this year. So the question now is; new set of Avons (don't want to buy a set and let them sit a year), data acquisition, wing, shocks (car could really use these), online driving coach (people will look at your gaming DA and coach you on driving) or buy fiberglass supplies and learn to do that better and maybe make a wing. If nothing happens this year, could just sit on the cash and see what's going on next year, since DA stuff seems to be getting cheaper over time. Thinking if I have to sit the majority of the year out, online coaching and fiberglass supplies makes sense because it gives me something to do and will improve results when the racing resumes.

Interesting. Cheap enough that if they fall off or get hit by a cone I wouldn't really care. Looks like some of them have remotes to turn them on and off or turn on via motion detection. That would probably be better than crawling all over under the car. Very cool. Thanks for the idea. I have a good phone mount that I've been using for a couple years. Works well, but I do feel a bit hesitant about the phone falling out and getting destroyed. I guess the advantage of the phone would be using a piece of software that would measure g forces and speeds and all that. Can't do that with $13 cameras yet... https://www.ebay.com/itm/Cop-Spy-Nanny-Camera-Wireless-Hidden-Motion-DV-HD-1080P-Mini-Car-Dash-Cam-USA/324272628932

What do you have running all the cameras? Or do you just have them plugged into old phones? Was thinking about wiring in some cigarette lighters so I could run phone chargers and then running a couple phones I don't use anymore and either using the phone cameras themselves or plugging into something else, tablet or laptop that would capture the video. I'm not a techie though, so not really sure how to synch them all up and all that.

Got some pics of fabbed arms. Looks pretty easy, basically just hacked the original arm off and welded up some boxed sections with some tube through to stiffen. Will put on list of things to do this winter..

No problem! If you're new to it, EP cars use cantilevered slicks, so don't get regular ones. Might hit up Greg Ira, he's a member here (gira) and also on FB. Helpful guy, think he's 3 time national champ now.

You can do better, but 17 lbs isn't that bad. Probably get a 15 x 7 race wheel down to 12 or 13 lbs. Wouldn't be first on my list of things to change on a restoration.

Heims joints on street cars are pretty well documented at this point, no huge mystery. Those who are sensitive won't like it, those who aren't will. I've told this story many times, but I took my dad for a ride in my Z when he was in his mid 70s, had stock ball joints but otherwise all heims jointed front end, with G Machine aluminum/delrin in the back, coilovers, 200/250 springs and Illuminas, and on getting out his comment was about how comfortable the Recaro seat was. Others complain about poly bushings and the stiff ride from lowering springs. Totally agree on point 2, and with Richard's point about the difficulty of proper suspension design. I would point out that all of your GT class SCCA racers are using SLA front ends and quick change solid axle rears, so at some point you have to decide what a Z is and when one is modded to the point that it no longer qualifies.

Don't post in the FAQ section. Nobody can reply. KYBs are comfort shocks. Konis are better for your uses.

Clark, I was taking it as advice and appreciating it, so thanks. I got that same feedback elsewhere Richard, will probably be revising. The good news is I won't have to figure anything out next time, just duplicate with thinner metal.

Interesting stuff Clark, thanks. 1. Same weight as MSA 1", so good there. Haven't run a rear bar in 20 years, so call that a weight savings... I will say that the ST rear bar is a LOT lighter than the MSA rear bar, you don't have to drill holes in the chassis to mount it, and if you space it back a little it doesn't bind. I have dents in my frame rails from the MSA bar end links hitting them, so back in the 90s and early 00s I was definitely doing it wrong. 2. According to my WTW, I'm at .99 degree for 1g, and I have a lot stiffer springs 550/600. I am a lot wider, maybe that makes the difference. So may need to stiffen up later as the car should be capable of more than 1g. Haven't measured g's yet. 4 and 5. Yes, definitely needed the adjustment on the bottom, and the double shear means I can run a clevis pin too. One thing I forgot to mention is that when I welded in the mounts on the previous iteration I had an end link solidly bolted in. This made it difficult to slide the end link into the control arm mount. This time I took a HF blister pack from a tool I had bought and used some of the clear plastic. Just cut out a square and punched out a 3/8" hole in the middle and put that in between the rod end and the arm before I welded. I measured the plastic at something like .006 or .010 thick, can't remember, but now if I want to move the rod end it slides nicely to the next position really easily. Probably would clunk in a street car, but I'm doubting I'll hear it or care... 6. I calculated the spring rate and matched it up. I can go stiffer or softer, so hopefully I'll have a setting that works, but won't know until I get it back out again. I have some spring options, so might need to change those to get what I want, and if it needs stiffer anyway, no biggie.

One of the main things that I wanted out of a circle track style hollow bar with splined ends was lighter weight. Turns out the arms that you can buy off the shelf are 3/4" thick steel and are REALLY heavy, so this ended up being a lb or two heavier than the modded MSA bar that I took off. If you're looking at this for a light weight bar, look elsewhere. This is probably revision 457 of my sway bar setup. Some of the highlights of my previous attempts: Started with an MSA front and rear bar set. I had originally bought MSA front and rear bars. Then I had changed the rear end links and they ended up hitting the frame rails. Then I got an ST rear bar and modded it by drilling out the bushing saddles and adding zerks. Made double shear control arm attachments for modified stock arms. I tried to get a guy who custom bends hollow bars to make me one, can't remember the name now (Simonson???), but finally gave up after repeated attempts to contact him, including ones like: "I've got cash in hand. Want to buy a bar. You have made the sale. All you need to do is answer this email." No reply, so I finally decided to do the same thing a friend of mine had done successfully: I cut the ends off of aftermarket MSA front and rear bars and welded on 3/8" x 1" steel bar and drilled the new ends for adjustment. Then I mounted the bars on heims joints to reduce friction (more on this later). Then I mounted the front bar on top of the frame rail for splitter clearance. Then I installed an oil cooler, and the bar interfered, so I moved it back underneath, and that is what led to these latest revisions. The previous bar in its last iteration had the 3/8 x 1" bar stock welded on at an angle so that the end links leaned in towards the fenderwell significantly. I had found that this would give me the best clearance around the suspension parts. Before I ever ran it, Richard (260DET) pointed out that this would give me a falling rate sway bar, so I revised it by bending the ends vertical. There were several adjustment holes on the bar, but after fixing the end link angle, the end links bottomed out on the bar or the control arm mount that I built, so I could only use one hole per side, so I basically spent a lot of time cutting up a sway bar and welding crap to it and ended up with a non-adjustable sway bar with a bunch of useless shit welded to it. I probably should have left it the way it was, but even in that state the whole thing was pretty janky, and the only saving grace was that my spring rates were so stiff that it probably kept the bar from being used enough to bend the ends or snap the welds off. People have a big problem with welding to a spring, and I get that, but having done it and knowing others who have done it on race cars with stiff rates (meaning not a lot of sway bar twist) it works. It's not ideal, and I'm not saying that it is, but it works. It did hold up for 5 or 6 autoxes with 2 drivers but I wouldn't put this up as my best fabrication project. I wanted the new one to be functional, mount on the bottom of the frame, fit under the splitter, and clear the power steering ram on the rack which sticks out quite a ways on mine. Mounting on heims is controversial. One of the main things I was after with my suspension was reducing friction, so when tube80z suggested this as an alternative to poly, I was immediately interested. The idea is to have ears on the sway bar that connect to a rod end that is installed into the frame. This allows the sway bar to move up and down much more freely, but it also allows the sway bar to twist and doesn't restrict its shape while it twists. The bar should make a (slight) S shape in the center, and allowing the movement that the heims joints do should make it just a little bit easier for the bar to do its thing. I don't know that this is a huge deal, I think the bigger thing is allowing the bar to move freely, but there are IMSA and GT cars running this kind of setup, which is what tube80z showed me, and that's what convinced me to try it. I already had reinforced the stock sway bar mounting areas with a plate on top and bottom of the frame rail, and tubes connecting top to bottom in the front and back of the plates. I had used a pretty thin walled tap tube, but later decided it was probably too flimsy, so changed to a much thicker walled tube welded nuts on top and bottom. I'm still using those tubes. This still produces a lot of "WTF are you doing?" kinds of comments. Back in the day Cameron (Heavy85) was pretty outspoken as a critic and Coffey seemed to like the idea IIRC. You decide whether it's great or a waste of time and effort or doesn't make any difference at all. I was convinced enough to do it. The stock bar has the dip in the middle for oil pan clearance, and with the ears I had on the stock bar the center part of the bar would hit the splitter as it moved. I was hoping that the straight center bar would improve things, but no, just created a different problem: it hit the power steering ram. I figured I could use longer mounting ears to drop the sway bar down away from the ram. It was tough to see how everything would line up when it was all done, so I made them longer than necessary. I spent a lot of time making sure that the end links wouldn't bind and that the bar could move all the way through the suspension travel without hitting the ram or anything else. Had to trim sections off of the arms as well for sway bar clearance. The arms are very thick and strong, and I was only able to put about 1/16" bend in one with my 12T press. Was thinking of cutting or grinding them thinner so that I could bend them, or just giving up, but found a local metal fab shop with a huge press. Took it down there and explained what I wanted and watched/helped as the guy bent them to fit. Also wanted double shear so I welded an extension to the arms as well, and used high misalignment bushings on both ends to keep it from binding. Found that 3/8 male and female rod ends weren't short enough, so had to trim the threaded part of both to get them short enough, but there is no binding. The front adjusting hole on the arms is for the droop limiters, not a sway bar adjustment. Cleaned it all up, welded, painted, stuck it in the car and the ends of the arms where the bolt holds the splines tight hits the splitter. Now that I had it all on the car though, I could see that the ears were longer than necessary. Cut an inch off of the ears, redrilled and they're on there now. I haven't put the splitter back on, but I'm sure everything clears. Couple pics of older iterations in here as well. Off topic: the brake duct doesn't clear the arm, so one of my projects for the winter is to point the brake duct inlet forwards for clearance.

As far as how much is too much on the spacers, I think fox body mustang guys run a lot, IIRC it's like 2 or 2.5 inches on that chassis. The other common solution would be to bend the steer knuckles. DP Racing does this for 510 knuckles to give Ackerman and to fix bumpsteer, no reason it couldn't be done to lower the tie rod attachment. Friend of mine had some bent for his 510, IIRC they heated them red hot with a torch, bent, then heat treated for strength. Alternatively could just take a huge chunk of billet steel and make a forked end so you'd get double shear on the tie rod, which would be better but is a huge PITA and wheel clearance is a real problem on the Z. I've even seen sheet metal used in boxed structures that are welded for strength, and I'm sure that could be done if you were so inclined. I'm skeptical that it would be worth the effort on a 50 yo Nissan strut front end. My guess is that there's enough flex in the other bits that the gains probably wouldn't be noticeable. The angle of the arm itself is kind of deceptive. You want the angle through the joints to be parallel. Since the ball joint sits entirely on top of the arm, that means that the arm will need to angle down to get the pivots level. A stock tie rod pivot is much closer, but still the angle of the tie rod isn't the the same as the angle of the joints. So if you line up the arms, you'll still be significantly off. Best way to fix bumpsteer is to measure it. I don't know if the guy who wrote the JTR manual that said to move the LCA pivot up 3/4" and out 1/4" actually measured anything, but when I measured on my stock(ish) front end 20 years ago, up 7/16" was what minimized it best. I suspect maybe he was looking at the arm angles, but that's a guess. I'll make another thread. Those pics were taken when I was still figuring things out. Got it all done and then couldn't put the splitter on, redid the front mounts over the summer and haven't touched the car since then, but it looks significantly different now and the drop downs are... different.

Couple pieces of advice from personal experience. Moving the rack forwards or back makes very little difference in practice. I moved mine back as tight to the xmember as possible, then decided to do a Woodward rack and the ps servo is right in the way, so I had to move it forward to fit. Had moved the rack back purposely to add Ackerman, and then a year or so later found a link that showed how to sketch it out on graph paper. Did that and found that the difference was tiny, so then when I had to move the rack forward, did it again, graphed again and ended up with something close to parallel steer. Not ideal for autox, but hey, throw some static toe out at it and it's just not a big enough difference to sweat over. As to using a lot of bumpsteer shims to move the tie rod down, I was running my car like that for a while, it was good enough. Bolt is better than a tapered pin though, according to an engineer friend of mine. He said the tapered pins move around more and are more likely to break, and also that the thin circle track bumpsteer shims that I was using are not the best. He suggested running a really thick walled tube tapered down to fit on the rod end. I don't have a lathe, so I welded a rod end spacer to some thick wall tubing and then ground it to the right length with my belt/disc sander. Took a while, but it worked. Here's a pic of the old and new versions. I have an extra length of this tube so if you want to do this give me $8.30 for flat rate shipping and I'll mail you a chunk.

I think at under 200 ft/lbs you're probably going to be OK. One of our members, zredbaron, has a 300bhp L31 (I want to say it was more than 250 ft/lbs) and he's been through 3 different types of CVs IIRC and destroyed 2 diffs, snapped a mustache bar, I might be forgetting one or two other mishaps. EDIT--If you do go with CVs, especially on a race car, safety wire them. They seem to have a way of loosening the bolts.