JMortensen

It's a race car thing, and even then it is usually a open wheel race car thing. The idea is to limit the roll by limiting how high the inside suspension can lift. This has the effect of increasing front roll stiffness and makes the car react quicker to steering inputs. There is more information on this thread: http://forums.hybridz.org/index.php?/topic/63492-suspension-tech-motion-ratio-unsprung-weight/page__st__60 It's been discussed other times too, might search. Here are some discussions from other forums, mostly about single seaters: http://www.eng-tips.com/viewthread.cfm?qid=207354&page=5 http://www.pistonheads.com/GASSING/topic.asp?h=0&t=781336&mid=0&nmt=Damper%20Movement%20on%20single%20seater%20race%20cars http://fsae.com/eve/ubb.x/a/tpc/f/125607348/m/18910968321

Did you get the beefed up version? After seeing your breakage, I've been thinking of doing the same.

The more I think about it the more I realize 8" springs are the easy answer, I think I'll take your advice. I would just prefer that it be idiot proof so that I couldn't possibly turn the collar down to where there was a problem. Guess I'm not going to get my wish this time...

This car is trying to kill me. I modded the bracket, which required grinding on the strut a little bit, and then bolted it all together and the caliper DOES hit the TC rod. Son of a... Not sure what to do next. I could just be careful and not lower it all the way down with 8" springs, but I'm not feeling real good about the whole thing. I suppose the other option is make a different caliper bracket, but there is no way I could do that myself. My drill press isn't nearly accurate enough. Any suggestions?

I went and stuck a wheel on with the coilover all the way down, looks like it's about 4" from the bottom of the wheel to the crossmember. Should have maybe 1" droop, so it will be close to or maybe actually a bit higher than Dan's car with the adjuster all the way down. I also took a look at the bracket, needs only to be clearanced about 1/4", and there is no issue with the TC rod or anything else, so I think I'll go ahead and do that. I could clearance the strut housing too, but I don't want to completely disassemble the thing in order to do that without spraying metal chips all over the shocks and camber plates and hubs. The bummer is that I don't think I'll be able to get the car as low as I wanted, so I may have to buy 8" springs for the front. I think I'll be alright in the rear with the 10" springs. I'm going to wait to get the loaded car on the suspension to see what it does then before buying anything though. I guess I didn't take into account that when I upped the spring rate I drastically reduced the sag, so even though the struts are sectioned and all that it might still ride higher than it did previously.

I see. Thanks for the correction there. I know the pan will be close to the ground at ride height, that's for sure...

I'm using a 10" spring, so I might be into that area. I probably should have used 8" springs, but when I bought them I was focused on whether the spring would bind before the car ran out of travel, not the fact that the spring won't ever bind because it won't compress that far. I believe with the 10" spring I have about 3.5" of bump before it coil binds. Can't remember what the 8" had, but it was significantly less. Part of the plan on this car was to fix all the suspension angles and issues that come from running REALLY low, so that I could do that without all of the ill effects. Plus my threaded collars are only 4" long, and they're installed so that the spring hits the top hat with the adjuster all the way up, so that throws people off too. I'm going to try and fix the bracket today, my only worry is that if I move the caliper down that it might hit the TC rod, but I think I'll be OK there. We shall see. EDIT--your oil pan looks really tall. The one I'll be using is 5.25" deep as I recall.

There was a member here by the name of Juan who made brake parts and sold them here and on ebay under the name JSK Innovations. I have his rear brake setup and these caliper brackets were his, although the hubs and rotors I'm using are not part of his kit.

Just found this today while I was checking everything in the suspension for clearance. Not sure if anyone else has experienced this problem. With the coilover adjuster all the way down there is still quite a bit of travel, but the caliper actually HITS the adjuster. Not good. This is a JSK brake setup. If you have this setup and are running really low, look out. Last thing you want is a brake failure at a critical moment. Also turning the wheel turns the adjuster too, doubly not good. I am going to try and modify the caliper bracket so it can be flipped and the caliper can be mounted at the 7:30 or 8 o' clock position instead of the 10:30 ish position it was originally designed for. Getting tired of finding new problems.

I looked for clearance of all the front suspension components today but particularly the turnbuckles, put the steering rack on and bolted on a wheel and checked for clearance and there is no issue. The brake line will be close, but will run to the outside of the turnbuckle. I was thinking that I may be able to zip tie the brake line to the turnbuckle if it looks like it might rub, but after checking it out I don't think that is going to be necessary. On the downside I did throw my 15x12 wheel on only to find out that it was apparently bent when the shop mounted the tire on it. It's a Hoosier slick too, and my understanding is that they don't have very stiff sidewalls, so I'm not sure what to make of that. It's a bummer because I had it mounted quite a while ago so I don't think I could take it back and ***** about it now. I know these wheels are thin so that they're light, but I hope this is not a recurring issue... So now I have one DRW in 15x10 with 4" backspace, and I'll need to get at least 3, but probably 4 new wheels since I was thinking of running 15x12s in front and 15x14s in rear. Two steps forward, one step back.

From recollection Mikuni is short, Cannon is long, and TWM and Nissan Comp were in the middle. I ran a Cannon with Mikuni carbs and Rebello Racing told me I had a better setup than the short Mikuni manifold when I talked to them on the phone about it.

Don't mix and match your gears. Just get another diff that has 3.54s in it.

The bracket doesn't rotate on the spindle pin.I don't know exactly what ride height will be, but I imagine it would be an inch or two lower than what's in the picture. Probably will depend mostly on the rear roll center height.

If they're close I may just do something else entirely. I don't think I can flip the whole assembly, but I might be able to figure out my small cable with adjusters, which would be more like Dan's but with a smaller turnbuckle. I have my limiters attached to the chassis through the thicker steel at the top of the strut tower (you can see it if you look from underneath), as far from the camber plate as I could get it.

One of the most common complaints on a Z is a clunking differential that makes noise when you get on and off the gas. The best solution in my opinion is the Ron Tyler diff mount. You can search here and at classiczcars.com and find numerous threads on them. It's a good, simple idea and is far superior to the backasswards stock front diff mount. I would bet that this solves most of your noise issues. I would start there and then work your way through any remaining issues. You might check and make sure it works for the R180 that came stock in your 72. I think most people install it with the R200 from the later cars.

I disagree with you Joe. Why bother modifying the car at all if the effect of the modification doesn't matter or isn't worthwhile? Why do people here install light flywheels in their street cars? If you've ever been in a car with one, it CLEARLY matters in that case. Reducing rotating mass makes a difference, even in a street car.

Don't know if you're on c-c.com, but I just saw this and thought of you talking about knockback at your last track day: http://forums.corner-carvers.com/showthread.php?t=42896 Jist of it is that there a radially floating rotor that doesn't cause knockback. I'm taking this to mean that any floating rotor like yours does, which makes sense because the rotor can move laterally. I suppose you can always just do the racer thing and tap the brakes before the braking zone just to get the pistons back into position, but this looks like a permanent fix to that problem. Whether they're available to fit your particular setup is another question.

There's always something else that could screw up the experiment. Like the gearing issue on the BMW. Doing it on paper removes the other variables. I'm sure it's possible to quantify the extra torque that is used spinning a set of larger rims up, and also that it is possible to determine in some unit (I guess that would be torque too) how much more braking energy is consumed.

You haven't been to Canada. When I went to Whistler a couple years ago I was on the freeway and I noticed that cars would change lanes when there was a freeway onramp merging into the right lane. My wife and I thought it was hilarious. Then two different people STOPPED at the end of an onramp getting onto the freeway. I was looking over my shoulder to merge with the traffic when my wife yelled "STOP!!!" Thank god she did too. Apparently that's not common practice, but it's common enough that people change lanes en masse to get away from the few who do it.

You're right, we need to do more proving. We have the formula to prove the assertion that the smaller wheel takes less force to accelerate. What we need is someone with some math skill that can work it out to figure out the disadvantage between a small diameter and larger diameter wheel. I'm not that guy unfortunately, or I'd do it myself. To really make that accurate you'd have to figure out exactly how far out the center of mass is, but I'd be willing to bet that there would be a noticeable difference on the same weight tire/wheel combo with just a couple inches difference in the center of mass. Here's an anecdote for you though, and this is not the first time I've told it. My friend wanted to trade me my Caroll Shelby 15x7's which are astonishingly heavy, probably 20 lbs each, for her 14x6 6 spoke wheels which are 14 lbs. I agreed after SPECIFICALLY WARNING her that they would make her car slower. I swapped out the wheels and she drove home (about 180 miles) and called me on the phone saying "my car is slower and the brakes don't work as well." I asked if she wanted to switch back, she said no, and she still has those heavy mesh 15x7's on her Z today.

It has to be a solid stop, bungee type stuff wouldn't work as well, might even be akin to adding rebound damping. Plus, I skipped Boy Scouts so I wouldn't be able to make quick changes if needed. There are lots of solutions that would be lighter and certainly cables or other ropey type stuff would work, but not for quick changes (for me). The cables and turnbuckles probably weigh 10-12 oz all together. The whole thing is not as heavy as it looks.

Not sure how I would keep them from rattling. I suppose a zip tie through the upper eyelet and around the strut maybe? I did grind the ends of the turnbuckle flat so that the jam nuts could get a better purchase. Hope that's enough.

Front diffusers aren't legal in many SCCA classes, including the one my car will be in, X/Prepared. The increase in drag from the front diffuser shown above may be worth the extra downforce it helps to generate even if there isn't a full undertray, I suppose you would have to measure that on a case by case basis. That splitter is pretty high off the ground. Wondering if it might be working under braking when the suspension compresses to get it closer. Not sure on that, but it would be interesting to see if it worked in the wind tunnel at the ride height shown. I would suspect that it doesn't.

Did the rears today. The cables were a bit short so I made my bracket a bit longer and put a couple holes in it for adjustment. I wanted to do the cable to a bracket attaching to the ebrake cable holder bolts on the strut housing, but that looked like it was going to be really close to the CV adapters, so I did it to the spindle pin instead. All I have to say is thank you to whoever invented the step drill. Drilling a 5.8" hole in sheet metal with a standard bit or a hole saw is such a pain, and with the step drill it was so easy. Pics:

It would work, old Alpha Romeo's have leather straps. The nice thing about the turnbuckles is that you can adjust the length easily. Can't do that with a strap or serpentine belt as easily. I did find a piece of 1/8" x 3" steel strap so I cut two pieces off of it about 5/8" wide and drilled holes in the ends. I'm going to use that as a spacer so I can adjust the length of the turnbuckles down. I figure I can drill an additional hole in the middle too, and I'll have two adjustment lengths and can also remove the spacer entirely if it is too long.