kj280z Posted May 20, 2005 Share Posted May 20, 2005 Hey all, I had to take a moment to say thank you to John and Ross. Both John and Ross came in for Z Fest back in April. I've installed a number of suspension and Brake parts from Ross and John came down to evaluate the supercharged motor and drive in the Z Fest autoX... Well it got rained out and we were forced to do some testing on a circle track... anyway... I just had the car out on the road coarse this Saturday (Sebring Long coarse) for the first time since John performed his "magic" on the suspension. Just so everyone is aware of the attention to detail and the time required to do it right, John spent a full day and a half setting it up. He was meticulous about his work and I learned a ton. The car handled AMAZING! My instructor couldn't believe how well the car performed. We logged over 150 miles on the track for the day! I can't say enough... so I'll just say THANK YOU! I would highly recommend these guys... they are experts at what they do... http://www.betamotorsports.com http://www.modern-motorsports.com The supercharged motor did great too! It was rock solid all day and was a total rip to drive on the track. Thanks again! Quote Link to comment Share on other sites More sharing options...
260DET Posted May 20, 2005 Share Posted May 20, 2005 Marvellous, if I was a man of money JC would get a air ticket etc out to Oz to do a few laps in my 260+. And that would put a smile on his face for sure Ah well, great to hear about the adventures of a new Zed wherever it is. Quote Link to comment Share on other sites More sharing options...
johnc Posted May 20, 2005 Share Posted May 20, 2005 Tell that instructor to keep his hands inside the car! From the pictures it looks like it needs a bit more rear camber and from the ride height it looks like you haven't put the rear camber plates on the car. We need to get the car down some more too. Still planning on relocating the front LCA? Quote Link to comment Share on other sites More sharing options...
kj280z Posted May 20, 2005 Author Share Posted May 20, 2005 John, Hey.... The instructor had to hold on because I still haven't put the 4 point harnesses in... those stock belts don't do too much on the track! I didn't want to touch a thing from where you had it setup when you were here until I had a chance to take it out once. Now that I've been out I have a good idea on the next steps as per your recommendations it looks to be the following... Install the rear camber plates that you sent me. Lower the car... do you remember how much? I think it needs to come down 3/4" in the rear and 1/2" in the front? Relocate the pivot point on the front LCA I think our final settings on camber were 2.8 in the front and 1.8 in the rear... Could you check your notes for me on that? Let me know what your recommendations are and we'll dial it in. You had also recommended that the front wheels needed to be spaced out wider in the front. I also need to bring the rears in slightly (around 1/4")... I'm going to have Ross make me some custom adapters that move the fronts out another 1/4" and move the rears in around 1/4" (I have a minor rub in the rear and plenty of room to move the wheel inbound with my coilovers)... Do you see any problems in doing any of that? Thanks for all your help! You Da Man! Quote Link to comment Share on other sites More sharing options...
johnc Posted May 20, 2005 Share Posted May 20, 2005 Notebook say: Front Ride Height 7.250" Camber 2.8 degrees neg Toe 1/8" out Rear Ride Height 7.750" Camber 1.7 degrees neg Toe 1/16" in Increasing the front track by 1/4" would be a good thing. Decreasing rear track by 1/4" would be a not so good thing. With the camber plates you'll want to get the rear camber to 2 to 2.250 negative which may give you enough clearance. If you have to move the rear wheels in, do it as little as possible. Drop the ride height the same amount front and rear, we want to keep about 1/2" of rake in the car. And, since its a street car, I suggest you shoot for 7" in rear and 6.5" in front. EDIT: Remember, those alignment numbers are approximate. Aligning a car that's not on a perfectly level floor is an exercise in frustration! Quote Link to comment Share on other sites More sharing options...
rags Posted May 21, 2005 Share Posted May 21, 2005 John, When you take a ride height measurement, where are you taking the measurement from? 7 3/4" sounds high but I can't argue with success! Joe Quote Link to comment Share on other sites More sharing options...
kj280z Posted May 21, 2005 Author Share Posted May 21, 2005 Joe, John can correct me if I've mis-stated anything. Measurements were at the front and rear of the rocker panel where it turns in and is horizontal to the ground. It is slightly high, thus John's recommendation to put the rear camber plates in... they will allow me to eliminate the large strut insulators (remember this is a 280z so the rear strut insulators are very tall) and lower the car a little more while keeping the LCA's at the correct angle. Once I get that in place, the next steps will be to lower the car slightly (front and rear) and dial in a little more rear camber. After that, I have a spare front cross member that I'm going to modify by relocating the front LCA pivots up 3/4"... I also need a front strut brace... Most likely I'll have to make my own since I have to clear the supercharger for it to fit. I'm using the rear strut brace from TEP, which is "OK"... I just wish it would have fit better without modification needed. Turn in at the track was "ok", but obviously would be improved and hopefully a little more crisp with a front brace installed. Someday to make my life easier, it would be nice to get/make a set of adjustable front LCAs similar to my rears (Modern Motorsports a real nice setup!). The greatest part about all of this is I feel like we're making the right changes a little at a time to dial the car in. I'm getting closer to the point where I am begining to be able to realize the changes on the track because I'm improving my driving skills (finally!) (I still need a lot of work though!). This is certainly the fun part! Tweaking and driving rather than all the development work that it took to get to this point WOW! I had forgotten how much fun it was to drive a properly prepared Z on the road coarse... It's good to be back out there with a fun car to drive! Quote Link to comment Share on other sites More sharing options...
johnc Posted May 21, 2005 Share Posted May 21, 2005 I measure ride height as Ken describes above. For a car that's driven on the street car I keep it no lower then 6.5". For a track or autocross only car 5" is about the lowest I'll go. But, the ride height limit is detemined by the control arm angles more then any "magic" number. A car with taller tires will need a higher ride height. Quote Link to comment Share on other sites More sharing options...
rags Posted May 21, 2005 Share Posted May 21, 2005 John, Do you have a preferred control arm angle? I do know they should drop down at the wheel end but at what amount I'm not sure. Thanks! Joe Quote Link to comment Share on other sites More sharing options...
TimZ Posted May 21, 2005 Share Posted May 21, 2005 Not questioning Johnc's suspension tuning prowess, as his suggestions are always spot on. However, is there some reason that you can't get the rear camber change with the LCAs? Also, the ride height issue can also be addressed by using front isloators in the rear - they are about 1" shorter. The adjustable spring perch and 2.5" id springs can still be made to work with this setup. Granted, adjusting camber with the LCA alone is not ideal, as you will be coupled to other settings there (track width, for instance), but in my experience, camber plates were just WAY too noisy for a street driven car that sees occasional track time. I had Carrera camber plates in mine and took them back out after about 6 months. I couldn't stand them any longer - every little suspension movement seemed like it was being trasmitted directly into my brain. Maybe some of the other brand plates will be better in this regard, but if they lack some sort of NVH isolation, I seriously doubt it. If you plan on using this car primarily at track events it won't matter, but my impression was that you were going to use this car substantially on the street. Quote Link to comment Share on other sites More sharing options...
johnc Posted May 21, 2005 Share Posted May 21, 2005 However, is there some reason that you can't get the rear camber change with the LCAs? Also, the ride height issue can also be addressed by using front isloators in the rear - they are about 1" shorter. The adjustable spring perch and 2.5" id springs can still be made to work with this setup. All of that 1.7 degrees of rear negative camber comes from the LCAs. There is no provision on Ken's car as its configured now for any top camber adjustment. Getting 1.7 degrees of negative camber from a LCA is big. And, I must say, its very easy to adjust toe with Ross' LCAs. I normally plan on spending about 4 hours getting a Z to track properly but the combination of a very straight 280Z chassis and MM LCAs mad it a 1 hour job. Quote Link to comment Share on other sites More sharing options...
johnc Posted May 21, 2005 Share Posted May 21, 2005 Do you have a preferred control arm angle? I do know they should drop down at the wheel end but at what amount I'm not sure. Thanks! There's no set number. Generally its a compromise between a preferred ride height and keeping the LCAs pointing down. IMHO keeping the LCAs pointing down is more important then dropping the car another fraction of an inch. On a 240Z the front LCAs most often determine the car's ride height. You get the front down as much as you can while keeping the front LCAs pointing down and then adjust the rear ride height to put in the amount of rake you want. Sometimes a car ends up like Ken's with a +7" ride height. Many folks would say that a 7" ride height won't handle well and the car should be down at 5". Absolute statements like that are always wrong when it comes to suspension setup. On the ROD I ran a 6.25" ride height in front and probably should have run it at 6.5" but I had a mental block that wouldn't allow me to believe that a 240Z with tires 2" bigger in OD then an ITS spec 240Z would have to increase its ride height almost 2" to get the geometry correct. Quote Link to comment Share on other sites More sharing options...
TimZ Posted May 21, 2005 Share Posted May 21, 2005 All of that 1.7 degrees of rear negative camber comes from the LCAs. There is no provision on Ken's car as its configured now for any top camber adjustment. Getting 1.7 degrees of negative camber from a LCA is big. Agreed. That's a lot of camber to get by moving the bottom of the strut outboard. That brings to mind one other point about the camber plates. The camber plates that use the three stock mounting holes in the strut tower (Carreras, for instance) don't allow negative camber adjustment greater than stock without relocating the three mounting holes inboard. You can adjust the top mounting point farther outboard than stock, but not farther inboard. My feeling was that if I needed to slot the holes to get camber, I could do that without camber plates. Am I missing something here? As I said before, I'm not disagreeing with JohnC's diagnosis - I just really hated having camber plates in the cabin on my street driven car, and I'm trying to come up with a viable alternative. Quote Link to comment Share on other sites More sharing options...
Jeff Posted May 21, 2005 Share Posted May 21, 2005 Hey Ken, I was running Sebring that day as well and was sorry I never caught up with you. I was driving a white 94 Trans Am btw. When I was in the pits I knew every time you were coming from the whine of the supercharger. It looked like you were moving along pretty well. Post up and let us know if you're going to do another track day any time in the future. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted May 22, 2005 Share Posted May 22, 2005 Agreed. That's a lot of camber to get by moving the bottom of the strut outboard. That brings to mind one other point about the camber plates. The camber plates that use the three stock mounting holes in the strut tower (Carreras' date=' for instance) don't allow negative camber adjustment greater than stock without relocating the three mounting holes inboard. You can adjust the top mounting point farther outboard than stock, but not farther inboard. My feeling was that if I needed to slot the holes to get camber, I could do that without camber plates. Am I missing something here? As I said before, I'm not disagreeing with JohnC's diagnosis - I just really hated having camber plates in the cabin on my street driven car, and I'm trying to come up with a viable alternative.[/quote'] You need a narrower spring and perch to get a lot of adjustment out of a Z, because the strut towers are so small. So even if you have a 2.5" spring, the size of the stock hat still limits the movement. The advantage to EMI's camber plates, and GC's, and AZC's and everyone elses' is that they use a small hat and eliminate the rubber which frees up room to move the hat in and gain the negative camber. The only other way I could see to do it would be to use a similar rubber isolated hat but have the hole for the strut offset so that the strut leaned farther in while the bolt holes lined up. The only problem is that the top of the strut probably wouldn't be accessible for strut adjustments if you moved it too far (or you'd need to cut the center hole in the tower to make it longer). These are all similar problems to the ones that the offset camber plates like EMI makes anyway, so maybe others have already figured out solutions to them. The other advantage of the offset plate idea is that it could also be offset to the rear, giving more caster in addition to neg camber. Quote Link to comment Share on other sites More sharing options...
Guest JAMIE T Posted May 22, 2005 Share Posted May 22, 2005 Just chiming in. This is a GREAT thread. Very informative. Quote Link to comment Share on other sites More sharing options...
Tim240z Posted May 22, 2005 Share Posted May 22, 2005 Just chiming in. This is a GREAT thread. Very informative. Post whore!!! Quote Link to comment Share on other sites More sharing options...
johnc Posted May 22, 2005 Share Posted May 22, 2005 I'm with Tim regarding camber plates on a street car. I must be getting older... Two things need to be isolated: the spring and the shock. The spring is easy because you can design the upper and lower spring perches so a .125 to .250" layer of some durometer rubber is incorporated to isolate the spring from the strut. The shock will be more difficult and I haven't thought of a good solution. I also thought about adding a .125" layer of polyurethane between the top of the EMI Racing camber plate and the inside of the strut tower. But further thought and discussion made me change my mind. That layer of flexible material would put the two bolts attaching the camber plate to the strut tower in shear. Quote Link to comment Share on other sites More sharing options...
datsunan Posted May 22, 2005 Share Posted May 22, 2005 This thread makes me realize how little I know about my suspension geometry. What is the best read for tuning Z suspensions? Quote Link to comment Share on other sites More sharing options...
kj280z Posted May 22, 2005 Author Share Posted May 22, 2005 Hey Ken' date=' I was running Sebring that day as well and was sorry I never caught up with you. I was driving a white 94 Trans Am btw. When I was in the pits I knew every time you were coming from the whine of the supercharger. It looked like you were moving along pretty well. Post up and let us know if you're going to do another track day any time in the future.[/quote'] Hey Jeff, I remember your car... I think you were talking to my Dad in the pits while I was in the classroom session... Were you the guy who approached my Dad about me passing ya at 120 on the back stretch? Anyway, I'll be back out to Sebring with Chin Motorsports on 7/30 if I can free up the time with work. As far as the handling of the car vs. ride height discussion.. Man I have to tell ya... with the exception of the rear feeling a little funny "on the edge" around the sweeper (turn 11?) the car seemed spot on... (at least for my driving skills). Jeff you can probably attest to how well we were doing out there with the current setup. That was the first time that I actually felt that I could give some accurate feedback to "a pit crew" (me) about improvements... "I think" in this case, John's recommendations to dial in some more camber in the rear and possibly a little more stiffness would resolve that... It's pretty cool to have some real world feedback now that we've been out to do some testing. To answer some questions about the "in car" noise from the camber plates... This car is slowly becoming my "fun track day" car... The exhaust is so loud that it muffles any suspension noise anyway (grin)... I already have the same camber plates in the front that I'll be adding to the rear, and it's really not too bad as far as noise. The rear LCA's from Ross are really nice, but in my case with the 280z insulators I think 1.8 negative camber in the rear is a realistic number without camber plates. John Mortensen makes a good point about the size of the insulators and how much room you have for slotting the strut towers... He's right, it's tight... My coil overs provided a good amount of room in the front, but I can't comment on how much I'll gain in the rear until I install them (soon). I will say that on the track, the rear was really crisp and predictable with the combo I currently have... which includes a rear strut bar... My springs are 200's in the front and 250's (I think) in the rear... I have no cage or any stuctural improvements, so John said that was about the max on springs... Feel free to correct anything that I may have mis-stated as this is still a big learning exercise for me (and very cool once you get to this stage!) Regards Ken Quote Link to comment Share on other sites More sharing options...
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