Tank Posted February 2, 2010 Share Posted February 2, 2010 So I am nearing the completion of a full suspension and brake over haul/modification. Thought others tackling this might find this useful. Here are the specs. Suspension: Ground Control coilovers Eibach springs (250lb f & R) Tokico Illumina BZ3015 F BZ3016 R Techno Toy Tuning camber plates Techno Toy Tuning upper hats Arizona Z Car steering knuckles Urethane bushings everywhere MSA sway bars New tie rods New ball joints Brakes: (wince) MSA rear disk conversion stage 3 In my defense I bought it many many years ago before my "do it myself, do it cheap" ways, don't hate. 1980 Toyota pickup 4 piston calipers for the front 1980 280ZX master cylinder Proportioning valve Tech: Welding in the camber plates wasn't that easy. The front metal was so thin I was burning it and chasing it. It looked ugly as hell so I smoothed it out with some JB Weld, great stuff. Also in the front I cut the lip that the fender mounts to so I could get a good bead along that side, then added a small gusset (see image 142). The rear was very simple in comparison with the front (see image 184). The steering knuckles interfere with the dust plates, so I notched a square in them so the knuckles would clear. I also trimmed them so the larger calipers would fit. I tried to take a picture of this so if you look hard enough, you can see it. (image 179) The wheels are Rota RBR 17x8.5 +4 and the tires are Dunlap Direzza Z1 Star Spec 245/40/17. They fit but I had to notch the lip of the frame just a little bit because it was to close for comfort at full lock. (see image 189) I sectioned the rear strut housing 1 1/4". Using the Tokico BZ3016, I cut 1 1/4" off of the bottom spacer. It's a good fit (see image 169) . I will probably end up taking out the front and sectioning them as well with the MR2 struts. I'll let you know how it works out as it sits now. I tackled the spindle pins so I am officially a Z nut. Getting those out is story of its own so I will spare you. I will be going with the 5/8" bolts instead of the pins now. Worth mentioning, I replaced the bushings on the steering rack. Easy to get out but hard to get back in. I ended up loosening the engine mounts and jacking the engine about 1/2" to get enough clearance to re-install. As far as the bushings in the control arms, I don't have the equipment or the patience, so I paid to have them taken out and pressed in. Worth it! At this point, the rear is ready to be reinstalled but I am holding off so I can run a new brake line to the rear with the line going somewhere within an arms length of the driver's seat for the proportioning valve. Questions? Comments? Concerns? Quote Link to comment Share on other sites More sharing options...
Kurai Posted February 2, 2010 Share Posted February 2, 2010 Very nice write up.....lots of useful info in there...lol esp for a noob like me thx. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted February 2, 2010 Share Posted February 2, 2010 The strut towers have about a 1/8" thick plate across the top and down about an inch on the sides. You NEED to get into that metal. They also have a sheet metal piece that covers over the thick stuff, but you really don't want your camber plates welded just to the sheet metal. They NEED to be welded to the thicker part. Can't trust that part to be welded to 20 ga sheet metal. Other than that I'd be a bit concerned about cutting on an aluminum steer knuckle. If you just reshaped the outside a bit that's not such a big deal but if you cut into the meat of it, I think I'd buy more and take the backing plates off. I looked at your picture, but I can't see what you did. Quote Link to comment Share on other sites More sharing options...
ModernS30 Posted February 2, 2010 Share Posted February 2, 2010 The strut towers have about a 1/8" thick plate across the top and down about an inch on the sides. You NEED to get into that metal. They also have a sheet metal piece that covers over the thick stuff, but you really don't want your camber plates welded just to the sheet metal. They NEED to be welded to the thicker part. Can't trust that part to be welded to 20 ga sheet metal. Other than that I'd be a bit concerned about cutting on an aluminum steer knuckle. If you just reshaped the outside a bit that's not such a big deal but if you cut into the meat of it, I think I'd buy more and take the backing plates off. I looked at your picture, but I can't see what you did. I believe he meant he cut into the backing plates to trim them. I don't advise taking them off because while driving if you hit a puddle (maybe you don't drive in the wet) but the water can splash on your rotor and then you get that wet brake catch every time you hit the brakes after hitting a puddle or a little bit of water. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted February 2, 2010 Share Posted February 2, 2010 I believe he meant he cut into the backing plates to trim them. I don't advise taking them off because while driving if you hit a puddle (maybe you don't drive in the wet) but the water can splash on your rotor and then you get that wet brake catch every time you hit the brakes after hitting a puddle or a little bit of water. Cutting the backing plate would be the thing to do. I drove my Z daily for years with no backing plates front or rear. Never had problems in the rain. YMMV. Quote Link to comment Share on other sites More sharing options...
ModernS30 Posted February 2, 2010 Share Posted February 2, 2010 Cutting the backing plate would be the thing to do. I drove my Z daily for years with no backing plates front or rear. Never had problems in the rain. YMMV. I guess its ok then, I just don't think its a very good idea. I hate wet brakes. Quote Link to comment Share on other sites More sharing options...
Tank Posted February 2, 2010 Author Share Posted February 2, 2010 The strut towers have about a 1/8" thick plate across the top and down about an inch on the sides. You NEED to get into that metal. They also have a sheet metal piece that covers over the thick stuff, but you really don't want your camber plates welded just to the sheet metal. They NEED to be welded to the thicker part. Can't trust that part to be welded to 20 ga sheet metal. Other than that I'd be a bit concerned about cutting on an aluminum steer knuckle. If you just reshaped the outside a bit that's not such a big deal but if you cut into the meat of it, I think I'd buy more and take the backing plates off. I looked at your picture, but I can't see what you did. I did get down to the thicker metal on the front, it scared me at first until I got to it. The rear had no problem whatsoever. As far as the knuckles, I cut the dust plate, I will take the hub off so I can get a better picture of it. I was stuck on keeping the dust plates but without the notch, they rubbed the rotors. Quote Link to comment Share on other sites More sharing options...
leftover z Posted February 5, 2010 Share Posted February 5, 2010 Thanks guys. Some good info that I can use, and lots of other members. Quote Link to comment Share on other sites More sharing options...
rat_ranger Posted February 5, 2010 Share Posted February 5, 2010 Weird, what brake pads are you guys running to have issues when it is wet out? I have run everything from factory to custom big brake set up on my ranger with stock, wanna be performance and hawk HPS pads and never had issues with no backing plates front or rear. Quote Link to comment Share on other sites More sharing options...
sileightygx Posted February 5, 2010 Share Posted February 5, 2010 nice writeup so far! keep up the good work. i'll be doing much of the same when i get my tax return haha. Quote Link to comment Share on other sites More sharing options...
johnc Posted February 5, 2010 Share Posted February 5, 2010 I will probably end up taking out the front and sectioning them as well with the MR2 struts. On a S30 its more important to section the front struts then the rear. The roll center problem is a much bigger issue up front. Also, with the front and rear wheel ratios so close its important to vary the spring rate by at least 25 lbs. front and rear. Same rates front and rear can induce porpoising in some situations due to equal suspension frequencies. Quote Link to comment Share on other sites More sharing options...
sileightygx Posted February 5, 2010 Share Posted February 5, 2010 another awesome informative post by john, i think 60% of what i learn on this forum has come from him...hrmmm haha Quote Link to comment Share on other sites More sharing options...
Tank Posted February 22, 2010 Author Share Posted February 22, 2010 On a S30 its more important to section the front struts then the rear. The roll center problem is a much bigger issue up front. Also, with the front and rear wheel ratios so close its important to vary the spring rate by at least 25 lbs. front and rear. Same rates front and rear can induce porpoising in some situations due to equal suspension frequencies. I'll admit I don't know what porpoising is but it sounds like I need to avoid it, so would you recommend 225 or maybe 250 in the front? Also, do you know the part number of adjustable struts for the front? Koni or Tokico, I would prefer to have tokico because they are 1/16th smaller than the koni and fit easily into the strut housing. Thanks for the input, I appreciate it! Quote Link to comment Share on other sites More sharing options...
Tank Posted February 22, 2010 Author Share Posted February 22, 2010 On another note, the stock proportioning valve in my 240 is on the firewall. The right front line goes through the top of it and the rear line through the bottom. My question is, can I loop the front line together and take out the factory PV to run the rear line into the car for the new PV? Would that effect the right front? I don't see how it would since the factory valve is only supposed limit the pressure the rear, not the front. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted February 22, 2010 Share Posted February 22, 2010 I'll admit I don't know what porpoising is but it sounds like I need to avoid it, so would you recommend 225 or maybe 250 in the front? Also, do you know the part number of adjustable struts for the front? Koni or Tokico, I would prefer to have tokico because they are 1/16th smaller than the koni and fit easily into the strut housing. Thanks for the input, I appreciate it! Porpoising is meant to evoke the image of a dolphin jumping out of the water repeatedly. Bucking bronco would be another way to describe it. The car gets into a harmonic where the front and rear start alternately undulating. There is a sticky thread where Dan 74_5.0L_Z did some pretty precise measurements and figured a bunch of the math out on these suspensions, you can read up on that more if you care to, it's pretty technical and not particularly useful for someone who just wants to build a hot street car. In any event, the motion ratio for the front suspension is .904 and for the rear is .882. This means if you ran 250/250 springs, you get a wheel rate of 204/194. If you drop it down to 225, you get 184/194. In either situation you're 10 lbs off from equal. 200/250 gets 163/194. My point is that if you really want to get a separation there, with lower spring rates you need a bit more separation than 25 lbs. That said, people have been talking about 225/250 as the go to spring rate since the mid/late 90s, and I haven't personally heard anyone complain about porpoising, but John's been the guy who they would come back to with a complaint, and I haven't. Quote Link to comment Share on other sites More sharing options...
johnc Posted February 22, 2010 Share Posted February 22, 2010 Jon's description above is spot on. It takes a pretty rare set of circumstances to get porposing (sympatheic pitch?) out of a Z and I've only encountered it once - at the Holtwille racetrack with a square (300/300) spring setup when we were testing the Penskes I put on my car. Sometimes I post obscure little factoids as if they are important and I should probably stop that. I'm sure you'll be fine with 250s all around. The shortened front Illumna shocks are typically the MR2 rears (BZ3099). Quote Link to comment Share on other sites More sharing options...
Tank Posted February 23, 2010 Author Share Posted February 23, 2010 Porpoising is meant to evoke the image of a dolphin jumping out of the water repeatedly. Bucking bronco would be another way to describe it. The car gets into a harmonic where the front and rear start alternately undulating. There is a sticky thread where Dan 74_5.0L_Z did some pretty precise measurements and figured a bunch of the math out on these suspensions, you can read up on that more if you care to, it's pretty technical and not particularly useful for someone who just wants to build a hot street car. In any event, the motion ratio for the front suspension is .904 and for the rear is .882. This means if you ran 250/250 springs, you get a wheel rate of 204/194. If you drop it down to 225, you get 184/194. In either situation you're 10 lbs off from equal. 200/250 gets 163/194. My point is that if you really want to get a separation there, with lower spring rates you need a bit more separation than 25 lbs. That said, people have been talking about 225/250 as the go to spring rate since the mid/late 90s, and I haven't personally heard anyone complain about porpoising, but John's been the guy who they would come back to with a complaint, and I haven't. I read the thread you speak of and didn't fully understand how I could use the information to better my setup. It's just a simple weekend autox/track day setup. Nevertheless I want it to be right. I have seen "porpoising" before and didn't know the cause. Thank you for the information. And johnc, thanks for bringing it up. Thoughts on the proportioning valve? Quote Link to comment Share on other sites More sharing options...
reintr0ducing Posted February 24, 2010 Share Posted February 24, 2010 quick question for you. i've just installed nearly the same suspension set up in my 240z. i've got techno toy tuning camber plates and top hats, ground control coilovers, shortened struts with tokico illumina mr2 shocks in the front and 240z shocks in the rear. i'm not too sure what brand my bumpsteer spacers are (previous owner installed them). i've got everything welded up and sitting tight, but everytime i hit a bump or a patch of bad road (lots of them where i live), i get all kinds of rattles. is your set up like this? is there anything i can do to combat this? Quote Link to comment Share on other sites More sharing options...
Tank Posted February 25, 2010 Author Share Posted February 25, 2010 quick question for you. i've just installed nearly the same suspension set up in my 240z. i've got techno toy tuning camber plates and top hats, ground control coilovers, shortened struts with tokico illumina mr2 shocks in the front and 240z shocks in the rear. i'm not too sure what brand my bumpsteer spacers are (previous owner installed them). i've got everything welded up and sitting tight, but everytime i hit a bump or a patch of bad road (lots of them where i live), i get all kinds of rattles. is your set up like this? is there anything i can do to combat this? I haven't driven mine yet, I am still ironing out the braking system. I expect it to make lots of noise and rattle. Keep in mind that where there once was rubber to insulate road "noise" at the upper mounts is now metal on metal. So all the vibrations are transmitted to the chassis. I don't know of a way to dampen this. Could also be the threaded sleeve vibrating on the strut housing, I have rubber o rings at the bottom and top of my threaded sleeves to try and alleviate vibration. I'll know more about mine when I test drive it, which should within a few weeks. Hopefully that helps a little. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted February 25, 2010 Share Posted February 25, 2010 (edited) Thoughts on the proportioning valve? The early 240Zs have the prop valve inside the right rear fenderwell screwed to a bracket near a frame rail. I don't know how the later ones work, but a bunch of people have put adjustable prop valves on those cars, so the answer is here, you'll have to keep looking for it though... EDIT--You guys really shouldn't be getting rattles. If you have a rattle something is wrong. Most likely culprit would be a gland nut that holds a strut insert in is loose, or it bottomed on the housing before it tightened down on the strut. When they're TIGHT there should still be a thread or two showing. After that you can start checking the bearings, but they're brand new bearings from the sound of it, so I'd be checking those gland nuts first... Edited February 25, 2010 by JMortensen Quote Link to comment Share on other sites More sharing options...
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