pparaska Posted March 13, 2003 Share Posted March 13, 2003 [this is a continuation of a post in the Announcements forum that got off topic. It's about suspension, so I started a new thread here. I'm bad about stealing threads, and trying to reform ] Hi Pete' date=' Good to hear from you, it has been sometime since we talked! The lower control arm is from ArizonaZ and the coilovers are from Ground Control. Everything went together just fine. “This is only a trial fit of all the parts†- no turning back after one cuts the lower spring perches off and you know it's final when you cut the transmission mounts off - not quite there yet. ...My only concern, which I think, is very minor is that there are no bushings used in this area so additional noise and harshness may be felt. I will however be using the original top hat and new inner control arm bushings so some dampening will take place.[/quote'] Yes, I'd be a bit concerned that the bolt OD and ID of the rod ends was snug. If not, even if you tighten the bolt hard, it would still have play laterally. Pete' date=' if I’m not mistaken you modified your OEM top hat to fit the upper coilover spring perch. What exactly did you do? The Ground Control conical piece seems to fit ok and then when I crank up on the spring to snug everything together it seem fine but I was curious on what you did. [/quote'] I used the stock top isolator and the stock top spring "hat". I simply got some muffler tubing that had a 2.5" OD and welded a short length (1.5" or so) to the center of the underside of the spring hat. That just keeps the spring centered on the stock hat. Also' date=' and this might be a tough one to answer, how much will that 2.5†dia. spring compress once the weight of the car is on it? I’m not in the position to install the coilover assembly just yet and I was just curious. These are 200 lbs springs.[/quote'] Well, figure the rear of the car weighs around 1300 lbs with you in it, divide by 2, and the load on the spring is going to be roughly that (actually a bit more due to geometry). So that's ~650lbs. That means that the spring will compress around 650lb/(200lb/in) = ~3.25" with the weight of the car and you on it. I think that's the correct way to figure it. Quote Link to comment Share on other sites More sharing options...
blueovalz Posted March 13, 2003 Share Posted March 13, 2003 Pete, I'd like to step in here on the last point made about the rear springs. My 200lb springs compressed at static ride height, just under 2" (this was with a total car weight of 2160 lbs). The unsprung weight on these cars is not ideal, and I found that I indeed had less than 400lbs resting on the spring itself (in race trim). My 315/35ZR17 tires and matching street wheels weigh about 60lbs per side. I think the struts (complete with rotors, calipers, half the arm weight, half the half-shaft weight, and other stuff will add another 70lbs to that. So that's 130lbs that is unsprung (per wheel). Unfortunately, even in a quasi-street legal weight of 2350 lbs, I still only compress the springs about 2" (this is after the suspension has been "set"). Yes, a stock bodied Z will be heavier with the interior in it, but I only wanted to emphasize that unsprung weight (in the case of the Z and a 200lb spring) will reduce the compression of the spring by about 1" Quote Link to comment Share on other sites More sharing options...
Danno74Z Posted March 13, 2003 Share Posted March 13, 2003 Jeremy, I will just try out the 200lb springs and see how they work. If you say they are too stiff they probably are. GC made the recommendation and I went wit it. Because I'm going to add 200lbs to the front of the Z over the inline 6, would it make sense to use those springs up front? Perhaps use 150 lbs in the rear? Would this work or would it just mess up everything? Pete, Sorry, about asking a suspension question in the announcement forum and thanks for moving it over. Yes the bolt and the rod ends are a very good fit. Not as tight as the spindle pin - thank God (I think Datsun put those pins in liquid nitrogen to contract them) but a 1-2 thousand clearance, perhaps less. I don't feel and lateral movement in this assembly. Good info on the spring! It might be a little too stiff according to Jeremy. What are your thoughts about putting the stiffer springs up front? As usual both you guy's are awesome! Danno74Z Quote Link to comment Share on other sites More sharing options...
pparaska Posted March 13, 2003 Author Share Posted March 13, 2003 Sorry' date=' about asking a suspension question in the announcement forum and thanks for moving it over. [/quote'] No apology neede to me, I steal threads all the time. It happens constantly. No biggie! Yes the bolt and the rod ends are a very good fit. Not as tight as the spindle pin - thank God (I think Datsun put those pins in liquid nitrogen to contract them) but a 1-2 thousand clearance' date=' perhaps less. I don't feel and lateral movement in this assembly. Good info on the spring! It might be a little too stiff according to Jeremy. What are your thoughts about putting the stiffer springs up front?[/quote'] Good to hear about the fit of the bolt and rod ends. Terry is absolutely right - I needed to subtract the UNSPRUNG weight from the 1/2 of the rear weight on the rear tire set. Duh, sorry about that. I'd guess that the compression of 200 springs will be more like 2.2-2.5 inches, based on a supposed 1300 on the rear tires, and 150 of unsprung weight (might be a bit high) and 200lb/in springs. I'd try 175 lb/in in the front, not stiffer than 200s. Quote Link to comment Share on other sites More sharing options...
Danno74Z Posted March 13, 2003 Share Posted March 13, 2003 BlueovalZ, I just saw your reply- cool - a lot of brainpower on board! So, in your opinion a 200 lb/in spring is just too stiff for a road car? Perhaps an occasional autocross run but this will be a streetcar 99% of the time. Danno74Z Quote Link to comment Share on other sites More sharing options...
blueovalz Posted March 13, 2003 Share Posted March 13, 2003 I never thought the 200lb spring was too stiff for the street. Of course, this has a lot to do with correct dampening too. I got lucky in that the dampening provided by my Tokico inserts was perfect. After 10 years on the 200s, I installed 260s in the rear, and I would have to say that to go any higher than this (260) would be too stiff for the street. Just my opinion. Quote Link to comment Share on other sites More sharing options...
stony Posted March 14, 2003 Share Posted March 14, 2003 200lbs too much??? i guess my 400 rear and 500 lb front springs are a tad much ;????? Quote Link to comment Share on other sites More sharing options...
Guest Want aZ Posted March 14, 2003 Share Posted March 14, 2003 Stony, Its probably OK so long as you like frequent trips to the Dentist to replace your fillings....... Quote Link to comment Share on other sites More sharing options...
S30Z Bushido Posted March 14, 2003 Share Posted March 14, 2003 what is the advantage, running stiffer springs in the front or rear Quote Link to comment Share on other sites More sharing options...
Modern Motorsports Ltd Posted March 17, 2003 Share Posted March 17, 2003 "I will just try out the 200lb springs and see how they work. If you say they are too stiff they probably are. GC made the recommendation and I went wit it. Because I'm going to add 200lbs to the front of the Z over the inline 6, would it make sense to use those springs up front? Perhaps use 150 lbs in the rear? " DanL, stiffer rear springs are typically used to combat squat with higher tq setups in addition to handling concerns. 200 is not too stiff for a tight street ride and is my rear starting point for customers with higher tq setups........... Quote Link to comment Share on other sites More sharing options...
Danno74Z Posted March 17, 2003 Share Posted March 17, 2003 Ross, Thank you for the input on the springs. I will give them a try and like I said, see how they feel. If I don't like the ride, I can always change the springs out - that is the beauty of coilovers. Danno74Z PS. I used the tool I bought from Dan to remove the Transverse Link Pin and one side came out just fine. The other side was a different story. I ruined part of the tool trying to get it out! After much frustration and agony, I finally said $%^& it and cut the TLP at two points with my Sawzall. Once I had the strut section separated from the control arm, I used my 15-ton harbor freight press to force that pin out and even with the press it was hard to remove! That sucker was rusted in there and the press kind of jumped as I applied pressure to the pin. Right to the limit! In hindsight, I think if I had heated the center section where the pin was rusted, perhaps it might of come out with Dan's tool. The only drawback to this is then your dealing with burning hot steel while trying to use that tool - I did not want to burn myself. Dealing with rusted parts just sucks! I just got thinking I was applying 30,000 psi to that pin with my press!!! Quote Link to comment Share on other sites More sharing options...
pparaska Posted March 17, 2003 Author Share Posted March 17, 2003 I have 300 lb/in springs in the rear. The Tokico Illuminas (240Z fronts in the rear strut tube) set to 5 damps that spring well. But it beats the hell out of you on the street. Rt 85 through N.C. about killed me. I turned them down to 4 with that spring and the ride is alot better, but it pogo's. I know that will wear the cartridge out, but I'm mostly just cruising around. I plan on putting 250 lb/in springs in the rear. That's supposedly the most spring you should run with the Illuminas. Anyway, with 300 lb/in in the rear, and the Tokico Illuminas set of 4, the ride is stiff, but not HORRIBLE. I have 225 lb/in in the front and the Illumina's set on 3. Just another data point/ ride opinion. The strut carts need to be selected / adjusted to the springs and the car. The 300s require a 5 setting (max) and it's too rough for street driving. Plus the 300s will wear out the Tokico Illuminas. So I'd think 200s would be fine for the street. Oh, another reason people say to use more spring in the rear is because you want a different (usually higher) natural frequency in the rear suspension than the front, to keep the for/aft pitching away as you hit tar strips, etc. Since the front/rear bias of the Z is so close to 50/50, the same springs front and rear COULD make the natural frequencies the same. Quote Link to comment Share on other sites More sharing options...
Danno74Z Posted March 17, 2003 Share Posted March 17, 2003 Pete, Thanks again for the advice. I don't have the front springs yet, but I probably will go with 175's. Very interesting about the front rear frequencies as I did not consider or even think about that possibility. Danno74Z Quote Link to comment Share on other sites More sharing options...
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