QWKDTSN Posted December 27, 2000 Share Posted December 27, 2000 I recieved my Ground Control kit for Christmas. It came with #175 rear springs and #150 fronts, I assume this should be good for a streetable autocross setup? I know many of you have much stiffer springs. It's going to be a while before I get the coilovers on the car, since I have a complete urethane bushing kit to install, so I'll have time to save up for shocks. My question is.. what kind, and where to get them from? I'd like adjustable ones, like Tokicos or KYB, that are made for use with the coilovers so I won't have to go through the rigors of grinding or welding with the stock shocks. Anything like this available? If not, what did you guys choose? I'd like to keep the price down as much as possible. Quote Link to comment Share on other sites More sharing options...
randy 77zt Posted December 27, 2000 Share Posted December 27, 2000 you are going to have to grind off old spring seats and weld retainer rings on strut housings.the ground control in structions are good on the measurments because i have them on my car.if you use a good 7" electric grinder it gets the spring seats off and a muffler shop can weld the rings on with a mig.the best strut cartridges for this app are 5 way tokico.call r&d enterprises alias shoks.com.they are in san diego so you should save some freight.the reason you need the 5 way shocks iis that the stiff springs rebound quick and if rebound is not controlled car will bounce .i run 225 lbs in front and 250 in rear but car is used for road courses in driver schools. Quote Link to comment Share on other sites More sharing options...
BLKMGK Posted December 27, 2000 Share Posted December 27, 2000 Ummmm http://24.4.88.29/ubb/Forum6/HTML/000307.html We just went over most of this in gory detail the last couple of days. I'm in the EXACT same position as you with the exception of using GC parts. I've decided to skip the adjustable stuff, I don't think it's needed that badly based on feedback I've gotten from those who've used it. If you've got the cash by all means go for it but expect to be into it about $450 a set. You WILL be grinding on the stut housing, NOT the strut itself - it's a cartridge. In my case I'm going to use a sawzall to cut the existing perches off and then grind the rest off. I don't think it'll be too hard to do. I've no welder so I'll be getting help from friend's there - not 100% sure on where the lower perch goes but I only have to get in the ballpark - this stuff is adjustable My spring rates are 200# and 225#. While you've got it all apart - consider doing brakes.... Quote Link to comment Share on other sites More sharing options...
johnc Posted December 27, 2000 Share Posted December 27, 2000 Anyone installing a coil-over suspension setup should seriously consider shortening the struts. Wayne Burnstien posted the most lucid description of the process and why it should be done. I'm reposting it below: ***** Lowering an early Z Let's start by defining the task at hand. We want to lower the car in order to lower the center of gravity. I'll skip all the analysis on why we want to do this because there are lots of good books on the subject, and confine my comments to what you might run into in performing this on a Z. First I need to define a couple of terms: Bump -- suspension travel in the compression direction (i.e. the result of hitting a high spot in the road). Rebound -- suspension travel in the opposite direction (i.e. the result of going over a hill and the wheels leaving the ground). The first problem we run into is that when we shorten the springs, we are reducing the available bump travel in the strut cartridges by the same amount we lowered the car. With all the travel available in a stock Z, this is not too much of an issue when we lower the car only an inch or so. For those of us who are racing our cars, we often lower them much more; for instance, in the SCCA's IT class, we are allowed to lower the car until the rockers are no lower than 5" above the ground. This causes a problem because the suspension is almost fully compressed when the car is sitting at rest. When you hit a bump, the suspension quickly bottoms out (hopefully on a bump stop of resilient material). This is a real problem because in effect, the spring rate increases very dramatically and negates all of our efforts to drive the car smoothly. When driving at or near the limit, this often is the beginning of a very impressive crash. Well, we now have the car at the desired ride height, but need to increase the travel in bump. The way to do that is to shorten the struts. Now things get pretty messy. Don was correct in stating that this is dependent on the length of the struts; however, this is only partly true. The struts need to be long enough to insert the cartridges of choice. For racing, the ones that I would recommend are Carerra, Koni, or Tokico, in that order ( this should cause a bit of discussion on its own). If we automatically shorten the strut to exactly fit the cartridge, we might actually shorten it too much. This leaves us without adequate rebound travel. Just in case this does not scare you, it should. I learned my lesson the hard way when I had the rear wheels pick off the ground while cresting a hill that had a slight turn to it. That made for a looooong full lock slide at 100 MPH! Ok, now we need to decide just how much we want to shorten the strut housing. The desired end result is to have about equal bump and rebound travel. In other words, when the car is sitting at rest, we want the struts half way compressed. On a street car, this is fairly easy to do, because we generally set the car up once and never play with it. Race cars are another situation entirely. First of all, different tires require different ride heights -- for instance, switching from 60 series to 50 series tires lowered my car by .75", causing me to have to raise the car by the same amount. We also play with spring rates, and assuming that we are using coil overs, need to keep the spring collar low enough on the strut housing to avoid it interfering with suspension travel. The bottom line is that before cutting anything off your struts, you should carefully think about what you anticipate doing to the car over the next few years as far as tire/wheel, strut, spring or ride height changes, and then come up with a compromise that works for you. FWIW, most people shorten struts 1-2". If you figure out that you want to go more than this, recheck everything before cutting. Yes, you can add a section, but speaking from experience, it is much easier to remove than to add. I almost forgot to mention this, but if your strut housing is longer than the cartridge, you need to put a spacer below the cartridge inside the housing -- typically, these are just pieces of tubing that is slightly smaller in diameter than the inside dimension of the housing. Just a couple of tips to consider: 1) The best way I have figured out to cut the struts is to use a large pipe cutter. This gives a fairly straight cut with minimal cleanup -- you need to grind the burr off the inside of the housing and bevel the outside edge before welding them together. Be careful not to make the cut so high on the strut that you hit the threads for the gland nut! 2) To remove the original spring perch, the quickest way I have found is to cut through it just above the housing with a grinder or cut-off tool, and then grind the remaining metal off. I found it much easier to do this before cutting the strut because even though I was not cutting the section with the perch off, it did interfere with the cutter. 3) After lowering the car, you need to align the suspension because you have added negative camber at both the front and rear wheels. Of course, you should probably do this any time you remove suspension components anyway. Sorry to be so long winded, but this is a fairly complicated task to plan and implement without too much trial and error. Wayne Burstein ***** As you can see, adding a coil-over suspension and getting the most out of it is not an easy task. Put a lot of though into it before you get out the cutters and welders. ------------------ John Coffey johnc@betamotorsports.com Quote Link to comment Share on other sites More sharing options...
pparaska Posted December 27, 2000 Share Posted December 27, 2000 John, I had no idea that "John C" was the famous John Coffey! Welcome! I followed Wayne's advice when doing my strut shortening, and took out 1.5" I needed to space up the VW Rabbit strut cartridges in the front shortened tubes, and the 240Z front cartridges in the rear shortened tubes. One thing that doesn't get mentioned is that the design of the strut top mount has ALOT to due with ride height. In fact, using some of the camber plates and short top spring perches can lower the car over an inch without having to use shorter springs, or shortening the strut tubes. ------------------ Pete Paraska - 73 540Z - Marathon Z Project pparaska@home.com Pete's V8 Datsun 240Z Pages Quote Link to comment Share on other sites More sharing options...
jeromio Posted December 27, 2000 Share Posted December 27, 2000 I have 150lbs in front and have ordered 175lbs for the rear. I went with 175 for the rear only because that seemed like the thing to do - most people have stiffer springs in the rear vs front. The 150 in the front is plenty stiff. I'm actually slightly worried about 175 being too hard in the rear. But, the beauty of coil overs is that the springs are fairly cheap and easy to swap. Quote Link to comment Share on other sites More sharing options...
BLKMGK Posted December 28, 2000 Share Posted December 28, 2000 Aww man, now I'm wondering if I should be considering this (sigh). Pulled my second KYB today - dead as a doornail! I'm wondering if it got bottomed out or not... Trouble is - I'm not sure how much lower than stock my car iswas! I never saw it "stock" and I forgot to measure it before I pulled it apart. I'm sure I can get a measurement by lowering the back end with the jack. From the rocker - what's stock ride height? If you look at my pics the ride height doesn't look too low, does it? Wheels fill the wells just fine but are kinda short IMO. [This message has been edited by BLKMGK (edited December 27, 2000).] Quote Link to comment Share on other sites More sharing options...
jeromio Posted December 28, 2000 Share Posted December 28, 2000 I'm no expert, but that looks pretty low to me. What size wheels are those? If they're 14" then I'd guess your car is around 3 inches lower than stock. My car has 14" wheels and is (I think) only 1 inch lower than stock in front (Ground Controls with thread tube 4 1/2 inches from strut bottom and collar set right in the middle): Yours looks good though. Really like those Panasports. [This message has been edited by jeromio (edited December 27, 2000).] Quote Link to comment Share on other sites More sharing options...
johnc Posted December 28, 2000 Share Posted December 28, 2000 Hi Pete, Be careful, most people consider me infamous and generally deny any knowledge of my existence. FYI... I'm "johnc" on this board and I've noticed HybridZ also has a "John C" from the Great White North. Hopefully that doesn't lead to a besmirching of his reputation. ------------------ John Coffey johnc@betamotorsports.com Quote Link to comment Share on other sites More sharing options...
pparaska Posted December 28, 2000 Share Posted December 28, 2000 Oops. Reading too fast. Yep, I got "John C" mixed up with "johnc" Sorry about that. Quote Link to comment Share on other sites More sharing options...
BLKMGK Posted December 28, 2000 Share Posted December 28, 2000 Some stray thoughts that kept me from sleeping last night... 1) I just ordered 4 "stock height" strut carts. 2) Z's supposedly have only 2-3inches of suspension travel according to JTR. 3) Lower the car an inch and you lose 1/3rd travel. Lowering springs or sectioning the struts - same thing. Removing "spacers" between the strut and the mount - same thing, loss of strut travel. Using cambercaster plates that raise the mount of the strut higher into the body of the car would be "safe" - they make these for Mustangs but I don't know about Zs. Shortening the Mustache bar bushings would also possibly not be safe - not sure this effects ride height. 4) To compensate for loss of strut "at rest" height you can use shorter strut carts - see #1 above. Grr! I never realized my car was this low. My 2nd rear cart was totally dead too. 5) You can use stock front carts in back to help solve #4. VW Rabbit carts go in front? Front carts for the Z were the more expensive of the sets so I've not thrown away too much if I have to go VW and section. 6) 2 reasons to lower the car - A)looks as in filling the wheel wells and B)handling as in lower CG and roll center. However too low and you get funky suspension angles and scrape everywhere! I didn't scrape that I could feel but there were some scrapes under the car and one rear arm took a nasty hit before I bought the car - it's being replaced just in case. I'm running 15inch wheels now I believe with some whacky tire size, I'll post tire height and tirewheel size tonight. Running a shorter sidewall should be a "safe" way to lower the car without screwing up the struts. This would give you a "quicker" rear gear too without adding stress to the rear end. As you go lower in gears torque multiplication goes up and so could parts breakage? So, since I'm going to 17's anyway - why not run a taller wheeltire combo? Overall ride height might go up but filling the wheel wells would be accomplished. Since I expect my oil pan to be down a bit raising overall height wouldn't be too bad I don't think. I've got 225/45/ZR17s on 17inch Konig Tantrums on the Z that I'm going to test fit as soon as I can. Overall height should be taller than what I've got now - which looks damned short to me. I've also got 245/50's on 17 inch Mustang wheels I'll try out - these are even taller I THINK. If 225/45's are too tall then I might drop to 16's since too short a sidewall invites wheel damage if you hit a damned pothole. Am I tracking right guys? Which VW struts work? Valving okay? Spacers needed under the cart? If I go taller wheeltire do I still need to section? Obviously given a choice I'd prefer NOT to since I've got parts on the way and it's a PITA to do and I'd have to have someone else do it. Jeronimo - can you measure your tire height please? I'd like to know how tall your's are to help compare. My tire was just under the edge but it never rubbed that I could feel. I also never felt the struts bottom that I could feel but it had NO bumpers so who knows. Top of strut itself showed no wear and the bottoms of the carts looked fine. Obviously my car looks lower than yours but I can't help but wonder if it's the tire package that's doing it as it's pretty short. Heh, good thing I'll be running an electronic speedo to compensate for all this whackiness! P.S. I'm going 5lug so the Panasports will be going. I like them and they're in good shape but I'd like 16s at least and 17s most likely. Panasport doesn't appear to make 17s or even 5lugs in that style dammit. TSW makes a nice wheel I admire, Konigs look good and so do some of the Mustang wheels. We'll see... [This message has been edited by BLKMGK (edited December 28, 2000).] Quote Link to comment Share on other sites More sharing options...
pparaska Posted December 28, 2000 Share Posted December 28, 2000 quote: Originally posted by BLKMGK: ... 2) Z's supposedly have only 2-3inches of suspension travel according to JTR. 3) Lower the car an inch and you lose 1/3rd travel. Lowering springs or sectioning the struts - same thing. Yes, they both lower the car, but lowering springs takes away bump travel, and strut sectioning (if done the correct amount) does not. quote Removing "spacers" between the strut and the mount - same thing, loss of strut travel. Not sure what you mean. If you are referring to removing some of the stock distance of the isolator/upper-spring-perch from what's above the top of the spring, then you are lowering the car WITHOUT losing any bump travel. quote: Using cambercaster plates that raise the mount of the strut higher into the body of the car would be "safe" - they make these for Mustangs but I don't know about Zs. Yep. Safe, as in it lowers the car without taking away bump travel. quote Shortening the Mustache bar bushings would also possibly not be safe - not sure this effects ride height. That will have NO effect on ride height, but will improve the driveshaft u-joint angle problem with many V8 engine swaps, and lessen the halfshaft u-joint angle when the rear of the car is squatting on take-off by raising the back of the diff relative to the wheel hub - especially useful if the car is lowered. quote: 4) To compensate for loss of strut "at rest" height you can use shorter strut carts - see #1 above. Grr! I never realized my car was this low. My 2nd rear cart was totally dead too. 5) You can use stock front carts in back to help solve #4. VW Rabbit carts go in front? Yes. Depending on how much you section the strut tubes, you will probably need spacers under the front 240Z cartridges in the rear shortened tubes and under the VW rabbit cartridges in the front shortened tubes. quote: Am I tracking right guys? Which VW struts work? Valving okay? Good question. I've heard the GTI struts have better valving. Another option is MR2 struts. Supposedly the guys at Dando's and Ground Control know this stuff well, so I'd call them. You might be able to get Tokico's for the GTI, that'd be good. Also, cartridges are just cartridges. Sure the lengths are different, and the method of holding them in the tube and at the top mount are different, but you can mix and match things if you know the lengths, so I've been told by Carrera guys. The issue is what are the differences in valving for the GTI strut and 240Z front strut from the same manufacturer. I think I've just talked myself into Illuminas. Of course double adjustable would be even better. quoteSpacers needed under the cart? Maybe, depends on what cartridges and how much you section. quoteIf I go taller wheeltire do I still need to section? Going taller will raise the hub height, so it will raise the car (obviously). Then to lower the car back to where it was (if that's what you want) then you need to either section the strut or shorten the space above the upper spring end to lower the car and keep bump travel. Hope I got all that right and helped some. ------------------ Pete Paraska - 73 540Z - Marathon Z Project pparaska@home.com Pete's V8 Datsun 240Z Pages Quote Link to comment Share on other sites More sharing options...
Mikelly Posted December 28, 2000 Share Posted December 28, 2000 Yes, covers it well, except I'm still not sold on sectioning the strut tube if you go with 17s. Also not sure that sectioning is needed if one were to use the camber plates or remove some of the matterials and spacers from the underside of the strut isolator for a street driven Z... also, the bearing under the struts upfront... is there a suitable thinner bearing out there that could replace that unit... it is about an inch thick isn't it? Jim, I don't recommend going to tall on that sidewall... especially in a 17. You have to wonder how much you will be driving the car, and I think that running a 17 with a 35 series tire on it will get you about a 25 inch tall tire.. I know the RE730 in a 275-40-17 is about 25 inches tall... Helping my gearing a bit since the 265-50-15 sold by GY was 26 3/4 inches tall.. Remember that you will need that extra gear with the T56... Mike ------------------ http://hometown.aol.com/dat74z/myhomepage/auto.html "I will not be a spectator in the sport of life!" mjk Quote Link to comment Share on other sites More sharing options...
Mikelly Posted December 28, 2000 Share Posted December 28, 2000 Also, Many of the racecar fab shops I have catalogs for offer a shock mount tab. Why not leave the strut tube alone, drill out the diamter of the isolator so the strut piston rises through and to the shock mount tab you weld in to the shock tower? That seems to me to be much easier than dealing with mixing and matching non-factory parts...also might help in selling the car down the road. I'm just thinking out loud here guys.. I'm not totally opposed to sectioning the strut housing, just not sold on it as the only way either! Mike ------------------ http://hometown.aol.com/dat74z/myhomepage/auto.html "I will not be a spectator in the sport of life!" mjk Quote Link to comment Share on other sites More sharing options...
pparaska Posted December 28, 2000 Share Posted December 28, 2000 Mike, not really sure what 17s have to do with sectioning. In fact, with a wide tires (255 and larger) and 17s on the street, and 45s, you end up with a taller tire, and it raises the car. Of course, you could go to 35s or 40s and get the car lower, but once you are at 265s, even a 40 is pretty tall compared to the stock ~24.8" tire diameter (265/40-17 = 25.4"). Granted the 275/35-17 is 24.6". But 35s on the street sounds pretty harsh to me. So the way I see it, going to 17s on the street (assuming you want to stay at or above 40 aspect ratio, and use 255s and larger) means you actually have to offset the effect of larger-than-stock tire diameter with either sectioned struts or less isolator/spring perch (top) height. Of course, 1/2" less bump travel with shorter springs or a lowered bottom perch on coilovers doesn't really call for sectioning, but if you are going to lower the car, it aggravates the situation of bump travel even more. As far as a shock tab on the tower, I'd be concerned that alot of impact loads/noise would be transferred to the strut tower. Not that anyone cares, but the purists hate 17s on the old Z's - all the more reason to do it, I say . Seriously, I don't care what they think, by finding decent performance tires these days means 16s at least, and even more selection in 17s. OE be damned! ------------------ Pete Paraska - 73 540Z - Marathon Z Project pparaska@home.com Pete's V8 Datsun 240Z Pages [This message has been edited by pparaska (edited December 28, 2000).] Quote Link to comment Share on other sites More sharing options...
Danno74Z Posted December 28, 2000 Share Posted December 28, 2000 "I'm sure I can get a measurement by lowering the back end with the jack. From the rocker - what's stock ride height?" I'm not sure this will help you, but I measured my early 260Z which is bone stock except for the wheels and tires (195-70-14) and the height(front)from the concrete floor to the top of the bumper next to the bumper mounting locations is 19.45" and in the rear, measured in the same manner is 20.85". Now, depending on your original tire size (aspect ratio) naturally this will raise or lower your car. One measurement I did not make is from the floor to the highest point on the roof line and according to the Haynes book it should be 50.6" for the 260Z and 50.5" for the 240Z. This is a hard measurement to get by yourself and truthfully I forgot to do it. As a side note, the original 260Z came with 175HR-14 5j-pressed steel rims. I assume this is a 70 series aspect ratio. So based on my calculations and by using the bigger tire (195), I raised the vehicle about 1/2" from stock condition. I don't think too may Z's still have 175 on them. The original tires have a diameter of 23.65" my tires are 24.75". I'm going in the wrong direction! Danno74Z Quote Link to comment Share on other sites More sharing options...
pparaska Posted December 28, 2000 Share Posted December 28, 2000 Danno - wrong direction - not necessarily! Largerdiameter tires help with straight line traction. You get more tire grabbing the pavement. Quote Link to comment Share on other sites More sharing options...
Danno74Z Posted December 28, 2000 Share Posted December 28, 2000 Pete, I'm just kidding and you are 100% correct on the added traction gain. All of the above posts are great! This stuff is really interesting. I have to admit, I did purchase a spare set of strut tubes for all four corners just incase I really mess things up. Danno74Z Quote Link to comment Share on other sites More sharing options...
johnc Posted December 28, 2000 Share Posted December 28, 2000 I didn't mean to stir up a bunch of confusion with my post about sectioning struts. In general, that's really something only racers do in conjunction with camber plates, offset bushings or monoballs, high spring rates, and other serious suspension changes. Its really not something you would do on a steeet driven Z because your ride height at the rocker panels will be between 5 and 6". In Nion's original post he states he's using 150/175 lb in. springs. Those are too soft for that low of a ride height and the car will be bottoming out constantly. Switching to a racing camber plate will lower the car 1 to 2" without affecting suspension travel, but it will increase the suspension noise inside the car. Also, most of the racing camber plates I've seen require a 2.5" coil-over spring kit. Racers generally want a car as low as possible given the rules and track conditions, but they also want suspension travel because compliance = traction. That's why struts are sectioned on 240Zs. FYI... good camber plates use Torington bearings in the front to allow the strut to pivot. IMHO... I know a number of people install coil-over kits to lower their car, but that's like using a sledge hammer to drive a nail. ------------------ John Coffey johnc@betamotorsports.com Quote Link to comment Share on other sites More sharing options...
pparaska Posted December 28, 2000 Share Posted December 28, 2000 John, I think this has been another of those good, long, detailed threads that we have here at HybridZ. Hopefully any confusion has been cleared up! You wrote: quoteIMHO... I know a number of people install coil-over kits to lower their car, but that's like using a sledge hammer to drive a nail. (All below in my opinion, obviously) Not sure I totally agree. The stock Z can benefit from an inch or two of lowering in handling, not to mention looks. And taking even an inch or so out the ride height using lowering springs will cause you to need some pretty large rates and/or hitting the bumpstops. I know, I've done it with MSA lowering springs - the ride was horrible (IMO), mostly because I was hitting bump stops too often. Yes, I even cut the stock springs and had the same bad experience - taking the bump travel away is what made the car such a poor riding skate. ...And coilovers really aren't that much trouble to install, even if you section the struts. I did mine (sectioning and coilover install) myself with a large pipe cutter, angle grinder, and MIG welder, and though it was pretty easy. (BTW, I used a piece of angle iron to keep the pieces aligned while I tacked it back together.) The prices on some of the coilover packages isn't all that much when you come down to how much Tokico Illuminas cost. Plus the availability of all those spring rates and lengths is a real plus! And the springs aren't obscenely priced either. In other words, if you take even an inch or so out of the strut tubes, use shorter cartridges, and coilovers, with not-too-stiff springs, you can tune the car to a good compromise much better than just putting lowering springs on the car. I think it would be better to have a shorter top spring perch/isolator than to shorten the strut. For me, I wanted the stock isolator there for NVH reasons, and the stock spring perch mod (welding in a piece of exhaust tubing) was what some might "backyard" but it was cheap, simple, and effective. Just my opinion. Mike, that bearing is maybe 5/8" tall. Not much room to gain there, unless you can find a way to put a Torrington thrust roller bearing in there, like the front of SBC's can have behind the timing chain cam gear. You might have something there. I've heard of taking the isolator apart and removeing some of the rubber and crimping it back together. That seems to be viable as well, for taking height out of the hardware above the top of the spring. ------------------ Pete Paraska - 73 540Z - Marathon Z Project pparaska@home.com Pete's V8 Datsun 240Z Pages [This message has been edited by pparaska (edited December 28, 2000).] Quote Link to comment Share on other sites More sharing options...
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