coil over swap/conversion questions

[afbrian13]

76 280z

 

I was going to go with tokico blues and AZ springs, along with my urethane kit for an easy fun streat setup. I started reading through coil over threads and realized it my be entertaining to give it a shot. I realize I don't NEED coilovers, but it would be a fun project, and conversation piece.

 

I read through everything I can find, and all the writeups are for full out racers it appears. Has anyone done a coilover for only a couple inch drop? If you went with shocks with a 2in shorter extended length, would you have to section the tubes? I'm talking about going coilovers, but not dropping it alot. It would make it so you could run Honda backspacing wheels( I test fitted a set from an accord, cool looking 17's, and the only reason they didn't fit was they just kissed the spring perches) You could drop it low for a car show, parade , or pics if you wanted to.

 

Have any of you done this? Any writeups, pics or suggestions of where to look? I have an extra stock suspension set that I'm talking about playing with, and doing all the work myself.

 

Thoughts, ideas?

 

Thanks,

 

Brian

[Leon]

What's the difference between installing coilovers, and dropping the car 1, 2, or even 4 inches?

 

Installation is the same. Your decision on strut tube sectioning should be based on how much you plan to lower the car. As detailed in the archives, the struts should be sectioned if you plan to lower the car more than 1.5-2 inches. Otherwise, just get a Ground Control kit, shave the perches, and go.

 

I don't understand your reasoning behind getting inserts with a "2in shorter extended length"? I recommend re-reading some of those threads until you have a solid grasp of what's involved, and the reasons behind performing certain tasks.

[RebekahsZ]

When you lower a McPherson strut-type suspension, you lose suspension travel. Bottoming out a strut feels terrible and I actually started developing stress cracks in my roof after I cut the springs on my 240z (20 years ago). It bottomed out constantly and became no fun to drive. As part of most coilover conversion, you cut a section of length out of the strut tube-this restores the suspension travel that you lost when you lowered the car. Because you are shortening the strut tube you need shorter inserts. Putting the stock front insert in the rear works great, but the front needs something different, either from a VW Rabbit or an MR2 (I don't know what years). A coilover kit does allow you to change your ride heigth anytime you want, but don't forget, you need to adjust toe-in after making adjustments in ride heigth. It takes me about an hour to raise or lower my car, but until now I have always had to take it to a shop to have the toe-in adjusted for $35. I just bought a toe-in guage, but the last time I had the car aligned (a couple times a year), the dude tightened the lock nut so tight I can't get it loose to adjust, so I guess I'll spend $35 one more time! Anyway, coilovers also allow you to change springs (rate and length) with relative ease, and aftermarket springs only cost about $50 each, so it makes it much cheaper and easier to play with your setup. For example, after now adding camber plates, my car is really too low even with the coilovers adjusted as high as possible, so next time I think about it, I'm ordering new front springs in the same stiffness, but 2" longer-no big deal. Once I have my new springs, it will take me about 2 hours to change them out. You need to have your strut inserts on hand when you cut down your strut tubes so you can cut them down to the proper length (it would suck to cut them too short). Make your life easy and just order your strut inserts from Betamotorsports and talk to John about what you are doing so that all your parts are compatible. You can get threaded collars and springs from Speedwaymotors.com pretty cheap-it looks like that is where Ground Control got the parts that they sold me after marking them up 100%. One of the issues with a coilover system is the top spring seat. Plus, lowering makes you have positive static camber (and lots of postive dynamic camber) in the front and increased negative static camber in the rear, a combination that increases the understeering tendencies of the z-car. For a lowered z to handle with neutrality, you need lots of static negative camber up front and some in the back (search for JohnC's alignment recommendations-he's just plain right). Go ahead and get DP camber plates from John at BetaMotorsports.com because they bolt right in and have an integrated spring seat, so in one part you get spring seat, camber adjustment plate, and steering bearing. The strut inserts and camber plate must be compatible (different brand strut inserts have different diameter rods and thread sizes), so consult with John before trying to put your kit together. You also need to know what you want in terms of spring rates before ordering. There is much debate, but you gotta go stiffer than stock (whatever that is). The aftermarket "lowering springs" people sell can't seem to quote a specific spring rate-so who knows what you are buying. You gotta go stiffer than stock because when you are lower you really need to go more stiff to keep from bottoming out and breaking things. I am very happy with 225# front springs and #250 rear springs. A good rule of thumb is 50# stiffer in back. Avoid "progressive" springs at all costs. My rates are a good compromise between street and track. If I start drag racing a lot, then I may go a lot stiffer on the rear to stop the car from squatting on launch-again, it will cost me $100 and about 2 hours to do the whole mod. A coilover system is the very best mod I have ever made to my car-even more value than installing a V8. A z-car is really nothing special until you coilover it, that is really all they did in the 1970s and they took the racing world by storm! I recommend you have at lease $1000 on hand before starting this project and it may even take $1500 before you are finished-but I say "Go For it." You don't need to do any searching, I just gave you everything you need to know. There are a lot of guys who all have their opinions but I just gave you the bottom line. PM me if you need more help once you start.

[afbrian13]

Leon-What I was saying was an example, not an exact #. I read them and re-read them and completely get HOW to do it, its just ariving at some of the numbers I was asking about. I've got some $$ to use, but not enough to take a guess.

 

Rebekahsz-THANK YOU. Thats pretty much what I was looking for. I would love to road race a car, or at least autocross, but that is so far off right now I'm not worried about it. What your talking about is what I'm looking at doing. Let me take this one thing at a time.

 

I have a complete extra suspension off a 78 parts car (mines a 76) to play with, so my car wont be down at all-great way to learn.

 

I suppose a "ground control kit" would be an easy way to start-same effect as normal drop springs but a coilover setup right? cut the perches off, slide on some sleeves and be about the same height as a "normal" drop spring. I'm game for starting a step beyond that.

 

I like being able to just swap out for the stiff rears to drag race, etc. Thats part of the idea.

 

I've read about different springs and strut combos. One reason I want coilovers is I've read a ton of bad things about springs bunching up, spending a bunch of $$ on a set and being to stiff/to soft, etc. I love how cheap these springs are by comparison. I'm always looking at ways to update things on the car to more available parts like this. The good ol days of tons of Z after market support are going away I think. Plus it will handle much better in the long run.

 

One of the things I was wondering about was the top spring seat. I'd seen in the faq's about shaving down a billet treaded nut, welding it back to the top etc. seems like if your going for a street-ish setup you could cut 2inches out of the tube, weld the stock top threaded part back on, get the right length strut insert, slide some sleeaves down, 225 and 275lb springs (I want to have my spare tire and whatever daily junk in the back)bolt in camber plates with the right top spring mounts in it, and get an alignment. I know that over simplifies it-but its really not that complicated. What am I missing?

 

What struts did you go with? To me if you can get a decent set of struts that already match the top mounts, why should I get some I have to modify? I want the most bolt together parts I can get. I don't like cutting new parts I just spent $$ on when I could have just bought the right part.

 

I was going to go with tokico blues and drop springs (to mixed reviews), but I might as well just do this instead and be better off.

 

 

I don't mind the Z riding a bit rough on the street. My truck is a leaf sprung superduty, and before that was a 70 4x4. It would have to be pretty stiff for me to mind, especially if its handling like its on rails. My current motor is a stock 81 140K miles. I know its not full power, but a good rebuilt one is enough to get you in trouble-of course so would a v8 I'm trying to get the suspension, brakes and body gtg first.

 

Whats the simplest/cheapest but effective means to accomplish what we're talking about? What struts should I go with?

 

Sorry if I'm going on and on, just don't want to screw it up!

 

Thanks again!

 

Brian

[RebekahsZ]

You HAVE TO section the struts if you lower the car more than about an inch. Tomorrow, email johnc and tell him what you want to do and get a price quote from him for:

1) Struts appropriate for coilover.

2) DP camber plates

3) Ask john what length and rate of coils to get.

4) Ask him what he will charge you for a kit.

 

Be honest with john about your plans for your car and how you plan to use it.

 

Go to Speedwaymotors.com and price 2-1/2 springs and threaded collars with lower seats (but check with john, as he may have his priced competitively).

 

If you buy these parts, you have everything you need. The upper seat and the DP camber plate is all one piece. You eliminate the stock top insulator, which lowers you an additional inch!

Call john if you are really serious, he doesn't like tire kickers, but he is really helpful and won't steer you wrong.

 

When the parts arrive, start cutting and welding. Don't start until you have the parts.

 

The diameter and contours of the strut rod must fit the spherical bearing of the camber plate-that is why I recommend buying them together from John. Otherwise, you may have to have machine work done, etc. All the other parts don't really matter. You could probably get away with cheap shocks for what you want to do, but you could run into imcompatability problems mating them to your camber plate. You need to be a pretty good welder to do this job. You will be cutting a tube, rewelding it STRAIGHT and hoping to insert a strut insert into it (I bought my struts already sectioned from a retiring road racer and I still had to use a rheemer to get slag and excess weld out of my tubes-it was a total pain. As I said, if you are not prepared to cut your tubes, do the 1" cheap lowering springs and go no further (stay away from progressive springs). My opinion on urethane bushings-not worth the trouble. Keep stock bushings except for steering rack bushings and plastic steering coupler, mustache bar bushings and RonTyler front diff mount. Replacing all the bushings is a HUGE, miserable job. Heck, getting the steering rack bushings in is tough enough. Do not disturb your rear spindle pins. Drop the whole suspension and work on the tubes with the lower control arms attached. Struts from cheap to expensive: KYB select-a-ride, Tokico Illuminas, Koni. John may only have camber plates for Tokico and Koni. I don't know why we all want "adjustable" shocks-I never adjust mine. The advice I have given you will save you a month of pain. With a tight, lowered suspension, your z will be more responsive and a lot more fun-you can get a ton of fun from it even with your stock motor. It will seem like you put in a new motor. The difference is like night and day. You can start autocrossing now, you don't need to modify your car to start autocrossing, although some new or used 225/50/15 tires on 81-83 280zxt swashtica wheels (or something similar) will really help. If you are still running stock 5 inch rims and 75-series tires, a set of wheels and tires will totally transform your z-car. Other easy improvements that really help include smaller (cheap Grant brand-$50) steering wheel and new plastic shifter bushings ($5).

 

The 76 280z is a good platform for an LS swap later, much better than my 240z. By then, I should have a LS swap "how to" cook book available to forum members. You'll be able to use it as a base and incorporate any new ideas you come up with.

[afbrian13]

Again-thanks a ton. I understand the info you gave saved a ton of research.

 

Cutting without the parts- thats just silly. Why would somebody do that? Its like pouring a foundation then designing the house-but I know why you said it.

 

I already have a urethane bushing kit. Swapped the steering coupler, rack bushings, and mustache bar(that had to be done, they were broke and the car squatted and clunked every time you aplied some power)I was going to swap out the other bushings on the extra suspension that I was going to use for the coil overs. Doing everything on the bench or in a press is much easier. I've swapped all the bushings on a 720 4x4 and most needed burned out.-amazing handling difference though!

 

BTW-steering rack bushings are easier without a motor in the way!

 

Still have to do the sway bars and make some adjustable end links until I buy some stiffer bars. I know that will help a lot.

 

For welding it I'm good enough for function, but I have a body guy - and farm boy - for a good buddy. He used to build dump mechanisms for contruction equipment - We'll get it welded straight.

 

I really don't want a small wheel until after I (maybe) add power steering. I am going to add a tilt column though. I had a little grant wheel when I got it and after my dad haviing a 240, I like the stock size wheel. Maybe A "D" wheel would work.

 

I'll send John an email with what I'm looking to do and see what he suggests. Thanks again,

 

Brian

[letitsnow]

I sectioned my struts nearly 2", and that was for a minor drop. It put the static ride height of my bilsteins dead in the middle of the travel. I needed a ~5/8" spacer under the strut, so I couldn't have taken much more out.

 

I'd really recommend measuring and calculating the amount you need to take out for your intended ride height, I had to take way more out than I thought I would.

[akeboshi]

email gabe from techno toy tuning. i got my ground control kit from them. he gave me the measurements i needed for the struts i used (which he recommended.) it was about $900. 425 shipped for the ground control kit and about the same for my tokico illumina struts.

[notheredave]

Leon-What I was saying was an example, not an exact #. I read them and re-read them and completely get HOW to do it, its just ariving at some of the numbers I was asking about. I've got some $$ to use, but not enough to take a guess.

 

Rebekahsz-THANK YOU. Thats pretty much what I was looking for. I would love to road race a car, or at least autocross, but that is so far off right now I'm not worried about it. What your talking about is what I'm looking at doing. Let me take this one thing at a time.

 

I have a complete extra suspension off a 78 parts car (mines a 76) to play with, so my car wont be down at all-great way to learn.

 

I suppose a "ground control kit" would be an easy way to start-same effect as normal drop springs but a coilover setup right? cut the perches off, slide on some sleeves and be about the same height as a "normal" drop spring. I'm game for starting a step beyond that.

 

I like being able to just swap out for the stiff rears to drag race, etc. Thats part of the idea.

 

I've read about different springs and strut combos. One reason I want coilovers is I've read a ton of bad things about springs bunching up, spending a bunch of $$ on a set and being to stiff/to soft, etc. I love how cheap these springs are by comparison. I'm always looking at ways to update things on the car to more available parts like this. The good ol days of tons of Z after market support are going away I think. Plus it will handle much better in the long run.

 

One of the things I was wondering about was the top spring seat. I'd seen in the faq's about shaving down a billet treaded nut, welding it back to the top etc. seems like if your going for a street-ish setup you could cut 2inches out of the tube, weld the stock top threaded part back on, get the right length strut insert, slide some sleeaves down, 225 and 275lb springs (I want to have my spare tire and whatever daily junk in the back)bolt in camber plates with the right top spring mounts in it, and get an alignment. I know that over simplifies it-but its really not that complicated. What am I missing?

 

What struts did you go with? To me if you can get a decent set of struts that already match the top mounts, why should I get some I have to modify? I want the most bolt together parts I can get. I don't like cutting new parts I just spent $$ on when I could have just bought the right part.

 

I was going to go with tokico blues and drop springs (to mixed reviews), but I might as well just do this instead and be better off.

 

 

I don't mind the Z riding a bit rough on the street. My truck is a leaf sprung superduty, and before that was a 70 4x4. It would have to be pretty stiff for me to mind, especially if its handling like its on rails. My current motor is a stock 81 140K miles. I know its not full power, but a good rebuilt one is enough to get you in trouble-of course so would a v8 I'm trying to get the suspension, brakes and body gtg first.

 

Whats the simplest/cheapest but effective means to accomplish what we're talking about? What struts should I go with?

 

Sorry if I'm going on and on, just don't want to screw it up!

 

Thanks again!

 

Brian

 

 

I know this is an older thread BUT I noticed that you wanted to use your extra setup for a 78' 280z which has a 56mm (2.21") rear strut housing instead of the standard 50.8mm (2") So almost all coilover kits use a 2" So from what I have read is that 76' on up have the bigger rear strut tubes 56mm (2.21"). I had to go with an older 1970-1975 rear strut tube with the new 280z spindles.

Edited March 7, 2012 by notheredave