iBang

The 240SX unit is going to be heavier for sure... here's a comple of pictures for comparison: There's definitely more steel in the S13 subframe to account for all of the mounting points for the various arms. The arms are a lot smaller however so I may or may not be right on my unsprung weight conjecture. There's certainly a lot more arms on the S13 which may compensate for the longer ones on the S30.

Good question, I don't have the figures on that. There certainly seems to be a lot less to the Z's rear suspension which would suggest that it is probably a lot lighter. The arms are a lot larger however so there may be more unsprung weight, but that is just conjecture on my part. Good point nonetheless - a hundred pounds would be a hundred good reasons to stick with the original setup. Of course if I do go with a completely custom subrame that uses the S13 arms and geometry then everyhing is out the window.

$300 is about right for a complete rear subframe with a differential, at least in the 240SX community for something in decent shape. I bet the numbers come in pretty close for the S13 stuff. Assuming a decent set of coilovers is acceptable for your purposes, half a set would be $600 and that would include the spring, collars and plates. Really the different is going to come down to busings since technically you could get the S13 equivalents to all of the parts you sell for the same price and have the same setup. Where the question is going to come in is aftermarket parts. This is comparing a completely stock S13 rear end to a completely stock S30 rear end. I would consider the proper setup for a S13 with performance parts to be Rear upper control arms ($350) and toe rods ($280). That's $630 in aftermarket parts. Likewise I would want to have rear lower control arms ($425) and a fresh mustache bar ($230) which is $655 in parts. It would be more if you added on the billet diff brace and less if you ditched the bar. Looking at it that way its pretty darn close between the two, both using quality race proven parts (SPL, AZC and techno toy tuning). Heck the more I look at it, the more of a toss up it becomes. You could go either way and by the time you get done putting it all together it will probably be a wash. For me I already have the parts, so it makes it a lot cheaper to go that way, but then again it is more work. I'll cross that bridge when I get done with the front end. In the mean time, I am still focused on determining the easiest way to get a quality shock/spring package for the road that comes as one package. I didn't know you had something you were selling though John, would that make for a decent road package for my Z or is it more race focused?

Much the same idea I had. I may use the Z32 aluminum uprights for less unsprung weight, but frankly if I do, I'll likely do it down the road since the 240SX stuff is proven to work fine on LS6 powered drift cars under huge abuse on the track. Wouldn't you have the same problem with the S30 stuff as well though? Irregardless of what setup you go with you are going to want to freshen up the bushings and replace the shocks and springs with something aftermarket. Is there a significant price difference for the S30 parts? Honestly curious there since I know I'm going to be spending quite a bit in poly bushings on the 240SX stuff.

Ok, I did a little more research and this is what I turned up: AZC setup for all the rear stuff I would want would set me back $1620 with no brakes or coils. The full race setup ready to go would be over $7k for all four corners with brakes and coils The rear end setup isn't actually that bad - I'll have to do some serious thinking about what I want to achieve before I start hacking on the S13 stuff. I can probably only get $5-600 for my existing parts so I'd be out another thousand or so, but I would save myself an awful lot of work. I also went and read the shock thread... my head is officially spinning. What emerged from all of that information is that the accepted tried and true setups are for the "build your own coilover" type shocks including bilstein and koni. That does make me a little sad as I was hoping to purchase a ready to go coilover system and install it. I figured there had to be something acceptable for street use that could be purchased as a complete package. The reason I would prefer to avoid the stand along shock setups is that as I suspected, I saw a lot of information in the thread to the effect of ...tweak in your spring rates and valving to get to how you want the car. That's all well and fine for an car that will see track duty but certainly there is an off the shelf setup for the street that will not require me to go through multiple springs and valving adjustments to get right. One thing of note is that I see that AZC actually offers a complete set of coilovers for the S13 chassis. There was not a lot of information on the AZC stuff in the shock thread, but it certainly seems to have a following here. Perhaps their offerings in the S13 market would be the way to go in order to get a complete package coilover since I plan on using the S13 parts anyway. I did do some searching for test results on the various coilovers that I am aware of and found mixed results on most of them. I did get fairly positive results for BC racing and tein, but both were qualified as "not ideal but acceptable for the street". BC is a bit tempting as I actually have a good friend that is employed by them as well as being one of their sponsored drivers, so I would likely be able to get a lot of support for choosing the best possible unit for my application... and maybe a few bucks off the list price if I'm lucky. I'm starting to move away from tein since all I could find were a few "its acceptable" comments and my own experiences in S13's. I'm beginning to see that an awful lot of the information I was searching for is a matter of opinion. One thing however that doesn't seem to be that way is spring rates. From what I can gather, a good place to start building a setup is to choose rates and then decide on the rest of the components to match. Any suggestions on that front?

I'll take a look at the cost of parts for the rear suspension and do the math on it. If I can make the numbers stay at least close to black by selling off the S13 parts I'll consider it. Time effective is less important here than cost to me... at least for the moment! As for the brakes and rear end, remember, this car is going to put 400hp to the ground and I'd like to have the brakes to match that. Honestly 300ZX brakes are the minimum I would want. I'm also pretty sure that the stock diff for the S13 is a shornose R200 not a 230. That is a smaller concern though - I can always track down a longnose R200 and get the strength I need and retain stock mounting. Interesting... I'll have to do some more research and see if I can't find out some more information there. I've had my best luck with S13's using the higher end tein stuff, but as I've mentioned before, I've never gone into detail with the tech on it. Maybe a set of bilstien's will do what I want. Do they make a short body shock that will allow me to get a reasonable ride height without losing all of my travel? Keep up the info guys! This is the information I was looking for!

Great points guys. Some of the reason is actually cost related. I parted out my drift S13 a couple years back leaving me with a beautiful set of SPL rear arms for S13, a complete rear subframe and differential, 5 lug hubs, etc. I also have the complete front end with the 5 lug S14 setup, tension rods, etc. I happened on a S12 subframe for some other cheap parts I wasn't going to use so I have that already. I have a complete set up mock up tein coilovers which depending on their performance might be ideal to send off for a rebuild and just use. In fact the only parts I'm missing for the complete swap are a set of camber plates to allow me to use the pillow ball mount coilovers, and a set of custom axles for the reduced track width of the S30. Other reasons are performance or advantage related. The front end of the S30 seems to be its weak point and it also lacks power steering. I had already planned on using S13 coilovers to take advantage of the wide range of parts out there, so going ahead and using the S12 rack and subframe with the S14 knuckles gains me power steering, a more solid front end, and I can just bolt up the bottom side of the coils instead of having to customize them. Another added bonus is the ability to use a set of Z32 front brakes I already have and the option to upgrade to any of the many big brake kits made for the S13/14. On the back side there's a few performance reasons as well. You can argue the advantages of multi-link vs. the original Z setup but I'm not going to get into that. I like the ability to use a easy to find shortnose diff (which I already have) for starters. I also like the fact that I'll be able to bolt up Z32 rear brakes (or any of the other big brake kits) and keep a hand brake without having to resort to a lot of custom work. The 5 lug hubs are also a bonus to expand my wheel selection. Frankly most of the rest of it is cost related. By my estimation it would cost me between $2-4k to buy all of the various bars, arms and what not to go through the entire rear end. Then I'd have to add on some more budget for a decent diff. Now all of this aside, the back end is still something I could be convinced to go ahead and use the S30 setup on since there's not a big performance advantage, but I would have to be convinced it could be done without blowing the cost through the roof. Its also worth mentioning that I am a fabricator and have access to all of the tools necessary to modify the front and rear subframes as well as mount them up to the car in house. There isn't a cost component there for labor to have that done. The only costs for all of that will be the raw materials and gas for the welder and what not. One thing I notice a lot of emphasis on is the bilstien/tociko shocks as opposed to a typical S13 type coilover system. Any reason behind that? (I'll be reading the shock thread in a minute, thanks for the heads-up on it) I've had great experiences with my various S13's on a quality set of coils which inspired me to go that direction with my S30. Of course on the S13's I was simply buying known quality components and bolting them up to the car. With the Z I'm taking a lot more pains to understand what each modification will do to the suspension and have a reason for each one. Adjustable arms are easy enough to understand - adjustability is always a good thing, but I'm less certain as to what shock will offer the best behavior and valving.

I've recently been doing a lot of reading on suspension tech and trying to figure out how I want to set up my Z. I now know a little more about terminology and what to look out for, but it doesn't help me a lot as the average Joe. I may now know what to tweak to compensate for certain handling deficiencies, oversteer, understeer, bump steer, etc, but without the money to go through tons of components the information isn't much good. What I would like to figure out is a good set of basics that will get me fairly close to the ideal setup to start with. Then I can adjust a few things to tweak it to perfect. First let me give some specs on the car for reference: '72 240Z. Power will be a RB25 tuned to between 350-450hp on pump gas with a garret 3076R. I'll be tweaking to optimize the car for street driving and a smooth power band. Interior will be complete and if possible I'd like to avoid as much in car bracing as possible. I'm still considering a rear section roll bar but I don't want anything with door bars for sure. Suspension is where the largest amount of custom work will be done so there is lots of room for adjusting it for maximum efficiency. Before I get to that let me talk about the car's mission. I'm building this car as a weekend street car. Something to be driven purely for enjoyment. Something to take on road trips to out of town car shows and events, nice dinners, and weekend drives. That means that there is a large emphasis on day to day drivability in normal street conditions. At the same time, it is to be driven for fun in the twisties and I'm willing to sacrifice some ride quality in the quest for improved performance beyond that of an average street car. Now, so far as the technology that will be going into the suspension: For various reasons I have decided to use modern S-chassis components as the basis of my suspension work. The front subframe is a S12 piece that will be used with modified S12 arms to get back to stock S30 track width (more on that later). Front knuckles will be S14 with 5 lug hubs. Steering rack will be from the S12 as well and will be a power unit. The rear subframe is still somewhat in the air. My original plan was to use a stock S13 rear subframe in complete form. I have amended that however to either modifying the stock subframe to reduce the track width to match the original S30 components or alternately designing a tubular rear subframe that would utilize all of the S13's arms and hubs in order to retain access to the excellent S13 parts available from a million manufacturers. The decision to modify or fabricate fresh will be determined when I start mocking up parts and seeing which direction will be simpler to achieve. Irregardless, S13 arms and geometry will be retained. All four corners will use S13 based coilovers, though if it is necessary, I may adjust valving and spring rates in order to better suit the S30. Given the versitality I have seen from stock S13 suspension and its ability to handle everything from lightweight drift cars to heavy V8 builds I don't expect to go down that road, but I leave it as an option. Currently I'm considering tein and driftworks coils, however that may change with more information. With all of that information in mind, I see several elements that need to be addressed: Spring rates - what is the ideal spring rate for a lowered S30 that is close to stock weight for street performance driving. Valving - should I have my S13 coilovers custom valved for any reason? Track width - I currently plan to run stock fenders, no fender flares. For appearance reasons I would like to flush up my wheels to the fenders and ideally would love to have some lip to the wheels. I'm not sure if I should adjust the track width any either front or rear in order to avoid any scrub radius problems while doing this. Anything else I have not yet thought of! Any opinions anyone can offer would be appreciated. I want to avoid as much trial and error as possible when building my suspension. Fabrication takes time and parts are expensive so I only want to do this once if possible!

That would be a nice thing to know. My balancer is in crappy shape and I'd love to have a domestic replacement available.

I bet! I've never had the chance to drive a C3 but the C4 has an awesome sea of hood. The C3 with all the same area and those wheel arches would be pretty awesome to be behind the wheel of. Besides, its old enough to wear a leather jacket and aviators and be cool instead looking like a reject from the 70's.

There's something cool about sitting on the rear tires with that awesome shaped hood stretching out in front of you isn't there. Kind of reminds me of my GF's father's mint '90 corvette. Its not fast, its heavy, but its just an awesome car to cruise in.

I've actually only ever driven a 280Z to compare to my miata. Honestly I was very impressed with the old Z. The car I drove was a pretty much un-molested stock 280Z. At that time I was dailying a 240SX and I was struck how similar they felt. The torque from the big 6 was nice and the power came on smooth, it went like I wanted it to, stopped like I wanted it to and turned like I wanted it to. The only real "old" feeling about it was the heavy non-power steering in the parking lot, and even that wasn't bad and went completely away once the car was in motion. Now bear in mind, I wasn't doing any hard driving. I was granny shifting, not cornering hard, nothing like that. I was just happy that a random guy I met at a drift event 10 minutes ago was nice enough to let me take his Z for a spin. I suspect that the car would have felt a lot heavier and more awkward had I pressed hard. A miata is so small and nimble that it is bound to feel different at the limit than an old Z car. The power band on the Z will also take a nose dive had I ran it out. Torque is great but I suspect it would have choked out much over the 3-4k I was shifting at.

I'm planning on changing out the entire steering column for one that has tilt and distance adjustment and I figure I'll use the matching controls from my donor column for the since I can. I actually really like the feel of the column controls in my '05 accord and it has all the adjustments I want so unless it turns out I can't make it fit, that is likely the donor car I'll use for those parts.

I've done a lot of research about the S12 front subframe and will be installing one into my own car. I got a lot of info from the original person with that swap as well as speaking directly to the shop that did the work for him. My reasons for the swap are a combination of a couple of things: Power steering - nice, but not really enough to justify all the work of the swap Suspension - I'm nice and familiar with what I like and want in the 240SX world and all of that becomes even easier to swap over if you use the S12 front suspension Hubs and knuckles - I want to go with a nice 5 lug setup to make finding wheels easier and that is really easy to do using a set of S14 front knuckles that I already have. When you put all the pieces together, it was just easier to use the S12 front subframe than to try and do anything with the stock S30 bits. I also suspect that the more modern setup may be a bit more advanced, but I am no suspension tech. I just know what has worked for me in the past on S-chassis cars. Feel free to contact me and I'd be happy to pass along the info about the swap that I've found out.

Can't wait to see those mocked up in the Z's buckets. Do they look like they will fit well?

Ooh... what are those lights from? I was thinking of something like that for the Z but I never got around to figuring out what would fit.

Alex, that you? I just saved most of those photos to my HD for reference since I love how it looks on those wheels before the screen name registered.

I love all the plastic work you are doing. I've got a lot of similar work in mind for my own car when I get to the interior and its great to see someone else doing something other than a stock dash or a complete replacement. I've got some different ideas for the direction I'm going to go with mine, but its still great to see someone doing it.

I haven't seen anyone using a 240SX subframe for the purpose of putting an RB25 in the car, in fact I doubt that would work... What I have seen are 240SX REAR subframes used to get the rear multi-link setup to replace the stock setup in the back. I've also seen one person with a S12 front subframe with RB25 for the purpose of putting power steering into a Z. I'm immitating that swap myself eventually, but I expect to have to fabricate something similar to the mckinney mounts used to put a RB into a 240SX. Only issue there is going to be the placement of the sump. So simply put - no, don't do a 240SX front subframe to mount your RB, it won't work.

I haven't posted up anywhere other than here. A lot of forums are pretty sensitive about people posting things that could be considered advertising without being forums sponsors. I figured that this was closely enough related to everyone's interests here that I could post this without any problem. I also would rather do it as a group buy on this forum than advertising on a number of them. We'll see what happens with it.

Well, not a lot of interest, but there is some. I've got a feeler out on getting at least a prototype made. I'll probably get that one done and bring it in and if some more interest in generated at that point, I'll move ahead with getting a run of them made. S30rb25, I designed these to be usable with both series 1 and 2. They use the same bolt pattern and top plate, the series 2 just doesn't have the igniter up there. I haven't put any holes for the igniter on a series 1, but you could just drill and tap them if necessary. If there is significant series 1 interest, I'll make some spacers and drill holes as needed.

Sadly the real greddy manifolds have the same problem, or at least mine did.

We used JB weld and it worked out fine, but it looked crappy. I plan on either tigging on a aluminum tube or an AN bung depending on which way I go with my radiator hoses in the new car.

I've got a thread gauging interest in getting a run of these made going in the RB forum. If I get enough interest, I'll get a few made. Thanks but yeah, I put a post here at the same time I PM'd you and got plenty of responses here quickly.

One of the things that has always bugged me about my RB25, and in fact RB25's in general, is that the plastic center plug cover always ends up looking crappy. The only thing you can do is paint it and that never seems to come out as nice as the valve covers which can be powder coated to look great. I have always been thinking of making my own center cover out of aluminum but I was reading a L-series build thread and inspiration struck: I started with a picture of this: Did a little cad work and ended up with this: I think it came out so nice that there might be some interest in getting more than just one made for me. I haven't found where I'm going to get them CNC'd at yet, so price is up in the air but given that machine time is never cheap and neither is aluminum, I figure these will end up well north of $100, maybe north of $200. At a price like that, would people be interested? I was thinking if I did do some sort of group buy that I'd just let them go out in raw aluminum so everyone can powder coat them to match their own engine bay schemes. Thoughts? If there's no interest I'm still getting one of these made for myself, but seeing as I'm going to be doing all the leg work anyway, it seems a shame not to share it with my fellow HZ members. BTW, in case anyone is concerned, I designed the cover to where the stock igniter on a series one engine and the stock breather tube will clear without covering up the artwork.