• This appears to use a knob under the dash to manually set a fixed level of assist.
• My worry here is the highway drive. S30s already get naturally light in the front end at speed. If I leave the manual dial turned up enough for local driving, is the highway cruise going to feel twitchy and annoying? Am I going to get completely annoyed having to constantly fiddle with a knob between street driving and autocross runs?

• This appears to use a GPS antenna to automatically give max assist at a standstill and taper it down assist at highway speeds.
• My big concern here is track reliability and lag. When you slam on the brakes right before a tight autocross hairpin, does the GPS signal lag keep the steering heavy, or does it suddenly surge and go super light mid-corner?
• I am also specifically looking for feedback from anyone with personal experience regarding the motor they use. There's a rumor floating around online that the SilverMine setup is actually using a cheap, under-powered electric steering motor designed for ATVs rather than a true automotive passenger car core. Is there any truth to that, or is it a solid automotive unit capable of handling track abuse?

• If anyone knows of any newer, more modern US-based EPS options on the market that I should look at instead, please let me know.

The first piece major piece of hardware to arrived is the Viking Performance Shocks from the Apex Engineered Track Attack Front/Rear Suspension kit. I noticed that Apex’s website lacks details on shock and spring selection, so I’m documenting my findings here for others and to start a discussion on their choices.

What's Included:

Box as it arrives from Viking Performance

Serial Numbers of each of the shocks (PN: C203)

Viking Performance Shocks Link

Part Numbers of Springs (600# & 700#)

Initial Impressions:

The car will be caged and used primarily/almost exclusively on track, so a stiffer setup is expected. However the spring rate selection still raises some concerns:

• The S30 chassis doesn’t benefit significantly from extremely high spring rates, even with a roll cage.

• The rear suspension uses inboard cantilevered shocks, which traditionally increase effective spring rate via the lever arm.

• This spring selection guide from Viking Performance indicates that the spring rate for a car with IRS and axle weights of ~1200-1400# is a lot lower than the supplied springs.

I'm hypothesizing that the high rates were chosen to prevent the shocks, which are short to fit the Z’s narrow frame and tight packaging within the front wheel wells, from bottoming out.

I’ve reached out to Apex Engineered to clarify the wheel rates for this setup and will update this thread when I hear back. Let me know if any of you have run this kit or high wheel rates.

I would like to stick with 15x10 to 15x11.  

I am currently looking at Work Meister 15x10 with 0 offset (5.5 backspace).  Has any had any experience with these wheels?

What is the inner diameter of the shell?  I am currently using 11.75" diameter rotors with Wilwood Calipers.  I'd like to have at least the same clearance for brakes with maybe some room to grow.

Any suggestions for 15x10 wheels that have good brake clearance?

Anyone have a good used set for sale?

Some of you have already seen my Apex Engineered Track Attack information/discussion thread here, I've decided after reviewing the design of the Apex Engineered front suspension kit, the best solution moving forward is to design my own. In this thread I will be documenting my progress and hopefully gaining knowledge on suspension design from you guys (or from what's left, f**k Facebook groups). 

To start...

Why don't you just use the AE kit? It was $4000, you're just gonna waste $4000??? (Yes)
Not enough shock travel, that's pretty much it. Once I received the shocks from Viking I realized immediately that 3.20" of stroke was not going to be enough and thus set out on a fool's errand to find alternative solutions. Viking shocks, from what I've found, have the most shock travel per the physical dimensions of the shock that I've seen so far. They're compact and the adjustment knob is well-designed to take the least amount of space with respect to the rest of the shock body. Very nice, but I will ultimately use either JRi's Mod series DA shocks or Penske's 7800/8300 series DA shocks as now, getting a shock long enough to reach between the strut tower and the LCA is more important.

Design (pictured with 17" diameter wheel)

The most prominent feature of my SLA design is the UCA pickup being located within the engine bay. The shock tower must be cut and a box structure is welded to the frame rail. This design is based on both the Maier Mod 2 design and Cortex Racing SLA kit seen here:

Maier SLA Design

Cortex SLA Design

The reason I moved the chassis pickup for the UCA inboard was to extend the length of the control arm which should allow for a more compliant spring than the offerings from Apex. Mike Maier inferred the reason for the obscenely high rates was to keep the super short UCA from camming over and ruining the geometry. Fine for a super stiff autocross car but for a road-course car with kerbs, burms, and undulations in the track surface? Unacceptable. With this shock, I'll be looking at around 7-8" of total shock stroke travel. 

The remaining part of the design lies with the spindle (not shown) and the boxed-structure (also not shown). The boxed-structure was fairly straightforward to design - shout out to @Ben280 for sending me frame rail measurements while my car's been at the body shop. The boxed structure welds to the chassis frame rail located in the engine bay which the cross-shafts then mount to. The spindle is obviously not straight forward, fortunately for me there's plenty of resources on the LocostUSA forums for me to look at as well as Chassis Design and Race Car Vehicle Dynamics by Milliken and Milliken.

Once the completed version 1 of the design is done, I’ll begin FEA with a safety factor of 1.15-2.00 at some lateral load to make sure everything should work without buckling. Until then, I have two separate designs, one utilizing Mustang II style cross-shaft mounting structures and one using Maier’s. The main difference being the orientation of the cross-shaft mounting bolts to the boxed-structure with the Mustang II’s bolts facing down, and Maier’s facing sideways. With the bolts facing sideways relative to the longitudinal axis of the chassis, side load is transmitted into the boxed structure through the bolts on their axial axis as opposed to their shear axis. Bolts do not like shear, however the Mustang II design is insanely popular so I suppose I could be overthinking this. 

Maier Cross Shaft Mounting Design

Cortex/Mustang II Cross Shaft Mounting Design

Methodology

Starting with a 3D scan of the 240z that I re-topologized into ~10000 quads, I modeled an accurate-enough solid body of the fender well and shock tower. From there, I (roughly) modeled the Apex Engineered LCA (will probably try to use the T3 ones I currently have installed on the car as they are boxed structures), the Penske 8300 coilover at ride height, and upper control arm. You may have noticed the bottom of the shock clipping into the LCA, please ignore that, you didn't see that.

In regards to swaybars, I will try to get the OEM sway bar design to work with my suspension, however due to the bottom of the shock being mounted on the LCA roughly where the swaybar links, this may be difficult to engineer. I could copy Maier’s LCA design, using a bent-tubular lower arm picture here:

Moving forward, it might be easier to design my own boxed structure and try to mount a blade-style sway bar instead. 

Procurement

While there's going to be a lot of custom laser cut metal from SendCutSend, I wanted to keep this kit as OTS as possible. I am not particularly interested in spending buku-bucks on one-off billet parts nor am I keen on dipping my feet into scaled automotive aftermarket product design & manufacturing. That being said, the spindles will likely need to be entirely custom if I can't find an alternative OTS. If I can find an upright on the market that fits my criteria I will definitely go for that, I’m trying to avoid using a Mustang 2 spindle as its shorter than I’d like it to be and completely wastes my steering knuckles and 370z spindles supplied from Apex Engineered (though steering knuckles and spindles are relatively cheap). 

Next Steps

The complete version 1 of this design will be complete soon. Once I've finished my spindle and boxed structures the real work starts, articulating the design through all of its axes of rotation and movement will reveal conditions of binding and the dynamic geometries of the suspension. I started work on this project about a week or two after I placed my order for Apex Engineered SLA kit and have been doing it in my free time which is quite difficult to come by. God willing I shall endure. 

are getting harder to find.   In some cases, they are impossible to find so rebuilding maybe the only solution.

I will have to take the car to a body shop to get the frame rails welded so I’ll be looking to get pre made frame rails to save on labor cost. That gives me two choices, 1,5mm thick reproduction rails from KF vintage or the 3mm thick rails from Apex. The KF rails are send trough a warehouse in Spain so that saves a lot on import cost for me but the Apex rails are twice as thick which may give the almost 50 year old car some much needed strength and rigidity. Does anybody have the Apex rails on there car and how are they holding up?

As for the rear suspension the question is if it is the chassis itself that’s crooked or something in the suspension. As I can’t find many stories of bend chassis online I’ll take the bet that it’s the rear suspension. That means I’ll have to look for adjustable rear control arms. That way even if the chassis itself is a little bit crooked I can tune it out for now till the car will be fully restored. Again that search let me back to Apex, there was also Silver Project from Europe which was a lot cheaper but I don’t hear much good from them. Has anybody installed the rear (or front) control arms from Apex with mostly stock suspension?

I currently have a list of products form Apex which interests me and I’ll probably wait till Black Friday to see if they got any good deals. I don’t know if I’ll order everything but the frame rails and rear control arms I’ll probably order. This is what I’m interested in at the moment:

-    Frame rails
-    Rear control arms
-    Fender brace (If the car gets welded anyway, why not)
-    Rear strut brace
-    Front control arms
-    Low profile outer tie rods (I run 15” atm)
-    Inner tie rods (because of the threat difference)
-    Steering knuckles

All combined should give the chassis and suspension a nice upgrade and the adjustability I need to get the car on the road. I do plan on keeping the four lug setup and the coilovers that are currently on the car. I do like there coilovers but That may be too much money for now. Yesterday I contacted Apex Engineered with some questions and they claim that the suspension components I’m looking at do work with the stock components.

Are there people on here running Apex components (except the track attack kits) and what is your opinion on them. 

Comments welcome

With the availability of the 280ZX 15/16 inch diameter master cylinder becoming limited there is now another option for a larger diameter master cylinder for the 1970-78 (S30) Z cars. Wilwood, long known for their automotive racing products, now makes a one inch diameter master cylinder that is almost a “bolt-onâ€, requiring only two minor modifications.

Why use a larger [one inch] diameter master cylinder?

The diameter of the brake master cylinder is determined primarily by the amount of fluid displacement that is required to move the caliper pistons against the brake pads so they contact the rotor surface. Other minor factors, such as the brake pedal lever ratio and the brake booster size, may be considered as well.

The diameter of the stock master cylinder on the 1970-78 Z cars is 7/8 inch. When Nissan introduced the 280XZ in 1979 they changed the brake system by going to disc brakes at the rear and added a vented rotor up front along with a floating caliper. The rear calipers and the new front calipers required more fluid and hence Nissan increased the diameter of the 280ZX master cylinder to 15/16 inch.

Brake modifications to the 1970-78 Z cars typically involve changing the rear brakes from drums to discs with calipers replacing the rear wheel cylinders. The front calipers are changed from the stock two-piston to a four (or six) piston one with increased piston area. Both of these changes require more fluid from the master cylinder and the change to a larger diameter master cylinder is always recommended as part of the brake upgrade.

The 280ZX 15/16 inch diameter master cylinder is typically used for the S30 brake upgrade, but as the supply of good used 280ZX master cylinders becomes scarce and the cost of NOS ones quickly increasing, going to an aftermarket one inch diameter master cylinder is a viable option. However, a larger diameter master cylinder will require more pedal force to build the same fluid pressure. Nissan used a larger diameter brake booster on the 280ZX to reduce the pedal force of the 15/16 inch diameter master cylinder.

The Wilwood one inch master cylinder

The Wilwood one inch diameter master cylinder which will work on the S30 Z cars is Wilwood part number 260-8794. There is also a 260-7563 part number which is the one inch diameter master cylinder but with remote reservoirs. The remote reservoir kit makes the 260-7563 slightly more expensive than the 260-8794.

http://www.wilwood.com/MasterCylinders/MasterCylinderProd.aspx?itemno=260-8794

http://www.wilwood.com/PDF/DataSheets/ds439.pdf

The Wilwood one inch diameter master cylinder is available from Jegs, Summit, StreetPerformance.com, and probably others.

Modifications needed

The Wilwood one inch master is a “vertical mount†type and although it initially appears to fit the S30 brake boosters as is, you have to do a modification to it first. The center-to-center spacing on the S30 booster mounting studs (for the master cylinder) is 60mm whereas the bolt hole spacing on the Wilwood one inch master mounting holes is 57.2mm (2.25 inches). So, you will have to elongate (slot) the mounting holes on the Wilwood master with an end mill or a file. You could also drill out the mounting bolt holes (on the Wilwood master) to the next larger drill size.

The second modification allows the Wilwood one inch master to connect with the S30 brake lines. The Wilwood one inch master cylinder outlets are designed to be used with standard 3/16 inch SAE double flare brake line fittings which have 3/8-24 threads. However, you need 10mm x 1.0mm female metric threads to interface with the stock Nissan double flared brake lines.

Fortunately the SAE threaded outlet fittings on the bottom of the Wilwood master cylinder can be unscrewed and replaced with the Nissan metric ones off your old stock master cylinder. However, this only applies if you have a 1972-78 stock master cylinder as your donor.

The outlet fittings of the 1970-71 stock master cylinders are different and will not fit the Wilwood master. This also applies to most the aftermarket (i.e., the non-Nabco/Tokico ones) S30 master cylinders.

The stock outlet fittings on the bottom of the Nissan master cylinder are part number 46038-B5012 which is still available from Courtesy Nissan:

http://www.courtesyparts.com/cylinder-p-p-362085.html

Note: Tighten the outlet fittings on to the bottom of the Wilwood master cylinder with 156 in-lbs of torque.

If you cannot locate suitable metric outlet fittings, then you can resort to cutting the metric fittings off your stock brake lines, installing 3/8-24 fittings, and re-flaring the ends of the lines. No manufacturer (that I am aware of) makes a single-piece 10mm x 1.0mm to 3/8x24 UNF brake line adapter.

Residual pressure check valves

According to the Wilwood 260-8794/260-7563 instruction sheet, the Wilwood one inch master cylinder contains internal residual pressure valves (for drum brake use only) which should be removed and not used in disc brake applications.

Adjusting the booster pushrod

The push rod projects from the front of the brake booster and activates the master cylinder pistons. The push rod length is adjustable and the push rod to master cylinder piston clearance (gap) should be checked any time the master cylinder or booster is replaced.

Problems can occur if the push rod is improperly adjusted. If the gap is too small (or non-existent) then the master cylinder piston will not return completely when you let off the brake pedal and there will be pressure remaining in the lines which will result in brake drag and premature pad wear. If the gap is too large then there will be a slight time delay in brake actuation, increased pedal travel and reduced pedal travel reserve distance.

The preferred push rod adjustment procedure is to use a special tool or gauge to determine the gap. However, if such a suitable tool is not available then an alternate method can be used (see the accompanying pictures).

Using a vernier caliper, measure the distance between the rim of the master cylinder bore to the mounting flange surface on the master cylinder (measurement “Aâ€).

Measure the distance between the bottom of master cylinder primary piston to the top of the rim of the master cylinder bore (measurement “Bâ€).

Subtract A from B to obtain the depth of the master cylinder primary piston to the mounting flange surface (measurement “Câ€).

On the booster place a precision straight edge across the face of the master cylinder mounting surface adjacent to the push rod. Measure from the top of the straight edge to the top of the push rod (measurement “Dâ€).

Measure the width of the straight edge (measurement “Eâ€).

Subtract D from E to obtain the height of the push rod (measurement “Fâ€).

The push rod clearance (or gap) is determined by subtracting F from C. Adjust the push rod to obtain 0.3mm (+/- 0.2mm) of clearance.

Warning: When adjusting the push rod length avoid pulling the push rod out of the booster to prevent the reaction disc from falling down into the booster. The best way to prevent this is to place the booster facing up when adjusting the push rod length. If that is not possible (i.e., booster is bolted to firewall) then apply moderate pressure on the push rod in a direction towards the booster during the adjustment which will keep the reaction disc from moving.

Appendix/Addendum

* The stock Nissan reservoir caps will fit on the Wilwood reservoirs. Likewise, the Wilwood reservoirs appear to be identical to the Nissan stock ones so that they will even fit the stock master cylinder. The Wilwood part number for the reservoir is 260-3386.

* The Wilwood master cylinder has o-ring sealing where the reservoir mounts, a nice improvement over the stock master.

* Use silicone sealant to seal the base of the master cylinder to booster as it should be an air tight seal.

* Tightening torque for brake line fittings. As a general rule tighten the nut finger-tight until you feel it draw down tight, then tighten with a brake flare wrench approximately 1/6 to ¼ turn more. Do not over-tighten.

* A nice explanation on the importance of the booster pushrod adjustment can be found here:

http://www.tegger.com/hondafaq/mastercylinderreplace/howworks.html

I have removed the brake booster on my 1972 240Z.

Mainly because I need the room for my turbo, and since this is a weekend cruiser anyway, I don't really need it.

For those who have removed the booster but kept the stock master cylinder, where did you source the push rod that goes from the pedal to the master cylinder?  Any lengths, etc. or advice would be greatly appreciated.

Thanks,

Joe

Do any of you have the Chase Bays master cylinder that eliminated the brake booster?  I have been looking at them, and wondering if any of you guys have one.  I'd love to hear about it, thanks!

https://gyraline.com/?srsltid=AfmBOoonzfGKwgL5wLRT_Wl5WHc9hYeCTI1hTJwmyUHGzwQpuW70pYvN

MEH I AM NOT MAD NOR PLEASED IN GREEN.

BAD POINTS WILL BE HIGHLIGHTED IN RED.

1. Removing the Stock Drums

There are tons of write ups on this. I chose to cut the back plate because I will never really go back to drums, and I have had it with the drums seizing or messing up or not adjusting right, and messing up my brake points.

OEM brake lines were easy to remove since I soaked them in PB. Clips were easy with pliers, and a wrench.

2. Bolting up the ZcarDepot bracket.

THE GOOD There is really only one way to bolt up the bracket and Zcardepot has many photos and write ups on this part. So here is a photo from their website(no copywrite infringement intended 😊)

Both the stock bolts work and the new JNC bolts that Zcardepot supplies.

3. Bolting up the Calipers

Clean up the hub and slide the rotor on. Put a lug nut on and hold the rotor to the hub surface. Now the rotor spins in line with the hub surface.

With the whole caliper try bolting up to the zcar bracket. 
THE MEH, the calipers needed to be shimmed on the driver side caliper in order to center the rotor in the middle of the caliper slot. The passenger side is okay and did not need any shims at all. I have installed willwoods on several cars and they also required shims to get the caliper and rotors inline. SOOO thinking I would rather have to shim the caliper outward than having to grind the back plate or caliper retainer. 

4. Hooking up the brake hose (hose is the flexible bit, hardline is the solid metal bit)

The brake hose used are some 240sx rear brake hose, I recommend a stainless braided hose. I had some 240sx braided hose sitting from my older projects so I used those instead and they are DOT, but for a 240sx.

THE BAD the idiot installing the kit ME  😂
This was my problem, caused by me but you might run into a similar issue with the normal rubber hose provided. 

The brake hose are quite short for the application and I recommend a brake hose that is at least 15inches long end to end. The 240sx brake hose is 12 inches end to end. The good thing is the 240sx brake hose is just long enough to clear all the critical points.

5. The handbrake.... THE BAD THE PAIN THE STRUGGLE

Everything was going smoothly, up until this portion of the install. Trying to get the oem handbrake to work with the 240sx calipers. There are two options now.

If you have the oem 240sx handbrake brackets (rare) you will need to make an adapter plate to link the 240sx caliper handbrake hook to the 240z handbrake cable. Here is a picture from a nice man who has a page on how to install the 240sx rear brakes from way back when.
  http://www.zhome.com/ZCMnL/tech/Calipers/zbrakeupgrade.htm

If you have the Zcardepot 240sx handbrake brackets (provided with the kit) you still need to modify a few things. I have both but I chose to go with the zcardepot handbrake bracket. On the OEM 240z handbrake there is a flat tab, that flat tab has to sit behind the flat of the caliper handbrake bracket. The Zcar depot brackets are shorter than the 240sx OEM handbrake bracket, this makes is possible to simply hook them up. BUT HERE COMES THE BAD the driver side bracket was too long and I could never get that tab behind the flat of the zcardepot handbrake bracket. The passenger side zcardepot bracket was perfect, and the 240z OEM handbrake fit perfectly. 

I ended up using some shaft collars on the oem handbrake to hold the handbrake tab on the driver side. 

6. CONCERNS JUSTIFIED 

After having bolted up everything I am really concerned with a few things.
1. The bracket for the handbrake is really close to the chassis and the OEM brake hardline. 

2. The handbrake cables being too close to the drive shaft. I know you can swap sides and it fixes it, but I just used a zip tie and held the oem cable to the mustache bar. 

As its turned out I the bracket made contact with the mountings. here is a photo of what happened when I compressed the suspension.

   THE SOLUTION COMES IN THE FORM OF TWO THINGS.

1. THE BRACKETS NEED TO BE PUSHED TO THE REAR OF THE CAR AND THEN BOLTED 2. BUMP STOPS NEED TO BE THERE AT LEAST 1INCH TO KEEP THE HANDBRAKE BRACKETS FROM MUNCHING YOUR BRAKE LINES.

Overall, the kit works perfectly fine. There aren't any major issues that cannot be fixed by normal means.
The braking is greatly improved, with much better pedal feel and heat capacity. I am running the 280zx master cylinder as well, so that helps.

BRAKE balance is just as good as properly adjusted drums, I will lock up the fronts a touch earlier than the rear, but all 4 wheels will lock up with R comp tires on the car. 

The rear of the Z gets a few mm increase in width because the oem drums are not as thick as the rotor.

The kit gets a 7.5/10. A passing grade. 

I am now looking into a ball joint adapter that bolts to the control arm of the 204z and uses press in 2014 mustang ball joints.

I intend to use this in conjunction with 2004 Subaru wrx coil over struts to allow the use of 5 lug 2014 mustang hubs and brakes. Which are 5x114.3

The intent is to have the outer wheel mount flange be pushed out roughly 35mm.... effectively converting our cars from a "zero offset" wheel to a "plus 35mm" wheel... aka just like the 300z and the 240sx, Toyota supra etc...

It's a front steer, rear caliper spindle just like the stock 240z, once I know what the bump steer geometry will be I will have a clearer picture of things.

Someone could use a widebody or flared setup if they chose to run a zero offset wheel, or use cheap and readily available 350z wheels and have stock track width.

Let me know if anyone has any input on this.  Good idea, bad, etc...

The metal is plenty thick enough to drill and tap for a small bolt, so that's where I'm leaning. Anyone have an opinion on this? 

You didn't say which u-joints were "too soft".  That would be helpful.  

Edit: on another note, my front diff mount is absolutely destroyed. I will be replacing it with a new rubber mount. Is the RT style mount from TechnoVersions needed/recommended in addition to a new stock mount or would I be good with just a new stock mount? It's just a stock R180 + L28, so no big power or anything. I already have to wait a week for the stock mount to come in, so everyone in my dorm parking lot is already gonna think I'm a dumbass while my car is on jack stands for a week. 

Also, if I do end up switching to poly, would something like a rubber washer or sound deadening material on top be a good idea to try to reduce some of the additional NVH? Again, thanks for the help. 

Not sure the best way forward.  I guess I could find the centerline of the car?  The frame rails could be an option, however those have been replaced and might not be perfectly square.  

Any advice welcome. 

Thanks

Hey everyone, just looking for some advice on this problem my cars been having. 1976 280z, the steering will make a pop/clunk noise when I turn either right or left. Sometimes I dont have to turn too much to get it to clunk, and sometimes I have to turn the wheel almost completely over. It will only do this when the car is moving, and only at low speeds as far as I can tell. (It totally might do it at high speeds but i havent turned the wheel enough for it to do so at high speeds). If I turn the steering wheel from lock to lock while the car is not moving, there are no problems and everything functions normally, no matter whether the front wheels are on the ground or in the air. I have already replaced front wheel bearings (NTN), outer tie rods (Moog), ball joints (Moog), sway bar bushings and end links (poly), tc rod bushing (rubber) all other bushings are poly and in good shape. I don't think its the inner tie rods because it only happens when the car is moving. I'm thinking maybe I could have somehow fucked things up on the swayer (although it looks fine), so I might try to take that off completely and see if that affects anything. The other thing i could see it being is a loose bolt or something somewhere causing this, because there have been many other things loose on my car causing me issues. Anyone got any other ideas/advice? It could totally be something obvious that I'm just overlooking somehow. 

Other random thing: does anyone know where this blue wire plugs into and what the fusible link looking things are for in this picture? They are under the driver side dash and I can't find where to plug them in. My dash lights don't work and I'm guessing this is probably why. Can't seem to figure it out by looking at the wiring diagram.IMG_8650.pdf

Thanks for the help! repost since I accidentally posted in faqs

Anyone with 8" wide rear wheels with +20mm? No spacers, etc.?

Thanks!!