Dr. Marus or: How I Learned To Stop Worrying and Love the RB26DETT

[bobbo]

I never had any issues with the AMS rotors and they certainly saw some abuse.
$hi+ Marc sorry to hear about your misfortune with your parts. If I were you I'd try to contact Vuk and inform him about this. Although we all know nothing will come of it at least you exercised due diligence.
Do you still have your oem RUCAs?

[EMAGDNIM]

wow, i didn't see that coming about the AMS RUCAs, but not really that suprising in the end, but bejesus it will be one of the first things to check this upcoming season

Really? Didn't they have a big issue with their Z32/GTR links a while ago? And then there was the rotors...Lots of people swore their parts off then.

[frankiman]

wow, i didn't see that coming about the AMS RUCAs, but not really that suprising in the end, but bejesus it will be one of the first things to check this upcoming season

and about the DW toe arms, i have problems with the rod ends getting really loose, obviously the rubber covers are completely torn too, i already found the right part number from a high quality manufacturer (aurora) if i ever need to replace them next season,

at one point, i would hear the rear left rod end "clunk" everytime i would get in or out of the car, so i took the rod end off, cleaned it, greased it and put it back on my duct tape to cover it

[MarusGTR]

2013 - Put me down; Things going wrong (Part 3)

While the inspection of the front suspension hadn't been exactly a joyous occasion, I still hadn't completed my assessment.

I was already loathing what I could find at the back of the car.

As I had been taken aback by the state of my front tension rods, I judged that it was time to make a thorough inspection of the bushings and links. Naturally, I started by checking for lashing by the classic way. The rear wheels were still on, so by grabbing the wheels and swaying them in pitch and yaw I could check for looseness. Nothing, stiff, on both sides... until I noticed a bit of a clunk sound on the right side. No play, just a clunk. A barely audible version of the clunk that would drive me crazy on slow bumps.

It was time to take the wheels off for a visual and more agressive inspection. I tried to spare myself the trouble and kept the rear left, that is what I was sure was the source of the sudden metallic noise I had experienced, for last.



I started by sliding myself under the car and pulling the right Driftworks toe arm.

*clunk* *clunk*

It didn't help that I immediately noticed the torn rubber covers on the pillowballs. In no way in hell they expected the rubber to actualy clear the subframe mounts. Also the paint made me reminisce of my old Tonkas from when I was a kid. Just old thick paint flaking in big chunks. Another dissapointment in super duper "brand-name" parts.

Still, the more I pulled, the more I focussed on the arm itself, the less I thought the arm was at the source of the clunk.

*clunk* *scrape* *clunk* *scrape*

"That's a new sound."

It then occured to me that the sound was coming from the same level as me, next to my head. The jackstand adjacent to my face was coming loose.

Welp that was a scare. A quick reset was due.

While I was putting the car back on the stand, something caught my eye.

... and would you look at that.



Hmmkay, completely bent rear swaybar link.

Although this wasn't the worst of it. I started pulling on the rear traction rod, nothing, AMS RUCAS, *clunk*.

*clunk, clunk*

*clunk, clunk, clunkclunkclunkclunkclunkclunk*

In my bit of anger I had taken off some grime off the welds of the knuckle mount.

Well I had to sit down for that one.



Don't see it? Here, let me help you.



Clean through. And it looked considerably aged from the oxidation. A year old, maybe?

It then went through me like lightning. I went to the left side, took the wheel off.



It was fresh, as I had suspected.

So I sulked and did what I've been doing for the past few years to keep me going, count my blessings. I was mortified of what could have happened that day at the track if I hadn't went so slow in the corners. I'm glad I had made that call.

That night I took the numbers off the rear windows. I wasn't a race driver and this wasn't a race car, not in the foreseeable future anyway.

It would only be a few days later where my dread would truly sink in though.

[MarusGTR]

2013 - Put me down; Things going wrong (Part 2)

So I had a fancy new intake shield and the interior was functional. It was time to go for a ride in the backroads.

Which I did, hoping to see some magical changes to the still-too-rich AFRs, but nothing. Ah well. Nonetheless, she was running like a top and as I was driving back home I brought her to... er, a high rate of speed and flew over a crest, to which the suspension came unsprung and suddenly loaded again.

*KLANG*

The sound came from the left rear of the car, I was sure of it. Still when I (obviously) bled off the excess speed, I couldn't feel anything wrong. Fortunately it was a very short trip back home, so slow and steady she went. Now back in the garage I lifted her up on all four corners, something that I had become oh-too-accustomed to.

My first hypothesis what that one of my coilover bushings had failed. I had been having a nasty slow-speed clunk in the past two years that I been driving me crazy, and I had bought Whiteline bushings to replace the strut mount bushings. How did I know that the Whiteline bushings would fit my ZEALs? I didn't. Well actually, I compared a picture that I had taken a year prior of my FL coilover's torn bushing to what was picture on the Whiteline site. I mainly concentrated on the scale of the cylindrical lip of the bushing to the shaft's hole. To my eyes they matched up. Yeah, big gamble, but I was desperate as apparently no one on the whole interwebs has even changed their Skyline's coilover bushings (including an unanswered thread I made on GTRC).

"Problem? Just pillowball this and pillowball that", ...right.

But even before that I had to inspect something that I had put off for too long. I knew for certain that it was going to be bad news, but ignoring it wouldn't make it go away.

The front AMS control arms.



My front wheels had been holding on for dear life since the control arms had failed at the track, and I needed to see how mental I was with still running them. I checked Bobbo's patched up FUCA first. Turns out I was completely mental.



The right collar had been the one crushed at the track. On what, I still to this day don't quite know. There were no indentations on the body, only on the (soft) clamp. My guess would be that they hit the inside of the kingpin arm at the angle between the two would get extremely acute as the unsprung assembly would rise in compression. That consideration would be taken into account later.

But for now, I had to accept the fact that I couldn't let myself drive the car like this. Basically, I had come to the exact reason I had delayed my inspection.

The first issue was the collars. While Bobbo's fix did hold the collar in place, and I hadn't detected the same front to back play as I had at the track, the locking mechanism was completely useless; the mounting end was free to rotate, there was no pressure on the threads. However, with the ends seemingly in great structural condition (except for the bushings already binding a bit...) I resolved to taking the arm apart, cleaning it and using T-bolt clamps to lock the assembly into place.





What's the little metal wires, you may wonder? They're the collars' threads.

Its only later that night I realized that maybe the problem was with the engineering, not just the materials. As I was lurking on Skylines Australia, I came across a thread debating a few local tuner shop designs, with one featuring a control arm extremely similar to the AMS control arm (in fact I'm willing to bet they're the same). They came up as being a 300ZX variation of a control arm designed by a Japanese tuning shop, Midori.

However, the further discussion on SAU of other control arms thread made me realize the idiocy of the Midori design. The threads were clamped. This meant that they were locked purely through interface shearing. This meant no thread deflection. its hard to convey, but I guess I could put it this way: this locked the coaxial movement but nowhere near what was needed to lock rotation.

If you've ever looked into why you should torque bolts to spec, this was the equivalent of properly torquing a bolt, to hand-snug.

So now I had total distrust of the control arms. GREAT. Its wasn't enough I didn't trust the car's capabilities and cheap parts before, now I couldn't even trust the principle of its FUCA's design. So T bolt clamping was out the window. That night, I decided on improving the Midori design. I actually came up with the solution as I got to sleep. It was a relatively simple modification, but some of it would need some machining.

So the next day I went to a local machine shop with a CAD drawing of my modifications. The manager, a guy about my age with good machining knowledgeability. He had another project in the works, modifying a pump action shotgun for competition use, so he had to put my work into backlog. So we discussed my material options in order of cost; aluminium, carbon steel, stainless steel. I went with carbon steel, since it was going to be a friction fit, but ideally I would have went with a two piece aluminium/chromoly design. Also, fastfoward to the end of the summer and the carbon developped (as I had anticipated) a nice thin coat of surface rust, even if I did coat them in grease prior to assembly. Beggars can't be choosers. It was a temp fix.

Turns out the machinist was pretty impressed with the simplicity of my solution. He asked if I had considered making arms from scratch, after which he proposed (out of the blue) that I should start a product line, which he'd back up with his machine shop. Oh okay, wow. Even if I didn't do a structural analysis of my designs we started talking about how much it would cost to build units simply on the complexity and materials. We could only come up with a competitive price at 10 units minimum (each). It was a fruitless but entertaining exercise.

I left the parts with him and it would take a few days for them to be completed.

So why the secrecy and lack of pictures? Well one of the designs I came up with (and improved my AMS FUCAS) could certainly, in my opinion, compete with what's currently avaiable on the market. Instead of locking by clamping pressure (e.g. Midori) or by classic turnbuckle (e.g. Stillen), I was using both at the same time, in the same component of the part. No wacky gktech-style fancy-dandy engineering, just pure solid function. So maybe one day, if I ever get the chance to test my designs on my car, I'd like to produce them.

It's nice to dream (again) but I had to go back home and continue working on the suspension.

So I took the front coilovers off and proceeded to clean them, grease them and reload the springs with the new Whiteline bushings. Fun fact, the black whiteline bushings are actually a very deep translucent red. Yum.





Guess which is which.

Like my fancy jig? Turns out the mount angle was 60deg, not 45deg. Oops. Close enough though, as with bushings, the less you rotate the damper shaft, the less chance you have of tearing a diaphragm.



As I was working on the front of the car, I also started thinking about swapping the brake fluid from DOT3 to my Motul DOT5.1. The DOT3 in the reservoir had already been changing colour (probably from dissolving what was left of the grime that had been caked in the system) so it was due for a change. But while I was at it... why not put some stainless brake lines in the front? I ended up finding some used Goodridge brake lines on GTRC.

This came at a right time because the car wasn't about to move anytime soon.

As I was putting the coilovers back on I noticed that, with the whole unsprung assembly was drooping on the LUCAs and tension rod, that the tension rod bushing wasn't looking too hot. Like veiny about to burst not too hot. Lo and behold.

I'd have to change them too.

[S13Jordie]

I have to say that I absolutely love this thread. Its refreshing to see someone making parts (well) and not buying everything off the shelf. Not to mention the updates are thorough and pictures are of decent quality. Makes me wish I could work on my car (I have to wait until spring for that)



Keep It up

-Jordie

[MarusGTR]

If you do the calculations, you'll probably find out a stock airbox panel filter flows slightly better than both of those pod filters combined. Main problem with stock airbox is getting enough air to it.

My thoughts exactly. That's one of the reasons (other than simplicity) that I settled with the heat shield, not knowing what kind of intake flow I required. It's interesting that, in the same vein, I think I'd keep something similar to the stock box on an R34 or R33, being that they're fed fresh air from an appreciably-sized induction box in the hood, they must be good until 500-600hp (just look at the Z-tune, even if it is in Kevlar, not plastic). Still though, I can remember the mental difference in sound that pods made to my car, from nothing to total awareness of the induction process.

Anyway, I'm glad (and surprised) that you guys like the shield, I wasn't sure if I had pulled it off.

[Skym]

I like.

I'm sure I could have made a better design with more than a 30$ budget. I had actually started with another design idea, a fully functional three-piece box design for the apex'i intakes that could be easily dissasembled at the track, but it would have required some proper CNCing and industrial bending. But if I'd go ever go that far, I'd be better off designing my own intake -box- from scratch and use a rectangular apex'i filter. Simpler and more efficient (I think?).

If you do the calculations, you'll probably find out a stock airbox panel filter flows slightly better than both of those pod filters combined. Main problem with stock airbox is getting enough air to it.

[bobbo]

If your ever back this way we could take your car to my buddy Steve. For $100 he'll corner balance your car and give it a basic set up.
He sets up suspensions for a Porsche Cup team. He's got skills.
... and yes. I'd be happy to take you out for a lapping session so you can compare.
BTW your build thread is way more interesting than mine. So much passion!

[MarusGTR]

Hahaha oh I knew it was a joke, hence why I took a jab back (actually, I had ment to put a smiley in there). Hey, tts the only thing I can do to save face right now, honestly I don't even know if I can drive truly fast since I purposely do not.

You're absolutely spot on about the logging trail analogy, the inconsistent loading in those corners just psyched me out, I didn't want to break anything. You also might be on to something with the spring rate, again it would be great to compare with your car. Although, I think my car with ZEALs is softer than when you tried it at the HPDS, as it had the old KYB shocks. I dip the car around 5mm on the driver side when I'm in it. That makes me think about damping rate too... too much bound would make the car jittery in inconsistent loading.

[bobbo]

"Over reaction stations-Over reaction stations"
I'm just picking on you Marc. Hence the winky face. I would never sincerely comment on someone's speed on a track or anywhere else for that matter. Unless it was a Porsche owner. They never seem to be able to drive.
If I'm to be completely honest it doesn't appear to be your driving or HP with your car. I'd take that bet you want to make and put it on your spring rate being too high for that track. It's very common for Japanese a/m suspension to have high rates. Their tracks a very flat and smooth. AMP is a logging trail in comparison.

[MarusGTR]

I've seen you drive. It's safe

Shots fired SHOTS FIRED!

For those of you, including our resident nautical chrome-dome here, who forgot about the issues I've raised on AMS control arms we'll soon see that I found some surprises that showed I was right for bleeding off so much speed for the corners. At least going slow I kept the car in one piece, not in pieces.

BTW, put your money where your mouth is and give me your car for a spin around the track sometimes (seriously I'd love to gauge it). If I'm so slow, there'd be nothing to worry about, right?

I had actually tried early in 2013 to figure out with 240sxcollector how we could lease a whole vacant parking lot or the old airfield used by MMSC to for a day during the summer, to do a custom skidpad and see the car's limits. Obviously, it didn't happen. I had expected to have some sort of income by then.

PS: I've said before, one day I'll take you up on a race. But this time, its for money. Lets say for the value of a used set of coilpacks and a couple sets of spark plugs? Those BKRs made a shitshow with my ignition btw . Give me a few years and I'll get back to you.

[bobbo]

Also I think one plate by itself, painted, would have chipped off from wobbling/vibrating at high speeds.

I've seen you drive. It's safe

[MarusGTR]

Blocking off the whole area like Franki's so that the exhaust-side and firewall can be air-cooled, is a better idea, yes. But I didn't know if the intake piping is fed enough air from the little box intake under the passenger light, so I conceided in making it more as a shield to block off excessive heat from the turbo side (and I found that it was actually noticibly cooler to the touch on the intake-side of the plate than the hot-to-the-touch exhaust side of the plate). But this brought a flaw in its simplicity; less cooling/venting for the turbos. Although, I did partially account for it. You may notice that there is a little flap on the big inward bend, the one that goes under the IC pipe; the flap blocks air from hot turbo-side air coming out to the intakes but lets air in.

For the double plating, it actually wasn't for the sake of cutting conduction. I thought the additional stiffness was necessary so that I could properly control my bends without warping the planes, make the lines straight and sharp in addition to making it structurally sound after installation. Also with some added thickness I was able to smooth out all the edges and with the paint it really looks like a proper big production item, it looks like it belongs in the engine bay. With one sheet just sanding it by hand it would have lost its shape, the grinder would have simply mauled it.

Also I think one plate by itself, painted, would have chipped off from wobbling/vibrating at high speeds.

I'm sure I could have made a better design with more than a 30$ budget. I had actually started with another design idea, a fully functional three-piece box design for the apex'i intakes that could be easily dissasembled at the track, but it would have required some proper CNCing and industrial bending. But if I'd go ever go that far, I'd be better off designing my own intake -box- from scratch and use a rectangular apex'i filter. Simpler and more efficient (I think?).

[bobbo]

Wouldn't make any difference. Minute detail. I'm holding out for an ARC air box.