Tech Note: The R33 GT-R had ELECTRONIC SUPER HICAS + Yaw Rate Sensor!

So I've decided that, on occasion, I will do a "Tech Note" based on interesting stuff I find in those R33 service manuals I got recently.

So today, let's talk about SUPER HICAS. In the technical/service manuals for the R33, I found this page interesting (I've added English translation in BLUE):

HICAS is one area where there is lots of controversy. Some people swear it makes the car handle strangely and so you are better off without it. Others say it weighs too much - which might be an argument on the hydraulically driven R32 GT-R, but not only the electrically driven 33 and 34 GT-Rs.  (and yes, it's heavy on the 32... but if you remove it, you increase weight bias on the front wheels, which is not something you want to do... and is the reason why the battery was moved to the back in the 33, for better weight distribution. But I digress...)

Anyway, it appears that most people who lock out their HICAS, don't really understand how it works, at least in a technical sense. So, since I found this, I thought I'd share my findings. It won't change some people's minds, but for me, as a purist R33 fan, it confirmed that I want to keep it.

First, what is interesting is that the previous version HICAS, found in the BNR32,  did not have yaw rate feedback control, like the R33 GT-R did. There appears to be a lot of confusion out there with regards to this:
http://www.skylinesaustralia.com/forums/topic/70832-how-does-hicas-get-yaw-rate-feedback-in-an-r33/

http://www.skylineowners.com/forum/showthread.php?t=116708

No doubt, these guys couldn't read Japanese nor did they have their hands on this manual I have. For those who can, see the above - the white is the "normal" SUPER HICAS (found in other 33s), while the grey is what was added for the GT-R.

The take away is that, compared to the "normal" SUPER HICAS, the R33 GT-R (manual doesn't say others) had the yaw rate feedback added, in addition to the inputs for vehicle speed and steering wheel angle.

Here are two photos showing the 33's yaw rate sensor - it's located in the trunk next to the battery:

Apparently there was a preset map of yaw rate values to correspond to the actual vehicle situation according to the driver's intent.  The system would read the actual yaw rate value, compare it against the pre-programmed values, and then cause adjustment to the rear wheel steering to match the driver's intent.

The next page of the manual describes the yaw rate sensor as a tuning fork, piezo-electric, oscillation gyroscopic type. There are basically two types that exist - piezoelectric and micro mechanical: http://en.wikipedia.org/wiki/Yaw-rate_sensor

So I'm not sure if these kinds of piezo-electric sensor wear out, or need to be replaced. Would a purely digital one improve the performance of the HICAS? I'm also curious to know about the software and the pre-set map - how complicated is it?

The white part above could very easily handle having the rear wheels steer in the opposite direction at low speed in a linear fashion, and then in the same direction, at high speed, in a linear fashion.

The grey part - the yaw rate input must therefore be for unusual, high performance/race type situations where the car's rear end is purposely being slipped or where the traction of the road surface is slippery.  Naturally, this raises the following questions on how the MAP has been programmed - What happens when the car skids, or the rear end is sliding? And would there ever be a situation where something would cause the car to "wobble" at speed?  HICAS computer malfunction, for example?

Has anyone had any experience in reading the HICAS Map?

Finally, I wonder what, if any, improvements were made to the BNR34 Super HICAS ECU and its programming. Obviously the 34 has a slightly shorter wheelbase, which means that the rear wheels would need to steer at slightly less of an angle to give the same level of response as the 33. This would suggest that transplanting the 34 HICAS ECU into a 33, would not have a beneficial effect, unless there was something else improved about the 34 ECU, such as better maps, or faster processing, etc.  So I will have to research this...stay tuned!

A First: Professional Interior Detail (warning for those easily disgusted...)

Now this is going to be a tough post. Because the photographs won't do justice to the work done.

As most know by now, I tend to keep my car clean.  Very clean. But I've never taken my car to a professional for any cleaning work - until now.

The primary reason I did this time, was because I had recently driven to a place where, I suspect enough pollen accumulated in my car so that, even with the recently installed A/C filter (and yes on recirculate), my hay fever was still triggered.  I was sneezing so much, and my nose running so much, I had tissues stuffed up my nostrils...

So I had to figure out a way to clean the interior without suffering, and clean it such that there was a significant reduction in pollen.

Enter Kabe-san at RAPT. I've gone to him before in the past for some minor body work and for tinting my windows, but his true profession is auto detailing. So I was curious to see what methods he used as well, perhaps there would be some techniques I could use.

As you can see, pretty busy times for RAPT, right during the Golden Week holidays.

What bothered me most, was the amount of dust in the air ducts, like this, that I just couldn't seem to remove:

See all that pollen, dust, etc. on the bottom of the vent?

Anyway, Kabe-san had told me that he would remove the seats, and use steam. So I was curious to see what kind of difference awaited me.

He was also nice enough, to post on the RAPT blog, the steps he took to clean my car. I've taken the following photos, and summarized the steps from the RAPT blog at: http://rapt.livedoor.biz/archives/1980827.html

First step, before he took the photos, was to clean the dashboard. Then...

Remove front seats

Oh my, look at that dirt under the front seat. Yes, it's been a while since I vacuumed the interior thoroughly...

Adding Steam to loosen up the embedded dirt in the carpet

Using a "rinser" he then vacuumed up all the dirt and grime

Wow looks cleaner already!

Here is the driver's seat before any work

The Japanese description talks about how I was concerned with "sebumsebaceous matter" - in other words, 17 years of human sweat and oils...

Steam to break up the oils

The "rinser" again to vacuum it up...

I am assuming that this brownish matter is... organic??

The dirt just from the floor

Thank the lord this was dirt from the carpet, not stuff embedded in the seats!

Nice and clean after the steam cleaning... letting the seats and floor dry.

I'm not sure why that (seat) bolt is on the floor there, lol.

This looks clean

He didn't mention in his blog, but it's clear he steam cleaned the cloth inserts as well (after this photo was shot).

But using a special cleaning solution and sponge he rubbed this off...

After the above, he finished off other sections of the car, including the trunk!

He also told me he used a special tool to clean the vents:

You can see there is much less dust here!

What the photos don't show, is how the cloth materials now feel cleaner - like brand new - and the car smells different.  Before it had a slight industrial smell, but somewhat "manly." (a combination of smoke and engine blow-by... or so I thought)?? But now the car smells like new car...

Interestingly, Kabe-san told me that the previous (and first) owner of my car was a smoker (I'm not)!  To me, everything looked very clean, but apparently when he steam cleaned the ashtray, there was some tell tale brownish runoff - Kabe-san surmises the previous owner must have smoked with the driver's side window open, arm resting on the armrest... And actually, this explains why my armrest shows some wear there (the cushioning is gone).

He was also kind enough to put an "after" photo up on his blog.

From: http://rapt.livedoor.biz/archives/1981355.html

Unfortunately the photo is a bit blurred, but it would be hard to tell from any photo the difference, especially as I keep my cars relatively clean. But as I stated above, the difference is readily apparent from a tactile and olfactory perspective!!  And yes, no more pollen!

Anyway, given the pricing, which is very reasonable, this may be something I do once a year, as I do love the new car feel and smell.

PS - One thing we discussed afterwards - does anyone know of any makers of high quality automobile carpet? Would love to do such an upgrade...