ACEMANN

I figured since I would be mentioning "custom mounts" and asking about swapping around motor mounts this would be the best place for the question. I assumed that if the custom mounts for the Z32 are designed for an RB25/26, there might be issues with the length or angle of the RB20's aluminum mounts versus the RB25/26 aluminum mounts. If I can swap around the aluminum mounts from the various motors, then I might be able to get away with using the custom 25/26 Z32 mounts with the RB20 IF there is such a problem. Longitudinal placement could still be an issue - again I do not have the resources to investigate. RB26's are terribly expensive, with 25's not too far behind. It would be nice to find an RB20 solution for the Z without the "premium" price tag. There are still logistical issues with finding 25/26 trans units and mounts - it really interests me since no one has even looked into it. Yes the R25 or 26 offers more, but the RB20 is capable of decent power. Personal preference really..

Oh wow - thanks! I'm in the US and no one here could give me a straight answer. I have access to custom RB25/26 mounts for my project (RB in Z32) but not "specifically" for RB20. I'm sure the 25/26 mounts (aluminum structure) are somewhat different lengths than the 20 units, but as long as the 25/26 mounts can bolt to the 20 block (like you say they can) the differences in mounting position should be neglegeble. If anyone has a second opinion or has additional experience please feel free to add to this. Thanks again!

Just wondering if anyone has had the opportunity to compare the RB20DET motor mounts with the ones from the 25/26 motors. Not just the rubber mounts (which from GTS-T to RB25/26 conversions seems to work) but the actual aluminum mounts that bolt to the block. From what I have "heard" the answer is "no" and I would tend to expect that much, but ANY insight would be appreciated. I just don't have the resources to look at this myself.

I need help: does anyone know if there is a difference between the transmissions supplied with the RB20DET vs. the RB25DET? My main concern at the moment is if the bellhousings are the same (interchangable). Any info on the differences would be appreciated! Thanks... Cameron

<_< Nothing like motivating peers This is the ORIGINAL link to the image...it is on Nissan Japan's website at this resolution and size. I dunno if it can be read if the original image is lame as well: http://history.nissan.co.jp/GT-R/9901GT-RF...IMG/ch_a3_h.jpg Thanks for any help, and even looking...

Did you click on the "View Pictures" link? It brings up another page that displays a small thumbnail of the diagram...when you click on it the larger image will be displayed. I have a link to the original diagram...I dunno if you can read it though: http://www.skylinesaustralia.com/forums/in...pic=70832&st=20 It is about halfway down...I appreciate any help! Even partial translations will give me helpful clues...

Doh...I used the actual picture's link...not the shared link. I updated the link in my first post... Thanks

This is the last HICAS document I have in need of translating...it explains how the R34's Yaw Rate Feedback Super HICAS calculates the rear steering angle. I have only a few lines in the picture that need translating, and I circled them in red. I have many HICAS related documents, and the complete R33 wiring diagram with wire colors and their functions...a by-product of my HICAS install in my Z. I promise your efforts will not go to waste! Here is the link...hopefully it will work: http://share.shutterfly.com/action/welcome...=8AZsm7Fm4cOGEQ Just list the translations as if you were reading top-down. Thanks guys...soon a wealth of HICAS info will be upon you... -Cameron

Thought I'd give an update... I am still waiting for my wheel bearing to come in...the only reason that I haven't installed the HICAS yet is because I want to pull the spindle and do all the rear suspension work at once. I have also installed HKS Hipermax II dampers since the HICAS system install. Looks hella awesome...and rides like a dream I have all of the ball joints, snap rings, bolts, etc to attach the HICAS actuator to the spindles. They are new of course! I have also aquired the steel sheet metal (3/16 inch thick hot rolled steel) to make the bracket that holds the actuator. I will minimize, if not eliminate, the need to weld the assembly. All bolts are Grade 8 of course. I'll probably get a few things seam-welded, but for it to actually function, it won't be necessary...more of a long-term durability precaution. Over a month, and no HICAS codes! It has been in my hatch the whole time, actuator and all lol. Covered up by a white towel... I will also post the wire colors, and a revised R33 system schematic later down the road. Nothing real soon, but I just want to give a little back for all the helpful insight this forum has given me. I have yet to reveal my creation to the stateside Z32 community...but I will soon enough...hehehe More pics and, maybe (if I can find the space), a vid of the system in action on the Z...more to come!! Cameron

bump

LOL...just realized I never posted pics of the HICAS module...here you go: http://share.shutterfly.com/osi.jsp?i=EeAM2TdizcOHDkg

Here are the pics: http://share.shutterfly.com/osi.jsp?i=EeAM2TdizcOHDi4 I added a few pics of the exterior of my car ('93 Z32) at the end...at 100K miles she doesn't look too bad don't you agree? And yes I know...I have fender gap...due to a diet. Suspension is coming very very soon. Hope you enjoy the pics and feel free to ask questions about what you are looking at! I will be working on a bracket design for the actuator when I find some time...hopefully I can get my local Z shop to fab it for me. They are really good with custom parts (intake manifolds, headers) and shouldn't have any trouble. NOTE: I had trouble clicking on the pictures on the first page...go ahead and view the pics on the second page, then go back to the first page...then it works fine. You might just want to go ahead and "view slideshow"...just a little FYI... Enjoy!

Pics will be uploaded soon...I took quite a few during the install. I'll probably just link the hosting site, it'll make it easier to view them. But yea, it works. LOL...I am so amazed I pulled this off...I'm not tripping any HICAS codes. I ran the diagnostic and at first came up with with a Main and Sub-Sensor code (note that I wasn't tripping the warning light during normal operation though). A quick scan of the service procedures ooutlined in the R34 manual descibes that this code can displayed under diagnostic conditions because the last known value for that sensor does not match what is being sensed. Makes sense, considering that the HICAS actuator came from an S14 and the control module came from an R33. Essentially the rear angles didn't match. After I ran through the full diagnostic the codes cleared (under diagnostoc mode). So, I have all inputs functioning perfectly. Amazing! FYI...I haven't mounted the actuator just yet...it is sitting in my rear hatch with the rats-nest of wires I have at the moment I think you guys will like the control box I made...I can switch off ALL power to the HICAS system just like I planned. I swear I about crapped my pants when I made the actuator move while in diagnostic mode...a very very rewarding experience indeed!! I can't really tell when it is moving while I am driving...mostly due to the fact I can't turn around while driving (not a good idea). BUT , I can hear the relay click above certain speeds and around some turns, telling me the control module is switiching power to the actuator. Like I said though, I am not tripping any codes, and I have performed the diagnostic many, many times. Like I said though, I've yet to mount the actuator, but I'll get that fab'd soon enough. I'm going to design a bracket that uses the existing lower-link bolt holes. The actuator will be bolted to the bracket, and the bracket bolted to the lower link bolt holes. I'm going with steel of course. For the curious, I have detailed drawings and have documented what I have been doing (no essays, but I kept track of things). I'll try to get the photos up tonight!

IT WORKS!!!!!!!! SUCCESSFUL INTERFACE BETWEEN R33 YAW-RATE FEEDBACK ELECTROMOTIVE SUPER HICAS AND Z32 FAIRLADY!!!!! MANY PICS SOON!!!! yea, I'm a little happy :uh-huh: -Cameron

lol...that would be pretty sweet. I have no clue as to how much that would cost...just finding the parts would be hard enough. I haven't seen too many G35x's running around, let alone wrecked already. Does the Stagea have the FM platform as well? I didn't know that. An AWD/4WS TT Z33 would definately kill some Porsche's, and maybe a Ferrari or two

That is a good point...I didn't really take into account the diagram is really just an advertisement on how the system works...not a real world setup and definately not a REAL system diagram. Funny thing is that you should mention this now...I considered that the rear steering angle sensors might be utilized for yaw calculations, but I just assumed they were used for motor control feedback. Another reason is because the Z32 has a similar actuator (electric of course), and it has two rear-steering angle sensors as well (steering angle main and sub-sensor). I thought "Why use these sensors when Nissan can design a control unit with gyros, etc" Well, this patent made me think different: http://patft.uspto.gov/netacgi/nph-Parser?...=hicas&RS=hicas Quote from above patent "In the instant embodiment the variable steering characteristic controller 19 can take the form of the rear wheel auxiliary steering device which is referred to as "Super HICAS" and which is disclosed in Nissan Skyline RS32 type vehicle Service Manual No. 622 pages C-97 to C-104 (published in May 1989) and English language publication entitled: NISSAN SUPER HICAS (EO-2000-8908). " This statement means nothing until you realize that the patent I just linked is for a Traction Control System that is spec'd to use either rate gyros or g-sensors to detect deviations from the desired path. This patent is really for a "Yaw-Rate Feedback" Traction Control System...if HICAS is indeed substituted, then you have "Yaw-Rate Feedback" HICAS. And what is a major problem with the older HICAS? In some situations it begins to produce understeer, because there is no way for the HICAS system to recognize if the "target yaw rate" is being held. Read the abstract for the above patent: "In order to prevent a traction control system and an auxiliary steering or the like from combining stabilizing effects in a manner which causes excessive understeer, when the traction control is functioning in a predetermined manner, a signal is issued to the auxiliary steering control and reduces the gain with which the control thereof is implemented. As a result excessive understeer is avoided while maintaining suitable vehicle stability." Now, this is what changed my thinking as to how Nissan would gather Yaw data: "It is further possible to use the outputs of the wheel speed sensors and to derive the vehicle yaw rate in place of the rate gyro 17 if so desired. In addition, it is possible to use the difference between the actual and target yaw rates for feedback control purposes and use the same to derive the duty cycles of the signals which are used to modify the amount of torque which is permitted to be transmitted to each of the driven road wheels and thus enable the division of drive torque therebetween to be controlled." So, they outline using either G-sensors, Gyros, or the wheel speed sensors to derive the vehicles actual yaw-rate. They don't mention using any type of rear-angle sensors, but knowing that there are NOT two distinct wheel-speed inputs into the HICAS control module leads me to believe that another method must have been used. The simple fact that so many methods were proposed to compute yaw rate, right down to using wheel speed sensors, makes me realize that the engineers were pretty open to using any option available to gather that data...this proves that they did not limit themselves to using expensive gyros. Whew...enough typing, but I seem to be closing in on how this system works. Maybe someday HICAS won't be such a big mystery...

Here you go: http://300zx-twinturbo.com/cgi-bin/manual....efault&total=98 hope this helps...and as far as I know, the Z32 and R32 systems are the same (??)

I am not familiar with how the R32's system is set up...but I am trying to understand what you want to do. Is wire 53 on the ECU or HICAS control module? You are right though...if you can verify the continuity between the HICAS control module and ECU, then you can rule out busted wires.

Found this on Nissan Japan's website, for the R34: The picture is titled: Yaw-Rate Feedback Electromotive SUPER HICAS System Figure It seems there really IS a yaw-rate sensor feeding data to the HICAS control unit...please note the cylinder-shaped object directly above the right-rear wheel. By using an online translator, I have been able to determine that the caption for this "sensor" pictured above the right-rear wheel is a yaw sensor. The text comes to within 2 characters of a direct translation (English to Japanese) of "yaw sensor": English: Yaw Sensor Japanese: ヨーイングセンサー Compare to the text displayed within the diagram This diagram displays an undisputable implementation of a yaw sensor of some type, feeding the HICAS system directly. After seeing this diagram I am even more confused as to how the system works...every schematic I have gotten my hands on (both R33 and R34) do NOT show ANY "yaw sensor" inputs of any kind going into the HICAS control module. That is why I assumed that the sensor must be on the PCB's themselves, but after a very thorough examination of the PCB's, there is obviously NO sensor of any type...I thought I had this cracked! :confused: Opinions??? BTW...the two white boxes seem to represent the "target states" of the vehicle's yaw motion. The top box seems to be the "ideal" model (i.e. steering angle, vehicle speed) while the bottom box seems to be the more complex of the two. It looks like it takes the result of the first calculation, and feeds it into the second calculation, as well as taking into account the vehicle speed and steering angle once more. Finally, it takes the actual yaw motion of the vehicle via the yaw sensor and compares it to what was desired. I guess some type of really complex subtraction takes place to see what needs to be reduced or added (for the rear-steering angle)...OK, enough...LOL Interesting movie for HICAS: http://www.nissan.co.jp/STAGEA/M35/0408/ME...ECHA/main2.html FYI, I also finished my schematics for the HICAS interface with my zed...should start wiring next weekend...woohoo!!

The HD6475328CP10 semiconductor is a 16 bit microprocessor made by HITACHI...there are two of them on the R33 HICAS module. Datasheet: http://www.digchip.com/datasheets/parts/da...475328-CP10.php I'm not seeing any piezo gyros or anything that could detect yaw motion...it must be recycling the calculations to fine-tune the output...???

Ok, last post for today, but I ran into some really interesting info...I found more patents from Nissan that pertains to HICAS...electric HICAS...as well as another patent that dives in to the mathmatical models used. Here are links for the brave "Vehicle Motion Control Apparatus" http://www.freepatentsonline.com/5957987.h...ghlight=5957987 "Vehicle Steer Angle System Based Upon Mathematical Model" http://www.freepatentsonline.com/4840389.h...ghlight=4840389 I have hardcopies of the following: "Four Wheel Steer Control System" http://www.freepatentsonline.com/4893690.h...ghlight=4893690 Development of "Super Hicas"--A New Rear Wheel Steering System With Phasereversal Control http://www.sae.org/servlets/productDetail?...&PROD_CD=891978 Steering control system for wheeled vehicle Contains info on the "Mild" and "Sporty" modes http://www.freepatentsonline.com/4949261.h...ghlight=4949261 Be sure to check out the Patent References as well...most are linked to similar systems by Nissan. Now for pics of the HICAS control module PCB's: http://share.shutterfly.com/osi.jsp?i=EeAM2TdizcOHDgw Just follow the link and click "view pictures"...you can view them individually or as a slide show. For the curious, here are the part numbers to the two big IC's you see in the pics Left IC Sticker 19US 80 31022 Right IC Sticker 19UM 80 31022 ID info on BOTH IC's 3K1 J HD6475328CP10 Japan Now, after reading all this info, pouring over schematics, and seeing the PCB first hand, I am in serious doubt (arrgh...again) as to the use of a "real" yaw rate sensor. There seems to be quite a bit of "feedback" (my god how many times have I said that word LOL...) of the orignial yaw-rate calculatons into other parts of the program AFTER the steering angle has been calculated...somewhat of a "check" in the system without sensor input...I might have that wrong...I dunno. Don't get me wrong, I don't feel as if I know everything about this system...really, the more I read the less I realize I know But hey, makes for a fun summer project before school kicks up again! Enjoy the info, and I look forward to any comments!

Thanks for the complement...I agree with you, I should be ok with the HICAS actuator disabled as long as I don't drive too hard. From what I have read, most guys that do this get away with it without too many problems. Of course, I would only do it when necessary, and I could turn it on immediately... As for your comments on HICAS and track use...I agree totally with what you said. Everything I have read (and personally felt) about HICAS was that the system was designed to give superior handling (high & low speed) on the street. Quick, high speed lane-change maneuvers, high speed stability, and more precise handling at moderate speeds (backroads anyone? :uh-huh: ) was what it was designed to augment. I wouldn't drive with HICAS on a track either...the actuators aren't fast enough, and the software just isn't written for the track environment. It might be a month or so until I finish the schematics, but when I get them done I'll post them in a dedicated thread. Hopefully it will alleviate some HICAS woes...at least you will know where to look, and what wires to check.

Yea, the electric HICAS was introduced in the '94 Z32's...but the system was not the same as the R33's. The control modules looked completely different, and there was never any mention of "yaw-rate" anything. What is even more strange to me is that they NEVER used the HICAS system from the Skyline in the Z32...they just stuck to the original system, albeit electric in later models.

I have verified ALL HICAS signal wire functions, colors, and pin assignments. I also have a system schematic drawn in the R34 PDF format...much easier to read than the R33 schematic. Right now it is hand-drawn, but I will whip up an electronic one soon enough. Big thanks to Alex Au on SDU for letting me have the Super HICAS steering chapter for the R33...I won't be giving out the the chapter, but my custom schematic is easier to read and has much more info. I have taken photos of the HICAS control module PCB's as well...maybe I can get some feedback on what you think you see. There are two big IC's with the same part numbers, but different "labels" (they have stickers on them with more ID numbers). I am trying to figure out where the yaw sensor is (be it a piezo gyro or the like) but it doesn't seem to be very obvious. I'll try to post pics later tonight...well, in the morning for you guys... I have also obtained SAE documents on the Super HICAS system...it is VERY in depth (control algorithms are explained, system schematics) but it only covers the pre-electrical system, and no yaw-rate feedback systems are explained. However, it is very obvious that any type of yaw data fed back into the control parameters would greatly enhance the responsiveness and accuracy of the system. In addition to the SAE article, I have also obtained 2 patents for the HICAS 4WS system...once again, no electrical / yaw systems are mentioned, but it is extremely in-depth. All the articles are dated 1991 or earlier, and I couldn't find any HICAS information after those dates. I guess all the modifications to the system were kept in-house at Nissan and not disclosed. Did you know that Nissan engineers wanted to incorporate a "Mild" and "Sport" setting for HICAS back in early '90? I didn't...it made me realize that Nissan must have made compromises to the system...it could be way more responsive, as the control algothims show a big difference in some of the constants used to compute the steering angles. Crazy stuff... And if you are wondering why I am even doing this, well, I am going to install the yaw-rate feedback electric HICAS on my NA 300ZX. Don't flame...I have ALL hardware, and have already drawn the necessary schematics to integrate the system into my zed...power supply, fusing, relays, signal wires, etc, etc. I have also designed a custom wiring harness (nothing hardwired here...using AMP connectors). I am also going to incorporate my own "HICAS lock" by installing a switch for the HICAS system power...I can turn it off at will...EVERY part of the system, not just the actuator. This will come in handy if I have to drive on crap roads, gravel, or if I just don't want the thing on. Also, the way I designed the harness, it will be really easy to diagnose any missing or busted inputs. I guess the big question is "Why??", and all I can say is "because I can" hahaha PCB pics soon, as well as the schematics for you R33 guys that need some diagnostic info...

Actually that does make sense..."SW" refers to a switch. This must be the parking brake switch input. Actually, I thought I had already found that but I guess I was wrong. Now I need to figure out what the other switch was that I thought was the parking brake switch lol Thanks!