R33 GTR Rebuild + Upgrading

[Duncan]

The more plates on the clutch, the less movement you have at the point where it is slipping/biting....it just takes some getting used to.

To be fair, I am comparing it to a standard clutch while I think you might be comparing to high clamping single plate clutch. The high clamping clutches are one way to hold far more power with a single (and that is what I have to use on the race car because of regs), but the downside is their driveability is terrible pulling away from a start, they are like an on off switch and also tend to shudder.

The other thing to be aware of is whether the clutch is sprung centre or not. Non-sprung centres are only suitable for race use, they exacerbate the problems at pulling smoothly from idle, and the shock when changing quickly can also break things....the unspring OS Giken triple and quads are a good example of what to stay away from for road use.

[soviet_merlin]

Thank you Duncan! That explains a lot. There are lots of comments on setups being good or bad to drive, but never what it is about it specifically.

I noticed the change in bite with the clutch but didn't know it was a thing. Say with a stock clutch there's about 10cm of clutch pedal travel between the clutch starting to bite and fully clamped. With the twin plate it's down to what feels like 4cm of pedal travel for the same. It does make it a lot less forgiving to drive. But after getting used to it I find it's really not an issue. I haven't driven a stock Nissan, but I don't find it any worse than driving a stock BMW or VW for example. It's possible to drive smoothly with it. Can take the in-laws or the dogs in the back and basically go full chauffeur mode and no one is the wiser. Though it's not in a GTR and it's not running 400kw either.

This is very much in contrast to some cars I have seen at events where people struggle parking their Skylines on an open parking lot on a level surface. Lots of revving, jerky clutch engagement and stalling. Probably running much more racy setups.

My main issue with that specific single plate clutch was actually that the clutch pedal was super heavy. I also have skinny nerd legs so that may add to that. The clutch pedal feel for the twin plate is so light it doesn't feel much different from any OEM clutch.

This may be one of those things where everyone's experiences and what people consider nice or not may differ quite a lot

[Predator1]

On 03/09/2023 at 10:50 AM, r32-25t said:

Ok fit gktech fan and when it keeps getting hot please post back here saying “you were right” thanks in advance 

I'm gobsmacked to hear people actually think the GayTek fan is an 'upgrade' for the RB motor... Either way, goodluck /unsub.

[oSkylines]

58 minutes ago, Predator1 said:

I'm gobsmacked to hear people actually think the GayTek fan is an 'upgrade' for the RB motor... Either way, goodluck /unsub.

I assume you missed the part where this was clarified , the order canceled , and a stock fan ordered in its place . I had only ordered this due to a few threads I found that were fan comparisons , with that fan having a decent percentage more air flow measured. That being said , I obviously had not had the entire picture, and as such, when corrected on this matter, proceeded to rectify this   
 

The meaningful feedback on a part I was ignorant of was, in fact , the whole reason I made the thread. I still have a lot to learn, and am learning more every day. People like GT explaining these things , allowing me to make changes before purchases or arrival of parts , are what may keep this car from having issues  and for THAT I am grateful. 

[joshuaho96]

12 hours ago, soviet_merlin said:

Thank you Duncan! That explains a lot. There are lots of comments on setups being good or bad to drive, but never what it is about it specifically.

I noticed the change in bite with the clutch but didn't know it was a thing. Say with a stock clutch there's about 10cm of clutch pedal travel between the clutch starting to bite and fully clamped. With the twin plate it's down to what feels like 4cm of pedal travel for the same. It does make it a lot less forgiving to drive. But after getting used to it I find it's really not an issue. I haven't driven a stock Nissan, but I don't find it any worse than driving a stock BMW or VW for example. It's possible to drive smoothly with it. Can take the in-laws or the dogs in the back and basically go full chauffeur mode and no one is the wiser. Though it's not in a GTR and it's not running 400kw either.

This is very much in contrast to some cars I have seen at events where people struggle parking their Skylines on an open parking lot on a level surface. Lots of revving, jerky clutch engagement and stalling. Probably running much more racy setups.

My main issue with that specific single plate clutch was actually that the clutch pedal was super heavy. I also have skinny nerd legs so that may add to that. The clutch pedal feel for the twin plate is so light it doesn't feel much different from any OEM clutch.

This may be one of those things where everyone's experiences and what people consider nice or not may differ quite a lot

I'm pretty confident I have the stock clutch in my R33. It is far and away the most forgiving clutch I've ever driven. The aggressive anti-stall + factory 950 rpm idle also makes it hilariously easy to get going even without throttle application in first. The slip zone feels a mile wide. The vacuum assisted clutch master also makes it feel lighter than something like an S2000.

The factory idle control is probably not intended to be anti-stall or anything like that but it reacts to persistent low idle by ratcheting up the AAC duty cycle to max which gets you to like 1400-1500 rpm and even higher when the engine is cold and the cold start valve is still open.

Edited September 6, 2023 by joshuaho96

[oSkylines]

I do feel that my stock clutch has a ton of travel before it grabs , and I don’t find it particularly easy to stall either, so I can see what you mean there. Unsure of how much of that is intent and how much is wear, but I have confidence that a twin will be just fine , just was making sure I wouldn’t be in a place where it couldn’t handle the hp. I think the old nismo I was advised against had been a single plate anyway , which is what brought on the anxiety on this part . I feel good about the twin copper mix nismo tho. I’ll likely end up going that route , especially if , per you guys, it feels the most street-able

[oSkylines]

I feel pretty decent with my parts list right now though, I’ll have to read about relocating the power steering . And I’ll have to look more at the tensioner stuff , if that’s apparently an issue that should be replaced . Other thing I’ll be considering is the mines cam baffles but I’ll prob just do that later , see how the baffled sump and catch can go  first . 

[oSkylines]

Of corse if anybody sees any other must haves , or sees anything that really should be done better not mentioned in this thread , feel free to share. Y’all already saved me from the fan, if there is anything else like that I’ll do my best to update and make sure it’s accounted for 

[MBS206]

6 hours ago, joshuaho96 said:

I'm pretty confident I have the stock clutch in my R33. It is far and away the most forgiving clutch I've ever driven. The aggressive anti-stall + factory 950 rpm idle also makes it hilariously easy to get going even without throttle application in first. The slip zone feels a mile wide. The vacuum assisted clutch master also makes it feel lighter than something like an S2000.

The factory idle control is probably not intended to be anti-stall or anything like that but it reacts to persistent low idle by ratcheting up the AAC duty cycle to max which gets you to like 1400-1500 rpm and even higher when the engine is cold and the cold start valve is still open.

Am I correct in assuming you're not running factory computer, and have changed the master cylinder?

 

I have no recollection of a vacuum assist clutch, or anti stall being factory.

 

For that matter, 950rpm is also high idling for an RB25/26, especially if stock.

[oSkylines]

1 minute ago, MBS206 said:

Am I correct in assuming you're not running factory computer, and have changed the master cylinder?

 

I have no recollection of a vacuum assist clutch, or anti stall being factory.

 

For that matter, 950rpm is also high idling for an RB25/26, especially if stock.

if youre asking josh, idk , but myself, As in the top of the post im running a haltech 2500 system, no upgrade to master cylinder. That being said, i could just be answering out of turn here, i have no idea about joshes setup lol

[GTSBoy]

7 hours ago, joshuaho96 said:

The aggressive anti-stall + factory 950 rpm idle

Yeah, nah. Stock idle should be ~650rpm. This is a number that can actually be set in the ECU - which is much easier with Nistune than without. I have mine set to 600 - actually saves fuel when you spend a bunch of time sitting at the lights on your daily commute like I do (or at least used to more so than now).

7 hours ago, joshuaho96 said:

AAC duty cycle to max which gets you to like 1400-1500 rpm and even higher when the engine is cold and the cold start valve is still open.

But these are entirely different effects, and unless the Nissan engineers were particularly sophisticated and thus had the AAC also contribute to cold idle up by running a higher setpoint when cold, I would expect the AAC to actually close down while the idle is being made high by the cold start valve. If the idle control strategy is in play all the time, then it should be trying to control the idle downward. And then, as the cold start valve closes, the AAC might be too closed and it will open back up again every time the idle speed drops below the setpoint.

1 hour ago, MBS206 said:

Am I correct in assuming you're not running factory computer, and have changed the master cylinder?

Josh is wedded to his factory computer because California.

1 hour ago, MBS206 said:

I have no recollection of a vacuum assist clutch

GTRs have the clutch booster.

[r32-25t]

2 hours ago, MBS206 said:

Am I correct in assuming you're not running factory computer, and have changed the master cylinder?

 

I have no recollection of a vacuum assist clutch, or anti stall being factory.

 

For that matter, 950rpm is also high idling for an RB25/26, especially if stock.

Anti stall is not a thing in these cars, GTRs have vacuum assisted clutches from factory 

[joshuaho96]

1 hour ago, GTSBoy said:

Yeah, nah. Stock idle should be ~650rpm. This is a number that can actually be set in the ECU - which is much easier with Nistune than without. I have mine set to 600 - actually saves fuel when you spend a bunch of time sitting at the lights on your daily commute like I do (or at least used to more so than now).

But these are entirely different effects, and unless the Nissan engineers were particularly sophisticated and thus had the AAC also contribute to cold idle up by running a higher setpoint when cold, I would expect the AAC to actually close down while the idle is being made high by the cold start valve. If the idle control strategy is in play all the time, then it should be trying to control the idle downward. And then, as the cold start valve closes, the AAC might be too closed and it will open back up again every time the idle speed drops below the setpoint.

Josh is wedded to his factory computer because California.

GTRs have the clutch booster.

Idle target on the emissions sticker says 950 rpm with 20 degrees of timing. I probably need a new harmonic balancer but I get nasty vibrations much below 800 rpm. I'm pretty sure the AAC also contributes to cold start airflow looking at the Consult logs, it just needs the extra help courtesy of the cold start valve. I'm probably not explaining it too well but the cold start idle target at 20C coolant temp is something like 1400 RPM, then if you start slipping the clutch and don't give it any throttle to compensate for the drop in RPM the ECU reacts by really opening up the AAC valve and keeping it there. Pressing the clutch pedal in it's not unusual in my experience to see it hit 1800 RPM until I wiggle the shifter in neutral enough for the neutral switch to work and the ECU to slowly drop the idle back down.

Anti stall in hindsight was definitely the wrong word for it, that's more like a clutch position sensor that will raise the idle proactively instead of reactively. It's more like the idle control is very willing to try and catch a falling idle and is not that quick to deal with a high idle.

I have dreams of finishing a Haltech base map eventually. No tuner is going to bother with my weird obsessions so I'm going to have to DIY all of this.

[Duncan]

I'm pretty sure the difference is RB20 vs RB26.

R32 GTR service manual says

[GTSBoy]

Hmm. Even though I've got that manual and have had it for.....more than 20 years, I never bothered to look or care to see what the 26 idle speed is. 950! Shit. It must be because of those stupid multithrottles not being able to close enough to keep the air out of the inlet ports. There can't possibly be a reason why it would need to idle that high otherwise. It's not like it's really any different under the cam covers than a 20, 25 or Neo.

FWIW, a 20 probably is the one engine that deserves to idle higher, owing to the tragic lack of torque at anything less than 40 psi of boost. Having a little help to get it off the line would reduce those embarrassing stalls.

[joshuaho96]

2 hours ago, GTSBoy said:

Hmm. Even though I've got that manual and have had it for.....more than 20 years, I never bothered to look or care to see what the 26 idle speed is. 950! Shit. It must be because of those stupid multithrottles not being able to close enough to keep the air out of the inlet ports. There can't possibly be a reason why it would need to idle that high otherwise. It's not like it's really any different under the cam covers than a 20, 25 or Neo.

FWIW, a 20 probably is the one engine that deserves to idle higher, owing to the tragic lack of torque at anything less than 40 psi of boost. Having a little help to get it off the line would reduce those embarrassing stalls.

I can get it to idle at 800 rpm if I wanted to, but the engine feels rough and genuinely unhappy to be there if you put any load at all on it. Not like my LS400 which will happily idle at 400 RPM if you put it in drive.

Edited September 7, 2023 by joshuaho96

[oSkylines]

Hey guys, gunna ask the hive mind here about another issue I’m presently dealing with . 
 

occasionally I’m running into a feeling with my skyline while driving where it feels almost as though somebody has grabbed the steering wheel and jerked it  while driving . I initially thought this was an issue with either the Hicas or Atessa related systems I haven’t touched , and it responding to some aged tires that needed replaced. I am now on brand new appropriately sized tires and just experienced this for the first time last night on my way home from work. I don’t imagine it matters , but it happened when a very loud motorcycle was passing on the passenger side , and it almost felt as though I was in a Tesla and it reacted to the significant noise / object to my passenger side and swerved away from it (thank god , since it was unexpected and if it swerved towards it … we’ll it could’ve been a lot longer of a night for both of us) . While leaving work today, I noticed backing out of my parking spot that something felt… off for the lack of a better word . Like the car just didn’t want to reverse smoothly like it normally does . It didn’t stall or resist, just didn’t seem happy doing it . I did not notice anything on the torque gauge , but with it being unable to be replicated on conditions, it’s hard for me to catch if the gauges were to show anything off of standard in these exacerbations . 
 

feel free to chime in with any ideas . Other threads mentioned this potentially being Afm related or shuffle or something but none of that sounds right (haltech doesn’t use AFMs, isn’t the turbo , it’s clearly in my opinion something suspension/dif/ a mount or something ?) but it’s so infrequent and not doing it on breaking or able to be replicated at hard acceleration or anything , it seems to just sometimes do it at a level of steady throttle . 

[GTSBoy]

HICAS is trying to kill you. That is the rear rack having a spaz because the HICAS CU is having a spaz because some input sensor to the HICAS is having a spaz. You need to connect a diagnostic handset to the car and pull the codes. There is a dance you can do to put the HICAS into diagnostic mode, but it often doesn't work when one of the sensors used in the dance (steering angle, brake pedal switch, etc) is not working properly.

[oSkylines]

3 minutes ago, GTSBoy said:

HICAS is trying to kill you. That is the rear rack having a spaz because the HICAS CU is having a spaz because some input sensor to the HICAS is having a spaz. You need to connect a diagnostic handset to the car and pull the codes. There is a dance you can do to put the HICAS into diagnostic mode, but it often doesn't work when one of the sensors used in the dance (steering angle, brake pedal switch, etc) is not working properly.

since from what i can remember , the computer system stock is OBDI , and obviously i have an aftermarket ECU,  but from what i gathered there is a separate computer for HICAS,  what are the odds its a somewhat commonplace reader?  None of the nissan dealers will touch this car with a 90 foot pole, they are all afraid to break something. 

[oSkylines]

Im thinking im probably going to be stuck doing the dance and trying to fish the codes out of it, praying it actually gives me one. But like i ( think ) i said, i dont have a code, so i dont know if ill actually get anything meaningful out of it to begin with